Bruel & kjaer 4440 User manual

Instruction

Manual

Gating System Type

4440

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TVP"

4440

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'I(~.

•

,..-

---

Measurmg

Gate- - -

--

Delay

An

instrument

that

al

lows

transducers

to

be

calibrated

accurately

even

in

the

presence

of

reflections,

the

4440

cuts

out

the

echoes

caused by

the

boundaries

of

the

en-

closure

so

that

free-field

conditions

are

arti

-

ficially

achieved

. The

input

continuous

sine

signal is gated

to

obtain

a

driving

tone

burst

. The

detector

is gated and delayed to

match

the

distance

between

the

transmitter

and

the

receiver, and

the

peak level is de-

tected

. The

gate

width

(pulse

length).

tone

-

burst

repetition

frequency,

and

delay

be-

tween

the

output

signal

and

the

measuring

gate

can

all

be

adjusted

to

suit

individual

re-

quirements

.

Apart

from

transducer

calibra-

tions,

many

other

applications

are possible:

for

example,

generation

of

accurately-timed

pulses

and

transients

for

echo

investiga-

tions

,

absorption

measurements

, and

medi

-

cal and

biological

research

measurements

.

~

BrLiel

& Kjrer

~

__. . __ _ _

._

_ _

-.J

GATING

SYSTEM

TYPE

4440

Revision November

1977

CONTENTS

1.

INTRODUCTION

AND

SPECIFICATIONS (PRODUCT DATA) ................................................. 1

2.

CONTROLS.

......................................................................................................................... 5

2.1.

FRONT

PANEL ........

..

...............

..

.............

..

....

...

..

..........

....

................... 5

Transmitter

section.....

..........

..

......

........

....

......

............

..

.........

....

..

5

Measuring gate section .........

..

........................

..

...................

..

.............. 6

2.2.

REAR

PANEL ...........................

..

...

..

.................

..

...

................

.................. 6

Transmitter section .......

..............

.

................

..

....

......

................................

7

Measuring gate section

...............

......

....

......

..

.

..

.

..

.........

..

.

.........................

7

3.

OPERATION ......................................................................................................................... 9

3.1. PRELIMINARY ......

..

.

...........

..

.....

..

...........

.

.............

..

.............. 9

Mounting

...............................................

~

...............................................

9

Mains

Voltage Selection and Fuse ..........

..............

......

..

...........................

9

3.2.

GENERAL

.........

..........

...............

.

.........

....

..

......................

.....................

9

Operation of the Transmitter Pulse section ...........

.....................

.................

10

Operation of the Measuring section

....................................................

.

..

....

11

3.3. OPERATION

OF

THE

4440

AS SAMPLE AND HOLD SYSTEM .....

.................

11

4.

ACCESSORIES ....................................................................................................................

13

4.1 . CABLES

....

...

..........................................................................................

13

4.2

. RACK MOUNTING

...............

..

..................................................................

14

4.3

. MOUNTING

IN

A MAHOGANY CASE

.........................................................

14

5.

BIBLIOGRAPHY ...................................................................................................................

15

5.1. HYDROPHONE CALIBRATION

....................

.........................

......................

15

5.2.

LOUDSPEAKER MEASUREMENTS ...............

................

.............

..

..............

15

FEATURES:

•

Output

tone

bursts

with

frequency

DC

to

200

kHz

• Gated

measurement

section

•

Variable

burst

repetition

rate

•

Adjustable

burst

length

•

Adjustable

delay

between

output

gate

and

measuring

gate

•

Variable

measuring

gate

width

-

• Peak

detector

with

sample

and

hold

•

DC

and

AC

outputs

for

measurement

and

display

•

Trigger

outputs

from

both

gate

circuits

USES:

• Free

field

measurement

in

reflective

environments

•

Automatic

recording

of

polar

and

frequency

response

diagrams

•

Calibration

of

hydrophones

and

projectors

in

small

bounded

water

tanks

•

Calibration

of

microphones

and loudspeakers

•

Generation

of

calibrated

tone

bursts

and

transients

• Checking

the

performance

of

amplifiers,

filters,

detectors,

and

the

ballistics

of

meters

• Research

into

echoes

and

reflection

effects

•

Accurate

division

of

an

input

sine

signal

•

Generation

of

accurately

delayed

trigger

impulses

14

-

177

type

4440

Gating

System

Gat

ing

Sy

stem

Typ

e

4440

On

Detector Reset

Flt1C

Pulse

OWrload

• Power

Tng Bruel & K

Jller

r--

-Tr3nsllu

ttcr

Pul

se

- -

--,

Ra

te

Wrdth

HI

OlS

Trig

The

Gating

System

Type

4440

is

the

instrument

that

allows

trans-

ducers

to

be

calibrated

accurately

even

when

reflections

are

present_

It is no

longer

necessary

to

calibrate

hydrophones

and

projectors

in

large

bodies

of

water

,

or

microphones

and

loudspeakers

in

anechoic

cham-

bers

to

achieve

free

field

conditions

,

as

the

4440

eliminates

the

echoes

caused by_

the

boundaries

of

the

en-

closure

.

