Ics Amt-1 User manual

ICS

AMT-1

Amtor

Terminal

Unit

USER

MANUAL

l.C.S.

Electronics

Ltd.

PO

BOX 2

ARUNDEL

BN18

ONX

WEST SUSSEX

ENGLAND

Phone:

(024 365)

~

S90

./

ICS AMT-1 Amtor Terminal Unit

User Manual - CW receive mod for

AMT-1 - AMT-1 Operating Guide -

AMT-1 Commodore 64 applications

operator manual

CONGRATULATION

S

ON

YOU

R PU

RC

HAS

E OF

AN

AMT

-1

.AJ.rroR

TERMINAL

U

NIT.

You

WILL

SOON

HA

VE

ON

E

OF

TH

E

WORLD

'S

MO

ST

ADVAN

C

ED

H.F

. R

AD

IO

D

AT

A

TR

A

NSMIS

S

ION

SYSTEM

S

ON

TH

E

AIR!

You

shoula

be

able

to

get

the

AMT-1

running

quickly

and

wi

thout

problems

with

any

modetn

SSB

trans

c

eiver

and

any

ASCII RS232

termina

l or

personal

computer

which

i s

equipped

wi

th

a

serial

i

nterface,

simpl

y

by

reading

th

e

enclosed

manual

.

Below

you

will

find

a

list

of

those

transcei

v

ers

and

personal

computers

which

are

pre

s

ently

known

to

go

"first

time"

with

the

AMT-1:

TRAN

SCEIVERS

PERSONAL

COMPUTERS

FT

ON

E TS

180

I TR 7 VIC 20

FL

101/

FT

707

FR

10

1

TS

520

T4XC

BBC

Model B

FT

901

TS

180S

TS

515

T4B

/

R4B

ABC

80

FT

902

TS

930

TS

820

FT 227ZD

FT

lOlZD TS

130

TS

700 IC 701

FT

10

1

TS

830

TS

120V

KWM

3

80

A

number

of

ready

debugged

applications

programmes

for

personal

computer

s

already

exist

. Some

of

th

os

e f or

the

mo

re

popular

computers

are

enclosed,

but

I.C.S.

ac

tively

solicits

ap

p

lications

inf

o

rmation

from

yo

u

for

th

e

benefi

t

of

fu

ture

u

sers.

Do

tak

e

care

with

sy

stem

grounds

and

ensure

adeuate

cable

screening

to

reduce

hash

radiation

into

your

receiver.

If

you

h

ave

not

already

purchased

a

personal

computer

and

~ish

t o

use

it

with

the

AMT-1,

check

that

a

serial

interface

is

available

f

or

it

and

that

it

can

run

full

duplex

at

110

or

75

Bauds

at

RS232

lev

e

ls.

Mak

e

sure

that

d

ata

c

an

be

transmitted

and

received

over

the

interface

simultaneously

and

that

CONTRO

L

and

ESCAPE

codes

can

be

sent

from

the

keyboard

.

Oth

erwise,

y

ou

will

have

to

use

the

CHRS

command

from

Basic

t o

generat

e

these

c

odes

from

other

key

d

epressions.

Che

ck

ing

y

our

sy

stem

ou

t

in

ARQ

mode

To

check

out

your

sy

stem

on

ARQ,

tu

ne

y

our

transceiver

(

on

upper

sideband

)

to

l4.075MHz

(

the

d

ial

reading

sho

uld

be

around

14

.07

3.7)

.

Then

press

control-A

followed

by

one

of

the

following

selcals:-

GPLX

(G3PLXl

HBAK

(

HB9AK

)

TDJT (

TI3DJT)

KRPA

(K4

PA

)

KBBT

(

KB6BT

)

VAGE

(VK

2AGE)

Th

ese

stations

are

amongst

th

o

se

most

active

on

AMTOR

at

the

present

time.

If

the

chosen

station

replies,

type

:-

(HIS

CALL)

de

(Y

OUR

CALL)

+?

If

t he

station

requests

further

instructions

type:-

HELP

+?

In

general,

14.075MHz

should

be

avoided

for

long

QSOs

and

used

onl

y f

or

specific

ARQ

calls.

O

nce

contact

h

as

been

established,

both

stations

should

Q

SY

up

several

KH

z.

When

calling

CQ,

you

can

call

on

14

.075MHz

in

FEC

m

ode

and

QSY

once

contact

has

been

made .

In

many

contr

i

es,

there

is

also

considerable

AMTOR

acti

vity

on

80

metres,

c

entred

on

3.588MHz.

Don't

f

orget,

if

yo

u

call

CQ

in

FEC

mode, m

ake

sure

y

ou

have

fi

rst

loaded

you

r own

selcal,

so

t h

at

yo

ur

system

will

respond

if

called.

LATE

N

EWS

As

the

F.C.C.

h

ave

ju

st

granted

oermission

for

U

.S

.

amateurs

to

use

Amtor

,

WlAW

is

about

to

commence

broadcasting

Amateur

Radio

N

ews

in

Amtor

FEC

mode.

1.

2.

3 .

4.

5.

6.

7.

8 .

9 .

10 .

11.

CONTENTS

Introduction

Basic

Theory

Getting

the

AMT-1

on

the

air

Operating

Hints

Escape

Codes

Control

Codes

Transceiver

Connector

Terminal

Connector

Front

Panel

Displa

y LEDs

Internal

Adjustments

Computer

Interfacing

w

it

h

the

AMT- 1

Cable

Connections

Specification

Schematics

M

icrocomputer

Applications

Programmes

Page

1

Page

1

Page

2

Page

4

Page

5

Page

6

Page

6

Page

7

Page

8

Page

8

Page

9

Page

11

Page

12

Pages

13

-

15

Page

16

l.

INTRODUCTION

The

AMT-1

is

designed

to

interface

between

an

SSB

radio

transceiver

and

an

ASCII

VDU,

teleprinter,

or

personal

computer,

using

the

error-correcting

system

known

as

TOR

or

AMTOR.

Normal

RTTY

and

ASCII

transceive

facilities

are

also

provided

as

well

as

cw

transmit.

The

interface

to

the

transceiver

is

via

an

audio

input

/

output

socket,

which

provides

frequency-shift

keyed

tone

signals

from

the

AMT-1

to

the

trans-

ceiver

mike

socket,

and

accepts

received

audio

from

the

transceiver

extension

speaker

connector.

Th

ere

is

also

a

keying

line

from

the

AMT-

l

to

switch

from

transmit

to

receive

.

This

will

normally

be

connected

to

the

"push-to-talk"

line

on

the

transceiver.

All

of

these

connections

can

normally

be

made

between

SKl

on

the

AMT-l

and

the

transceiver's

mike

or

accessory

socket.

The

interface

to

the

terminal

sends

ASCII

serial

data

from

the

AMT-1

for

display

or

printing,

and

accepts

data

in

the

other

direction

from

the

key-

board.

These

signals

are

represented

by

R.5232

logic

levels.

M:>st

terminals,

or

small

computers

which

can

be

used

as

terminals,

will

connect

directly

to

the

AMT-l

via

SK2

. The

AMT-l

can

be

set

to

communic-

ate

with

them

at

either

75

or

110

Bauds.

Do

NOT

OPERATE

YOUR

TRANSCEIVER

CCfffINUOUSLY

IN

FEC

oR

Rm

TRANSMIT

f>'()DE

wITHOUT

FIRsT

REDUCING

I

TS

OUTPUT

TO

UNDER

HALF

POWER.

SERIOUS

DAMAGE

TO

YOUR

TRANSCEIVER

MAY

OTHER-

WISE

RESULT.

2.

BAS

IC

THEORY

Teleprinter

communication

over

radio

links

has

always

been

achieved

via

frequency-shift-keying

of

the

transmitter

carrier

frequency,

the

higher

frequency

representing

one

logic

level

and

the

lower,

the

other.

In

traditional

RTTY,

32

characters

are

transmitted

by

various

combinat-

ions

of

5

data

bits,

transmitted

serially

and

preceeded

by

a

start

bit

which

synchronises

the

receiver

decoding.

It

is

separated

from

the

followir,g

character

by

a

stop

bit.

This

system,

although

usually

generated

and

decoded

in

modern

equipment

electrically,

was

originally

designed

to

be

decoded

mechanically,

and

suffers

from

problems

when

used

on

radio

links

which

are

subject

to

fading

and

interference.

Any

such

interference

or

noise

which

causes

a

data

bit

to

be

received

in

the

wrong •

polarity

results

in

an

incorrectly

printed

character.

Furthermore,

the

start-stop

technique

used

often

results

in

several

characters

being

in

error

if

a

start-

bit

is

mutilated.

The

conceptual

basis

of

the

TOR

system

is

that

steps

are

taken

to

ensure

that

an

error

in

the

received

signal

does

not

necessarily

cause

an

error

in

the

output

character.

This

is

done

by

transmitting

extra

information

along

with

the

data,

which

enables

the

distant

receiver

to

detect

the

presence

of

errors.

Instead

of

5

data

bits,

7

are

transmitted.

Three

bits

are

of

one

polarity

and

four

are

of

the

other.

The

vast

majority

of

randomly-occuring

errors

result

in

this

3:4

ratio

being

altered

at

the

receiver,-

enabling

the

receiving

station

to

detect

that

the

data

is

erroneous.

There

are

35

possible

combinations

of

7

bits,

and

32

of

these

are

translated

directly

to

the

standard

RTTY

character

set.

others

·

are

used

as

special

control

characters.

The

start-bit

mutilation

problem

is

over

-

come

by

transmitting

the

data

bits

synchronously

at

accurately-controlled

intervals.

The

synchronisation

at

the

receiver

is

achieved

by

accurately-controlled

timing

rather

than

by

using

a

start

bit.

There

are

two

different

types

of

communication

avail-

able

i n

AMTOR:

Forward

Error

Correction

(FEC),

and

Automatic

Fequest

(ARQ)

.

In

the

FEC

mode,

the

7-bit

characters

are

transmitted

twice

,

and

the

receiving

station

can

choose

which

of

the

t

wo

passes

the

3:4

ratio

test

.

Up

to

half

of

the

received

codes

can

therefore

be

in

error

before

errors

occur

in

the

out-

put

. The

second

transmission

of

each

character

is

delayed

relative

to

the

first,

so

that

a

prolonged

fade

or

burst

of

interference

will

only

result

in

one

transmission

of

several

characters

being

mutilated,

rather

than

both

transmissions

of

a few

adjacent

characters.

EVen

if

both

transmissions

are

mutilated,

the

receiving

station

prevents

an

eJ:roneous

character

being

printed,

suppressing

the

character

completely

and

signalling

the

presence

of

the

error

via

the

ERROR

lamp.

In

ARQ

mode,

the

transmitter

sends

a

group

of

three

7

-bit

characters

in

a

block-

The

distant

receiver

examines

each

one,

and

if

any

containes

an

error,

an

automatic

request

to

repeat

the

whole

block

is

made.

In

this

case

,

the

receiving

station

sends

a

repeat

request

character

to

the

transmitting

station

.

In

this

way

interference

or

fading

does

not

generally

result

in

errors,

but

merely

a

slowing-down

of

the

transmission

of

information

each

time

a

repeat

is

requested.

Data

blocks

and

control-codes

are

trans-

mitted

back

and

forth

by

the

two

stations

working

in

quick

break

fashion

,

usu~l!y

en

the

same

frequency.

Th

is

gives

rise

to

the

familiar

chirp-chirp-chirp

of

AMTOR

signals

on

the

air.

In

both

FEC

and

ARQ

modes,

accurate

synchronisation

is

essential

between

both

ends

of

the

link,

and

this

is

achieved

by

special

phasing

signals

transmitted

at

the

start

of

each

contact,

and

maintained

by

crystal-

controlled

timing.

In

practice,

it

is

possible

for

error&

to

occasionally

"beat"

the

3:4

ratio

check,

and

result

in

printed

errors

.

Nevertheless,

FEC

is

considerably

better

than

conventional

RTTY,

and

ARQ

is

very

much

better

than

FEC. The

reason

for

i

ncluding

both

FEx::

and

ARQ

features

is

that

ARQ

can

only,

by

its

nature,

be

used

between

two

co-operating

stations,

whereas

FEC

can

be

transmitted

by

one

station

to

any

number

of

stations.

Thus

FEC

is

often

used

for

broadcast

messages

such

as

news

bulletins

and

CQ

calls

.

In

the

ARQ

mode,

it

is

necessary

to

know

the

iden

t

ity

of

the

other

station

before

establishing

the

contact,

hence

FEC

is

often

used

at

the

start

of

a

contact,

followed

by

a

change

to

ARQ.

