




The G8CUL Repeater Logic Technical Manual



This manual is intended to contain all the information required for building, 
setting up and using the G8CUL Repeater Logic.

The logic itself is a relatively complex piece of electronic design, with a 
processor containing its own control programme, customed designed for the 
use of amateur repeaters.  The control programme listing is currently over 
100 pages in length!

 

Not all of us are this lucky!  This is the tower where GB3TE and GB3CL are 
located.

From an original photograph by Tony Horsman, G0MBA.

Table of Contents

Table of Contents	2
1 Introduction	4
2 Scope of this Document	4
3 System Description	4
4 Specification	7
5 Operational Characteristics	8
5.1 Setup	8
5.2 Operating	8
6 Component List	9
6.1 Resistors	9
6.2 Capacitors	10
6.3 Discrete Semiconductors	10
6.4 Integrated Circuits	11
6.5 Other Components	11
7 Build Instructions	12
8 Test and Set-up Specification	13
8.1 Introduction	13
8.2 Equipment Required	13
8.2.1 Power Supply	13
8.2.2 Audio Signal Generator	13
8.2.3 Oscilloscope	13
8.2.4 Multimeter	13
8.2.5 PC	13
8.2.6 Test Leads	13
8.3 Hardware Set-up	13
8.3.1 Visual Inspection	13
8.3.2 Initial Link Settings	14
8.3.3 Resistance Checks	14
8.3.4 Initial Powered Checks	14
8.3.5 Initial PC Setup	15
8.3.6 Pre-set Adjustments	17
8.4 Main Parameter Set-up	19
8.4.1 'Ack' Characters	19
8.4.2 Timings	20
8.4.3 Beacon	23
8.4.4 Remote	25
8.4.5 General Commands	28
8.4.6 Configuration Dump	30
8.5 Password Setup	30
8.6 Records Result Sheet	31
9 Commands	32
9.1 Computer Commands	32
9.1.1 Enable Commands	34
9.1.2 Disable Commands	35
9.1.3 Read Commands	36
9.1.4 Write Commands	37
9.1.5 Set Commands	37
9.1.6 Test Commands	40
9.2 DTMF Control	42
10 PC Setup Programme	42
10.1 Setup Invocation	43
10.2 SETUP Function Keys	43
11 Hardware and Circuit Description	44
11.1 Introduction	44
11.2 Analogue Sheet	45
11.3 Digital Sheet	46
12 Block Diagram	48
13 Board Layout	49
14 Circuit Diagrams	50
15 BayComm Adapter	50
16 Current Installations	50



1 Introduction

The G8CUL Repeater Logic has been designed to provide most features for 
the control logic of a modern repeater.  Nearly all these features can have 
their parameters individually programmed and set-up using a normal PC with 
the supplied SETUP.EXE programme.  This can be done either locally with 
the PC plugged directly into the logic, or 'on-air' via a BayComm type modem 
and a simple adapter.

To avoid all the previously configured parameters being forgotten when the 
power is removed, an EEPROM device is used to store them.

All setting up is done by simple (normally) 2 character commands with 
associated optional parameters.  This is explained later in section 9.

The control logic is controlled by a microcomputer system which operates the 
repeater itself, as well as controlling many of the operating parameters of the 
repeater.

2 Scope of this Document

This manual contains information on building, setting up and using the 
G8CUL Repeater Logic.  Those of you (like me) who like to look at the circuit 
diagrams will find them in fold-out form at the back of this manual!

3 System Description

In its simplest form, the logic only required 5 connections.  These are:-

*	Power
*	Audio in from the repeater receiver
*	Squelch in from the repeater receiver
*	Audio to the repeater transmitter
*	PTT to the repeater transmitter

The audio signal from the repeater receiver must have its de-emphasis 
removed, otherwise the incoming CTCSS low frequency tone will be 
enhanced by the de-emphasis circuitry.  Likewise the repeater transmitter 
must have its pre-emphasis removed otherwise the outgoing CTCSS low 
frequency tone will be removed.  Believe me, it is true, exactly this happened 
to me on the first installation (GB3CL)!  The through audio tailoring is thus 
'neutral', with the transmitted audio being the same as that received (within 
the audio pass band of 300 - 3500Hz).

