Ericsson C605 Maxicom User manual

ERICSSON ;i5
Service manual
470 MHz Mobile radio station
C605 Maxicom
Standard version for cipher,
duplex and data communication
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Contents
1. Introduction
General ........................................... 7
2. Technical data
General ........................................... 7
Transmitter
....................................... 7
Receiver
.......................................... 7
Tone receiver and tone transmitter
............... 7
Regulator
......................................... 7
Cipher
............................................ 7
3. Installation
General ........................................... 8
Divided installation
............................... 8
Installation of the control unit
.................... 9
Installation of radio and cipher
................... 9
Installation of handset
with holder
........................................ 9
Installation of loudspeaker ......................
10
DC power connection .......................... 10
External alarm relay ............................ 10
Antenna installation
............................ 10
4. Operating instructions
General ......................................... 11
Controls and indicators ......................... 11
Button set ....................................... 12
Display
......................................... 12
Incoming calls
.................................. 13
Outgoing calls .................................. 13
Other functions ................................. 14
Who has called ................................. 14
Status reporting ................................. 14
Accessories
..................................... 15
5. Circuit description of radio parts
Regulator ....................................... 15
Reciver
......................................... 15
RF section and first IF section .................. 15
Second IF section ............................... 15
Squelch and
AF sections ........................ 15
Duplex transmitter .............................. 16
Generation on the carrier
....................... 16
Controlling the
VCO ........................... 16
Power amplification
............................. 16
Frequency generator
............................ 16
Generation of the carrier ....................... 17
Generation
of the voltage ...................... 17
Acquisition sequence ........................... 17
Control sweep when the
VCO is locked on ..... 19
Divisior and control voltage .................... 19
6. Description of the logic parts
General ......................................... 20
Block diagram description of the
micro computer
................................. 21
General program description
of the
100 channel standard program
.................. 21
7. Description of the cipher circuits
General ......................................... 23
Mechanical design ..............................
23
Transmission of plain text ...................... 24
Transmission of enciphered message ............ 24
8. Checking and adjusting
General ......................................... 25
Test equipment ........ .. ....................... 25
Test set up ...................................... 25
Checking the regulator .......................... 26
Checking and adjusting the frequency
generator ....................................... 26
Checking and adjusting the 1 band receiver ....
27
Checking and adjusting the duplex transmitter 27
9. Trouble shooting
Trouble shooting on unit level
in the car ........................................ 28
Central service ..................................
28
10. Spare parts
Duplex transmitter .............................. 29
1 band receiver ................................. 30
Frequency generator ............................ 31
Regulator ....................................... 31
Logic board ..................................... 32
Control board ................................... 33
PROM board ................................... 33
Display board ................................... 34
Bridgin board ................................... 34
Interconnection unit for cipher ................. 35
Connection unit ................................. 35
Interconnection unit ........................... . 35
Handset with holder ............................ 35
Interface board ................................. 35
Complete units ................ .................. 36
11. Block diagram, circuit diagrams and
component layout
Block diagram .................................. 39
Regulator board ................................ 41
Antenna filter board ..
.. ........................ 43
Connector board for de and radio .............. 45
Connector board for loudspeaker and
handset
......................................... 47
Connector board for radio and logic boards .... 49
Connector board for cipher .....................
51
Bridging board for cipher ....................... 53
Cipher board 1
................................. 55
Cipher board 2 ................................. 57
Interface board for data communication ........ 59
PROM board ................................... 61
Display board ................................... 63
Control board and code board .................. 65
Frequency generator board ..................... 67
Duplex transmitter board .. ..................... 69
1 band reciever board ........................... 71
Basic logic boards ............................... 73
5

6
List of figures
Fig 3.1
The location of the control unit and the radio,
logic
and cipher units in the car ........... 8
Fig 3.2
The front panel, the control board, the display
board
is put together in a housing to form the
control unit ............................... 8
Fig 3.3.
The control unit is installed in plastic housing
and installed into the dashboard of the car
and connected to the radiostation via a flat
cable ................................. ..... 9
Fig 3.4.
The installation of the radio and cipher cas-
settes and the location
of the duplexfilter and
data interface ...... ....................... 9
Fig 3.5.
The connection of the handset to the circuit
board
of the holder ................... .... 9
Fig 3.6.
The connection of the holder's circuit board
to the connection unit .............. ..... . 9
Fig 3.7. The connection of the loudspeaker to the
holder's circuit
board ..................... 10
Fig 3.8.
The connection of the station to the car's
battery
.................................... 10
Fig 3.9.
The connection of the external alarm relay to
the connection unit ....................... 10
Fig 4.1.
The station consists of a control unit, radio
and logic units, cipher unit and duplex filter,
radio
and cipher cassettes .. . .. .. .. .. .. . .. . 11
Fig 4.2.
The control unit and the code memory plug
in board
................................... 11
Fig 4.3.
The handset and its holder with controls and
indicators ................... . . ...... ..... .. 11
Fig 4.4.
The button set includes number buttons for
entering digits
and function selection buttons
for selecting the different functions ..... .. 12
Fig 4.5.
The stations display with channel indicator,
number indicator
and function lamps ..... 12
Fig 5.1.
The control sweep <luring lock-on, measured
at test point Tp7 .......................... 16
Fig 5.2 Control voltage
at TPI when cpA> cpb and
the
VCO is not locked .................... 18
Fig 5.3 Control voltage
at TPI when VCO is locked
and cpA=
cpb from cpA> cpb ........... 18
Fig 5.4 Control voltage at
TPI when cpA< cpb and
the VCO is not locked .................... 18
Fig 5.5 Control voltage
at TPI when VCO is locked
an cpA= cpb from cpA< cpb ............ 19
Fig 5.6 Control sweep when the
VCO locked in
transmission mode. ....................... 19
Fig 5.7 Control sweep when the
VCO locked inre-
ception mode. ............................ 19
Fig 6.1 Block diagram
of the logic parts .......... 20
Fig 7.1.
The ciphering unit .... .. .. .. .. .. .... .. . .. . 24
Fig 8.1 Removing the logic unit from the radio
unit
....................................... 25
Fig 8.2 Connecting the logic eliminator, the duplex
filter and the control unit to the stations
radio unit. ................................. 26
Fig 8.3 Regulator's testpoints
..................... 26
Fig 8.4
Fig 8.5
Fig 8.6
Fig 11.1.
Fig 11.2.
Fig 11.3.
Fig 11.4.
Fig 11.5.
Fig 11.6.
Fig 11.7.
Fig 11.8.
Fig 11.9.
Fig 11.10.
Fig 11.11.
Fig 11.12.
Fig 11.13.
Fig 11.14.
Fig 11.15.
Fig 11.16.
Fig 11.17.
Fig 11.18.
Fig 11.19.
Fig 11.20.
Fig 11.21.
Fig 11.22.
Fig 11.23.
Fig 11.24.
Fig 11.25.
Fig 11.26.
Fig 11.27.
Frequency generator's testpoints
and
trimmers .............. ..... . .... .......... 26
1
band receiver's testpoints and trimmers . 27
Duplex transmitter's testpoints and
trimmers .............. . .... . .... . ......... 28
Block diagram .......... .... . .... . ..... ... 39
Regulator, component layout
............. 40
Regulator, circuit diagram ................ 41
Antenna filter, component layout ......... 42
Antenna filter, circuit diagram ............ 43
Connector
board for de and radio, component
layout
..................................... 44
Connector
board for de and radio, circuit dia-
gram
......... , ............................ 45
Connector board for loudspeaker
and hand-
set, component layout
........ .. ...... .. .. 46
Connector
board for loudspeaker and hand-
set, circuit diagram
.... .. ............ . .. .. . 47
Connector
board for radio and logic boards,
component layout .............. . .... . ..... 48
Connector board for radio
and logic boards,
circuit diagram .......... .... . .... . ........ 49
Connector board for cipher, component lay-
out ........................................ 50
Connector
board for cipher, circuit
diagram
................................... 51
Bridgin
board for cipher, component
layout
..................................... 52
Bridgin board for cipher, circuit diagram . 53
Cipher
board 1, component layout ....... 54
Cipher
board 1, circuit diagram ..... ..... . 55
Cipher
board 2, component layout ....... 56
Cipher
board 2, circuit diagram ..... ..... . 57
Interface
board for data communication, com-
ponent layout ................... . .... ..... 58
Interface
board for data communication, cir-
cuit diagram
.............................. 59
PROM board, component layout ......... 60
PROM board, circuit diagram ............ 61
Display board, component layout .........
62
Display board, circuit diagram ............ 63
Control
board and code board, component
layout
..................................... 64
Control board and code board, circuit dia-
gram
...................................... 65
Fig 11.28. Frequency generator, component layout .. 66
Fig 11.29. Frequency generator, circuit diagram
..... 67
Fig 11.30. Duplex transmitter, component layout
.... 68
Fig 11.31. Duplex transmitter, circuit diagram ....... 69
Fig 11.32. 1
band receiver, component layout ....... 70
Fig 11.33. 1
band receiver, circuit diagram .......... 71
Fig 11.34. Basic logic, component layout ..... ..... .. 72
Fig 11.35. Basic logic, circuit diagram ..... ..... ..... 73
List
of tables
Table 5.1. Divisors
and control voltage .............. 19
Table 8.1.
De levels of regulator board .............. 26
Table 8.2.
De levels at connector Pl ................. 26