The

requirement

to

identify

the

intended

ARQ

contact

first

arises

from

the

initial

process

which

is

required

at

the

start

of

the

contact.

This

feature

also

enables

the

ARQ

mode

to

be

used

to

selectively

contact

one

particular

station

among a number

who

may

be

monitoring

a

common

frequency.

As

well

as

the

facility

to

transmit

and

receive

FEC

signals

and

make

or

receive

calls

in

ARQ

mode,

the

AMT-1

has

a

facility

to

enable

it

to

monitor

one

side

of

an

ARQ

contact

between

two

other

stations.

This

ability

is

not

inherent

in

the

ARQ

system

itself,

but

is

included

since

it

is

always

interesting

to

be

able

to

listen-in

to

other

contacts.

Apart

from

the

AMTOR,

the

AMT-1

can

also

operate

in

conven-

tional

RTTY

mode

both

in

transmit

and

receive.

It

can

also

be

used

to

send

morse

code

(CW).

The

microprocessor

in

the

AMT-1

carries

out

code

conversions

and

other

processing,

bu~

can

be

bypassed,

allowing

the

ASCII

terminal

to

connect

direct

to

the

FSK

modulator

/

demodulator

and

communicate

in

ASCII

over

the

air.

Page

2

3.

GETTING THE AMT-1

ON

THE

AIR

This

section

acts

as

-a

quick

guide

to

the

install-

ation

and

operation

of

the

AMT-1.

Those

sections

which

follow

give

more

complete

details,

and

may

be

consulted

after

the

basic

system

is

working,

or

whenever

problems

are

encountered

in

getting

the

system

working

properly.

References

given

in

brackets

refer

to

lat

er

sections

where

fuller

in-

formation

can

be

found

.

The

AMT-1

shou

ld

be

connected

as

follows:

SSS

TRANSCEIVER

D

~

o~

0

00

0

12v

PSU

Jo

f

ORM

YOUR

OWN

SELCAL

SIMPLY

COMB

I

NE

TI-iE

FIRST

LETTER,

TOGETI-iER

WITI-i

TI-iE

LAST

TI-iREE

LETTERS

OF

YO

UR

CALL-

SIGN,

THUS

TI-iE

SELCAL

FOR

WJ.AW

SHOULD

BE

!;MAW.

THIS

IS

AN

11

UNOFFICIAL

RULE"

OF

TI-iE

AMToR

COl'MuNrTY!

HOME COMPUTER

OR

ASCII

TERMINAL

D

! D D D D

SPKR

PTT

MIC

.