Audio in from the receiver is split to all devices that need it.  They are:

*	CTCSS tone detector and generator
*	'Normal' 1750Hz tone burst detection
*	DTMF tone detector
*	Computer data to the MODEM

The squelch line in from the receiver is also used by the processing system.  
The processor control programme detects the squelch opening and, if a valid 
CTCSS tone or tone burst is detected, operates the PTT signal to the 
transmitter, and feeds the incoming audio to the transmitter input.

Normally, the CTCSS on receive is only used for initial access in a similar 
way to a tone burst.  Once accessed, no further CTCSS tone (or tone burst) 
is required to keep the repeater open.  This is not the conventional PMR use 
of CTCSS and is basically applicable to 2m and 70cms repeaters.  If the 
CTCSS was used in its more conventional continuous mode, then only 
those lucky amateurs equipped with CTCSS would be able to use the 
repeater at all.  All others would not have their incoming audio re-transmitted 
as there would be no CTCSS to allow it.  The outgoing CTCSS is, however, 
used in a continuous mode (if enabled), except when the repeater is giving its 
callsign on shutdown or beacon, although the CTCSS may be enabled even 
for these callsigns if required.

For 6m use, a conventional, continuous CTCSS on receive is required, and 
this mode of operation can be selected by suitable commands.  Likewise, the 
use of toneburst to initially access the repeater can be disabled.  These two 
features give the required access specification for 6m repeater use.

The CTCSS device itself is interesting, and deserves a bit more explanation.  
Any incoming CTCSS tone is filtered and detected, and the processor is then 
informed what the actual received tone frequency is.  The processor can then 
decide if it is the correct tone or not, and act accordingly.  The through audio 
is also filtered by the CTCSS device to remove any incoming tone, and an 
internal audio switch can be used to control the audio input to the transmitter.  
The transmit tone is generated independently to the receive detection, thus 
making the device suitable for repeater operation.

The CTCSS device thus has two outputs, through audio and CTCSS tone.  
Both of these are mixed together with the outputs from the tone oscillator and 
computer control MODEM before being peak clipped and finally filtered ready 
for the transmitter input.

Other facilities include the control of a second receiver/transmitter 
combination which should be used for remote control on a different frequency 
(or even band) to that of the repeater itself.  Control signals are also provided 
for the option of a synthesised voice, as well as inputs for repeater linking.

The control programme built in to the repeater logic contains many 
commands to allow the simple control of all the parameters that can be 
varied.  All control in this way is contained in 'packets' (not to be confused 
with packet radio packets!), which contain 'to' and 'from' callsigns, as well as 
a checksum for data integrity.  To simplify this control, a programme written 
for a PC is freely available, which provides simple keyboard access to all the 
built-in commands.

These commands consist of:
 
1.	Enable commands - turning options ON.

2.	Disable commands - turning options OFF.

3.	Read commands - reading things from the logic.

4.	Write commands - writing things directly to the memory, used with 
extreme care!

5.	Set commands - setting things to required values.

6.	Test commands - control of individual devices for testing.

Of these commands, all can be used with the PC plugged directly into the 
logic, while only some can be used remotely while 'on-air'.

The original design used a Plessey MV8870 for the DTMF decoder which has 
now become obsolete.  A similar device is now available from MITEL, the 
MT8870.  Unfortunately, the codes it gives for the '0', '*' and '#' keys are 
different!  The firmware provides a command to select which part is used.  
See sections 8.4.4.8, 9.1.1.3 and 9.1.2.3 for details.  Note that a small wiring 
modification to the PCB is required if a MITEL device is used and the DTMF 
digits 'A' - 'D' are also required.

4 Specification

Power requirements		+8 to +20V DC at about 100 mA. Normal or 	
				Standby power input.

Audio input			300 - 400 mV P:P (adjustable) into 10k* 	
				composite signal:  Through audio (reference),
				CTCSS at * -16 dB,
				Tone burst at -6 dB,
				DTMF at -6 dB,
				Data tones at 0 dB.
				