Calibration

is

achieved

by

emit-

ting

an

impulse

from

the

transmit-

ting

side

of

the

Gating

System

(shown

schematically

in

Fig.1).

and

then

measuring

the

received

signal

for

only

a

short

period

during

the

time

when

the

direct

signal

is

being

received.

This

locks

out

the

re-

flected

signals

completely

', and

gives

measuring

results

corresponding

to

those

obtained

under

free

field

con-

ditions

.

As

transducers

and

enclosures

are

available

in

various

sizes,

the

frequency

,

length

,

and

repetition

rate

of

the

output

burst,

and

the

po-

sition

and

width

of

the

measuring

gate

in

the

4440

can

be

adjusted

to

(

Delay

ms

match

a

wide

range

of

dimensions

.

These

ranges

of

adjustment

have

been

chosen

to

be

equally

suitable

for

calibrating

hydrophones

in

small

water

tanks

, and

for

calibration

of

microphones

and

loudspeakers.

Gating System

Pul

se

Pea

k Level

Generator

r--

Detector

Out

Time

Sequence

Input

Zero

Delayed

~

Crossing

'---

Measuring

Gate Gate

r--

'-

-----_.

-_ . -

Direct Signal Echo

Trans-

-----

mitter

..

-----

.

~~~

Receiver

740628

Fig.1 .

The

basic

principle

of

the

Gating

Sys

-

tem

Generator

Input

Amplifier

Tone

Burst

Gate

Pulse

Out

Output

f--------I

Overload

Ampl

ifier Circuit Overload LED

Pul

se

Gate

L-----

__

--------~--------------------------------~.---------------_{O

Output

Int

ernal

Rep

etition

Rate

Generator

Squaring

Circuit

Synchro -Sequencing Adjustable Pul

se

Width

nising Logic

Adju

stable Measuring Gate Delay

LC:..:ir~

c

:.u

i:.:.t

-1------i......-_-.-JAdjustable Measuring Gate Width

I Trigger Mode Measuring

Gate

Output

L-----------

__________________

~O

Single Shot

External

Trigger

Input

o}----------------------'

Detect R

eset

6±

r-

--------

-,

I I Offset

Signal

Input

I I

I

Filter

I

-12

dB

I

.-----1.

__

-,

Reset

Input

Ampli

fier 1 ,

oct

. 2kHz-

. 200kHz

Many

other

applications

are

possi-

ble

using

either

the

transmitting

or

the

measuring

,

or

both

sides

of

the

instrument

.

These

further

applic

-

ations

include

checking

the

per

-

formance

of

compressor

amplifiers

,

measuring

the

bandwidth

of

tuned

filters

or

amplifiers

,

and

generation

of

accurately

timed

pulses

and

tran-

sients

for

echo

investigation

,

absorb

-

tion

measurements

,

and

for

medical

and

biological

research

.

Description

The

Gating

System

Type

4440

consists

of

a

tone

burst

gate,

and

a

measuring

gate

followed

by a peak

detector.

A block

diagram

of

the

Gat-

ing

System

is

shown

in

Fig.2

.

Transmitting

Section

The

burst

generator

,

consisting

of

Input

Amplifier

and

MaS

Tone

Burst

Gate, receives

the

signal

from

an

external

generator

via GEN

IN

,

and

emits

it

as

calibrated

tone

bursts

via

the

PULSE OUT sockets.

Triggering

mode

is

selected

by a

front

panel

knob

.

When

"Int.

Rate

Gen."

is selected,

triggering

is

con-

trolled

by

the

Internal

Repetition

Rate

Generator

which

has

fre-

.

quency

adjustable

from

0,5

to

15Hz

.

This

frequency

range

is

suit

-

2

Buffer

1

Com -

parator

Measuring

Gate

Logic

DC

Output

1---4---\.O

AC

Output

L-----------------~--------------------------_40

740627

Fig.2.

Block

diagram

of

the

Jype

4440

Gating

System

~

IV

.~

~

AC OUlput

FIller

Q

Lon

Gate

OU

l

put

C

Mad

e

In

Denmark

/I.J

Fig

.3.

The

rear

panel

of

the

Type

4440

able

for

transducer

calibration

in

water

and

in

air

.

Selection

of

"

Single

pulse

"

allows

triggering

of

single

pulses

, released by a

spring-

off

switch

on

the

front

panel.

When

"Ext.

Trig."

mode

is

selected,

trig-

gering

is

accomplished

by

an

exter-

nal TTL

compatible

source

applied

at

the

EXT. TRIG . socket.

This

per-

mits

remote

controlled

triggering,

for

example

by

a

computerised

cali-

bration

system

.

The

input

signal

is also fed via a

Squaring

Circuit

to

the

Synchronis-

ing

Circuit

which

ensures

that

the

Tone

Burst

Gate

opens and closes

on

a zero

crossing

point

in

the

input

signal

to

get

a

coherent

burst.

with

-

out

transients

or

phase

distortion

.

The

Synchronising

Circuit