I

it · 1

AMT

-1

I D D D

L..

~~~~~~~~~-t.:~~~-T~E~R-M_l_N_A~L.....:.

U

_N~IT~~~~•o--~~~~~~~+

110 Baud RS232 ASCII

or

75 Baud

3~

.

I

POWER

SUPPLY

A 12 -14

Volt

power

supply

is

required,

capable

of

providing

800mA.

The

negative

side

of

the

supply

should.

be

connected

to

the

outer

contact

of

the

power

connecto

r.

The

AMT-1

is

protected

against

accidental

polar

i

ty

reversal

or

overvoltage,

but

an

incorrectly

applied

voltage

may

blow

the

internal

1

Amp.

fuse.

3 •2

TRANS

.

CE

IVER

CONNECTOR,

SKl

This

is

a

7-pin

socket,

although

a

5-pin

DIN

plug

can

be

used

in

it.

1

is

the

audio

input

from

t he

transceiver,

and

should

be

connected

via

a

screened

cable,

the

screen

of

which

should

be

taken

to

2.

3

is

the

audio

output

from

the

AMT-1

to

the

transceiver

(u

sually

to

the

MIKE

sock

.

et)

and

should

be

similarly

screened,

with

the

. ·s·

creen

taken

to

2.

An

internal

pre-set

(RVl)

can

be

used

to

vary

the

audio

output

level,

although

an

external

attenuator

may

be

needed

to

reduce

the

level

in

some

cases

(7

.

3).

5

is

the

transmit-changeover

line

from

the

AMT-1

to

the

"p

ush-to-talk"

line

on

the

transceiver.

In

most

cases

all

of

the

connections

from

SKl

can

be

made

to

the

MIJ<E

·

~ocket

of

the

transceiver,

the

speaker

output

of

the

transceiver

being

taken

to

a

spare

·

on

the

MIKE

socket.

The

connections

and

signals

levels

for

SKl

are

described

more

fully

in

section

(7).

3.3

TERMINAL

CONNECTOR,

SK2

This

is

a 5

240°

DIN

connector.

l

is

the

serial

data

input

to

the

AMr-1

from

th

e

terminal

k

eyboard,

5

is

the

data

output

fr~m

the

AMT-1

to

the

terminal

display,

and

3

is

the

common

return

for

these

pins.

The

signal

levels

are

RS232

compatible.

Pins

2

and

4

carry

control

signals

which

need

not

be

connected

initially

(8.4

and

8.5).

The

signal

polarit

y

can

be

changed

by

internal

link

s (

8).

However,

most

terir.ir.als

~r

smcll

computers

will

interface

directly

without

alter-

ations.

Any

CTS

or

RTS

control

lines

from

the

terminal

can

initially

be

left

unconnected

or

strapped

into

the

"unused"

state,

as

appropriai:e

to

the

terminal

in

question.

further

details

about

the

CTs·

and

RTS

are

given

in

sections

(8)

and

(11).

..

::,

~:~.

,.

If

your

terminal

cannot

operate

at

110

Bauds,

remove

the

cover

of

the

AMT-1

and

cut

link

12

to

give

75 Baud

operation.

Connect

power

to

the

AMT-1.

The

front

panel

display

should

step

through

all

the

combinations

of

the

display.

This

verifies

that

it

is

working,

and

it

stops

with

the

ESC

LED

lit,

together

with

the

ARQ,

FEC,

RTTY

and

CW

LEDs

all

dimly

lit.

A

carriage

return

and

linefeej

(

newline)

are

sent

to

the

terminal

on

power

up.

A

further

check

that

the

terminal

interface

is

working

can

be

obtained

by

typing

the

letter

Q,

whereupon

the

following

line

should

be

displayed:

V:Ol

I:????

T;30

B:45

S:20

L:l

N:l

The

V:

number

may

be

differenct

on

later

versions

of

the

software.

The

significance

of

this

orint-out

is

exolained

in

(5

.8).

- -

Memorise

the

LED

panel

display

at

this

point,

with

the

ESC

LED

lit

and

all

mode

LEDs

lit.

This

is

called

the

ESCAPE

condition,

and

from

it,

the

AMT-1

can

be

commanded

to

enter

any

of

its

three

operating

modes.

It

can

also

be

commanded

to

alter

or

set

up

any

of

its

internal

para-

meters.

The

ESCAPE

condition

is

always

reached

by

entering

an

ESCAPE

character

from

the

terminal,

(except

in

the

by-

pass

mode)

(5.4).

The

three

modes may

be

entered

by

key-

ing

the

letter

A,R

or

C,

for

AMTOR,

RTTY

or

CW

(morse).

Thus,

to

change

from

any

mode

to,

for

example,

RTTY,

enter

ESCAPE

followed

by

R.

The

ESCAPE

character

can

normally

be

sent

from

the

terminal

by

means

of

the

key

labelled

ESC

.

However,

in

some

computers

this

key

may

be

used

for

a

different

function,

in

which

case

some

other

way

must

be

used

to

send

an

ESCAPE

code

to

the

AMT-1

(11.4).

3.4

TUNING

DISPLAY

The

AMT-1

has

a 16-LED

tuning

display

located

in

the

centre

of

the

front

panel.

It

is

not

illuminated

in

the

ESCAPE

condition.

To

observe

how

it

operates,

key

the

letter

A

on

the

terminal.

The

tuning

display

should

light.

If

there

is

sufficient

background

noise

from

~he

receiver

input,

a

broad

flickering

band

should

be

seen.

TUne

in

an

unmodulated

carrier

in

USB

mode

on

the

receiver,

and

slowly

tune

the

tone

across

the

passband.

At some

point

the

display

should

stabilise

to

one

or

two

LEDs

lit

at

one

end,

the

spot

of

light

moving

across

the

display

to

the

other

end

as

the

tone

frequency

is

tuned

across

the

passband

of

the

audio

filter

in

the

AMT-1-

The

display

wil

finally

break

up

into

a

broad

band

of

noise

as

the

tone

is

tuned

out

of

the

filter

passband

•

Now

tune

in

an

FSK

signal,

and

notice

how

the

signal

appears

as

two

dots

joined

by

a

dimmer

band

of

light,as

the

signal

keys

from

one

tone

to

the

other.

Practise

tuning

such

signals

to

the

point

where

the

two

dots

are

placed

symmetrically

either

side

of

the

centre

line

of

the

display.

Note

that

the

AMT-1

is

designed

to

receive

the

170Hz

FSK

shift

standard,

and

it

may

not

always

be

possible

to

tune

in

wider

shift

commercial

signals

without

one

or

the

other

(or

both)

tones

remaining

outside

the

300Hz

filter

bandwidth

of

the

AMT-1.

Ch

some

transceivers

with

variable

bandwidth

capabil-

ities,

it

may

be

advantageous

to

narrow

the

passband

of

the

transceiver

so

that

it

just

brackets

the

AMT-1

passband.

Not

all

trans-

ceivers

with

a

CW

filter

fitted

will

operate

in

this

way

if

.

the

position

of

the

BFO

is

not

suitably

placed

relative

to

the

CW

filter

passband.

3. 5

RTTY

OPERATION

To

switch

to

RTTY

mode,

enter

ESCAPE

then

R.

T

he

RTTY

mode

LED

will

light,

and

some

garbled

characters

will

appear

at

the

terminal

until

an

RTTY

signal

is

tuned

in.

At

this

point

,

text

will

become

intelligible

and

the

TRAFFIC

and

IDLE

LEDs

will

light

alternately.

If

copy

still

remains

garbled,

there

could

be

several

reasons

for

it:

the

Baud

rate

of

the

signal

could

be

wrong;

the

signal

may

not

be

RTTY

at

all,

or

it

may

be

transmitting

reverse

polarity.

To

try

another

Baud-rate,

enter

ESCAPE

followed

by

B,

followed

by

the

Baud-rate

desired,

entered

as

a

two-digit

number

(5.2).

Common

Baud-rates

in

use

are

45,

SO

and

75.

Then

enter

R

to

get

back

to

RTTY

mode.

If

the

signal

is

reverse

polarity,

try

receiving

it

on

the

other

sideband

.

A

good

indication

that

the

signal

is

reversed,

should

it

sound

to

be

a

hand-keyed

signal

with

periods

of

no

keying,

is

that

the

ERROR

LED

will

be

lit

during

such

periods,

indicating

that

the

stop-bit

is

of

the

wrong

polarity

(9 .

3).

If

the

signal

is

not

RTTY,

it

may

be

an

AMTOR

FEC

mode

signal,

in

which

case

try

entering

ESCAPE

A,

as

described

later.

To

transmit

an

RTTY

signal,

enter

control-A

from

the

terminal

.

This

is

normally

done

by

holding

down

the

CONTROL

key

and

simultaneously

keying

the

letter

A.

If

this

is

not

possible

on

some

personal

computers,

then

a

software

routine

must

be

written,

or

a

special

function

key

programmed

to

send

the

ASCII

code

01

(11.4).

on

entering

control-A,

the

AMT-1

turns

the

transmitter

on

via

the

PTT

line.

Check

that

the

drive

level

on

the

transmitter

does

not

exceed

the

continuous-carrier

level.

kijust

RVl

in

the

AMT-1

to

achieve

the

desired

level

(7

.3).

Having

set

the

system

to

transmit

an

RTTY

carrier,

type

on

the

keyboard

and

the

text

will

be

transmitted

over

the

air,

simultaneously

appearing

on

the

terminal

display.

If

the

terminal

displays

each

letter

twice,

then

enter

ESCAPE

L

~

and

remember

in

future

to

do

so

each

time

the

terminal

is

switched

on.

Also

refer

to

section

(5.6).

To

end

an

RTTY

transmission,

enter

control-D

(ASCII

code

04).

The

AMT-1

will

then

return

to

receive.

3.6

CW

OPERATION

To

send

CW,

enter

ESCAPE

c.

The

CW

LED

will

then

light.

Enter

data

via

the

keyboard

and

the

.l\MT-1

will

send

it

as

CW

by

keying

the

PTT

line.

The

PTT

line

can

be

shorted

to

earth

to

keep

the

transmitter

on

between

code

elements,

and

the

AMT-1

will

still

send

perfect

CW,

since

the

tone

output

is

also

keyed.

Page

3

The

transmitted

text

is

displayed

on

the

terminal

as

it

is

sent.

It

is

possible

t.o

type

faster

than

the

CW

send-

ing

speed,

but

remember

to

use

the

space

bar

between

words.

To

change

the

sending

speed,

enter

ESCAPE

S

followed

by

the

required

speed

in

words-per-minute

(5.10)

followed

by

C

to

return

to

CW

mode.

Do

not

initially

use

sending

speeds

higher

than

50

w.p.m.

without

consulting

section

10.2

regarding

setting

RV2.

3.7

AMTOR

OPERATION

Enter

ESCAPE

followed

by

A

to

enter

AMTOR

mode.

The

FEC

LED

will

light,

together

with

the

STBY

LED.

The

tuning

display

will

also

light.

In

this

condition

the

AMT-1

will

do

nothing

further

until

an

FEC

signal

is

received.

If

such

a

signal

is

tuned

in,

at

first

nothing

will

happen

until

the

signal

sends

a

phasing

pattern,

recognisable

as

a

characteristic

rhythm

which

is

sent

from

time

to

time.

It

is

this

which

distinguishes

an

FEC

signal

from

an

RTTY

signal

to

the

ear,

since

when

an

RTTY

station

pauses,

it

emits

an

unmodulated

carrier.

When

an

idle

pattern

is

detected

by

the

AMT-1,

it

will

synchronise

to

it,

the

FEC

and

IDLE LEDs

will

light,

and

the

tuning

display

will

change

from

continuous

mode

to

the

"two

dot"

display,

the

line

joining

the

two

dots

being

no

longer

present

(9.2)

•

When

the

distant

operator

begins

to

type,

the

TRAFFIC

LED

will

light

and

the

.

message

will

be

received

at

the

terminal.

At

the

end

of

the

transmission,

the

STBY

LED

will

come

on

as

the

distant

station

sends

an

"end

of

transmission"

code.

If

the

signal

fades

out

and

no

such

code

is

received,

the

STBY

LED

will

come

back

on

after

some

garble

has

been

printed

for

a

few

seconds.

To

make

an

FEC

transmission,

enter

control-a

from

the

terminal

(ASCII

code

02).

The

transmitter

will

switch

on.

Enter

the

message

at

the

terminal,

and

end

the

transmission

by

entering

control-D

(ASCII

code

04).

It

is

important

to

end

with

control-D

and

not

ESCAPE,

in

order

to

ensure

that

the

"end

of

transmission"

code

is

properly

sent.

If

the

characteristic

"chirp-chirp"

sound

of

an

ARQ

signal

is

heard,

then

it

should

be

possible

to

monitor

it

by

entering

control-F

(ASCII

code

06).

If

two

signals

are

present

on

the

same

frequency,

·

indicated

by

interleaved

long

and

short

bursts

of

signal,

possibly

at

different

signal

strength,

then

it

will

be

the

one

that

is

transmitting

-

sending

long

bursts

-

which

can

be

monitored.

If

only

one

signal

is

heard,

sending

only

short

bursts,

then

the

ARQ-iisten

mode

will

not

lock

until

that

station

changes

to

sending

long

bursts.

After

entering

control-F,

tune

the

signal

in

as

·

a~curately

as

possible

and

the

AMT-l

will

lock

to

the

signal,

possibly

blinking

the

tuning

display

a

few

times

at

first

if

the

signal

is

noisy,

but

endin~

with

the

display

in

the

"two-dot"

mode

synchronised

to

the

timing

of

.

the

signal.

The

text

being

transmitted

by

the

distant

station

will

be

displayed

at

the

terminal.

If

the

signal

changes

to

receive

mode

(sending

short

bursts),

the

AMT-l

will

drop

out

of

sync.,

the

PHASE

LED

will

come

on

·

~gain

and

the

tuning

display

will

revert

to

' '

t.be

continuous

mode,

trying

to

sunchronise

to

another

signal.

It

will

also

do

this

if

it

has