Audio output			* 0.5V rms. into 1k*, (adjustable)
				composite signal: Through audio (reference),
				CTCSS at * -16 dB,
				Ack/callsign tone at -6 dB (high) -16 dB (low),
				Data tones at 0 dB.

Squelch input		5V logic signal, either polarity (other voltage 	
				levels possible).

PTT output			Diode protected open collector output,
				100 mA max. (ON), 25V max. (OFF).

Control			9 pin RS232 connector for direct connection to PC 
				for logic set-up and 'fine-tuning'.
				Data tone decoder/encoder for limited 'on-air' 	
				control.
				N.B., the DTMF and data signals can be 	
				linked to a separate RX/TX combination if 	
				required.  This is highly recommended.

Shutdown			Local (via switch) or remote (DTMF or computer 
				data).

Voice				Control signals to and audio input from external 
				synthesised voice unit (Maplin board suitable).

Repeater linking		Extra squelch and audio input for second (link) 
				receiver.

Configuration		All configurable parameters held in non-volatile 
				EEPROM for easy modification via built-in serial 
				port.

Temperature Range	Standard 0C to 50C
				Extended -20C to 50C.
5 Operational Characteristics

5.1 Setup

To provide simple control and versatility for a wide variety of uses, a 128 byte 
EEPROM is included to store all the configuration data which give the 
repeater its characteristics.  These data include the following:-

*	Callsign
*	Locator/location
*	DTMF tone sequence for shutdown/start-up
*	Beacon time
*	Option selection
*	Various timings, etc.

All modifiable features are stored in the EEPROM, so are relatively easy to 
change.  All features are accessible via a direct connection to the logic board 
itself (RS232), some may also be changed 'on-air' while the repeater is 
operational by using the datalink and a 'BayComm' modem.  These latter 
changes are only simple ones, and do not affect the fundamental operation of 
the repeater.  They are also protected by a password scheme which, 
although not unbreakable, is sufficiently difficult to break so as to deter the 
casual 'hacker'.

All modifiable features are controlled by a set of simple commands via the 
built-in RS232 serial port.  A normal PC is suitable for this control, and a PC 
programme is freely available to implement all the configurable features 
(including automatic password generation).

5.2 Operating

During normal use, the G8CUL Repeater Logic gives the repeater the normal 
repeater characteristics.  The intention is to provide a control system which 
makes the repeater simple for users to operate through, yet versatile for set-
up purposes.  All the normal features are available; tone burst minimum 
length, input carrier minimum length before the repeater will stay up, etc.  
Long over time-out is also provided if required.  If this is enabled, the 
repeater will shut off the incoming audio if required, replacing it with or super-
imposing upon it the normal time-out 'pips'.  This stage of time-out can also 
be set to eventually time-out itself, when the repeater will give its callsign and 
shutdown.  In this situation, when the incoming signal eventually goes away, 
the repeater transmitter will briefly come on, and send 'OK' on CW, to inform 
all the bored listeners that the talkative operator has finally let go his/her 
PTT!  During the normal time-out 'pip' phase as well as after the timeout 
shutdown, the time-out may be reset, and the incoming audio re-enabled, by 
a tone burst of the correct length detected on the input.  This signal will, of 
course, have to be stronger than the 'timed-out' signal.
6 Component List