is

the

master

triggering

unit

for

all

time

se-

quencing

components.

It

starts

the

pulse

width

timer,

which

is a one-

shot

multivibrator

in

the

Sequen

~

cing

Logic,

and

closes

the

Tone

Burst

Gate

again

after

receiving

a

return

impulse

from

the

timer.

The

Synchroniser

is

inhibited

from

start-

ing

another

burst

until

all

the

se-

quences

are

completed.

This

self

ad-

justment

means,

for

example

,

that

despite

incorrect

control

settings

,

the

repetition

rate

can

never

be

made

shorter

than

the

pulse

width.

The

total

combined

coarse

step

and

fine

adjustment

of

pulse

width

, al-

lows

the

selection

of

bursts

with

widths

between

0,1

milliseconds

and

1,0

second

.

Measuring

Section

Similarly

,

the

Synchronising

Cir-

cuit

starts

timers

in

the

Sequencing

Logic

that

control

the

Measuring

Gate

delay

,

and

the

Measuring

Gate

width

.

These

timers

are

also

equipped

with

coarse

and

fine

ad-

justment

so

that

the

Measuring

Gate

can be

delayed

after

the

start

of

the

emitted

burst

for

periods

that

are

adjustable

between

0,1

millisec-

onds

and

1,0

second,

while

the

Gate

width

can

be varied

from

0,03

milliseconds

to

1,0

second.

The

signal

to

be

measured

enters

at

the

SIGNAL

INPUT

socket

and

passes

to

a

filter

that

can be

switched

into

the

line

for

use

dur

-

ing

hydrophone

calibration

.

It

gives

a slope

that

falls

12 dB/

oct.

over

the

frequency

range

2 kHz

to

200

kHz to

counteract

the

12

dB/

Gen. I

Sine Random Generator 1027

Power

Amplifier

Projector

I.

~

_

____

_

I.

8100 d

Water Tank

oct

. rise

in

response

to

v~ltage

when

a

piezoelectric

hydrophone

is

used

as a

projector.

It

aIso

gives

-

12

dB/ oct.

from

2 kHz

to

attenu-

ate

low

frequency

noise

in

the

sys-

tem

.

From

the

Filter,

the

signal

passes

through

a

Buffer

into

the

measuring

section

.

The

Measuring

Gate

Logic

is a

control

gate

that

only

allows

the

peak

sampling

to

occur

during

the

preset

"

gate

"

interval

,

blocking

sampling

at

all

other

times

.

To

obtain

a

fast

response

time

,

great

sensitivity

,

and

a good dy-

namic

range

from

the

Peak

Detec

-

tor,

the

peak level

of

the

i

ncom

ing

signal

is

sampled,

held

,

and

com-

pared

with

the

held

peak

level

ob-

tained

during

the

in

the

burst.

If

the

incoming

peak level

is

the

lower,

the

earlier

held

level is

retained,

but

if

the

new

level is

the

higher,

the

output

from

the

Compar-

ator

increases

stored

level

up

to

the

higher

level.

In

this

way

the

voltage

stored

in

the

Hold

circuit

at

the

'

end

of

the

measur

ing

period

is

exactly

proportional

to

the

peak lev-

el

attained

while

the

gate

was

open.

Further,

holding

the

level also

prevents

discontinuities

in

the

Level

Recorder

trace

during

the

"o

ff"

peri-

ods

in

the

duty

cycle.

The

Hold

circuit

is

reset

automati-

cally

by

the

internal

Logic

just

be-

Receiver

8100

Measuring

Amplifier

2606

c = velocity

of

sound (in water)

fore

each

measuring

period.

When

necessary,

the

held

level can be

cleared

manually

by

selecting

"De-

tect

Reset

"

on

the

front

panel

toggle

switch,for

example

to

clear

the

Hold

circuit

after

a

single

pulse

.

Examples

of

Use

The

main

application

for

the

Gat-

ing

System

is

for

automatic

record-

ing

of

fixed

frequency

polar

curves

and

fixed

direction

frequency

sweeps.

Transducer

Calibration

Fig.4

shows

a

typical

arrange-

ment

that

permits

automatic

plot

-

ting

of

polar

ca

libration

charts

for

a

hydrophone

(or

projector)

. The

out-

put

of

the

Sine

Random

Generator

Type

1027

is gated

into

a

series

of

tone

bursts

by

the

4440

and

ampli-

fied

if

necessary,

by a

Power

Ampli-

fier

to

give

a

suitable

signal

level.

It

is

transmitted

to

a

Standard

Mea-

suring

Hydrophone

Type

8100

that

operates

as a

proje

c

tor

,

emitting

a

series

of

pulses

under

water.

Where

an

Oscilloscope

is being

used

to

display

the

received

signal

and

to

monitor

the

measuring

gate

position,

the

output

from

Transmit-

ter

GATE OUT can be

used