not

received

an

error-free

block

for

15

seconds,

or

if

control-F

is

entered

to

force

the

unit

to

start

synchronising

to

a new

signal.

It

is

a

characteristic

of

this

ARQ-listen

mode

that,

if

the

distant

signal

is

idling,

false

synchronisation

is

quite

possible.

In

this

case,

garble

will

be

displayed

and

the

ERROR

LED

may

be

on

even

if

the

signal

is

clean.

The

terminal

may

well

display

strings

of

IIIII,

FFFFF,

88888,

or

%%%%%characters.

In

this

case,

enter

control-F

again

to

attempt

another

sync.

Synchronisation

will

always

be

achieved

quickly

when

the

signal

stops

idling.

Tc

exit

the

ARQ-listen

mode,

simply

enter

control-D.

The

signal

being

monitored

may

be

making

an

ARQ

phasing

call.

If

this

is

the

case,

·

the

terminal

will

display

a

repeated

4-letter

groµp

and

the

RQ

LED

will

be

on

continuously.

This

·

4-letter

group

is

.

the

selective-call

code

of

the

station

being

called

by

the

station

being

monitored.

It

is

normal

practice

in

AMTOR

operation

for

each

station

to

choose

its

own

unique

,

-4-letter

group,

usually

chosen

from

the

letters

of

·

the

'Station

callsign.

The

AMT-1

may

be

set

to

respond

to

its

own

unique

code

by

entering

ESCAPE

I

followed

by

the

4

letters

chosen

(5.5),

followed

by

A

to

return

to

AHTOR

standby.

In

this

case,

the

FEC,

ARQ

and

STBY

lamps

will

light.

If

you

have

entered

your

own

selcal

in

this

way,

and

a

station

calls

using

this

code,

then

your

station

will

respond.

·The

STBY

LED

will

go

out,

the

transmitter

will

be

keyed

to

reply

with

short

bursts

between

the

·

received

long

bursts

of

the

calling

station,

and

his

message

to

you

will

appear

at

the

terminal.

This

is

one

way

that

an

ARQ

contact

can

be

initiated.

The

other

way

is

to

initiate

the

ARQ

call

oneself,

using

the

selcal

code

of

the

station

called.

To

do

this:

While

the

AMT-1

is

in

the

AMTOR

mode,

enter

control-A

(ASCII

code

01)

followed

by

the

four

letters

of

the

other

station's

selcal

code

.

The

PHASE

LED

will

light

,

and

the

transmitter

will

be

keyed

with

l

ong

bursts

to

initiate

the

call

. When

the

other

station

replies

,

the

PHASE

LED

will

be

replaced

with

the

IDLE

LED.

You

may

then

type

your

message

to

the

distant

station.

With

either

method

of

initiating

an

ARQ

contact,

the

direction

of

sending

can

be

changed

in

one

of

two

ways.

The

normal

way

is

for

the

sending

station

to

end

his

transmission

with

the

characters

+?

(no

gap

between

them) .

This

signals

the

other

station

to

commence

the

change-

over

procedure.

When

this

is

completed,

the

two

stations

will

have

changed

over

from

sending

long

bursts

to

short

and

vice

versa.

The

other

method

which

must

be

used

with

care,

is

for

the

receiv-

ing

station

to

enter

control-C

(ASCII

code

03).

To

end

an

ARQ

contact,

the

last

station

to

be

sending

should

enter

control-D

(ASCII

code

04),

whereupon

an

"end

of

contact"

code

will

be

sent,

switching

both

stations

back

to

STBY.

Refer

to

(10. 2)

if

you

have

problems

with

ARQ

contacts

.

If

propagation

between

the

two

stations

is

poor,

the

contact

may

sometimes

be

held

up

by

repeat

sequences

,'

i~dicate

d

by

either

the

ERROR

or

RQ

LED

being

.

~

it.

In

this

case,

the

terminal

data

output

will

pause

whilst

the

repeats

are

in

progress.

this

occurs

at

the

receiving

end,

and

also

during

.

"local

copy•

at

the

sendinq

end.

If

the

ERROR

or

RQ

LEDs

are

on

continuously

for

15

seconds

or

more,

then

a

PHASE

operation

will

take

place,

during

which

the

original

calling

station

will

repeat

the

call

and

the

originally

called

station

will

cease

keying

and

attempt

to

re-synchronise.

1'b

intervention

by

either

operator

is

needed

during

this

operation.

Typing

may

continue

at

either

end,

provided

the

internal

buffer

stores

do

not

overflow

(4.2).

If,

in

the

PHASE

condition,

contact

is

not

re-established

within

30

seconds,

then

the

station

will

revert

to

STBY.

This

30

seconds

time-out

can

be

changed

to

any

value

between

one

and

100

seconds

by

entering

ESCAPE

T

follow-

ed

by

the

required

time-out

figure

(5.11).

4.

OPERATING

HINTS

4.1

In

RTTY

and

AMTOR

modes,

transmission

is

by

means

of

a

code

with

32

different

combinations.

Two

of

these

are

used

to

switch

ensuing

text

between

one

set

of

30

letter

characters

and

another

set

of

30

figures

and

punctuation

marks.

These

"lettershift"

and

"figureshift"

characters

are

automatically

generated

by

the

AMT-1

in

the

translation

from ASCII

code.

In

most

cases

the

user

need

not

be

aware

of

the

operation.

However,

it

sometimes

happens

that

the

received

text

gets

in

the

wrong

character

set

by

mistake.

If

the

received

text

appears

in

figure-shift

erroneously,

enter

a

DELETE

character

from

the

terminal

(ASCII

code

127,

or

HEX

7F).

This

will

force

the

following

received

text

back

to

letter-

shift.

The

AMT-1

has

an

automatic

system

for

sending

an

extra

shift

character

after

either

a

carriage

return,

linefeed,

or

NULL

character,

which

ensures

that

a

distant

station

will

always

start

a new

line

in

the

correct

shift.

Since

the

rec-

eived

shift

will

be

unknown

at

t he

start

of

a

transmission,

therefore,

it

is

always

good

practice

to

start

each

transmission

with

a

carriage

return

and

a

line

feed.

Page

4

This

al

so

has

the

effect

of

ensuring

that

both

the

sending

and

receiving

print-positions

are

synchronised

and

ensures

that

the

distant

receiving

station's

first

line

does

not

overrun

the

end

of

the

line.

The

AMT-1

also

has

an

automatic

system

to

generate

a

carriage

return

and

linefeed

if

a

space

character

is

entered

after

the

60th

character

in

a

line.

This

ensures

that

overprinting

can

not

occur

at

the

receiv-

ing

end,

particularly

if

the

user

is

typing

faster

than

the

terminal

is

echoing

the

text

and

is

not

aware

of

approaching

the

end

of

a

line.

This

facility

can

be

disabled

by

entering

ESCAPE

N

~

(5.7).

During

RTTY

and

ARQ

contacts

,

it

is

possible

to

type

into

the

AMl'-1

even

wh

il

st

receiving.

Any

text

so

entered

will

be

held

in

the

internal

buffer,

and

will

the

n

be

transmitted

as

fast

as

possible

when

the

terminal

unit

bas

changed

to

transmit.

This

type-

ahead

facility

is

not

available

on

FEC

mode,

although,

if

text

is

entered

faster

than

six

character

per

second,

it

will

build

up

in

the

buffer,

as

it

will

in

CW

mode.

Since,

when

transmitting

in

FEC

mode,

distant

stations

can

only

synchronise

when

the

signal

is

idling,

each

transmission

must

start

with

a

period

of

idles.

The

AMT-1

does

this

automatically

for

a

short

period,

but

if

a

longer

period

would

help

the

distant

station

to

tune

in,

then,

after

entering

control-B,

simply

leave

a

suitable

pause

before

commencing

typing.

The

practice

common

in

RTTY

of

sending

a

line

of

RYRYRYRY

at

the

start

of

a

transmission

to

allow

the

distant

station

to

tune

in

is

not

helpful

on

FEC

mode.

4.2

The

internal

t

ransmit

buffer

will

hold

960

characters,

allowing

a

useful

amount

of

text

to

be

typed

in

advance

if

required.

If

the

buffer

fills

,

any

more

text

entered

·

will

be

lost.

It

is

possible

to

prevent

this

if

the

user's

terminal

is

an

intelligent

computer,

by

using

the

RTS

output

from

SK2

4

to

inform

the

computer

that

the

buffer

is

full.

See

section

(8.4

and

11.l).

To

cancel

the

buffer

contents

completely,

enter

contrcl-X

(ASCII

code

24,

or

HEX

18).

Note

that

if

there

is

still

some

text

waiting

in

the

buffer

when

control-D

is

entered

to

end

the

transmission

(in

RTTY

or

FEC)

or

end

the

contact

(in

ARQ

mode),

then

the

remaining

text

will

be

transmitted

before

closedown.

If

control-X

is

entered

after

control-D

and

before

the

closedown

has

ta.ken

place,

then

the

closedown

is

cancelled.

The

transmission

will

then

idle

w

hen

the

buffer

has

emptied.

In

the

it

was

mentioned

that

the

use

of

control-C

to

"break-in"

to

the

other

station's

transmiss-

ion

during

and

ARQ

contact,

must

be

u

sed

with

care

. The

reason

is

that

any

subsequent

+?

sent

after

the

break

will

probably

leave

the

remainder

of

the

distant

station's

broken

transmission

in

figureshift.

The

DELETE

key

will

have

to

be

pressed

quickly

to

correct

this.

It

can

also

be

confusing

to

the

distant

operator

if

he

is

interrupted

in

the

middle

of

a

transmission.

If

the

distant

station

interrupts

you

in

this

way,

and

you

wish

to

respond

to

the

interruption,

then

enter

control-X

to

clear

the

buffer

and

enter

a

carriage

return

linefeed

to

set

the

correct

shift.

The

normal

method

of

establishing

contacts

on

RTTY

is

to

put

out

a

CQ

call

and

then

listen

for

a

reply,

or

to

call

a

station

after

hearing

him

end

a

contact.

Ch

AMTOR,

it

is

normal

practice

to

make

CQ

calls

in

FEC

mode,

announc-

ing

your

own

selcal

code

during

the

call.

At

the

end

of

your

call,

a

distant

station

can

then

call

you

back

in

either

FEC

or

ARQ

mode,

provided

of

course,

that

you

have

previously

entered

your

selcal

code

using

the

ESCAPE

I

procedure

(6.5).

Another

way

to

initiate

an

ARQ

contact

is

to

call

a

station

directly

in

ARQ

mode,

perhaps

as

he

is

ending

a

contact.

You

must,

of

course,

know

his

selcal

to

do

this.

It

is

also

common

for

AMTOR

stations

to

maintain

a

listening

watch

on

a

common

frequency,

in

which

case

a

selcal

transmitted

on

the

frequency

will

quickly

establish

if

the

station

is

available.

When

making

an

ARQ

call

using

a

transceiver,

it

can

happen

that

the

replying

station

comes

back

slightly

off

-

tune,

indicated

by

an

off-centre

tuning

display.

rt

is

tempting

to

correct

this

error

by

adjustment

of

the

main

tuning

dial.

This

temptation

should

be

resisted,

as

it

will

result

in

the

transmitter

frequency

changing

as

well,

and

this

will

probably

result

in

the

distant

station

having

to

retune

at

his

end.

This

can

result

in

an

endless

series

of

retune

operations

at

·

both

ends.

The

rule,

therefore,

is

for

the

calling

station

to

leave

his

main

tuning

control

untouched,

and

to

retune

any

offset

with

the

receiver

clarifier

control

(RIT).

The

called

station

should

leave

his

RIT

in

the

central

pos-

ition,

and

use

the

main

tuning

to

ensure

his

tuning

display

remains

central

throughout

the

contact.

A

different

technique

may

be

needed

if,

for

example,

one

station

is

crystal-controlled.

It

is

ev

en

possible

to

adjust

the

transmitter

frequency

independently

of

the

receiver,

whilst

w

atching

the

RQ

LED.

Set

th

e

fr

equenc

y

to

the

midp

oint

of

th

e

range

outside

of

which

th

e

RQ

LED

comes on

as

a

result

of

the

di

stant

station

req"

~

esting

a

repeat

wh

en

y

our

signa

l

is

off

tune

in

his

receiver!

A

similar

operation

can

be

used

to

optimise

the

transmitter

power

level.

The

power

output

of

the

transmitter

can

be

reduc-

ed

progressively

during

an

ARQ

contact

to

the

point

just

before

the

RQ

LED

starts

to

come

on.

Remember

that

no

text

will

be

l

ost

if

the

power

is

reduced

too

far

for

a moment

or

two,

It

is

even

possible

to

make a

pre-arranged

change

of

frequency

or

band.

With

care,

this

can

be

achieved

in

the

middle

of

a

contact

without

l

osing

any

text.

The

calling

station

must

be

the

first

to

change

frequency

in

this

way,

with

the

called

station

following,

so

that

the

calling

station

begins

to

send

the

phasing

pattern

on

the

new

frequency

if

the

change

tak

es

longer

than

15

seconds.

4.3

There

are

some

inherent

operating

limitations

associated