6.1 Resistors

Value
Type
Number Off
Location
100*
1/8 W, 2%
7
R27,R31,R32,R33,
R60,R61,R62
220*
1/8W, 2%
3
R2,R4,R5
1k*
1/8W, 2%
2
R47,R76
2.2k*
1/8W, 2%
4
R28,R30,R34,R48
2.7k*
1/8W, 2%
2
R57,R58
3.3k*
1/8W, 2%
1
R63
3.9K*
1/8W, 2%
1
R15
4.7K*
1/8W, 2%
11
R3,R6,R9,R16, 
R19,R20,R26,R29,
R52,R71,R72
6.8k*
1/8W, 2%
1
R24
10k*
1/8W, 2%
15
R14,R17,R18,R35,
R38,R39,R40,R41,
R42,R43,R53,R54,
R59,R73,R79
12k*
1/8W, 2%
1
R37
15k*
1/8W, 2%
1
R25
18k*
1/8W, 2%
2
R50,R74
22k*
1/8W, 2%
2
R13,R36
33k*
1/8W, 2%
1
R45
47k*
1/8W, 2%
3
R1,R12,R68
56k*
1/8W, 2%
1
R7
82k*
1/8W, 2%
1
R46
100k*
1/8W, 2%
4
R10,R44,R51,R55
150k*
1/8W, 2%
4
R8,R23,R49,R56
330k*
1/8W, 2%
1
R11
390k*
1/8W, 2%
1
R22
1M*
1/8W, 2%
1
R21
10M*
1/8W, 2%
1
R7
1k*
10 pin, 9 way SIL
1
R75
4.7k*
Variable Resistor 
RS187_012
1
R65
22k*
Variable Resistor 
RS187_034
4
R66,R67,R77,R78
47k*
Variable Resistor 
RS187_040
3
R64, R69,R70


6.2 Capacitors

Value
Type
Number Off
Location
22pF
Ceramic, 100V
2
C45,C66
33pF
Ceramic, 100V
1
C28
47pF
Ceramic, 100V
2
C27,C30
56pF
Ceramic, 100V
1
C29
4700pF
Polystyrene, 63V
5
C31,C32,C33,C34,C35
0.01F
Polyester, 100V
3
C37,C40,C41
0.1F
Polyester, 100V
21
C36,C38,C39,C42,C43,
C46,C47,C48,C49,C50,
C51,C56,C57,C58,C59,
C60,C61,C62,C63,C64,
C67
1F
Polyester, 63V
3
C44,C52,C53
1F
Radial electrolytic, 
63V, RS107_561
7
C9,C10,C14,C15,C20,
C21,C65
10F
Radial electrolytic, 
35V, RS107_397
15
C1,C2,C3,C4,C5,C6,C7,
C12,C13,C16,C17,C18,
C19,C54,C55
22F
Radial electrolytic, 
35V, RS107_404
1
C8
47F
Radial electrolytic, 
16V, RS107_325
1
C11
100F
Radial electrolytic, 
25V, RS105_969
5
C22,C23,C24,C25,C26

6.3 Discrete Semiconductors

Type
Part Number
Number Off
Location
Diode
1N4006
2
D1,D9
Zener Diode
BZY79C4V7
1
D10
Diode
BAY74 or 1N916 
or 1N4148
7
D2,D3,D4,D5,D6,D7,D8
Transistor
ZTX109C
5
TR3,TR4,TR5,TR6,TR8
Transistor
ZTX450
3
TR1,TR2,TR7
Miniature LED 
(RED)

4
LED1,LED2,
LED3,LED4

N.B.	The values of C37, C40 and C41 may be varied to produce different 
audio frequencies for the CW ident according to the following table.

C37, C40, C41 Value (uF)
Audio Frequency (Hz)
0.01
~1700
0.015
~1200
0.022
~850
6.4 Integrated Circuits

Part Number
Number Off
Location
MC68HC705C8CS
1
IC1
UA7805
1
IC4
NMA0505S
1
IC5
XLS93C46P
1
IC6
LT1080
1
IC7
74HCT4053
1
IC8
MV8870
1
IC2
FX805
1
IC3
FX614
1
IC9
NE567
1
IC10
74HCT14
2
IC16,IC17
TLC272
3
IC18,IC19,IC20

6.5 Other Components

Description
Parameter
Number Off
Location
Crystal, HC18u
3.579545MHz
2
XL1,XL2
Crystal, HC18u
4.000MHz
2
XL3,XL4
Links
2 pin
3
LK1,LK6,LK7
Links
3 pin
4
LK2,LK3,LK4,LK5
Inductors
10H, Axial 
RS240_494
1
L1
Inductor
100H, Axial 
RS240_523
2
L2,L3
Test points