1. Introduction
General
C605 Maxicom isa 470 MHzmobileradio stationwith ciph-
er, duplex and data communication facilities.
In
its standard version, C605 Maxicom has functions for in-
dividual calls and group calls, full number calls, automatic
calls, semiautomatic calls, emergency calls and programm-
ing of automatic calls.
Further standard functions are open monitoring, externa!
alarm and retransmission to another station.
In addition to showing channelnumberand call number, the
display tells you if somebody has called you while you were
away, ifthe channel you want to use
is engaged, and also in-
dicates incorrect operation. Optional functions in C605
Maxicom include "Who has called" and status reporting.
Allthese functions areincludedin thismanual. Yourstation,
however, may not have been programmed to incorporate
them
all.
Accessories to C605 Maxicom include carrying case and
desk-top console.
2. Technical data
General
Frequency range:
Mode of operation:
Modulation:
Number
of channels:
Channel spacing:
Frequency stability:
Antenna impedance:
Power supply:
Power consumption
transmission:
reception:
Ambient temperature
specified data:
operational:
storage:
Weight:
Dimensions:
Transmitter
380 ... 470 MHz.
Simplex andduplex.
FM.
10, 20or100.
12.5 or 25 kHz.
+5ppm.
50Q.
12 or24V.
4.5A.
0.5A.
-25"C.
.. +55"C.
-40"C.
.. +70"C.
-55"C.
.. +85"C.
l.9kg.
180 x 212 x 54 mm.
Number of partial bands:
3.
Bandwidth within each partial
band.
12.5 kHz channel separation:
1. 75 MHz.
25 kHz channel separation: 3. 5 MHz.
Output power: 10 or 20 W +1 dB.
Hum and noise: -40 dB.
Unwanted radiation: < 0.25 uW.
Attenuation of modulation
products in adjacent channel.
12.5 kHz channel spacing:
60 dB.
25 kHz channel spacing: 60 dB.
Audio response
12.5 kHz channel spacing:
25 kHz channel spacing:
Reciver
300 ... 2550 Hz, tol-
erance
+l ... -3 dB
rel. -6 dB!octave.
300 ... 3000 hZ, tol-
erance
+l ... -3 dB
rel. 6 dB!octave.
Number of partial bands:
1.
Bandwidth within each partial band.
12.5 kHz channel separation: 1. 75 MHz.
25 kHz channel separation: 3.0MHz.
Sensitivity
(1/2 EMF at 12 dB SINAD).
12.5 kHz channel spacing: 0.45 u
V.
25 kHz channel spacing: 0.35 uV.
Hum and noise: -40 dB.
Selectivity
12.5 kHz channel spacing:
25 kHz channel spacing:
Intermodulation attenuation:
AF power to loudspeaker:
Spurious response attenuation:
Spurious emission:
Distortion:
Audio response.
12.5 kHz channel spacing:
25 kHz channel spacing:
Regulator
Supply voltage:
Regulated voltage:
Voltage tolerance:
Maximum current load (at the
regulated voltage
of 9.3 V):
65dB.
70dB.
70dB.
4W.
80dB.
<2nW.
< 10%.
300 ... 2550 Hz,
tolerance +1... -3 dB
rel. 6 dB!octave.
300 ... 3000 Hz,
tolerance +1... -3 dB
rel. 6 dB!octave.
12 V.
9.3 V.
+O.l V.
""'250mA.
Tone reciver and transmitter
CCIR: 5 tone and
5 and 7 to:?.e.
ZVEI: 5 tone.
No. of selectable combinations:
100 000.
No. of coded calls: 11.
No.
of codes, tone receivers: 4.
Cipher
Traffic type:
Speech digitizing method:
Data rate:
Duplex.
ADM (adaptive delta
modulation).
14.4 kbitls.
Data modulation:
NRZ (non return to
zero).
Data bandwidth: 14-8500 Hz.
Radio bandwidth -60 dB: 55 kHz.
Radio bandwidth -70 dB: 70 kHz.
Temperature range: -1o·c.
.. +55"C.
Number of key combinations: 272
(4. 7x 10
21
).
7

Life of back-up battery
for cipher key: 5 years.
Level to modulator
Cipher mode:
1. 7Vp-p·
Plain text mode: Nom 360 m V,
Level from discriminator
1. 7Vp-p max
increasing 6 dBI
loctave within
300...
2500 Hz.
Cipher mode: 470 m Vp-p·
Plain text mode:
AF level to the radio's
loudspeaker amplifier
Cipher mode:
Plain text mode:
Digital squelch
Cipher reception:
Plain text reception:
Cipher transmission:
Plain text transmisssion:
Link:
Non-link:
AF in at link:
Microphone input:
Data out:
Data in at link:
Clock output:
Key loading:
Supply voltage:
Current consumption:
8
Nom lOOmV,
470 m vp-p max
increasing 6 dBI
loctave within
300 ... 2500 Hz.
Nom 200mVat
1 kHz
increasing 6 dB
loctave within
300 ... 2100 Hz.
Nom 100 mVat
1 kHz
increasing 6 dBI
loctave within
300 ... 2500 Hz.
Grounded.
Open.
Grounded.
Open.
Grounded.
Open.
Nom lOOmV,
470 m vp-p max
increasing 6 dBI
loctave within
300 ... 3000 Hz.
Nom40mV.
7VP-P'
14.4 kbitls.
7V-15 Vp-p
14.4 kbitls.
7VP-P'
14.4 kbitls.
300 bitls
ASCll,
Logic0=7V,
Logic l=OV.
10 ... 16V.
30mA.
3. Installation
General
A complete mobile radio station C605 with cipher, duplex
anddatafacilities consists
of radiowithradiocassette, cipher
unit with cipher cassette, handset with holder, antenna,
du-;
plexfilter, cables for interconnection ofthe parts, a connec-
torunit, mounting platefor thecassettes, housings, covers, 4
wire interface for the data communication and antenna.
Fig. 3.1. Thelocation of thecontrol unit and theradio, logic and ci-
pher units in the car.
Divided installation
Divided mounting means that the station's front panel, dis-
play board, control board and code
board is put in a plastic
housing to
forma control unit and then installed in thecar's
dashboard.
The radio with the logic, cipher and duplex filter is installed
in the luggage compartment
of the car.
Fig 3. 2. The front panel, the controlboard, the display boardis put
together in a housing to form the controlunit.