with

the

us

e

of

different

transmission

speeds

at

each

end

of

the

AMr-1.

For

example,

if

an

RTTY

signal

is

received

at

100

Bauds,

and

is

sending

traffic

at

fu

ll

speed

with

no

gaps,

characters

will

be

entering

the

unit

at

a

rate

of

13.33

per

sec.

If

the

terminal

is

operating

in

110 Baud

ASCII,

then

characters

will

be

sent

to

the

terminal

at

a

rate

of

10

per

second.

5.

Text

will

buil

d

up

in

the

internal

64 ch

aracter

buffer

and

this

may

eventually

fill.

If

it

does,

some

text

will

be

lost.

Although

the

unit

is

capable

of

copying

RTTY

at

a

data

rate

of

100

Bauds,

it

cannot

handle

a

character

rate

faster

than

10

c.p.s.

when

operating

with

a

terminal

at

110

Bauds,

and

no

faster

than

6.66

c.p.s.

when

operating

at

75

Bauds.

There

is

no

restriction

on

receive

speeds

when

operating

in

AMTOR

mo

de,

as

the

maximum

character

rate

receivable

on

AM

TOR

is

6.66

c.p.s

.

There

m

ay,

however,

be

a

problem

when

transmitting,

as

text

entered

at

110

Bauds

from

the

terminal

may

build

up

in

the

transmit

buffer

when

operating

in

AMTOR

mode

or

in

RTTY

mode

at

Baudrates

lower

than

75.

The

transmit

buffer

is

much

larger

(960

characters)

and

the

RTS

handshake

line

is

available

to

extend

this

when

required

in

computer

applications

(11.l)

•

Ch

slow

speed

CW,

text

will

normally

build

up

in

the

buffer

anyway,

and

since

CW

is

sent

at

a

non-uniform

character

rate,

it

is

an

advantage

that

some

text

is

held

in

the

buffer

to

keep

the

letter

spacing

correct.

If

sending

at

high

cw

speeds,

especially

from

a

75

Baud

terminal,

the

buffer

may

always

remain

empty,

and

this

will

give

rise

to

uneven

letter

spacing

in

the

output

morse

code.

ESCAPE CODES

From

it

should

be

clear

that

other

than

changing

from

one

mode

to

another

by

using

t he

ESCAPE

key,

further

functions

may

also

be

carried

out.

These

will

now

be

described

in

detail.

These

codes

are

normally

preceeded

by

ESCAPE,

but

if

the

AMT-1

is

already

in

the

ESCAPE

condition,

as

shown

by

the

ESC

LED

plus

all

four

mode LEDs,

then

another

ESC

code

is

not

needed.

Page

5

5.1

ESCAPE

A

This

code

enters

the

AMTOR

standby

mode

from

.

whence

FEC

signals

may

be

received.

ARQ

can

also

be

received

if

the

selcal

code

has

been

entered.

FEC

or

ARQ

transmissions

can

be

made,

or

ARQ

signals

may

be

monit-

ored,

by

using

control-B,

control-A,

or

control-F,

as

described

above.

5.2

ESCAPE

B

This

mode

enables

the

user

to

set

the

Baudrate

at

which

the

AMT-1

is

t o

operate

when

in

the

RTTY

m

ode.

After

entering

B,

follow

it

with

a

two-digit

number,

indicating

the

desired

Baudrate

.

Although

th

e

common

Baudrates

are

45

, 50

and

75,

th

e

AMT-1

will

accept

any

figure

between

01

and

99.

l'Cte

that

if

Baudrates

below

10

are

required,

the

leading

zero

must

be

entered.

If

00

is

entered,

the

unit

will

be

set

to

100

Bauds.

Both

transmit

and

receive

are

set

to

the

same

Baudrate.

If

a

character

other

than

a number

in

the

0 - 9

range

is

entered

by

mistake,

the

terminal

will

print

a

questionmark

and

the

AMT-1

will

return

direct

to

the

ESCAPE

mode.

While

the

Baudrate

is

being

entered,

the

ESC

and

RTTY

LEDs

will

be

lit.

When

the

second

digit

has

been

entered,

the

AMT-1

will

return

to

the

ESCAPE

condition.

5.3

ESCAPE

C

This

code

enters

the

CW

mode,

as

previously

described.

5.4

ESCAPE

D

This

code

enters

the

"direct"

or

bypass

mode ,

in

which

the

microprocessor

is

bypassed

and

serial

data

from

the

terminal

is

passed

direct

to

the

output

frequency-shift

generator.

Serial

data

demodulated

from

incoming

received

audio

is

fed

directly

v

ia

the

serial

output

to

the

terminal.

In

this

mode, ASCII

code

cap.

thus

be

transmitted

and

received

(simultaneously,

if

required).

The

Baudrate

is

determined

by

the

terminal

,

and

indeed,

any

code

or

speed

can

be

transmitted

through

the

system

under

these

conditions,

subject

to

the

limitations

of

the

receive

filter,

which

limits

the

top

speed

to

about

120

Bauds.

l'Cte

that

in

this

mode

the

PTT

line

is

c

ontinuousl

y

enabled.

This

is

necessary

in

order

to

keep

the

tone

generator

switched

on.

The

PTT

line

must

be

externally

d

isconnected

from

the

transceiver

to

allow

it

to

pass

received

signals.

The

AMT-1

will

not

respond

to

any

ESCAPE

code

in

this

mode .

An

ESCAPE

code

wi

ll

be

trans-

mitted

directly

over

the

radio.

The

only

way

to

"escape"

from

this

mode

is

to

switch

the

power

suppl~·

off

and

then

on

again.

5.5

ESCAPE

I

This

code

enables

the

user

to

set

the

selective

call

"

ident"

of

the

unit.

This

is

the

four-letter

group

to

which

t

he

unit

will

respond

in

ARQ

mode.

If

the

ESCAPE

I

function

has

not

been

used

since

the

unit

was

switched

on,

then

the

unit

will

not

respond

to

!

\NY

ARQ

call,

but

o

nl

y

to

FEC

transmissions.

To

set

th

e

ident,

enter

ESCAPE

I

followed

by

the

required

four-letter

group.

Only

the

l

etters

A - z

are

accepted.

If

any

other

character

is

entered,

the

terminal

will

display

a

questionmark

and

revert

to

the

ESCAPE

condition.

Whilst

the

ident

is

being

entered,

both

ESC

and

ARQ

LEDs

will

be

lit

.

When

the

fourth

letter

has

been

entered,

the

unit

will

revert

to

the

ESCAPE

condition.

5.6

ESCAPE

L

This

code

turns

on

or

off

the

"echo"

facility,

whereby

i

nput

from

the

terminal

is

sent

back

to

the

terminal

to

appear

on

the

display.

This

is

the

normal

way

in

which

it

will

be

used,

with

the

terminal

effectively

working

as

a

separate

keyboard

and

display.

If

_

the

terminal

ha

s

its

own

"echo"

or

"local

copy"

facility,

then

this

should

be

disabled.

In

the

event

that

this

cannot

be

done,

then

the

echo

facility

of

the

AMT-1

will

have

to

be

disabled.

This

is

achie

v

ed

by

entering

a

zero

after

the

L.

The

lack

cf

t~e

AMT-1

echo

facility

is

a

distinct

disadvantage,

especially

in

ARQ

mode ( w

here

the

presence

of

the

echo

indicates

when

each

character

h

as

been

transmitted

and

accepted

by

the

receiving

station.

ESCAPE

L 1

is

used

to

turn

the

echo

on

again.

On

switch-on,

the

echo

is

enabled.

5.7

ESCAPE

N

This

code

turns

the

automatic-newline

facility

on

or

off.

It

i s

enabled

at

switch-on

and

will

automatical

ly

ensure

that

both

a

carriage

return

and

a

line

feed

are

inserted

into

the

text

in

substitution

for

any

space

which

occurs

after

the

60th

character

position

in

any

l

ine.

This

ensures

that

no

line

is

too

lo

ng

for

the

distant

station's

printer.

In

cw

m

ode,

carriage

return

and

linefeed

codes

are

not

transmitted,

but

nevertheless

the

auto

n

ewline

function

serves

to

format

the

echoed

text

on

the

terminal

into

neat

lines..

When

it

is

desired

to

use

a

different

linelength,

the

auto-newline

function

may

be

disabled

with

ESCAPE

N

~

and

enabled

with

ESCAPE

N

1.

5.8

ESCAPE

Q

!i.

This

code

causes

the

AMl'-1

to

output

to

the

terminal

values

of

all

of

the

parameters

that

have

been

programmed

via

other

ESCAPE

functions.

This

explains

the

print

out

wh

en

Q

is

entered

to

test

that

the

AMI'-1

is

w

orking

. The number

printed

after

the

V:

is

the

version

number

of

the

software.

When

the

unit

is

switched

on,

the

ident

will

be

shown

as

I:????,

to

indicate

that

no

ident

has

been

set.

The

unit

will

not

respond

to

any

ARQ

call.

The

AMTOR

timeout

is

set

to

T:

30,

the

Baudrate

to

B:45,

the

CW

speed

is

S:20,

and

the

L:

and

N:

are

both

l

at

switch-

on.

N

ote

that

all

these

parameters

are

retained

even

though

the

mode

may

be

changed.

It

is

not

necessary

to

"

re-enter

the

ident

before

entering

AHTOR

mode

each

time.

5.9

ESCAPE

R

This

code

selects

RTTY

mode.

on

selection,

the

AMT-1

will

receive

RTTY.

Control-A

will

change

it

to

transmit,

and

control-D

returns

it

to

recei

v

e,

as

previously

described.

5 •10

ESCAPE

S

This

code

allows

the

user

to

set

the

word-per-

minute

speed

that

will

be

used

in

cw

mode.

one

should

enter

a

two-digit

number

after

the

S,

in

a

similar

fashion

to

that

used

for

Baudrate.

Use a

leading

zero

for

speeds

less

than

10

w.p.m.

Entering

00

will

set

100

w.p.m.,

and

if

a

character

other

than

a number

is

entered,

a

questionmark

will

be

printed.

5.

11

ESCAPE

T

6.

This

enables

the

user

to

set

the

time-out

in

the

ARQ

phasing

condition,

i.e.

the

length

of

time

in

seconds

during

which

the

unit

will

keep

try-

ing

to

resynchronise

with

the

other

station

be-

fore

giving

up

and

returning

to

STBY.

Again,

a

two-digit

number

between

Ol

and

99

can

be

entered,

with

00

giving

100

seconds

:

CONTROL

CODES

A

part

from

ESCAPE

sequences,

other

functions

executed

by

the

AMT-1

are

selected

by

ASCII

control

codes,

usually

entered

from

the

terminal

by

depressing

the

CONTROL

key

and

simultaneously

k

eying

a

letter.

Not

all

control

codes

have

the

same

meaning

in

different

modes,

nor

are

all

active

in

all

modes.

6.1

CONTROL-A

In

RTTY

mode,

this

code

forces

the

AMr-1

from

receive

to

transmit.

In

AMTOR

mode,

followed

by

four

letters

to

form

the

outgoing

selcal

code,

it

initiates

an

ARQ

call.

If

a

character

other

Page

6

6.2

than

a

letter

(A

-

Z)

is

entered

as

any

of

these

four,

the

unit

will

print

a

questionmark

and

then

revert

to

AMI'OR

STBY.

Control-A

has

no

effect

in

CW

mode.

CONTROL-B

In

RTTY

mode

this

code

has

the

same

effect

as

control-

A.

In

AMrOR

mode,

it

will

initiate

an

FEC

transmission.

In

cw

mode

it

has

no

effect.

6•3

CONTROL-C

This

code

has

the

same

effect

as

control-D

in

RTTY

mode.

During

an

ARQ

contact,

it

can

cause

a

"break-

in"

if

the

distant

station

is

sending.

Control-C

has

no

effect

in

other

modes.

6.4

CONTROL-D

In

RTTY,

control-D

switches

from

transmit

to

receive.

In

AMTOR

FEC

transmit,

it

causes

an

"end

of

transmiss-

ion"

code

to

be

sent,

followed

by

switching

off

the

transmitter

and

reverting

to

STBY.

During

ARQ

contacts,

control-0

will

cause

the

contact

to

be

terminated,

switching

both

stations

to

STBY.

This

works

only

when

the

station

that

entered

control-D

is

in

send

mode

and

has

finished

sending

any

text

that

may

be

in

the

buffer.

If

control-D

is

entered

whilst

the

station

is

in

receive,

then

closedown

will

be

delayed

until

the

station

switches

to

send.

In

the

ARQ-listen

mode,

control-D

terminates

the

listening

mode

and

returns

the

unit

to

STBY.

Control-D

has

no

effect

in

cw

mode.

6 •5

CONTROL-E

This

code

is

a

special

one

and

causes

a

specific

non-

ASCII

code

to

be

sent

from

the

AMl'-1

to

the

terminal.

This

code

can

be

interpreted

by

a

computer,

the

details

of

which

are

described

in

section

(ll.3).

Ch

most

simple

terminals,

this

"status"

code

may

or

may

not

print

as

a

character

of

some

sort.

It

might

be

interpreted

as

a

control

character

by

the

terminal,

and

for

this

reason

control-E

should

be

used

with

care.

6.6

CONTROL-F

This

is

only

valid

in

AMl'OR

mode,

where

it

will

initiate

the

ARQ-listen

mode.

6.7

CONTROL-G

This

is

not

strictly

a

control

code,

but

will

cause

a

BELL

character

to

be

transmitted

to

the

distant

station.

The

echo

back

to

the

terminal

will

be

an

asterisk.

This

ensures

that

if

the

terminal

itself

is

configured

to

respond

to

a

control-G

by

issuing

an

audible

alarm,

it

will

not

do

so

if

an

alarm

code

is

transmitted.

If

a

BELL

code

is

received

over

the

radio,

the

AMT-1

will

send

a

control-G

to

the

terminal,

however.

6.8

CONTROL-X

In

RTTY,

CW,

ARQ

and

FEC

transmit

modes,

control-X

will

cancel

any

text

which

may