11
TP1,TP2,TP3,TP4, 
TP7TP11, TP12,  
TP15,TP16,TP17, 
TP20
Connection Pins

39
P1 - P39
PWB
Repeater Logic, 
G8CUL, Issue 2
1

IC Socket
8 pin DIL 0.3"
5
For IC6, IC10, 
IC18, IC19, IC20
IC Socket
14 pin DIL 0.3"
2
For IC16, IC17
IC Socket
16 pin DIL 0.3"
2
For IC8, IC9
IC Socket
18 pin DIL 0.3"
2
For IC2, IC7
IC Socket
24 pin DIL 0.6"
1
For IC3
IC Socket
40 pin DIL 0.6"
1
For IC1
Serial Connector
9PIN 'D' Socket, 
PCB entry, 
Upright
1
PL1

7 Build Instructions

The method of construction of the repeater logic is really no different to any 
other similarly complex piece of equipment.  I would certainly not recommend 
that a total newcomer to soldering should attempt it, but anyone with 
reasonable soldering experience should have no problems.  As in all these 
things, a stage-by-stage methodical approach should be taken.

Initially, it is probably advisable to inspect the PCB, and check that it appears 
fault-free.  There should be no problem, as the PCB's have been designed 
and produced using high-quality professional techniques, but faults do 
sometimes occur!

I would strongly advise the use of IC sockets for all IC's.  Their cost is small 
compared with the rest of the components, and the advantages soon come to 
the fore if a fault is discovered.  Certainly, a socket MUST be used for the 
processor.  I cannot provide future software updates for free if the processor 
has been soldered in!

The best method is probably to solder in all the IC sockets, followed by all the 
discrete passive components, (resistors, capacitor and pins/links).  The 9 pin 
'D' type can be put in at this stage.  Note that it should be mounted up on 
pillars bolted to the PCB.  Ensure that none of the pillars or nuts make 
connection with any of the adjacent tracks.  I have tried to ensure that there is 
plenty of clearance, but a quick check will not come amiss.  Follow these with 
the active components, (LED's, diodes and transistors) and the 5V power 
supply (NMA0505S).  LED1 (which indicates when in local set-up mode), can 
be mounted directly on the PCB, but the other three (which indicate 'on-air', 
channel 1 transmit and channel 2 transmit) can be either board or box 
mounted, the latter giving external indication of their relevant states.

The +5V regulator should have some minimal heat sink.  Its leads and 
location on the PCB allow it to be bolted to the side of the logic box, which 
gives ample heat sink capability.  With no heat sink and +12V on the input, it 
will get quite warm, but a minimal TO220 tab type heat sink is quite sufficient.  
With +12V on the input, the power dissipated by the regulator is about 
700mW.

Having completed soldering in all the components, the IC's may be inserted 
ready for the big moment of initial switch on!  This is dealt with in greater 
detail in section 8 below.

When completed, the logic can be mounted in any convenient box/housing.  
The PCB was designed to fit an Eddystone diecast box, type 7970P, (what 
DID we do before Eddystone diecast boxes?), but any suitable housing 
should be sufficient.  It is probably best to put the logic in a metal box of some 
kind, just in case any RFI from it gets into the repeater receiver, or RF from 
the transmitter gets into the logic.  The logic has been in use in 70cms, 2m 
and 6m repeaters without any RFI problems, but individual installations will 
vary greatly.

8 Test and Set-up Specification

8.1 Introduction

This section gives instructions for the testing and board setting up of a new, 
recently assembled board.  The general procedure is initially to visually 
inspect the Unit Under Test (UUT) and then check for no shorts on the supply 
rails.  The UUT may then be powered and further tests implemented.  Finally 
the on-board presets can be adjusted followed by configuration set-up using 
a PC computer.

8.2 Equipment Required

The following equipment is required for the testing and setting-up of a new 
board:-

8.2.1 Power Supply
Power supply providing 8 - 20V DC. at about 100 mA.

8.2.2 Audio Signal Generator
Calibrated audio signal generator, capable of giving 1.0 and 1.75 kHz 
with variable output amplitude.