Installation of the control unit
The control unit is put in an installation housing andmount-
ed to the dashboard ofthe car,
and connectedvia a flat cable
to the radiostation in the luggage compartment.
Control unit
Rearview
Fig 3. 3. The controlunitis installedin plastichousing and installed
intathedashboard
of thecar and connectedto theradiostation via a
flat cable.
__, Installation of the radio and cipher
-
--
--
-
-
The radio and cipher cassette is mounted together on a case
with fast lock facilities and locked
to a mounting plate fixed
to the floor of the luggage compartment.
The duplex filter is fixed to the top of the radio cassette, an-
tennafilter and datainterface are fixed
to the rearend of the
radio cassette.
The radio parts are connected to the control
unit via a flat cable.
Installation of handset with holder
The handset is a modified "Diavox" handset for telephone
traffic.
The holder has controls for power on, cipher on with lamp,
volume control and disconnection
of call. The handset hasa
T/R switch.
Fig 3. 5. The connection of the hand.set to the circuit board of the
hand.set holder.
Thehandset is connectedto the holder via a 6 wire cable and
the holder
is connected to the connector unit via a 14 wire
cable.
---W Fig 3.4. The installation of theradio and ciphercassettes and thelo- Fig 3. 6. The connection of the holder's circuitboardto the connec-
cation
of the duplex filter and data interface. tian unit.
-9

-
Installation of loudspeaker
The loudspeaker has 60 ohms impedance and is connected
to the circuit board
of the handset holder by a 2 wire cable.
Fig 3. 7. The connection of the loudspeaker to the holder's circuit
board.
DC power connection
The stationis connected to thebatterybya 2 wire cable, and
a 1 pole fuse holder.
The earthpole of the cable is grounded _to the chassie of the
car, the plus pole
of thecable is connected to theplus pole of
the battery. The other end of the cable is connected to the
connector unit.
Externa) alarm relay
The extemal alarm relay unit is connected to the connector
unit via a 2 wire cable.
The othertwo terminals of therelay can be connected to the
horn of the car, the headlights or other source of alarm.
'l::::::=====+12V
Fig 3. 9. The connection of the externa/alarm relay to the connec-
tion unit.
Antenna installation
The antennais fixed to the car and connected to theantenna
filter
at therear of theradio cassettebya coaxialcablewitha ~
Fig 3.8. The connection of the station to the car's battery. fast connector.
10

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-
4. Operating instructions
General
The C605 MAXICOM consists of a control unit placed in
the dashboard
of the car and radio, logic and cipher units
placedin cassettes in the trunk
of the car. The duplexfilter is
mounted at the top of the radio cassette.
Fig 4.1. The station consists of a controlunit, radio and logic units,
cipher unit
and duplex filter, radio and cipher cassettes.
Controls and indicators
Button set
Code memory plug Display
Fig 4. 2. The control unit and the code memory plug in board.
Display
Display with two-digit channelindicator
and five-digit num-
berindicatorand indicatorlampsfor transmission, incoming
call, open monitoring, retrans- mission extemal alarm and
automatic functions dis- connected
Button set
For selection
of channel, call number and other functions.
Code memory plog
Replaceablecodememoryplugwhich containsall individual
information about the station, e.g. its own call number.
Handset
Handset off answers an incoming call. Handset on discon-
nects an ongoing call.
Transmission button
Volume control
Poweron
Handset
Fig 4.3. The handset and its holder with controls and indicators.
Transmission button
Placed on the handset. For switching from reception to
transmission. Press to transmit, release to receive.
Power on
Placed on the holder. Tums on power to the station.
Cipher
on
Placed on the holder. Tums on cipher function.
Cipher lamp
Placed
on theholder. Lamp on indicatesthatcipherfunction
is on.
Volume control
Placed on the handset.
Tum theknob clock-wise to increase
the volume.
11

Button set
Number buttons
Channel selection
Number
selection
Function selection
Light intensity/Status
Programming
Call
Emergency
Disconnecting and listening
Fig 4.4. The button set includes number buttonsfor entering digits
andfunction se/ection buttons for se/ecting
diff erentfunctions.
Number buttons
The number buttons
~ to ~ are used for entering digits in
On/Off
The button (@ is used for power on/ off.
Function selection
button
The function selectionbutton ~is usedto selectopenmoni-
toring, extemalalarm, retransmission to anotherstationand
automatic functions disconnected. During a call, the button
has a squelch
on/ off function.
Disconnecting
and listening button
The disconnectingandlisteningbutton(tJ is usedfor discon-
necting the station after a call
and for temporary listening in
onaselectedchannel.
The buttonmayalso beused to restore
the function lamps.
Emergency
button
The red button ~ is used to transmit an emergency call.
Display
Call indicator/
Who has called
Number indicator
automatic calls, semi-automatic calls, full number calls and Channel indicator
channel selection. The buttons 0, 7, 9 may have a double
function, 0 as
WHC button, 7 for status reporting and 9 for
retransmission.
Channel selection
button
The channel selection button ~ is used when selecting the
channelfor an outgoing call
or for openmonitoring. It is also
used for reset after incorrect operation.
Number selection button
The number selection button 8 is used when selecting the
call number for an outgoing call,
or in own programming of
automatic calls.
It is also used for reset afterincorrect opera-
tion.
Programming
button
The programming button ~ is used for programming auto-
matic call numbers and for displaying automatic calls num-
bers.
Call button
The call button
~ is used to transmit a manual full number
call, a
WHC recall, or a status call.
Light
inten~/Status button
The button ~ is used to showthe display contents with high
light intensity. With the station in stand-by and the display
extinguished, this buttonwill displaythelastmobile number.
In systems with status reporting, thebutton
is used to display
the currentstatus. When enteringdigits, this buttongives en-
try of the entry
symbol"-".
12
Open monitoring
Retransmission ExternaI
alarm
Automatic functions
disconnected
--
Fig 4. 5. The station 's display with channelindicator, number indi-
cator
and function /amps.
Channel indicator
The two-digit channel indicator shows the channel in use.
Flashing digits indicatethat somebody has calledyou onthat
channel while you were away. In stations with extra func-
tions, channelselection
00 means thatthe stationwill selecta
free channel automatically.
Number indicator
Thefive-digit channel indicatorshows theselectedcall num-
ber. In stations with WHC, the number indicator also shows
the number
of the calling station. In stations with status re-
porting, the status code
is shown here. Incorrect operation,
e.g. selection
of a channel which does not exist, will bring up
the word
Error in the number indicator.
Call
indicator/"Who has called"
The yellow lamp is lit with steady light <luring a connected
call.
It flashes to indicate unanswered incoming call.
..,.
....,.
.........
.........
.~
-
r-
r-
-
-