not

yet

have

been

sent

from

the

buffer

• .

In

addition,

if

control-D

had

previously

been

entered

~ o

signal

the

end

of

the

transmission

or

contact,

control-X

will

effectively

cancel

control-D.

6.9

DELETE

7.

In

RTTY

and

AMTOR

modes,

this

has

the

effect

of

forcing

any

subsequently

received

text

into

the

"lettershift"

character

mode.

It

can

be

used

to

correct

'1IlY

received

signal

which

has

switched

into

figureshift

in

error.

Carriage

retur

n ,

linefeed

and

NULL

control

characters

are

treated

as

text

and

passed

to

the

transmitter.

They

also

have

the

effect

of

causing

t he

control

character

to

be

preceeded

by

the

appropriate

lettershift

or

figureshift.

SKl:

TRANSCEIVER CONNECTOR

7.1

2

is

the

common

earth

return

for

the

other

signals

carried

by

this

socket.

It

is

also

strapped

to

the

metal

chassis

of

the

AMT-1

to

ensure

good

immunity

from

external

RF

fields.

The

screens

of

the

leads

to

pins

l

and

3

should

be

connected

to

this

pin.

Page

7

7. 2

l

is

the

audio

input

from

the

receiver.

The

input

impedence

is

lOOK

Ohms

and

the

audio

level

should

be

between

SQn

V.

and

l

V.

rms.

This

signal

may

be

derived

from

the

external

loud-

speaker

socket

of

the

transceiver,

but

it

is

better

if

the

audio

can

be

taken

from

a

point

ahead

of

the

gain

(volume)

control

such

that

the

speaker

volume

can

be

varied

(or

turned

off)

without

affect-

ing

the

audio

level

to

the

AMT-1.

An

audio

output

is

often

available

from

the

accessory

socket

or

phone-patch

socket

or

it

can

simply

be

wired

to

a

spare

on

the

MIKE

socket.

'lb

ch

eck

t

hat

the

audio

level

is

within

the

correct

range,

tune

in

an

unmodulated

carrier

that

can

be

varied

in

level.

The

position

of

the

tuning

dis-

play

should

not

vary

as

the

audio

level

is

varied

slightly

up

or

down.

7.3

3

is

the

audio

output

from

the

AMT-1

to

the

transceiver

.

This

is

a

sinewave

and

can

be

varied

between

zero

and

l

v.

rms

by

means

of

the

internal

preset,

RVl. The

tone

is

keyed

on

and

off

by

the

microprocessor,

turning

on

a

little

after

the

PTT

line

does,

such

that

there

is

no

drive

to

the

transmitter

until

the

changeover

to

transmit

is

completed.

This

ensures

that

no

key-clicks

are

radiated.

3

can

be

connected

to

an

auxiliary

audio

input

on

the

transceiver

if

such

an

input

is

available

.

~rmally

it

will

be

taken

to

the

MIKE

input.

If

the

audio

level

from

the

AMT-1

is

too

high,

fit

a

resistor

in

series

with

the

MIKE

input

connection

at

the

transceiver

end

of

the

lead.

This

will

drop

the

audio

level

to

that

normally

expected

from

a

microphone.

It

should

be

possible

to

leave

the

MIXE

gain

control

in

its

normal

position.

Choose

a

series

resistor

such

that

RVl

can

be

set

to

give

the

correct

transmitter

drive

level

with

its

slider

somewhere

near

the

middle.

It

is

important

not

to

overdrive

the

MIKE

input

of

the

transceiver,

or

spurious

emissions

can

be

produced

on

either

side

of

the

wanted

signal,

even

if

the

transmitter

output

stage

is

not

overdriven.

7.4

5

is

the

PTT

line

connection.

This

is

driven

from

the

AMT-1

by

an

open

collector

transistor

which

connects

the

line

to

ground

when

the

AMT-1

enters

transmit

mode.

The

PTT

line

must

be

positi

ve

with

respect

to

earth

at

the

transceiver

·

when

in

receive

condition.

This

is

true

of

all

popular

transceivers.

A

simple

connection

can

therefore

be

made

between

the

AMT-1

and

the

PTT

l

ine

which

will

normally

be

available

on

the

MIKE

socket.

In

the

event

that

.

the

PTT

input

on

the

transceiver

is

not

of

the

"earth-to

transmit"

type,

then

a

small

relay

should

be

connected

between

the

AMT-1

PTT

output

and

the

+ 12

V.

supply.

The

contacts

can

be

connected

to

the

transceiver

.

Pins

4,

6

and

7

are

not

connected.

8.

SK2:

TERMINAL CONNECTOR

8.1

3

of

SK2

is

the

common

earth

return

'"

for

the

other

pins

on

the

socket.

It

is

also

connected

to

the

A.'fl'-1

chassis.

8.2

l

is

the

serial

input

from

the

terminal

to

the

AMI'-1. A

negative

voltage

on

this

corres-

ponds

to

the

stop-polarity,

and

a

positive

voltage

to

the

start

polarity.

The

terminal

should

output

a

negative

voltage

to

the

AMT-1

on

this

when

in

idle

condition.

If

the

polarity

needs

to

be

reversed,

the

internal

link

LJ.O

in

the

AMI'-1

can

be

cut.

The

data

into

the

AMT-1

must

be

ASCII

code

with

one

start

bit,

8-bit

data

bits,

and

either

one

or

two

stop

bits.

The

eighth

data

bit

(sometimes

called

the

parity

bit)

is

ignored

by

the

AMT-1,

and

can

be

either

zero,

one,

odd,

or

even

parity.

The

data

rate

accepted

by

the

AMT-1

is

either

75

or

110

Bauds,

selected

by

internal

DIL

switch

SW3

(10.5).

8.3

5

is

the

ASCII

output

from

the

AMI'-1

to

the

terminal.

The

logic

l

evels

and

data

format

are

as

per

the

input

on

l.

The

AMT-1

outputs

are

zero

(start

pol'arity)

in

the

parity

bit

with

the

exception

of

the

"status"

character

output.

This

is

sent

when

the

AMr-1

responds

to

a

control-E

character

from

the

terminal

(11.3).

In

this

case

the

parity

bit

is

one.

The

polarity

of

the

output

signal

can

be

inverted

by

cutting

LKS.

8.4

4

is

the

RTS

(Request

To

send)

output

from

the

AMT-1

which

can

safely

be

ignored

in

most

applications.

!bwever,

its

purpose

is

to

inform

the

terminal,

or

compu-

ter,

when

the

AMT-1

can

or

cannot

accept

text

for

trans-

mission.

For

example,

if

the

internal

960

character

buffer

fills

during

entry

of

text

from

the

terminal,

then

RTS

changes.

The

cemputer

should

respond

by

stopping

the

flow

of

data

until

the

AMT-1

signals

that

there

is

a

space

in

the

buffer.

This

line

also

indicates

that

the

AMT-1

cannot

accept

data

when

it

is

not

in

a

transmit

mode,

such

as

FEC-receive

or

ARQ-listen,

or

during

an

ARQ

call

before

the

distant

station

has

replied.

A

positive

volt-

age

on

this

line

indicates

that

text

can

be

accepted,

and

a

negative

voltage

indicates

that

it

cannot.

!bte

that

the

AMT-1

will

still

accept

control

characters

even

if

this

line

is

negative.

The

polarity

of

this

signal

can

be

inverted

by

cutting

link

LK4

(11.l)

•

8.5

2

is

the

CTS

(Clear

'lb

Send)

input

to

the

AMT-1.

For

most

applications,

this

can

be

left

disconnected.

It

serves

a

similar

purpose

to

that

of

4,

but

in

the

opposite

direction.

It

can

stop

text

from

being

sent

out

by

the

AMT-1,

e.g.

when

the

computer

is

temporarily

busy

with

another

task,

such

as

storing

a

block

of

text

on

disk

or

cassette.

During

this

time

any

data

from

the

AMT-1

might

be

missed.

If

this

is

taken

negative,

then

any

received

text

will

be

held

in

a

temporary

64-

character

buffer

within

the

AMT-1.

It

will

be

released

when

CTS

is

taken

positive

(or

left

open)

• •

The

polarity

of

this

signal

can

be

reversed

by

fitting

a

iink

in

LK6

position.

If

this

is

done

and

CTS

is

left

open,

then

the

AMI'-1

will

not

permit

any

data

output.

In

this

case,

CTS

must

be

held

negative

if

it

is

not

used.

see

section

(11.2).

9.

FRONT PANEL

DISPLAY

LED'S

There

are

three

displays

on

the

front

panel.

The

right-

hand

one,comprising

four

red

LEDs,

indicates

which

of

the

principal

modes

the

AMT-1

is

in.

The

centre

display,

com-

prising

green

LEDs,

is

a

tuning

display.

It

gives

an

analogue

indication

of

the

frequency

of

the

received

tones.

The

left-hand

display

indicates

the

status

of

the

unit

within

each

mode. The

significance

of

each

LED

·

is

described

below:-

9.1

MODE

DISPLAY

ARQ

is

lit

when

the

AMr-1

is

in

AMTOR

standby

mode

and

is

ready

to

receive

either

FEC

or

ARQ

calls,

or

if

it

is

in

ARQ

conta

ct

or

making

an

ARQ

call.

FEC

is

lit

if

the

AMI'-1

is

either

receiving

or

transmitting

an

FEC

signal.

RTTY

is

lit

when

the

AMT-1

is

in

RTTY

mode,

either

transmit

or

receive.

CW

is

lit

in

the

CW

mode.

9.2

TUNING

DISPLAY

The

tuning

display

is

turned

on

only

when

the

AMT-1

is

i.~

receive.

A

high-frequency

tone

will

give

a

spot

on

the

·

left

side

of

the

display,

and

a low

frequency

tone

on

the

right

side.

In

RTTY

receive,

the

display

will

be

lit

continuously.

A

signal

will

show

as

a

dot

which

should

flicker

rapidly

between

the

left

and

right-hand

side

of

the

display.

In

FEC

receive,

the

display

changes

to

the

"two-dot"

mode,

where

the

display

is

only

gated

on

at

the

exact

centre

of

each

data

bit.

Thus

the

display

will

not

show

the

dot

as

it

traverses

from

one

side

of

the

display

to

the

other,

but

only

as

two

separated

dots

-

one

on

each

side.

Inter~erence

and

distortion

on

the

incoming

sig-

nal

will

show

clearly

as

spurious

dots

in

the

centre

of

the

display.

In

ARQ

mode,

either

during

contacts

or

in

listening

mode,

the

display

will

illuminate

in

synchronisation

with

the

incoming

signal,

in

two-dot

mode.

This

makes

it

very

easy

to

tune

signals

in,

even

when

sending,

when

the

distant

station

is

only

transmitting

short

bursts

of

signal.

The

display

will

change

to

continuous

mode

during

periods

of

phasing.

9.3

STATUS

DISPLAY

ERROR

is

lit

in

RTTY

mode when

the

received

character

has

a

stop

bit

of

the

wrong

polarity.

This

is

a

useful

indication

that

the

rece

i

ved

polarity

is

wrong,

or

the

Baud ·

rate

is

incorrect,

although

a weak

signal

will

also

show

short

flashes

of

ERROR.

In

FEC

receive,

the

ERROR

LED

will

flash

if

both

repeats

of

a

character

cont-

ained

errors

and

the

AMl'-1

has

not

attempted

to

print

it.

In

ARQ

mode,

whether

sending

or

receiving,

the

ERROR

~""'D

will

indicate

that

the

received

signal

is

bad

and

that

the

AMl'-1

is

mEJ<ing

a

request

for

a

repeat.

The

ERROR

LED

will

light

in

ARQ-listen

mode

if

the

received

block

contains

an

error.

In

this

case

the

remaining

characters

in

that

block

will

be

printed.

RQ

will

light

in

ARQ

mode,

when

the

distant

station

requests

a

repeat

due

to

his

received

signal

being

bad

{his

error

LED

will

also

have

come

on

at

this

time).

In

ARQ-listen

mode,

the

RQ

LED

indicates

that

the

signal

being

monitored

is

either

requesting

repeats

from

the

station

he

is

working

or

he

is

sending

an

ARQ

phasing

call,

in

which

case

the

sel-

cal

code

will

be

printed.

TRAFFIC

will

be

lit

in

any

mode when

text

is

being

processed

through

the

unit

-

either

being

transmitted

in

"send"

mode,

or

received.

IDLE

will

be

lit

when

no

traffic

is

being

processed.

In

SEND

mode,

this

means

that

the

unit

is

waiting

for

input

from

the

terminal.

In

RECEIVE

mode,

it

means

that

the

distant

station

is

not,

for

the

moment,

sending

text.

OVER

will

light

only

in

ARQ

contacts

when a

change-over

in

sending

direction

is

in

progress

or

when a

closedown

is

about

to

occur

.

PHASE

will

light

in

ARQ

mode when

the

AMl'-1

is

trying

to

synchronise

with

a

distant

station

during

either

an

ARQ

call,

or

during

a

contact

when

signals

have

been

lost

temporarily.

In

ARQ-listen,

the

PHASE

LED

has

the

same

meaning.

STBY

is

li

t

only

in

AMl'OR

standby

mode.

The

·

unit

is

then

waiting

to

receive

an

FEC

or

ARQ

call.

ESC

is

lit

when

the

AMI'-1

is

in

the

ESCAPE

mode.

In

this

case,

all

four

mode

LEDs

will

be

lit.

The

typed

will

be

interpreted

as

a

mode command.

ESC

is

also

lit

dUring

certain

parameter-setting

commands

in

which

case

one

or

other

of

the

mode

LEDs

will

also

be

lit.

The

SEND

LED, a

red

one,

is

lit

in

any

send

mode.

When

lit,

input

from

the

terminal

for

subsequent

transmission

will

be

accepted.

During

a

phasing

operation

in

ARQ

mode

{though

the

unit