to

trig

-

ger

the

Oscilloscope

.

The

receiver

Hydrophone

(a

Type

8100

is

shown)

is

mounted

on a

Turntable

Type

3922

so

that

the

po-

lar

characteristics

ca n be

charted.

Waveforms

with

Frequency approx. 70 k

Hz

I Emitted Tone Burst

----1

d/c

~-

I

11&

Receiver

Signa

l

______

..-..i

...

---.4IM~I

..........

_-

n Measuring Gate

_---1

L-

__

----=--

__

_

I Measured Signal

7

40

62

6

Fig.4.

Arrangement

used

for

calibrating

hydr

ophones

in

small

water

tanks

3

The

receiver

signal

is

amplified,

it

may

also be

filtered

to

remove

low

frequency

components,

then

the

sig-

nal

is passed

to

both

the

Oscillo-

scope

and

to

the

SIGNAL

INPUT

on

the

4440.

A

suitable

delay

is

arranged

to

match

the

dimensions

of

the

tank

in

use, so

that

the

measuring

gate

is

open

only

while

the

direct

signal

is

being received,

and

shut

when

the

reflected

signals

arrive.

The

figure

also

shows

a

typical

emitted

burst,

the

received

signal

complete

with

echoes, and

the

Measuring

Gate

sig-

nal

showing

the

position

of

the

meas-

uring

period. ·

Since

the

transmitting

response

of

the

Standard

Hydrophone

8100

can

readily

be

determined

by

per-

forming

a

reciprocity

calibration

,

the

sensitivity

of

the

unknown

can

be

obtained

from

:

Sh

= -

20

log E - Sv +

20

log d

+

20

log e

where

Sh

Voltag

e

sensitivity

of

unknown

E =

Voltag

e across

transmitter

TRANSMITTING

SECTION

Input:

0,3 to 1 V RMS

Output

:

15

V peak

(200

mA

peak cu

rr

ent

,

10

nF

/

200

kHz,

800)

Output

Impedance:

Less

than

1 0

Frequency

Range

:

DC

to

200

kHz ±

0,5

dB

Pulse

Gate

Output:

500

impedance, TTL

compatibl

e

Pulse

Rate

(int

ernal rate

generation)

:

0,5 to

15Hz

±

10

%

Pulse

Duration

:

100

Jl.S

to 1 s ±

10

% (coarse steps and

fine

adjustment)

External

Triggering:

DC

to

200

Hz (usable up

to

2 kHz), TTL

comp

a

tjble

Zero

Crossing

Accuracy:

± 1

Jl.s

at

low

frequencies

,

10

°

at

high

fre

-

quency

Sv

Transmitting

response

to

voltage

d

Distan

ce

between

transducers

e

Voltage

across

receiver

Thus,

by keeping E and d

constant,

it

is

only

necessary

to

measure

e.

Microphones

and

loudsp

eakers

can

be

calibrated

in

air

using

a

simi

-

lar

arrangement

and

method

.

Echo

Investigation

When

a

calibrated

source

and re-

ceiver

are

being

used,

the

delay

be-

tween

the

generated

pulse

and

the

measuring

gate

can be

extended

and

the

echoes

examined

to

find

ab-

sorbtion

and

reflection

coefficients

and

the

reverberation

time

of

the

en-

closure.

Transmission

line

echoes

can

be

examined

in

a

similar

way

.

Use

of

Tone

Burst

Generator

alone

The

tone

burst

generator

can

also

be used

in

making

the

following

per

-

formance

checks on

electronic

com-

ponents

and

circuits:

response

time

of

detectors

and

compressor

amplifiers,

Specifications

4440

MEASURING

SECTION

Delay

:

Initial

delay = 50Jl.s ±

10

%

100

Jl.s

to 1 s ±

10

% (coarse steps and

fine

adjustment)

Gate

Width

:

30

Jl.S

to 1 s ±

10

% (coarse steps and

fine

adjustment)

Measuring

Gate

Output

:

500

impedance TTL

compatible

Gain

in

Linear

Mode

(20

Hz to

200

kHz):

OdB

±O,5d

B

between

SIG . INPUT and

AC

OUT

OdB

(peak) ± O,

5dB

between

SIG. INPUT

and

DC

OUT

Filter

:

-

12

dB/oct.

between

2 kHz and

200

kHz

Dynamic

Range

of

Amplifiers

and

Detec

-

tor

:

Greater

than

50dB

AC

Output

:

Maximum

1

OV

peak

overshoot

of

compressor

amplifi-

ers

and

the

ballistics

of

meters

,

settling

time

for

meters,

amplifi-

ers,

etc.,

rise

time

,

and

hence

the

band

width

of

tuned

circuits,

recovery

time

of

compressor

am-

plifiers,

power

rating

of

audio

amplifiers

.

The

zero

crossing

gate

can also

be used as

an

accurate

frequency

divider

on

input

sine

signals.

Tone

bursts,

and

also noise

bursts

can be

generated

for

use

in

medical

and

biological

research

into

hearing,

and

to

stimulate

nerves

and

muscles.

Use

of

Measuring

Gate

and

Delay

alone

When

a

TIL

compat

ible

switching

pulse

is

applied

to

the

EXT. TRIG.

socket, and a

signal

(such as

200

kHz) applied