Transmission/Channel engaged
The red lamp lights with steady light to indicate that the se-
lected channel
is engaged. An attempt to make a call on an
engaged channel will result in busy
tone and disconnection.
During an outgoing call, the lamp
is lit with steady light, but
flashes when the transmission button
is pressed down.
Open monitoring
The lamp by the symbol
111111 lights up when the station is in
open monitoring mode.
Retransmission
The lamp by the symbol Plights up
to indicate retransmis-
sion on.
Externa) alarm
The lamp by the symbol M lights
up to indicate external
alarm on.
Automatic functions disconnected
The lamp by the symbol 6.lights up when automatic func-
tions are disconnected
(= the station is locked on the select-
ed channel).
Incoming calls
Individual calls
A call signal
is heard over the loudspeaker, the channel
indicator flashes
and the yellow lamp lights up.
Take the handset and answer. Press the transmission
button
on the handset to talk, release it to listen. Flash-
ing red lamp verifies own transmission.
Disconnectthecall by replacingthehandset
or bypress-
ing the disconnecting button
ltJ.
Group calls
The yellow lamp lights up.
Listen tothegroup message.
If youneed to answer, pick
upthehandset andpressthetransmissionbutton. Flash-
ing red lamp verifies own transmission.
Do not replace
the handset until the entire group call
is finished.
The call
is automatically disconnected.
Outgoing calls
Full number calls
Press the channel selection button
§l
Enter the channel number with the number buttons @)
to m. The selected channel number appears in the
channel indicator.
Press the number selection button
8.
Enter the call number with the number buttons @) to
m. The selected call number appears in the numberin-
dicator.
Press the call button
~ to transmit the call.
A reply tone confirms that your call has been connect-
ed. Take the handset
and make your call.
Disconnectthecall by replacingthe handset
or pressing
the disconnecting button
ltJ.
Memory
The stationwill rememberthelastnumberyouentered,even
when
the display
is extinguished or the station switched off.
To repeat this call, press the button ~ (the number is now
displayed)
and then the call button ltJ.
Automatic calls
Automatic call means making a complete call with channel
numberandcallnumbersimplybypressingonenumberbut-
ton,
on which all the necessary information has been pre-
programmed.
Presstheappropriatenumberbutton@)
tom. The pre-
programmed channel and call number appear in the
channel indicator
and number indicator.
A reply
tone confirms that your call has been connect-
ed. Take the handset
and make your call.
Disconnectthecall by replacing thehandset
or pressing
the disconnecting button
ltJ.
Semi-automatic calls
Semi-automatic call means that part
of the call number has
been programmed in advance,
and that you must enter one
or several digits to complete the call number.
Press the number button
@) to m. The display shows
the pre-programmed digits followed by dashes in the
positions where you must enter a digit.
Enter the remaining digits of the call number with the
number buttons
@) to m.
A reply tone confirms that your call has been connect-
ed.
Take the handset and make your call.
Disconnectthe call byreplacing the handset
or pressing
the disconnecting button
ltJ.
Programming automatic calls
Programming an automatic call means storing a call, com-
plete with channel number
and call number, on one of the
number buttons.
Press the channel selection button
~-
Enter the channel number with the number buttons @)
to m. The selected channel number appears in the
channel indicator.
Press the number selection button
8.
Enter the call number with the number buttons @) to
m. The selected call numberappears in the number in-
dicator.
Press the programming button
(@.
13

Press the number button ~ to ~ on which you want
the call stored. You have now stored an automatic call
for convenient access simply by pressing the chosen
number button.
You may check what call numbers are pre-programmed on
the different number buttons by pressing the programming
button
~ and then one of the number buttons. The display
will show the automatic call number.
Other functions
Temporary listening
By pressing the listening button (t) you can listen in on on-
going conversations on the selected channel for twenty sec-
onds, whereafter the station returns to stand-by mode.
Open monitoring
Selectthechannelyou want tolisten to by pressingthechan-
nel selection button
~ and then enter the channel number
with the number buttons ~ to ~. Press the function selec-
tion button muntil the lamp by the symbol for open moni-
toring -4 lights up.
To return to stand-by mode, press the function selection
button muntil all the function lamps are extinguished.
External alarm
Withtheexterna!alarmfunction, aspecialtoneforincoming
calls is heard. Via a relay, this tone can activate the vehicle
horn.
To select externa! alarm, press the function selection button
muntil the lamp by the externa! alarm symbol M lights up.
To retum to stand-by mode, press the function selection
button muntil all the function lamps are extinguished.
Retransmission to another station
Presetchannelandcallnumberinthesameway as when pro-
gramming an automatic ca1l and store on number button ~.
To retransmit calls, press the function selection button m
until the lamp by the symbol for retransmission Plights up.
To
retum to stand-by mode, press the function selection
button muntil all the function lamps are extinguished.
Automatic functions disconnected
Automatic functions disconnected means that the station is
locked on the set channel and will not receive calls on other
channels.
Todisconnect automaticfunctions, press the function selec-
tion button muntil the lamp by the symbol for aatomatic
functions disconnected
!::,. lights up.
To retum to stand-by mode, press the function selection
button muntil all the function lamps are extinguished.
Error indication
Incorrect operation will bring up the word Error in the dis-
play. Start from the beginning.
If you have selected the wrong channel numberorcall num-
14
ber, press the channel selection button ~ orthe number se-
lection button 8 respectively, and
enter the correct
number.
Time limits
The station may be programmed with various time limits,
e.g. automatic disconnection if the station neither transmits
or receives carrier wave
<luring a longer time period.
Transmission limit
This means that <luring a call you may transmit only for a li-
mited time. After this time, the station will automatically
change to receiving mode.
To continue transmission you
must release the transmission button on the handset and
then press it again.
Who has called?
Unanswered call
If a call is not answered the caller may request a recall by
pressing the number button
~. When contact has been
established the station will disconnects automatically and
the yellow call lamp goes out.
Recall
Uponyour retum afteran absence, your station may display
a channel number and call number. This tells you who has
called while you were away.
To recall the displayed number, press the call button ~.
Queue function
Thestation can storeup to fifteen unanswered calls. Thelast
call is shownin the channel andnumberindicator of thedis-
play. The digits in the channel indicator and the yellow call
lamp flash.
To checkwho has called, you may step back in the queueby
repeated pressings of number button
~ until you reach
stand-by mode.
Pressing once more
will bring up the latest call again. You
can also stepback in thequeuewith thebutton (t), but it will
at the same time erase the previous call in the queue.
To callthenumbershowninthedisplay, pressthecall button
~.
The entire queue is erased when the station is switched off.
Status reporting
Status reporting means that instead of personally making a
call you transmit a two-digit code with a meaning earlier
agreed upon.
Press the status button
~. The first two digits in the
five-digit numberindicator show thelatest selected sta-
tus code.
Enter a new status code with the number buttons
~ to
~. Thenew status code appears in thelast two position
of the number indicator. When the entry
is complete,
the new codewill replace the oldonein thefirst two po-
sitions of the number indicator.
.-
-
. I
~
I
• I
~
~-

Transmit the status call by pressing number button (?J
and the call button [8.
An acknowledgement tone confirms that the call has
been received.
Accessories
Desk-top console
C605 Maxicom can be used as a base station, for instance in
an office.
It can be suitably located as a desk-top console
with built-in connections for antenna and power supply.
Whenthestation
is suppliedas a basestationit is calledB605
Maxicom.
Carrying case
Thecarryingcasemakes it possibleto carryyourC605 Max-
icom stationwith you
on site. It canalso receive and retrans-
mit emergency alarms for example from a portable pocket-
size alarm transmitter.
5. Circuit descrip-
tion
of radio parts
Regulator
Refer to fig. I I.I., 11.2 and 11.3.
Regulation is accomplished by series element Vl, a transis-
tor.
The output voltage of the series element is sensed by
comparingthevoltage
dropped acrossresistorR5 ofthevol-
tage divider consisting
of R6, R7 and R5 with a reference
voltage
of 4.7V. The difference in voltagecontrols the series
element.
Befeeding in a logic
"l" or a logic "O" inta input "SIR" (pin
P1:6) the 9V output voltages,
+9T and +9R, can be con-
trolled.
If a logic "l" is fed in, then +9V will be fed out on
output "+9R" (pin Pl :5), while +9V will be fed out on out-
put
"+9T" (pin P1:7) if a logic "O" is fed in.
The +9V can be adjusted using test resistor R7.
Reciver
Refer to fig. Il.I., 11.32and11.33.
The receiver is a double superheterodyne which obtains its
local oscillator signal from an extemal frequency generator.
The voltage value of logical "l" is +9, of logical "O'', OV.
The voltage +9 VT is present <luring transmission and the
voltage
+9 VR is present <luring reception.
RF section and first IF section
The local oscillator signal from thefrequency generator is at
a frequency that
is bellow the receiving frequency, at a dis-
tance equal
to the first intermediate frequency.
Following first mixer
U8, thedifference between the LO sig-
nal andthe
RF signalfrom the aerial is obtained. The differ-
encefrequency
is thefirst intermediatefrequency and is 21.4
MHz.
Second
IF section
The frequency of the second oscillator may be above or be-
low the first IF, at a distance equal
to the second intermedi-
ate frequency, which
is 455 kHz.
Following the second mixer the difference frequency be-
tween the outputsignal
of the second oscillator and thefirst
IFsignal
is obtained. This differencefrequency is thesecond
intermediate frequency.
Squelch
and AF sections
The squelch circuitfilters of thenoisein the AF signal atfre-
quencies greater than 15 kHz.
When there is noise, a logic
"l" is fed out from the squelch circuit (pin Z3:5). When
there
is no noise, that is when the carrier is being received,
the output
of the squelch circuit will be at logic "O".
The blocking of the AF path through the AF amplifier in
case
of noise in dependent on external circuits.
Volume
is controlled by external componentsin all types of
receivers.
15