may

or

may

not

be

sending

a

call

to

try

and

resynchronise),

the

SEND

LED

will

indicate

which

direction

will

re-establish

itself

when

the

resynchronisation

is

success-

ful.

Page

8

iO

. INTERNAL ADJUSTEMENTS

10.l

RVl

This

sets

the

audio

output

level,

as

previou

·

sly

described.

It

should

be

set

such

that

the

audio

output

level

matches

that

of

the

input

to

the

transceiver.

10.2

RV2

sets

the

time

delay

between

the

turn-on

of

the

PTI'

line

and

the

turn-on

of

the

audio

tone

and

the

commence-

ment

of

transmission

of

data.

This

allows

for

t he

in-

evitable

delays

in

change-over

circuits

within

the

trans-

ceiver

.

As

it

l

eaves

the

factory,

this

is

set

to

mid-

position,

giving

a

delay

of

25mS.

This

setting

is

not

important

for

RTTY

or

FEC

.

transmissions

or

slow-speed

cw,

but

f

or

high-speed

cw

and

ARQ

contacts,

it

is

important

that

the

transceiver

has

fully

changed

to

transmit

by

the

end

of

this

delay.

Turning

RV2

clockwise

will

increase

the

delay

if

the

trans-

ceiver

is

particularly

slow

to

change

over

-

up

to

a

maximum

of

SOmS.

However,

a

long

setting

for

RV2

will

limit

the

maximum

distance

over

which

an

ARQ

contact

can

be

made,

and

will

also

limit

the

maximum

speed

at

which

CW

can

be

sent,

so

it

is

often

necessary

to

set

RV2

accurately.

1'0

do

this

requires

an

oscilloscope.

Arrange

the

oscilloscope

to

trigger

externally

from

the

negative-going

edge

of

the

PTT

line

signal.

Display

the

RF

output

signal

fran

the

transmitter,

either

direct-

ly

at

RF

frequency

or

via

a

detector

arrangement

and

from

a

point

on

the

antenna

side

of

the

antenna

change-

over

relay.

set

the

timebase

speed

to

lOmS

per

division,

and

set

the

AMl'-1

to

send

an

ARQ

call

.

Turn

RV2

fully

anticlockwise.

The

oscilloscope

should

trigger

at

the

start

of

each

transmitted

burst,

and

should

display

the

start

of

the

output

envelope.

Note

the

point

at

which

the

output

first

reaches

full

power

and

turn

RV2

slowly

clockwise

until

this

point

just

starts

to

move

to

the

right.

At

this

point

the

AMT-1

is

turning

on

the

tone

just

at

the

point

where

the

transmitter

first

achieves

full

gain.

If

this

point

cannot

be

found

before

RV2

reaches

its

endstop,

then

the

transmitter

is

taking

more

than

SOmS

to

turn

on.

Scme

modification

may

therefore

be

needed

in

the

trans-

ceiver

if

ARQ

contacts

are

to

be

possible.

See

section

(12)

for

assistance.

An

alternative

trial-and-error

method

of

setting

RV2,

with

the

help

of

another

station,

is

to

send

an

ARQ

call

and

ask

him

to

monitor

it

in

the

ARQ-listen

mode. Ask

him

to

check

for

missing

first

and

third

characters

in

the

printed

se

lc

al.

Such

missing

characters

{or

no

synchronisation

at

all)

indicates

that

the

setting

of

RV2

is

too

short

for

the

transceiver.

CO

not

adjust

RV2

d~ing

a

call,

but

make a

small

alteration

and

start

a new

call

in

order

to

arrive

at

the

optimum

setting.

10.3

RV3,

RV4

AND

COIL

These

presets

need

not

normally

be

touched,

having

been

aligned

at

the

factory.

However,

for

reference,

here

is

a

procedure

for

adjusting

them.

They

form

part

of

the

receiver

demodulator.

With

the

AMT-1

in

ARQ

standby

such

that

the

tuning

display

is

on,

feed

an

audio

signal

generator,

or

variable

tone

(perhaps

from

the

receiver

tuned

to

an

internal

calibrator

signal)

into

the

AMT-1.

Turn

VR4

fully

clockwise

and

adjust

the

input

frequency

until

the

tu..~ing

display

is

as

far

to

the

left

as

possible

without

folding

back

to

the

right

or

breaking

up

into

noise.

Then

adjust

RV4

until

the

displayed

spot

just

reaches

the

lefthand

end

of

the

display.

Be

careful

not

to

go

too

far,

as

the

spot

will

hold

on

the

end

position

rather

than

"go

off

the

end".

Now

turn

RV3

fully

anti-clockwise

and

adjust

the

input

frequency

until

the

display

is

farthest

to

the

right

without

folding

back

to

the

left

or

breaking

up.

'lllen

turn

RV3

urttil

the

spot

just

reaches

the

right

end

of

the

display.

Swinging

the

frequency

over

the

whole

range

should

move

the

spot

across

the

full

display.

Now

remove

the

transceiver

connector

(SKll

and

make a

shorting

link

between

pins

l

and

3,

to

connect

th

e

transmit

tone

back

to

the

receive

side.

Enter

ESCAPE

D

from

the

terminal

,

and

a

spot

should

appear

in

the

left

half

of

the

dis-

play.

Key

any

characters

on

the

terminal,

and

th

e

spot

should

key

into

the

other

h

alf

of

the

display.

Adjust

the

coil

until

the

displayed

spots

are

symmetrical

about

the

centre.

Switch

the

AMT-

l

off

and

on

again

to

return

to

normal

operation.

10.4

V

Cl

This

trimmer

adjusts

the

main

crystal

oscil

l-

ator

in

the

AMT-l

and

has

been

set

accurately

at

the

factory.

The

accuracy

of

this

adjust-

ment

is

m

ost

critical

in

ARQ

mode.

If

ARQ

contacts

are

pe

riodically

interrupted

by

phas-

ing

operations

in

the

absence

of

any

other

cause,

then

VCl

may

need

adjusting

(or

the

equivalent

trimmer

at

the

other

station).

To

set

VCl, a

counter

is

required

with

a

period-average

mode.

Q:lnnect

the

counter

to

TP2

and

adjust

VCl

until

the

period

is

exactly

1000.000

micro-seconds.

6-Digit

accuracy

is

preferred

for

this

m

easurement,

which

should

therefore

only

be

attempted

if

the

counter

accuracy

is

kn

o

wn

to

be

of

this

order.

l

0.

5 INTERNAL

LINKS

Two

internal

links,

LlO

and

Lll,

respect-

ively

allow

the

transmit

and

receive

keying

polarities

to

be

changed.

With

both

in

the

factory

set

position,

an

upper

sideband

SSB

transceiver

will

give

the

correct

polarity

for

amateur

RTTY

station

s

and

for

all

TOR

stations.

If

transmission

has

to

be

made

in

the

opposite

polarity,

or

the

transmitter

is

only

capable

of

operation

in

l

ower

sideband,

then

link

the

two

pins

at

LlO.

Th

e same

applies

to

Lll

for

the

receive

polar-

ity.

When

working

through

certain

amateur

satellites,

it

may

be

necessary

to

have

LlO

and

Lll

in

opposite

positions,

but

normally

they

would

both

b·e

in

the

same

position

.

Ll2

determines

which

data

rate

the

terminal

interface

will

operate

at

.

Op

en

gives

75

Bauds

and

connected

gives

110

Bauds.

For

convenience,

LlO

and

Lll

are

brought

out

to

unused

s

on

the

XCVR

connector.

Switches

can

be

connected

between

these

lines

and

ground

for

external

operation.

11

COMPUTER

INTERFACING

WITH

THE

AMT-1

Although

the

AMI'-l

can

be

used

effectively

with

a "dumb"

terminal

that

is

simply

capable

of

displaying

its

input

on

a

printer

or

video

display

and

outputting

serial

ASCII

data

from

keyboard

entry,

many

users

will

want

t o

use

a

small

computer

to

carry

out

the

function

of

a

terminal.

In

this

case,

the

pro

ce

ss

ing

power

of

the

computer

can

be

used

to

expand

the

system

into

a

powerful

co~ications

facility.

U.l

For

the

simPle

co

nne

c

tion

of

an

ASCII

terminal

to

the

AMl'

-

1,

it

has

been

assumed

so

far

that

no

connection

has

been

made

to

the

two

contr

ol

line

s

RTS

and

CTS

on

SK2. Ho

wever

,

if

these

are

connected

back

into

the

compu

ter,

th

en

complete

control

of

the

two-way

flow

of

data

between

the

two

equipments

is

po

s

sible.

For

example,

if

the

960-character

transmit

buffer

in

the

AMI'

- 1

fills

due

to

a

hold-up

in

an

ARQ

contact,

then

RTS

will

go

negative,

and

the

computer

will

then

hold

any

further

output

until

RTS

goe

s

po

s

itive

again,

indicating

that

there

is

now

space

in

the

buffer

.

In

this

way,

the

computer

can

send

v

ery

long

texts

without

risking

the

loss

of

any

part

of

it.

Page

9

Th

is

will

indicate

i f

the

buffer

is

full

in

CW,

RTTY,

ARQ

and

FEC

transmit.

It

will

also

go

negative

in

mo

des

where

the

AMT-1

will

not

accept

text,

such

as

in

ARQ-listen,

FEC

receive,

ARQ

standby,

and

during

an

ARQ

call

(in

the

interval

between

starting

the

ca

ll

and

the

distant

station

replying)

• N::lte

that

when

RTS

is

negative,

the

AMT-1

will

still

respond

to

control

codes.

It

will

often

be

nece

s

sary

t o

ent

er a

control

when

RTS

is

negative,

to

change

modes . The

computer

will

be

required

to

have

tw

o

output

routin

e

s,

one

to

output

a

character

provided

the

line

is

positi

ve ,

and

another

to

output

control

codes

regardless

of

the

state

of

th

e

RTS

line.

11.2

2

of

SK2

(CTS)

can

be

taken

negati

ve

by

the

computer

to

temporarily

stop

·

the

flow

of

re

c

eived

(or

ech

o

ed)

text

from

the

AMT-1.

In

this

case,

text

will

"pile

up"

in

an

internal

64

character

buffer

within

the

AMT-1.

Depending

on

the

rate

at

which

text

is

being

received,

this

buffer

will

then

start

to

fill.

In

FE

C

receive

and

RTTY

receive

modes,

text

will

be

lost

if

the

buff

er

fills

completel

y,

so

there

is

a

definite

limit

to

the

length

of

time

that

th

e

com

p

uter

can

take

CTS

negative

whilst

it

is

busy.

In

ARQ

contacts,

if

the

buffer

fills,

then

no

text

will

be

lost

since

the

AMI'-l

will

send

a

"dummy"

request

for

repeat

to

the

distant

station

until

there

is

space

ag~in

in

the

receive

buffer.

There

is

one

situation

wh

e

re

the

AMT-l

will

s

end

a

character

even

if

CTS

i s

held

negative.

That

is

when

the

status

character

is

sent

by

the

AMT

- 1

in

re

s

pons

e

to

a

control-E

code

from

the

terminal.

This

enabl

es

the

computer

to

establish

the

statu

s

of

the

AMI'-l

even

in

the

middle

of

a

period

of

reception.

It

pulls

CTS

nega

tive

to

stop

the

received

traffic,

then

sands

a

control

- E

and

receives

the

status

from

the

AMT-l,before

releasing

CTS

to

copy

the

following

rec

e

ived

data.

11.3

STATUS

CHARACTER

At

any

time,

sending

a

control-E

chara

c

ter

from

the

terminal

to

the

AMl'-l

will

cause

it

to

resp

o

nd

with

the

status

character.

If

this

status

character

is

considered

as

an

8-bit

byte,

then

the

individual

bits

can

be

interpreted

by

the

computer

in

the

follow-

ing

way.

Bits

O,

l

and

2

indicate

'"hich

of

the

left-hand

status

LEDs

is

lit,

as

follows:-

bit

2 l 0

LED

0 0 0

error

0 0 l

RQ

0 1 0

traffic

0 1 l

idle

l 0 0

over

l 0 1

phase

l l 0

STBY

l l l

ESC

Bit

3

is

1

if

the

SEND

LED

is

on,

and

0

if

it

is

not

.

Bits

4,

5

indicate

which

of

the

right-hand

MODE

LEDs

is

on,

as

follows:-

Bit

5 4

LED

0 0

ARQ

0 l

FE.C

l 0 RTT'i

l 1

cw

Note

that

in

the

ES

CAPE

condition,

where

all

the

mode

LEDs

are

on,

bits

4

and

5

will

contain

random

data,

i.e

.

they

may

indicate

any

of

the

four

modes.

Bit

6

is

a 1

if

th

er e

is

some

text

in

the

internal

64

character

buffer

waiting

to

be

outputed,

e.g

.

CTS

has

been

held

negative

and

some

message

h

as

been

received

but

not

read

by

the

computer.

Note

that

an

ESCAPE

is

the

only

way

of

clearing

the

64

character

buffer.

Bit

7

of

the

status

byte

is

always

l.

This

is

in

contrast

to

bit

7

of

any

other

character

outputed

from

the

AMI'-1.

It

can

thus

be

used

to

distinguish

a

status

byte

from

a

text

character,

e.g.

_

if

control-E

is

sent

to

the

AMI'-l

whilst

reception

is

in

progress.

In

this

case

the

status

byte

will

be

mixed

in

with

the

text.

The

status

byte

can

be

used

for

a

variety

of

purposes.

For

example,

if

it

is

desired

to

automatically

send

the

station

call-sign

on

CW

between

periods

of

operation

on

RTTY,

then

the

computer,

when

it

wishes

to

send

the

cw,

can

first

test

to

see

that

the

transmit

buffer

is

empty

by

waiting

until

a

returned

status

byte

has

0 l l

in

bits

2,

l,

O.

It

then

sends

ESCAPE

C,

followed

by

the

station

call-sign,

then

waits

again

until

a

returned

status

byte