to

GEN . INPUT

to

provide

the

zero

crossing

required

to

operate

the

time

sequencing

,

the

measuring

gate

and

delay

may

be

used

alone,

for

example

when

some

other

burst

generator

is

to

be used.

DC

Output

:

Maximum

+ 1

OV

to - 3 V

Detector

Modes

:

R

epetitive

:

Internal

or external

triggering

Single

Pul

se

: Less

than

± 1 dB

drift

after

10

minutes

Hold

time

(the detector is au-

tomatically

reset in

both

modes)

Detector

Free:

Hold for

single

pulse,

with

less

than

± 1 dB

drift

in

10

minutes

Operating

Temperature

Range

:

+ 5°

to

40

°C (41 ° to

104

°

F)

Power

Supply

:

100

to

240

V

50

to

60

Hz, approx.

10

W

Accessories

Supplied:

Power

Cable

AN

0010

Dimensions

:

Height:

132

,6

mm

(5,2 in)

Width

:

209

,5

mm

(8

;3 in)

Depth

:

200

,0

mm

(7

,9 in)

(KK

0025

Cabinet, 6/

12

of

19

" rack mo-

dule)

Weight

:

3

kg

(6,6

Ib)

2.1.

FRONT

PANEL

Ot~le(:tIlt

At~s(n

Fr~e

SWt91l~

l"ulsc

TOil

2.

CONTROLS

Gating

SY$t

em

Type

4440

On

Overload ?cw(H

• Bruol

&I(Jo1I!'f

,----Transmittcr

PoIse

-----,

,----

Measuring Gate

-----,

Rate

H,

Trig

Width

ms Delay

ms

Width

Fig. 2.

1.

Front

panel

of

the

Gating

System

Type

4440

ON

:

Switch

for

turning

the

instrument

on and

off

.

POWER:

Indicator

lights

when

the

power

is

switched

on

.

OVERLOAD:

Light

emitting

diode

indicating

when

lit

that

the

output

amplifier

is

overloaded.

2.1 .

1.

Transmitter

section

TRIGGER SELECTOR:

RATE

:

3-position

switch

allowing

the

choice

of

trigger

mode:

"Internal

Rate

Gen.

":

this

position

allows

the

transmitter

section

to

be

triggered

by

the

internal

rate

generator.

"Single

Pulse":

allows

the

transmitter

section

to

be triggered once by

depressing

the

toggle

switch

SINGLE PULSE

"Trig"

.

"Ext.

Trig":

connects

the

rear panel BNC socket EXT. TRIG

for

the

in-

put

of

an external

trigger

signal.

Potentiometer

which

controls

the

rate

of

the

i

nternal

generator

from

5

WIDTH:

0,5

to

15

Hz

±

10%

when

the

TRIGGER SELECTOR

switch

is

set

to

"In-

ternal

Rate

Gen.".

Two

controls

to

set

the

width

of

the

transmitted

signal:

The

a-position

rotary

switch

gives

the

lower

values

of

the

a stepped

ranges

of

width

of

the

transmitted

signal

from

0,1

ms

to

300

ms,

while

the

potentiometer

provides a

continuous

adjustment,

multiply-

ing

the

range indication by 1

to

3.

SINGLE PULSE TRIGGER: A toggle

switch

having

two

fixed and one

press/release

position:

"Detector

Reset":

resets

the

peak detector.

"Single

Pulse

Free":

stand-by and hold position.

"Single

Pulse

Trig":

for

single tone

burst

generation only.

2.1.2.

Measuring

gate

section

DELAY:

WIDTH:

2.2.

REAR PANEL

6

Two

controls

to

adjust

the

delay

of

the

measuring

window:

The a-position rotary

switch

gives

the

lower

values

of

the

a stepped

ranges

of

delay

from

0,1 to

300

ms,

while

the

potentiometer

provides

a

continuous

adjustment,

multiplying

the

range indication by 1 to 3.

Two

controls

to

adjust

the

width

of

measuring

window:

The 9-position rotary

switch

gives

the

lower

values of

the

9 stepped

ranges

of

the

width

of

the

measuring

window,

from

0,03

to

300

ms,

while

the

potentiometer

provides a

continuous

adjustment,

multiplying

the

range indication by 1

to

3.

r Measuring Gat'"

--,

~

l/)

Offset

Actj

oc

0!J.

tpUI

• G

c:

....

A,

C

Output

Filter e

lin

GOlte

Output

~

Made

In

Denmark

(][)

Fig. 2.2.

Rear

panel

of

the

Gating

System

Type

4440

MAINS

VOLTAGE SELECTOR

AND FUSE:

MAINS

SOCKET:

2.2.1.

Transmitter

section

GEN. INPUT:

EXT

. TRIGGER:

GATE OUTPUT:

PULSE OUTPUT:

2.2.2.

Measuring

gate

section

DC

OUTPUT:

OFFSET

ADJ.

:

AC OUTPUT:

Voltage selector

for

selection

of

the

appropriate mains voltage;

the

se-

lector also

contains

a

slow-blow

mains

fuse. See section 3.1 .

Input

socket accepting

the

power

cable AN

0010

provided

for

connec-

tion

of

an AC

mains

supply. Its

wiring

connection is

shown

in

Fig.2.3.

Blue

Neutral

Brown

~~p~~ywer

"oJ

Live

[

I~

I J

~

Green and

Yellow

Ground

172246

Fig

.2.3. Connections to

AC

Power

Socket

A BNC socket

for

the

input

of