Duplex transmitter
Refertofig 11.1., ll.30and 11.31.
The transmitter has three main functions:
Generation of the carrier signal
Control
of the VCO
Power amplifications of the signal
The carrier signal
is generated using the outputsignals from
the frequency generator, the
VCO anda crystal-controlled,
frequency-modulated oscillator (FMO). The
VCO is con-
trolled by a
DC voltage generated with the aid ofa detector
circuit and a transmitterloop circuit. Theoutputsignal from
the
VCO is amplified in a power amplifier.
The voltage value oflogic
"l" is +9V, of logic "O", OV.
The voltage +9 VT is present <luring transmission.
Generation of the carrier
The carrier is the output signal of the VCO. To permit the
adjustment
of the carrier frequency (fl) to the correct fre-
quencydistanceform theoutputsignal
of thefrequency gen-
erator (f2), these two signals are mixed in mixer Z4. When
theVCO
is oscillatingatthecorrectfrequency, theoutputof
the mixer (thedifference frequency
fl-f2 will be of a certain
frequency). This signal
is compared in the detector circuit,
Zl, withthesignal from theFMO,f3, (the FMO is designat-
ed U2:V2,
Vl) which is the reference signal.
Controlling the VCO
TheVCO is controlledinthefollowingway. The two signals,
fl -f2 and f3, are comparedin the detector circuit Zl. When
the radiotelephone
is tumed on, the difference between
thesetwo signals
is large. Thedetectorcircuitfeeds outa DC
voltage that differs from 7V.
The transmitter loop circuit senses that the voltage differs
from 7V and tums off the transmitter by closing the elec-
tronic switch on the transmitter loop circuit's upper output,
generatesa control sweep that
is fed out on theloweroutput
ofthetransmitterloopcircuit Tp7 and blocks theintegrator
built into the transmitter loop circuit
Thecontrol sweep alters thefrequency ofthe
VCO untilthe
differencefrequency, fl-f2,
is exactly 11.4MHz. Thedetec-
tor circuit senses that the f1-f2 and
f3 frequencies are the
same and feeds out
7V DC.
Thetransmitter loop circuit senses that
7V is fed in on its in-
put and locks the control sweep to the control voltagethat
hasjustset the
VCO to the correctfrequency. The transmit-
ter loop
is now locked on.
The
VCO can now vary so much in frequency that the DC
output voltage decreases as much as to 1V oras increases as
much as to
8V without causingthe loop to lose lockon (i.e.,
the holding range
is 1-SV). The transmitter loop circuit will
immediately change the value of the control voltage to re-
tum the VCO to the correct frequency any time it varies.
However, ifthe
VCO should deviate so greatelyin frequen-
cy thatthedetectorcircuit producesa voltagelowerthan 1V
or greater than 8V, the loop will be broken and the lockon
procedure will start over from the beginning.
16
The AF signal from thehandset is continuallysuperimposed
on the
DC voltage fed out from the detector circuit. When
the loop
is locked on, the transmitter loop circuit acts as an
integratorandthevariations
of the AF signalresultinavary-
ing control voltage which changes the frequency of the
VCO. In this way modulated carrier
is obtained and then
transmitted.
Fig 5.1. The controlsweep during lock-on, measuredattestpoint
Tp7.
Power amplification
Theoutputsignal from the VCO receives its final amplifica-
tionin thepoweramplifier. Thepower
out mayberegulated
byvaryingtheoutputvoltagefromthevoltagecontrolcircuit
consistingofV5-V9. Thedesiredpower outcan beadjusted
using potentiometer R25.
If alogic "1" is fed in on pinP 1: 2, "Powercontrol",thepow-
er output will be decreased to approximately half. Unless
both ofthe voltage control circuit's input conditions are sa-
tisfied, the power amplifier will
be shut off.
Frequency generator
Referto Jig 11.1, 11.28 and11.29.
The Frequency Generator is of the digital synthesizer type.
Thecarrier
is generatedinafree-running, voltagecontrolled
oscillator (VCO) which oscillates directly at the radio fre-
quency by means of a phaselocked feedback loop.
Thevarious channelsareselectedbymeansofa binarynum-
ber, thedivisor N,
sentto thecontrolcircuits oftheFrequen-
cy Generator. Eachdivisorcorrespondsdirectly toa channel
frequency.
The output signal from the
VCO can be used as
local oscillator signal from the receiver
transmitter signal
<luring simplex operation
oscillator signal to a transmission loop
<luring duplex
operation (the transmission loop consists
of a transmit-
ter that generates a transmitter signal at the proper du-
plex distance from the receiver signal).
The frequency generator has two main functions:
Generating the carrier signal
Controlling the
VCO

-
The carriersignalis generated by the VCO anda channel os-
cillator.
The output signal from the VCO serves as the out-
put signal of the frequency generator, while the channel os-
cillator
is used to provide an intermediate frequency, which
after division is
compared with a reference signal.
The VCO is controlled by a DC voltage generated in a loop
filter. The magnitude of the control voltageis determined by
the factor by which the intermediate frequency is divided
(the divisor, N). When the VCO commences oscillating, an
error signal will result from the comparision mentioned
above and be used to change the control voltage, and thus
the frequency of the VCO, until the error signal is zero.
The voltage value of logical "1" is +9, of logical "O", 0 V.
The voltage +9 VT is present during transmission and the
voltage +9 YR is present during reception.
Generation of the carrier
The output frequency of the VCO (fi) is used as the trans-
mittersignal during simplex
operation, as the local oscillator
signal for
the receiver and as the input signal to a transmitter
loop, which in tum generates the transmitter signal at the
proper duplex distance from the receiver frequency during
duplex operation. (The transmitter loop is not included in
thefrequency
generator.) The VCO is modulated directly by
the AF signal from the handset preamplifier.
The VCO can be made to operate on up to three partial
bands, since
the channel oscillator Z8 is equipped with three
crystaloscillators. The desired frequency band is selected by
feeding in logical "1" on the appropriate input, P1:4. If no
logical "1" is fed in, the oscillator shown lowest on the func-
tional diagram
is connected up.
This position is normally
used to generate the transmitter
signal in simplex (and both the transmitter signal and the lo-
cal oscillator signal in duplex).
The three oscillators in the channel oscillator are fully com-
patible.
One of the oscillators is connected by feeding a current into
one of inputs Z8:2/6 via resistors R12 and R14. These are
the bias resistors for the oscillators.
The output signal from the channel oscillator (f
2) is mixed
with
the output signal from the VCO (f
1
). The differencefre-
quency is filtered
out and an intermediate frequency is ob-
tained. This intermediate frequency is divided by means of a
programmable divider,
Z3, to obtain a frequency of 25 kHz.
The divider is programmed with a binary number, the divi-
sor N. This
number corresponds directly toa channel. The
divider is clocked by the difference signal f1 -f
2
and counts
from the number N down to 0, at whichtime the output pulse
is generated.
The output signal from the VCO is composed according to
the following formula:
f1 = f2
+N0.025
where f1 = the output freqeuncy of the VCO (MHz)
f2 = the output frequency of the channel oscil-
lator (MHz)
N = the divisor
It is apparent from the formula that the divisor corresponds
directly to a channel freqeuncy and that the difference fre-
quency, f1
-f
2, also
corresponds directly toa channelfrequen-
cy.
The divisor may assume values between 50 and 190 and
the difference frequency may assume values between 1.25
and 4.75 MHz. The VCO hasa bandwidth of 3.0 MHz.
Generation of the control voltage
The output signal at 25 MHz, whichis obtained from divider
Z3, is compared in phase detector Zl with the signal from
crystaloscillator
Z2b. The signal from the crystaloscillator is
divided (within the phase detector) to obtain a signal at the
frequency of
25 kHz and then a comparison is made of the phases ( c:p) of
the two input signals.
Ifthe phase angle (c:pA) ofthe divided signal from the VCO
is less than the phase angle of the reference signal ( c:pB) (the
divided signal from the VCO leads the reference signal) the
phase detector feeds out a positive pulse train. This pulse
train is integrated in loop filter Z6 and converted toa control
voltage which
is a DC voltage between 2 and 4.5 V that sets
the VCO to operate at the desired frequency. The control
voltage affects
the capacitance diades in the oscillatorcircuit
of the VCO. Each channel frequency corresponds toa spe-
cific value
of the voltage.
If the phase ( c:pA) of the divided signal from the VCO is
greater than the phase angle of the reference signal (c:pB)
(the divided signal from the VCO lags the reference signal)
the phase detector feeds out a negative pulse train. In this
case
the control voltage will be between 4.5 and 8.3 V.
Loop filter Z6 is an activefilter consistingprimarily of an in-
tegrator.
The integrator comprises operation amplifier
Z6:Zl, capacitor C4 and resistors R3 and R16. The charac-
teristics
of the integrator must be adapted to the various op-
eratingconditions by connecting and disconnecting the var-
ious resistors in
the resistance network which provides the
bias for the operation amp.
/ StCltion tur ned on
4,5 v ---innnnnnnnrn •.........•...•........ mnnnnnnnnnnnr
ov __ uuuuuuuuuu uuuuuuuuuuuuu
a. Output signal from phase detector Z1:13
4,5·5V -----
1
-+- U Value depends
1
on loop ampl.
I
I
ca 2V I
1 110·20ms1
1
1-1
I I
---1 1--~~~~~~~-
2· 4ms/ \40·100ms
Z5:Z1b on ZS:Z1a on
b. Control volta ge at Z6: 10 TP1
111111111 I I I I
Il I I I I 11111 I I I I
c. Ouiput signal from VCO U1:5
with wrong frequency
Fig 5.2. Control voltageat TPI whencpA >cpB and the VCO is not
lock ed.
17