indicates

the

idle

condition

before

sending

ESCAPE

R,

to

return

to

RTI'Y

mode.

If

the

wait

is

not

included,

then

the

AMT-l

will

be

cut

short

in

sending

the

CW

call-sign

when

ESCAPE

is

send

immediately

after

sending

the

call-sign

to

the

AMT-l

from

the

computer,

since

the

speed

of

sending

CW

will

usuall~·

be

slower

than

the

speed

of

sending

from

the

terminal.

In

AMTOR

standby,

the

computer

can

continuously

send

control-E

to

the

AMT-1

to

.

detect

the

start

of

a

received

call,

and,

for

example,

choose

to

print

out

only

ARQ

calls

and

not

FEC

calls,

by

examining

bits

4

and

S

to

see

which

mode

is

present

when

bits

2,

l,

0

change

from

l,

0

(standby)

to

0,

l,

0

(traffic).

In

most

computer

controlled

applications,

the

local

copy

facility

may

be

more

of

a

nuisance

than

a

help.

It

can

easily

be

turned

off

with

ESCAPE

L

~.

as

also

can

the

newline

facility

if

it

is

not

requ

i

red,

or

if

an

automatic

new-

line

algorithm

is

used

in

the

computer

itself.

The

computer

can

also

be

programmed

to

auto-

matically

detect

that

the

incoming

received

text

is

wrongly

in

figureshift,

and

send

a

RUBOUT

character

to

co=ect

this.

11.4

some

computer

keyboards

may

not

have

keys

such

as

ESCAPE

or

CONTROL,

or

these

keys

may

have

already

been

assigned

to

other

tasks.

12

For

example,

the

ESCAPE

key

may

always

cause

the

computer

to

exit

from

its

program

back

to

a command mode.

In

these

cases

it

will

be

necessary

to

write

routines

in

the

program

to

re-assign

other

keys

to

send

these

control

codes

to

the

RS232

port.

In

some

computers,

special-function

keys

are

available

and

can

be

programmed

for

this

function.

The

follow-

ing

table

shows

the

control

code

names

by

these

instructions,

and

their

ASCII

code

equivalents,

both

in

decimal

and

hexadecimal

representation.

decimal

hexadecimal

control-A

01 Ol

control-B

02 02

control-C

03 03

control-D

04 04

control-E

OS OS

control-F

06 PG

control-G

07 07

control-X

24

18

ESCAPE

27

lB

DELETE

127

7F

TRANSCEIVER

CHANGEOVER

PERFORMANCE

In

ARQ

and

CW

modes,

a

reasonably

fast

change-

over

from

transmit

to

receive

and

vice

versa

is

essential

.

If

your

transceiver

takes

longer

than

SOmS

to

change

from

receive

to

transmit,

then

it

will

not

be

possible

to

find

a

setting

for

RV2

that

will

allow

the

AMI'-1

to

operate

in

ARQ

mode

correctly.

Even

if

the

change-over

time

is

less

than

SOmS

and

it

is

possible

to

set

RV2,

it

may

be

necessary

to

modify

the

transceiver

to

shorten

the

delay

time

as

much

as

possible.

Page

10

The

shorter

the

delay

time,

the

greater

will

be

the

maximum

distance

that

can

be

worked

in

ARQ

mode.

This

is

because

radio

waves

take

a

finite

time

to

travel,

and

the

ARQ

mode

allows

a maximum

of

l70mS

for

the

radio

signals

to

travel

from

one

station

to

the

other

and

back.

If

there

were

no

other

delays,

this

would

give

a maximum

distance

of

170 x

300

km

between

ARQ

stations.

Since

radio

waves

travel

at

300

km

per

mS,

this

would

give

a maximum

distance

of

2S,SOO km. The

ARQ

mode

cannot

work

at

a

greater

distance.

kly

additional

delays

will

redu

ce

this

range,

and

it

is

for

this

reason

that

the

shortest

possible

changeover

delay

is

advantageous.

With

changeover

delays

of

lOmS

at

both

ends,

it

is

just

possible

to

work

from

one

point

of

the

globe

to

the

antipodeal

point.

Most

transceivers

perform

well

in

this

respect,

especially

the

more

modern

ones

and

those

noted

for

fast

break-in

cw.

However,

some

require

small

modif-

ications

to

be

able

to

change

over

faster.

The

first

approach

is

to

contact

your

transceiver

dealer,

who

may

already

have

details

of

the

necessary

modifications

and

can

either

carry

them

out

or

supply

the

necessary

modification

kit

or

information.

In

the

absence

of

such

help,

contact

other

AMI'OR

operators

who

may

already

have

devised

modifications

on

the

same ·

type

of

equi

.

pment.

As

a

last

resort,

obtain

the

service

handbook

or

circuit

diagram,

and,

·

with

the

aid

of

an

oscilloscope,

trace

the

path

taken

by

the

signal

from

the

microphone

socket

through

to

the

transmitter

output,

synchronising

the

scope

from

the

PTT

line,

and

observing

the

time

interval

immediat-

ely

after

the

PTT

line

goes

low,

looking

for

any

source

of

e>tcessive

delay.

It

may

often

be

found

that

excessive

delays

occur

due

to

the

charging-up

of

large

capacitors

-

either

those

bypassing

supply

lines

that

are

switched

on

or

off

between

receive

and

transmit,

or

those

coupling

signals

between

stages

that

are

operating

from

differently-

swi

tched

supply

lines.

The

cure

is

usually

to

reduce

the

value

of

the

off

end-

ing

capacitor.

In

some

cases,

it

may

be

possible

to

move

part

of

the

circuitry,

for

example

the

microphone

pre-amplifier,

from

a

supply

line

that

is

switched,

to

one

that

is

not,

without

affecting

the

performance

of

the

transceiver.

Experience

has

shown

that

the

speed

of

operation

of

relays

is

quite

adequate,

except

possibly

some

very

large

relays

in

high

power

amplifiers.

The

speed

of

changeover

from

transmit

to

receive

is

also

important

in

ARQ

mode.

M:>re

especially

for

a

station

making

the

initial

call

when

working

a

~

earby

station

-

when

the

reply

has

to

be

received

very

soon

after

the

end

of

the

transmit

burst.

If

problems

are

encountered

when

trying

to

initiate

such

a

contact,

but

not

when

the

other

station

initiates

the

call

from

his

end,

then

suspect

that

the

receiver

is

taking

too

long

to

switch

back

to

full

gain

after

the

transmitter

burst.

Again,

the

transceiver

dealer,

manufacturer,

or

other

AMTOR

users

may

be

able

to

provide

the

solution.

A

similar

analysis

technique

to

that

used

for

the

transmitter

may

be

used,

but

this

time

triggering

the

oscilloscope

from

the

trailing

edge

of

the

PTT

signal

and

tracing

the

signals

through

the

receiver.

I.Dok

for

the

effects

of

large

capacitors

in

decoupling,

coupling,

or

AGC

positions.

It

is

also

possible

that

some

relays

may

be

slow

to

drop

back

to

the

receive

condition

if

a

diode

is

connected

across

the

relay

coil

to

suppress

back-EI-F

spikes.

This

has

the

effect

of

slowing

the

drop-out

of

the

relay.

~e

cure

is

to

add

a

resistor

in

series

with

the

diode,

with

a

value

equal

to

that

of

the

relay

coil

impedance.

Pag

e 11

CABLE

CONECTIONS

E

nt

er

the

connections

for

y

our

equipment

for

future

referen

ce

SKl (

XCVR)

!

TRANSCEIVER

CONNECTOR

I

SIGNAL

i

SIGNAL

l

Audi

o

Inpu

t I

!

2

Common

Earth

Return

i

3 I Aud

io

O

utput

!

4 ! N/ C I

!

5 I

PTT

I

I I

6 ! N/ C I

7 I N/ C ii

SK2

(

TERMINAL)

TERMINAL

CONNECTOR

PIN i

SIGNAL

I

1 i

Data

I

nput

2 !

CTS

3

Common

Earth

Return

4 R

TS

5

Data

Ou

tput

LAYOUT:

SKl (

XCVR)

SK2

(

TERMINAL

)

2

S P E C I F I C A T I 0 N

SU

PPLY

VO

LTAGE:

12

-14 V

olt

s

SUPPLY

C

URRENT:

800mA

typical

1

Amp

fuse

fitted

inte

r na

lly

MO

DES

OF OPERATI

ON:

M

orse

code

send

l - 100 w. p.m.

RT

TY (I

TA

2 c

ode

)

Transmit

and

receive

l - 100

Baud

FEC

(CCIR

recommendation

476)

Transmit

and

receive

100

Baud

ARQ

(CCIR

recommendation

476)

AU

DIO

INTE

RFACE:

In

put:

Input

Level:

Bandwidth:

T

one

Frequencies:

O

utput:

Ou

tput

Level

:

O

utput

Tone

Frequ

e

ncie

s:

P

TT

Lin

e:

TERMINAL

INTERFACE

:

·

In

terface

St

anda

r d :

Data

Rate:

Data

Format

:

INTERNAL

BUFFERS:

DIMENSIONS:

TEM

P

ERAT

U

RE

RANGE:

·£ ..

50mV

- l V

olt

rm

s

300Hz,

four

pole

filte

r

1275,

1445Hz.

(170Hz

shift

)

Cont

inu

o

usl

y

variable

0

to

l

Volt

rms

127

5,

1445Hz. (

Crystal-controlled

s

in

ewa

ve

)

Ground

to

transmit,

open

-

circuit

(

positive

)

to

recei

ve

RS232

75 or

110

Bauds ,

selected

by

intern

a l

switch

l

St

ar

tbit

, 7

data

bits,

pa

rity

bit

send

0,

igno

r e

receive,

send

2 st

opbit

s ,

recei

ve l

or

2

stopbits,

ASCII

cod

e

960

Characters

tran

s

mit.

64

Characte

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recei

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310

mm

(

W)

x 60

mm

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Page

15

APPENDIX

1:

MICROCOMPUTER

APPLICATIONS

PROGRAMS

Commodore

VIC-20

BBC

Model

B

ABC

80

Page

16

1

REM

JICJIC)I(

PROGRAM

TO

ENABLE

VIC-20

WITH

RS-232

INTERFACE

TO

BE

USED

WITH

AMT-1

MTOR

TERMINAL

UNIT

••

.

2

REM

xx:« THIS

PROGRAM

USES

THE

FUNCTION

KEYS

TO

PRODUCE

THE

NECESSARY

CONTROL

~(EYS

•••

3

REM

:«

::«

:«

Fl

=

ESCAPE

4

REM

)l(:;()I(

F2 =

CTRL

c

5

REM

:«::«)!(

F3 =

CTRL

A

6

REM

)!(:;()!(

F4 =

CTRL

x

7

REM

x:«:ic

F5 =

CTRL

D

8

REM

*

:C)I(

F6 =

CTRL

B

9

REM

)I(

:C:te

F7 =

CTRL

F

10

REM:c:uc

FB

=

RUBOUT

<ERASE>

11

REM

:ncx

PROGRAM

WRITTEN

E:Y

D.

J.

INGLEDEW

<G8AXZ>

15

REM

XJICJIC)I(

CLEAR

SCREEN

,OPEN

RS232

CHANNEL

AND

20 PRINT·<CLR>"!OPEN

2,z,3,cHR$(131)

+ CHRS(Q)

25

REM

X***

CHECK

FOR

KEY

DEPRESSION

••

30 A = PEEKCZ03) :

IF

A =

64

THEN

zto

35

REM

X::«:tellC

CHEC~(

FOR

FUNCTION

KEY

DEPRESSION

40

IF

A =

39

THEN

K =

i:

GOTO

90

50

IF

A =

47

THEN

K =

3!

GOTO

90

6 0

IF

A =

55

THEN

~{

=

5!

GOTO

90

70

lF

A =

63

THEN K =

7:

GOTO

90

••

--...-

r"'1AI

Ir"\

.:)C..

I C:•M\.J...,

RATE

ETC,

75

REM

x*llC*

FUNCTION

KEY

NOT

PRESSED,

GET

CHARACTER

FROM

KEYBOARD

80

GOTO

190

85

REM

X)l(JICllCllC

CHECK

IF

SHIFT

KEY

WAS

DEPRESSED

••

90 B = PEEKC653) :

IF

8 > 1

THEN

8 = 0

:iGO

K

~

i<

+

E;

105

REM

:«:uc:te

ALLOCATE

CONTROL

CODES

TO

FUNCTION

110

IF

K = 1

THEN

AS

=

CHRSCZ7>

GOTO

zoo

120

IF

K = 2

THEN

A$

= CHRS<03)

GOTO

zoo

130

IF

I{

= 3

THEN

AS

= CHR$(01)

GET

ZS

•

GOTO

•

140

IF

~(

= 4

THEN

AS

= CHR$C24)

GOTO

200

150

IF

~{

= 5

THEN

A$

= CHR$(04)

GOTO

200

160

IF

I{

= 6

THEN

A$

= CHR$(02)

GOTO

200

170

IF

~(

= 7

THEN

A$

= CHr\$(06)

GOTO

200

180

IF

K = 8

THEN

AS =

CHR$027)

•

GOTO

zoo

.

l<EYS

>:>:::·

200

185

REM•~••

IF

NOT

A

CONTROL

CODE

THEN

GET

CHARACTER

FROM

KEYBOARD

• •

190

GET

A:S

195

REM

*~**

SENU

CHARACTER

TO

RS-232

PORT

200

F'

I~:

INT

t:2 ; A$ ;

?05

REM

~~**

GFT

CHARACTER

FROM

RS-232

PORT

210

GETt2~8$

:REM

GETS

~HARACTER

FROM

RS-232

PORT

215

REM

PRINT

CHARACTER

ON

VDU

••

22

0 PRINT

E:

:5;

230

GOTO

30

Page

17

10

REM

DR

I

VER

PROGRAM

FOR

AMT-1

20

REM

WITH

BBC

MODEL

B

COMPUTER

30

REM

VERS1DN

0,

1

OPERATING

SYSTEM

4'

3

REM

50

REM

AMT-1

MUST

BE

SET

TO

75

BAUD

60

REM

STRAP

CTS

TO

RTS

ON

BBC

RS423

SOCKET

70

REM

BEWARE.

USE

BREAK

TO

EXIT

PROGRAM.

:312)

DIM

CODE

112)12)

90

FOR

X=0

TO

2 STEP 2

100

P1-=CODE

110

STATUS=&FEeJ8

120

RS423=&FEeJ9

130

OSBYTE=~,FFF4

140

OSWRCH=8SFEE

150

C 'ASSEMBLER

CODE

150

OPT

X

1

70

•

LOOP

i

812)

LDA

#12l

1

190 BIT

STATUS

\ANYTHING

RECEIVED?

200

BEQ

getkeY

\BRANCH

IF

NOT

210

LDA

RS423

220

BMI

getkeY

\DON'T PRINT

STATUS

BYTE

230

JSR

OSWRCH

2412l

.9etkeY

250

LDA

#8,81

250

LDX

#00

270

LDY

#00

280

JSR

OSBYTE

290

TYA

300

CMP

#&-FF

3 10

BEQ

LOOP

\NO

KEY

PRESSED,

LOOP

320

CMP

#&1B

\IS

IT

ESC?

330

BNE

CHAR

340

LDA

#&7E

\YES

CLR

ESC

FLAG

...

350

LDX

#0

350

LDY

#12l

370

JSR

OSBYTE

380

LDX

#&-1B

\...

REPLACE

BY

ASCII "ESC"

390

.CHAR

400

TXA

410

CMP

#8,8A

\IS

IT

"CURSOR

DOWN"?

420

BNE

OUT

43©

LDA

#8.·A

\

RE?LACE

BY

II

LINEFEED

II

440

.OUT

\RS

423

OUTPUT

ROUTINE

450

PHA

450

LDA

#&02

470

.

lJUT1

480

BIT

STATUS

4'30

BEQ

OUT1

500

PLA

510

STA

RS423

520

JMP

LOOP

530

J

540

REM

END

OF

ASSEMBLER

CODE

550

CLS

570

REM

DISA~LE

CURSOR

KEYS

CGET

ASCII)

580

=+=FX4,

1

530

REM

TC=75

baud

S01Zl

:+:FX

8,

1

510

REM

RC=75

baud

520

=+:FX

7,

1

S30

CALL

CODE

ICS AMT-1 User manual

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