the

signal generator. Accepts

the

stan-

dard BNC plugs B & K No.

JP

0035

or

the

cables

AO

0064

and

AO

0087

(see section 4).

Input

impedance:

11

kO.

A BNC socket

for

the

input

of

the

trigger

signal.

Input

impedance:

1 kO,

TIL

compatible.

A BNC socket

for

the

output

of

digital

information

of

the

opening

of

the

transmitting

gate. Impedance

500,

TIL

compatible.

One

standard B & K socket and one BNC socket, connected in parallel,

for

the

output

of

the

tone

burst. The standard B & K socket accepts

the

plug JP

0101.

Output

impedance less

than

1 O.

A BNC socket

for

the

output

of

the

continuous

peak level

of

the

signal

received

during

the

opening

of

the

measuring

window.

Multiturn

potentiometer

to

adjust

the

DC

offset

of

the

DC

OUTPUT

from

-5

to + 10 mV.

A BNC socket

for

the

AC

output

of

the

signal applied

to

the

SIGNAL IN-

PUT,

the

AC OUTPUT signal being

filtered

or

not

according to

the

filter

switch

setting.

Output

impedance

500;

should

not

be loaded by less

than

3,3

kO.

Note:

With

the

filter

bypassed,

there

is 0 dB gain

between

the

SIGNAL

INPUT and AC OUTPUT,

however

there

will

always

be a

170

0 phase

shift

between

the

two

.

7

FILTER

:

SIGNAL INPUT:

GATE OUTPUT:

8

A

2-position

slide

switch

with

the

following

functions:

"Lin

.

":

the

input

signal is

directly

fed

to

the

AC

output

buffer.

"Filter":

the

input

signal is

weighted

by

-12

dB/octave

in

the

2 kHz

-

200

kHz

frequency

range to

counteract

the

12

dB/octave rise

in

re-

sponse to voltage

when

a piezoelectric hydrophone is used as a projec-

tor

.

A BNC socket

for

the

input

of

the

received signal to be measured.

Input

impedance:

50

kO.

A HNC socket

for

the

output

of

digital

information

of

the

opening

of

the

measuring

window

. The GATE OUTPUT is

TIL

compatible, fan

out

of

10TIL

.

3.

OPERATION

3.1.

PRELIMINARY

3.1.1.

Mounting

The

4440

can be used free-standing (cabinet type A) on its

four

rubber feet or in the

Bruel & Kjrer Rack

Mounting

System described in

the

KA, KK,

KS

Instruction Manual.

See section 4.

The

4440

is a

KK

0025

cabinet,

6/12

of

19"

rack module. Its dimensions and

weight

are given in

the

specifications, chapter 1.

3.1.2.

Mains

Voltage

Selection

and

Fuse

3.2.

GENERAL

Before use,

the

4440

should

be

checked

for

proper mains voltage operation. The mains

voltage selector holds

the

fuse and allows

the

choice

of

mains voltage operation at:

100V, 115V, 127V, 150V,

220V

and

240V,

at

50to

60Hz.

The power consumption

is approximately

10W.

To change

the

fuse

or

to select

the

proper mains voltage,

the

procedure is as follows:

Unscrew

the

black central knob and pull

it

straight

out

with

the

fuse. To select

the

mains voltage, pull

the

black voltage selector bush straight

out

and replace

it

so

that

the

metal pin

of

the

bush is opposite

the

appropriate voltage

which

appears

in

the

window

of

the bush. Then replace

the

fuse and

the

black central knob.

The rating

of

the

fuse is

O,2A/250V

slow-blow

type, B & K reference

VF

0012.

Once

the

VOLTAGE SELECTOR has been set to

the

correct mains voltage, the mains sup-

ply may be connected

to

the

MAINS INPUT socket using

the

power cable AN

0010

pro-

vided. To

fit

a suitable mains plug to

the

cable, see

Fig.2.3.

The

4440

is

now

ready

for

operation since no calibration is needed.

The operation

of

the

4440

requires

the

use

of

a

twin-channel

.oscilloscope

to

monitor

the

wave forms and adjust

the

respective positions

of

the

pulse gate and measuring

win-

dow. In certain instances, a 4-channel oscilloscope may be found useful. See Figs.3.1

and

3.2.

See section 4

for

the

references

of

the

standard B & K cables to

be

used.

9

Sine Random Generator

1027

To "Gen. Input"

From "Pulse

Output"

Gating System

4440

Emitted tone burst

Trigger Signal from

"Gate

Output"

150570

Fig. 3. 7.

Set-up

for

the

4440's

Transmitter

Pulse

Section

adjust-

ments

Sine Random Generator

1027

Lf

ating System

4440

'I

."";

• •

Oscilloscope

From "Gate

Output"

.;

.~

~

@'e':I,:

:

••••

I I

I,

•

--I!.@'

".

:-'l

Trigger Signal from

"Gate

Output"

From"

AC

Output

"