4,SV~
OV-- I
I
a.Output signal from phase detector Z1:13
n.--+-- uvalue depends
. "J on loop ampl.
T', 'VCO locked on.
I '----- Voltage is equal
to selected channel
b. Control voltage at Z6:10 TP1
I
Wrong frequency i Correct frequency
\ i I
1111 I 11111 Ii Ul.flJUU1JUUU1J
c. Output signal from VCO U1:5 with
wrong and correct frequency
Fig 5.3. Controlvoltageat TPI when VCO is lockedandcpA=cpB
from cpA > cpB.
Acquisition sequence
Whenthere isa largeerror(forexamplewhentheunit is first
tumed on)it is necessary to ascertainthatthe VCO operates
within the range
of regulation. This is accomplished as fol-
lows. When the error
is great the phase detector provides a
pulse train from output 12.
The pulse train is integrated and
shaped in the fast acquisition circuit Z5 and triggers a mon-
ostable multivibrator
Zlb, which is also part of the fast ac-
quisition circuit.
The monostable multivibrator closes electronic switch
Z5:Z2a, which in
tum shorts the integrating capacitor, C4,
of integrator Z6:Z1.
The integrator will now operate as an
amplifier with unity gain and its output voltage will be 4.5 V
which
is approximately in the centre of the range of regula-
tion.
After 2 to 4 ms monstable multivibrator
Zlb triggers mon-
ostable multivibrator
Zl a to prevent Zlb from being trig-
gered again.
At this point of time theshorting of theintegra-
tor Z6:Z1 ceases.
If the output signal on Z 1: 13 of the phase
detector
is a negative pulse train, the controlvoltagewill fall
sharply
to a value U depending on the amplification in the
phaselocked loop.
Then the controlvoltage drops according
to a curve determined by the characteristics
of the integrator.
As the control voltage drops, the frequency
of the VCO is
changed and when the frequency has dropped so far that is
correspondstothefrequency of thechannelthathasbeense-
lected (bymeans
of thedivisorN usedto programmethediv-
ider
Z3) the VCO will be locked on to the frequency of the
channel andthe loop filter will provide a voltage that
is pro-
portional to the channel frequency.
18
If the output signal from Zl: 13 is a positive pulse train, the
process will be identical except that the voltage will rise
sharply to a certain value U when monostable multivibrator
Z5:Z 1b
is reset. As in theabovecase, the voltage U is deter-
mined by the amplification in the loop.
If the VCO does not
lock on, the above sweeping process will
be repeated when
monostable multivibrator
Z5:Zla is reset.
To ascertain that the loop filter has the appropriate charac-
teristics
<luring the locking-in phase, electronic switch
Z5:Z2d is blocked and diode V3 conducts <luring the lock-
ing in, causing the resistor network that determines the bias
to the loop filter's integrator
to be switched. The diode con-
ducts
<luring the locking in because the phase detectorfeeds
out narrow positive "spikes", sufficient to keep the diode
open, from output
Zl: 13 at the same time as the negative
pulse train
is produced (if A> B). When the frequency has
locked in, that
is when A= B, a positive voltage of 4.5 V is
fed out and is sufficientlylow (and has no positive spikes) to
keep the diode blocked.
The diode blocks and opens at
about 5
V.
Di ode V4 in fast acquisition circuit Z5 is openedinthesame
manneras diodeV3 by the positive spikesfrom
output 13 of
the phase detector. DiodeV4 is an extrainput for triggering
monostable multivibrator
Z5:Zlb, which is normally trig-
gered from output 12
of the phase detector.
Duringtheentireacquisition periodtheradio trans- mitter
is
blocked by electronic switch Z5:V3 which is kept closed by
Schmitt trigger
Z5:V2/Z2e.
9V =nJUUlfUUUlJ\l ·..................·lilllilimlilIUl
4,SV
a. Output signal from phase detector Z1:13
8,3 V - - - - - - - ...,.
1
,..--------,
Value U
depends X
on loop
ampl.
I
I
I
_,
2-4ms/
ZS:Z1bon
I
I
I
I
I
I
I
I
I
I
I I
I 20 ms I
1-1
I
~ 40-100ms
ZS:Z1aon
b. Control voltage at Z6:10 TP1
11111 I I 1111 I I Il I I
c. Output signal from VCO U1: 5
with wrong
frequency
I 111 111
Fig 5.4 Control voltage at TPI when cpA <cpB and the VCO is not
lock
ed.
r-
-
r-
r-
r-
r-
r-
.__,
-

u
Voltoge ~
depends
on loop
ompl.
,,---
/
/
VCO is locked on.
/ Voltoge is equol
Jj----- to selected chonnel
o. Control voltoge ot Z6:10 T P1
I
Wrong frequency I Correct freq uency
\ i I
11111111 Il: rlJUUU11l
D. Output signal from VCO U1: 5 with
wron g ond correc t frequenc y
Fig 5.5 Control voltage at TPI when VCO is lockedan cpA= cpB
from cpA
<c.pB.
Control sweep when the VCO is locked on
The characteristics of the sweeping for transmission and re-
ception must be somewhat different.
For transmission e.g.,
the
VCO must notreactto rapidly,forthatwouldcounteract
modulation!
Fig 5.6 andfig 5.7, showstheappearance
of thesweepfor re-
ception and transmission.
The differences in characteristics
betweentransmission
and receptionareaccomplishedbyus-
ing electronic switch
Z5:Z2b.
Sweep when not locked on 'fA <'fB
,..........-t--- 8,3V
.................... ...- I
-----ro--.......... I
I
0-40 ms J
-----
Voltoge levet corresponding
to the frequency of
selected chonnel
"""
-----i-...._
I --
Sweep when locked on 'fA > <fB
1 --
1 -'t---~2V
I 0- 40 ms I
I I
Fig 5.6 Controlsweep when the VCO locked in transmission mode.
Sweep when not locked on <f'A <<fB
,,+---7V
//I
// I
I
I
0-25ms I
Voltoge level corresponding
to the frequency of
selected chonnel
"""
----h.
Sweep when locked on 'fA ><fB
I',
I ',
I 't---3V
I I
I 0
-25 ms I
~ ..
Fig 5. 7 Controlsweep when the VCO lockedin reception mode.
Divisor and control voltage
The characteristics of the loop filter must be changed for
!argedivisors, that
is for divisors largerthan 128.This is done
with electronic switch Z5:Z2c. This switch
is closed when
the most significant bit (128)
of the binary divisor N is 1.
As mentioned above each divisor corresponds to a certain
control voltage. Table 5.1 shows the voltage corresponding
to certain divisors.
Divisor N
50
130
170
220
Control voltage V
3
4
4.5 -5
6
Table 5.1 Divisors and control voltages.
19

6. Description of the logic parts
Block diagram description of the micro computer
INPUT DEVICES PROGRAM MEMDRY
CDNTRDL LDGIC
DATA MEMORY OUTPUT DEVICES
Adress bus
lnput port
ROM
CPU
Fig 6.1 Block diagram af the logic parts.
General
The logic parts consists of a micro computer, a control unit
anda code memory.
The micro computer has in- and output gates, program and
data memory and control logic.
Those parts are connected to each othervia the address bus,
the data bus and the control bus.
Theinput
and outputdevices ofthemicrocomputerform the
interface between the computer
and the external environ-
ment.
The inputdevicesmaybea keyboard or inputportsfor
signals from other units in the system.
The output devices
may
be a display or output ports for signals to other units in
the system.
The program memory
isa read-only memory, i.e. a memory
containing permanently programmed information.
The
memory contains the program which controls the micro-
computer.
The control logic reads this program, instruction
by instruction, and controls the other units accordingly.
The data memory is used to store the data required by the
program.
It may be a read-only memory or a read/write
memory.
The control logic addresses, through the address bus, the
memory cell to
or from which the data is to be communicat-
ed.
The address signal which consists of a binary number in
parallel form,
is fed from the control logic to the other units
of the microcomputer. This address signal points out the
corresponding unit.
Data and instructions are transmitted through the data bus
between the control logic, the memories and the input and
output devices.
Data is passed between the units which are
addressed in the form
of binary numbers in parallel form.
Reset synchronizing signals and data direction signals are
passed through the control bus. Synchronization
and data
direction signals indicate the direction in which data
is to be
20
Output por!
RWM
Code rnemory
Control bus
-Data bus
fed throughthedatabus and they dock thedatafrom thebus
inta memories
and registers.
The controllogic carries out the programinstructionsin two
stages. First, an instruction
is fetched from the program
memory, the control logic then carries
out the instruction.
The control logic then fetches the next instruction and so on.
The control logic fetches an instruction by passing the add-
ress through the address bus
to the appropriate memory cell
in the program memory.
At the same time, the control logic
feeds an outputsignal
on to the control bus, which indicates
thatdata
is to be passed from thedatamemory to thecontrol
logic. In this way, datais fed from theaddressedmemorycell
to the control logic through the data bus.
lf, for example, the instruction that is fetched requires that
datashould befed from an inputdevice
to the datamemory,
the control logic addressesthecorrectinputportandmemo-
ry cell throughtheaddress bus.
At thesame time, the control
logic feeds an output signal in
to the control bus to indicate
thatdata
is tobe fed from the input port to thedatamemory.
Data which is carriedthroughthedatabus is clockedintathe
indicatedmemorypositionin thedatamemoryby one
of the
signals
on the control bus.
Microcomputer program
The microcomputer is controlled by the instructions in the
program as follows: the control logic reads an instruction,
carries out the instruction, then reads the next instruction
and so on.
The instructions may be of the following types:
supply output data
to memory or output device
supply input data from memory
or input device
process previously entered data
jump to another place in the program
call for a sub-routine
....,...
r-
r-
r-
I
.--

Processing of previously entered data may include, inver-
sion, shifting, addingetc. A
jump to antoherplacein thepro-
gram may bea conditionaljumpsuchas
"Jump ifthe value0
is obtained", or unconditional.
A call to a sub-routine
is used when the same operation is to
be performed
on a number of occasionsinthe program. The
instruction causes a jump to a sub-routine; the sub-routine
ends by a
jump back to the place from which the initialjump
to the sub-routine was made.
A jump
to a sub-routine may also be initiated by a logic sig-
nal to the control logic. This signal, called an "Interrupt"
(INT)
is used when a unit in the system requires immediate
attention. When the signal
is activated, the control logic in-
terrupts the program
and jumps to a special "Interrupt rou-
tine". This routine finishes by returning
to the interrupted
program; running
of the programis resumed from the point
at which the interrupt signal was received.
General program description of the
100-channel standard program
The program description is intended to explain how the set
works togetherwith its program.
The program ofthe set has
two mainfunctions:
to handleradio traffic and to controlthe
set intemally.
Code memory
In order to operate the set must
be provided with a code
memory.
The codememoryconsists of a read-only memory
which contains
512 words, 4 bits wide. This memory con-
tains information about for example: Channels
and radio
frequencies, monitoring
of incomming calls, what actions
are to becarried
out when an incoming call has beenaccept-
ed, what call number that will be sent when a direct dialling
key
is pressed.
Start, on-switching
When the switch-on key
is pressed certain initialising rou-
tines are performed in order
to check the code memory.
The channel which was
on the display immediately before
the set was switchedoff
is still storedina certainmemory. At
on-switching a check is madeto see ifthis channel is still de-
fined in the code memory.
Operation
When operating the set the content
of the display is showed
with strong light intensity
<luring a certain time after each
key-pressing. This time
is 5 or 10 seconds. The short time is
used when showing a direct selection channel and at those
stateswherenormally nomorekeyis expectedto
be pressed.
The long time
is used at those cases where key-pressing is to
be expected.
Anyincorrect operation
of the set causes "Error" to appear
onthe display
<luring 2 seconds. After the 2 secondsthedis-
play shows the same content as before the incorrect opera-
tion.
Incoming calls, monitoring
mode Is -
Channel changing
is carried out in accordance with the de-
finition contained in the code memory, where a maximum
21 channels can be defined. For eachchannel there is speci-
fied ifopenmonitoring,carrierwave monitoring,tonemoni-
toring and auto-channel monitoring are permitted. When
thestation
is switched on, channelchanging starts at thefirst
channelfollowed by the next
and so on until the last channel
is reached, and then begins again at the first channel. '
Open monitoring. This mode can be selected manually by
the mode selector
or automatically after channelselection if
the channelhas been definedfor this inthe code memory. In
this
mode carrier wave monitoring is carried out on the dis-
playchannel
and on thosechannelswhich havebeendefined
for this in the code memory.
Carrierwave monitoring
is onlycarried out whenthe"open
monitoringmode" hasbeenselected. Carrierwavemonitor-
ing always takes place
on the display channel and on the
channels which are defined for carrier wave monitoring in
the code memory.
When a carrier wave is found, the channel selector stops
on
thechannelin question andthechannel number is shown on
the display with the engaged lamp lit. When a carrier wave
hasbeendetected, thechannelselectorremains
on thechan-
nel until the carrier wave has been disappeared for 5 sec-
onds. This delay timeis
to preventthechannelselector from
moving
on when minor interruptions occur on a channel.
If the T /R key is pressed when the channel selector has
stopped
on a channel, connection of call will be made on this
channel.
Tone monitoring. The set can monitor up to 4 different
types
oftone calls on a maximum of21 channels. The chan-
nels which are to
be tone monitored are defined in the code
memory.
The display channel is always tone monitored.
Beforecommencing monitoring, the setnoticeswhich chan-
nel
is display channel. A search is then made in the code
memory for information about this channel. Using this in-
formation, the frequency generator
is adjustedfor reception
on the channel concerned. There is also includedin thecode
memory which 4
tone calls that are to be monitored. Notice
that these 4 tone calls are identical for all 21 channels.
The
set now searches in the code memory for the first of these
calls
and therefinds thefirst tonein this call. Withthis infor-
mation, thestationnow sets
out to detectthefirst tonein the
first call; the actual
tone monitoring now begins.
The set nowtries to receive thefirst tone in the first call. If a
tone
is not received or thereceived tone does not agree with
thefirst tone, the set tries
to recieve the first tone in the sec-
ond type oftone call. The four types of tone call on thefirst
channel are monitored followed by a change
to the second
channel. This channel is monitored in the same way, fol-
lowed by the monitoring
on the third channel and so on.
When the final channel has been monitored for tones, the
procedure starts again from the beginning.
21