To "Signal

Input"

Signal

to

be

sampled

750571

Fig. 3.2.

Set-up

for

the

4440's

Measuring

Section

adjustments

3.2.1

.

Operation

of

the

Transmitter

Pulse

Section

10

1.

Switch

the

power on. The POWER indicator should light.

Allow

a

few

seconds for

stabi

Iisation.

2. Set

the

external signal source generator to

the

required frequency and adjust its out-

put

level to

suit

the

4440's

GEN. INPUT level requirement, i. e.

within

0,3

and 1 V

RMS.

3. Connect

the

signal from

the

generator

to

the

GEN

. INPUT socket on the rear panel

of

the

4440

.

4. To adjust

this

arrangement, set TRIGGER

SELECTOR

to

"Internal

Rate Gen

."

and

RATE

to

"15

Hz".

5. Check

that

no overload occurs. If

the

OVERLOAD indicator is lit. monitor

the

in-

put

signal.

An

overload due to capacitive loading can be indicated

without

overload-

ing the amplifier itself, i. e.

the

rise

time

of

the

burst

draws

peak current. thus trig-

gering

the

OVERLOAD indication. For instance,

with

10

nF capacitive load, overload

is indicated

from

approximately

100

kHz and up

with

an

output

of

14,1 V peak. The

1V RMS

input

level is an indicating

limit

set by specifications,

but

the

amplifier

can

output

without

distortion

up to

15,5

V peak,

230

mA

peak; therefore an oscilloscope

is very useful

for

setting

up

and monitoring.

6.

Monitor

PULSE OUTPUT on

the

first

channel

of

the

oscilloscope and,

if

desired, the

in-

put

signal on

the

second one. The oscilloscope may be synchronised in external

trig-

ger mode by

the

GATE OUTPUT signal, giving precise

information

of

the

tone

burst

length

which

can be measured

with

the oscilloscope.

7. Set the required

trigger

mode and trigger rate

if

necessary.

If

the

external trigger

mode is used, the external trigger signal should be applied to the EXT.

TRIG

. socket

on

the

rear panel.

The

transmitter

section

of

the

4440

now

operates and gives a well-defined tone

burst.

8. Apply the tone burst to the relevant

equipment

and

monitor

the

PULSE

OUTPUT

to

ensure

that

the characteristics

of

the

tone

burst

still

remain

the

same.

3.2.2.

Operation

of

the

Measuring

section

1.

Short

circuit

the

SIGNAL INPUT socket and

monitor

the

DC

OUTPUT.

If

necessary ad-

just

the

DC

offset by means of the screwdriver-operated OFFSET

ADJ.

potentiome-

ter. The

DC

offset voltage is adjustable

within

-5

and +

10

mV.

2. Apply the received signal

or

the

signal

to

be sampled to the SIGNAL INPUT socket

and

monitor

it

through

the

AC OUTPUT socket on channel 2

of

the oscilloscope.

3.

Monitor

the

GATE OUTPUT on channel 1

of

the

oscilloscope and make

the

neces-

sary adjustments to

the

delay and

width

of

the

measuring

window.

The oscilloscope

remains synchronised by

the

GATE OUTPUT signal

of

the

transmitter

section.

4.

If

necessary, move

the

FILTER

SWITCH

to

"Filter",

e. g.

if

the

purpose is to calibrate

a piezoelectric hydrophone to be used as a projector, in order to compensate

for

its

12

dB/octave

rise

when

used as a projector.

The measuring gate

now

operates and provides at its

DC

OUTPUT socket a

DC

voltage

proportional to

the

maximum

value occuring

when

the

measuring

window

was

open.

The

DC

voltage is held to avoid the voltage dropping to zero between pulses.

3.3.

OPERATION

OF THE

4440

AS

A

SAMPLE

AND

HOLD

SYSTEM

The Gating System Type

4440

can be used as a sample and hold system because

of

the

ability

of

its

output

section to detect

whether

the

input

signal is greater

or

lower

than

the

DC

hold level. See

Fig.3.3

. The hold level is compared

with

the

input

signal, and

the

comparator logic decides

whether

a positive-going

or

negative-going

current

is to be

fed

through

the

capacitor,

thus

allowing

a positive

or

a negative signal to be held, corre-

sponding to

the

positive

or

to the negative

input

signal

which

has been sampled.

For

that

particular operation,

the

delay and

the

width

of

the

measuring

window

are ad-

justed to sample

the

required part

of

the

input

signal. The peak detector

then

gives a

DC

voltage (maximum value

of

+ 7 V) for a sample of

the

positive part

of

the

input

signal,

and a

maximum

negative value

of

-3

V

DC

for