Automaticity disconnected. In this mode, the channel se-
lector
is locked on to the display channel. Tone monitoring
and carrier wave monitoring
is carried out continously on
this channel, Incomming calls are connected as normal. Af-
ter disconnection, the set remains locked
on to the display
channel.
There
is nomaximumtimefor thechannelselectortoremain
on a continous carrier wave.
Pressing the T
/R key gives connection of call.
Outgoing calls
Directselection.
If a directselectionis to betransmitted one
of the keys which is intendedfor direct selection, a direct di-
alling key,
is pressed. The set then reads the information
storedin the codememoryfor the keythathasbeenpressed.
If thechannelnumber is correct, a tonecallwhich is specified
in the memory for direct selection,
is transmitted. If there is
any error, e.g. the channel numberin the memory for direct
calling
is incorrect, the set continues monitoring on the se-
lected mode.
Relay. In the code memory information
is stored, ifrelaying
ofincoming calls
is to be carried out and in that case, which
direct selection that will
be transmitted.
When an incoming call has been accepted this agress with a
certain call-memory area in the code memory. This area
contains information about relaying.
Here it is specified
which direct selection that will be transmitted. In other
wordsthesetsendsonanincomingcall intheform
of a direct
selection.
Auto-channel monitoring. This monitoring always talie
place, provided that auto selection channels are defined in
the code memoring.
During the monitoring, the first unoccupied autoselection
channel
is given. If this channel is engaged, thenthenext un-
occupied autoselection channelis given. Thismeans thatthe
autoselectionchannelsaremonitored
fora longertimeinter-
val to give greater certainty that a particular channel
is ge-
nuinely available.
When transmitting
on autoselection channel, channel 00
shall be entered.
Handshaking procedure
Radio traffic between mobile andcontrol centre
is preceded
by thehandshakingprocedure. Whena mobile calls the con-
trol centre the call consists
of the ordinary 5-tone call num-
ber followed by a special numbercalled the identitynumber
(ID). When the control centre receives the
5-tone call num-
ber and the ID number it sends back the ID number
to the
mobile as a call acknowledgement. By doing this themobile
knowsifthetransmissionhasbeensuccesful
or not. After the
mobile has received a correct ID connection
of call can be
made.
22
Alarm traffic
Whenthe alarm call key
is pressed, attemptsare made to es-
tablish contact with the alarm centre.
If the alarm traffic op-
erates with alarmrepetitionwith ID-transmission procedure
1 takes place, if not the set continues with procedure
2.
1. Handshake attempts are made first on all free channels
which are defined for alarm traffic in thecodememory.
If the handshakingfails, thefirst busy channel is set and
a handshaking attempt
is made on the channel in order
to "breakin".
If handshakingfails heretoo, the next bu-
sy channel is set andthe shaking attempt is repeated on
all busy channels and then back to free channels again,
and so on.
If any of thehandshakingattemptssucceeds, thesetswitches
to the conversation state and a conversation can take place.
2. Inthis casethere is only one channelwhere alarm trans-
mission takes place. No carrier wave test
is carried out
before transmission.
Time limits
Transmission time limit. This time limit is intended
to pre-
vent unintentional locking
of the T /R key in the transmis-
sion position.
When the time limit is reached, the set changes over auto-
matically from transmission
to reception, as if the T /R key
hadbeen released. In order
to againmove into the transmis-
sion mode, the T
/R key must first be released and then
pressed again to restart the transmitter.
A new time limit
is initiated each time the T /R key is
pressed.
No activity time. This time limit concems the time when a
mobile has been connected but neither has transmitted nor
received any carrierwave.
At a certainmaximum time auto-
matic disconnection
of the call take place. However when
dealing with alarm traffic this time limit
is inoperative.
Listen time limit.Thistimelimit corresponds
toa "no-activ-
ity time" which
is independent of incoming carrier wave. If
themobilemisses adisconnection tone thena newcall onthe
same channelshall not
be able to keepthemobile connected
on this channel longer than the listen time limit. When this
time
is reached automatic disconnection of the call take
place, however not when dealing with alarm traffic.
A new time limit
is initiated each time the T /R key is
pressed.
Disconnection
A call
is terminated by disconnection, either automatically
or manually. After disconnection monitoring is started.

Automatic disconnection. The following cases cause auto-
matic disconnection:
Incoming disconnection tone
Time limit for
"no activity" reached
Time limit for "listen time limit" reached
Automatic disconnection
is not accompanied by transmis-
sion ofdisconnection tone. In the case ofalarm calls, auto-
matic disconnection
is inoperative.
Manual disconnection.
The following cases cause manual disconnection:
Operation of the L key
Change of channel while in voice mode
Retum of handset to holder
Transmission of disconnection tone.
Fortransmission
of disconnectiontone, thefirst stationmust
be an A-subscriber. In addition, the code memory must al-
low transmission of disconnection tone.
Telephone mode
Thetelephone modeoperatesas special kind ofdirect selec-
tion. A call
is initiated by pressing the telephone button on
theset. Thesystemwill thenautomaticallyselecta free chan-
nel and connect a line circuit to a P
ABX orpublic network.
A dialling tone will then be heard in the receiver. The user
can now dial any number
or combination ofnumbers up to
16 digits
on the keyset. The call is nowonly limited by those
limits existing in the telephone network.
7. Description of
the cipher circuits
General
In the ciphering unit enciphering oftransmitted signals and
deciphering of received signals take place simultaneously.
The electronic circuitry ofthe ciphering unit
is mostly con-
tained in five hybridcircuits placed
on two circuit boards Ul
and U2: see fig 11.16 to 11.19.
A modem circuit
Z2
A delta modulator Zl
A delta demodulator Z3
A transmit (Tx) cipher circuit Zl (on U2)
A receive (Rx) cipher circuit Z6
The delta modulatorI demodulator circuits are identical as
well as the ciphering circuits. Their function is determined
by the logic level on the mode-select inputs of the circuits.
Processing of analog signals, for both transmission and re-
ception,
is carried out by the modemcircuit. It also digitizes
all received signals for further processing by the Rx-cipher-
ing circuit.
Analog-to-digitalconversionoftransmissionsignals
is carri-
ed out in the delta modulator. The circuit also contains an
analog noise generator. Digital-to-analog conversion ofre-
ception signals
is carried out in the delta demodulator.
TheTx ciphering circuit enciphers the handset signal orthe
linked datasignal before it
is transmitted. The Rx ciphering
circuit deciphers the received cipher signal.
Theciphering unit
is intendedfor NRZ codedsignals with a
data rate
of 14.4 kbit/ s.
On the U2 boardthere is also a circuitfor generationofa da-
ta clock by which the deciphered (plain) data signal
is
clocked out into the B ciphering unit at link traffic.
A voltagesupervisor circuit
on the U2 boardshutsofftheci-
phering circuits if the battery voltage
is too low, in order to
avoid incorrect ciphering.
Mechanical design
The Ciphering Unit is housed in a plug-in type metal case
which
is placed in the cipher compartment ofan A station
unit.
Connectors for connection
to the radio and the key pro-
grammer are located on the rear side ofthe case, see
fig. 7 .1.
Thecase is disassembledbyunscrewingfourscrews. Thetwo
printed circuit boards inside are joined by a multipole con-
nector.
23