a sample

of

the

negative part

of

the

in-

11

DC

o-----t

>-_~

Comparator

Logic

AC

Input

<

DC

Measuring

Gat

e

Input

>

DC

+12

V

Output

-6V

150572

Fig. 3.3. Block

Diagram

of

the

Output

Section

of

the

Measuring

Gate

of

the

4440

12

put

signal. This means

that

if

the

peak-to-peak value

of

a symmetrical signal is less than

6 V (+ 3,

-3

V), every part

of

the signal can be sampled and held (Fig.3.4a);

the

same

applies to a non-symmetrical signal

within

a peak-to-peak value

of

+ 7,

-3

V, see Fig.

3.4b.

One sample remains held

if

the

4440

is used

in

the

"Single

Pulse"

triggering

mode, or

in

the

"Ext."

triggering mode,

when

a single trigger pulse is delivered.

Hold Le

vel

o

a)

-=------------

+7 V - - - - - 1 Hold

Level

o

b)

-3

V

750

5

73

Fig

.3.4. Sample

and

hold

possibilities

of

the

4440

4.1.

CABLES

4.

ACCESSORIES

Fig.4.1 shows the cables for

use

with the

4440

with

their

respective B&K

stock

num-

bers. The

plugs

can

be

ordered separately, if required.

CEE Plug (Female)

AN

0010

472181

JP

0101

AC

0002

JP

0101

AO

0013

470037

JB

0002

JP

0101

AC

0002

JP

0101

AO

0014

1.2

m

470038

JP

0035

AC

0002

JP

0101

[II[]

/

7 AO

0064

I

-

1.2 m 470046

JP

0035

AC

0002

JP

0035

mIP

I j

It

am

AO

0087

1.2m

472183

JP

0106

AC

00J4

JJ

0205

AO

0100

1.3m

412223

Fig.4.1. Cables

for

use with the

4440

13

4.2.

RACK

MOUNTING

The Gating System Type

4440

is housed

in

a B & K KK

0025

cabinet taking

6/12

mo-

dule

of

the

KK

0014

frame. The

mounting

flanges

GV

1037

included in

the

KS

0022

mounting set enable

the

KK

0014

frame to be mounted

in

a

19

inch rack system.

4.3.

MOUNTING

IN

MAHOGANY

CASE

14

The

4440

being in a KK

0025

cabinet

fits

into

a

KA

0042

mahogany case

if

desired. It

is also possible to

mount

the

KK

0014

frame

into

KA

0027

mahogany case.

0A0049f

i @ •

YQ

8087

Itrn!m~~~....-:--

Ji

·

KS

0022

Fig.4.2.

Adaptation

of

the

KK

0014

frame to

19

inch

rack system

5.

BIBLIOGRAPHY

5.1.

HYDROPHONE CALIBRATION

Peter

A.

Levin:

5.2.

LOUDSPEAKER MEASUREMENTS

Henning MlIlller:

Calibration

of

Hydrophones. B & K Technical Review No. 1

1973.

Contains a comprehensive list

of

references.

"Electro Acoustic Free Field Measurements

in

Ordinary Rooms

-Using Gating Techniques". B & K Application Note.

May

1975.

15

BROEL

&

KJ~R

instruments

cover

the

whole

field

of

sound

and

vibration

measurements

.

The

main

groups

are:

ACOUSTICAL

MEASUREMENTS

Condenser

Microphones

Piezoelectric

Microphones

Microphone

Preamplifiers

Hydrophones

Sound

Level

Meters

Precision

Sound

Level

Meters

Impulse

Sound

level

Meters

Noise Dose

Meters

Noise Level

Analyzers

Standing

Wave

Apparatus

Calibration

Equipment

Reverberation Processprs

Sound

Sources

ACOUSTICAL

RESPONSE

TESTING

Sine

Generators

Random Noise

Generators

Sine

-Random

Generators

Artificial

Voices

Artificial

Ears

Artificial

Mastoids

Hearing

Aid

Test Boxes

Audiometer

Calibrators

Telephone

Measuring

Equipment

Audio

Reproduction Test

Equipment

Tapping

Machines

Turntables

VIBRATION

MEASUREMENTS

Accelerometers

Force

Transducers

Impedance Heads

Accelerometer

Preamplifiers

Vibration

Meters

Accelerometer

Calibrators

Magnetic

Transducers

Capacitive

Transducers

Complex

Modulus

Apparatus

Bump

Recorders

VIBRATION

TESTING

Exciter

Controls

-

Sine

Exciter

Controls

-

Sine

-Random

Exciter Equalizers, Random

or

Shock

Exciters

Power

Amplifiers

Programmer

Units

S'troboscopes

STRAIN

MEASUREMENTS

Strain

Gauge

Apparatus

Multipoint

Selectors

MEASUREMENT

AND

ANALYSIS

Voltmeters

Phase

Meters

Deviation

Bridges

Measuring

Amplifiers

Band-Pass

Filter

Sets

Frequency

Analyzers

Real

Time

Analyzers

Heterodyne

Filters and

Analyzers

Distortion

Measuring

Equipment

Psophometers

Statistical

Distribution

Analyzers

Tracking Filters

RECORDING

Level Recorders

Frequency Response Tracers

Tape Recorders

Alphanumeric

Printers

Digital

Event Recorders

DIGITAL

EQUIPMENT

Computers

Tape

Punchers

Tape Readers

Bruel &

Kjcer

DK-2850 NJERUM.

DENMARK

.

Telephone:

+

452800500

.

Telex

: 37316

bruka

dk

BRUEL & KJAER 4440 User manual

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