8.2.3 Oscilloscope
Oscilloscope with calibrated Y amplifier with 1 MHz B/W or greater.

8.2.4 Multimeter
Multimeter, such as Avo 8 or DMM.

8.2.5 PC 
PC computer with G8CUL Repeater Logic set-up programme, 
SETUP.EXE and serial cable with 9 pin 'D' plug.

8.2.6 Test Leads
Various test leads.

8.3 Hardware Set-up

8.3.1 Visual Inspection

After completing assembly, visually inspect the UUT, checking for dry solder 
joints, shorts or solder slivers etc.  Visually check that all polarised 
components such as electrolytic capacitors, diodes, transistors and 
integrated circuits are in their correct orientation.

8.3.2 Initial Link Settings

There are 4 'change-over' and 3 'on-off' links.  These are used for a variety of 
uses.  The initial settings should be as follows:-

*	LK1	SET-UP link.  IN for normal repeater running, OUT for set-up.

*	LK2	Processor reset.  Set to A-B for normal running.  The 		
		processor can be reset by setting this to A-C, and back again.

*	LK3	Source of DTMF and computer inputs.  	A-B repeater input,
									A-C auxiliary input.

*	LK4	Destination of computer data output.	A-B repeater output.
									A-C auxiliary output.

*	LK5	Auxiliary tone output.  If LK4 is set to use auxiliary output, this 
		link provides a tone output to the auxiliary output.		
		A-B No auxiliary tone.
			A-C Auxiliary tone output.

*	LK6	'Spare' inverter input.  Link to P34 to provide the DTMF 	
		controlled digital output1 on P29, or GND if not used.

*	LK7	'Spare' inverter input.  Link to P35 to provide the DTMF 	
		controlled digital output2 on P30, or GND if not used.

8.3.3 Resistance Checks

In good QA fashion, the following resistance, monitored voltages and current 
should be recorded for posterity.  I'll leave that for you to decide.  If you do 
wish to record the results, a suitable form may be found in section 8.6.

Connect the multimeter to the power supply pins, P1 and P2, and measure 
the resistance.  It should be greater than 10k *.

8.3.4 Initial Powered Checks

If all appears correct in 8.3.1 and 8.3.3 above, connect a nominal 12V DC. 
power supply to the UUT, with 0V to P1 and +12V to P2 with the multimeter in 
circuit to measure supply current.  Switch the power supply ON and measure 
the supply current.  It should be in the range 80 mA - 100 mA.  Switch OFF, 
disconnect the multimeter and re-connect the power supply.  Switch back ON 
and measure the following voltages:-

8.3.4.1

Digital +5V at the top end of L1, just to the left of the 9 pin 'D' socket.

8.3.4.2

Analogue +5V at the right hand end of L2.

8.3.4.3

Analogue -5V at the right hand end of L3.

These should all lie between 4.8V and 5.2V.

Remove the set-up link LK1, just to the left of the processor, and measure the 
following voltages:-

8.3.4.4

RS232 +10V at TP2 (near LK1).

8.3.4.5

RS232 -10V at TP1 (near LK1).

These should both lie between 6V and 11V.

8.3.4.6

With the oscilloscope, measure the wave form at TP4.  This should be 
a 4 ms period, TTL amplitude square wave, indicating that the 
processor is correctly running its programme.

8.3.5 Initial PC Setup

Connect the PC to the UUT with the serial cable.  Remove LK1, and run the 
G8CUL Repeater Logic set-up programme, SETUP.EXE.  This can use either 
COM1 or COM2 by invoking it with 'setup' or 'setup 1' to use COM1 or 'setup 
2' to use COM2.

For more information on the use of SETUP, refer to section 10.  In fact a read 
of section 10 before commencing the set-up procedure would probably help 
in the understanding of the use of the SETUP programme.

All commands and callsigns MUST be entered in uppercase, so to avoid 
forgetting, press the <Caps-Lock> key.


8.3.5.1

Press <F3> (the F3 key on the PC!) and enter YOUR callsign (not the 
repeater's callsign!) followed by <enter>.

8.3.5.2

Press <F4> and enter '---' (3 minus signs) followed by <enter>.  This is 
the default callsign which the logic will respond to via the serial port, 
when in SET-UP mode (LK1 removed).

Set the repeater callsign by issuing the following command:-

8.3.5.3

SCGB3xx<enter>	where GB3xx is your repeater callsign.

This should provoke an '-OK-' reply.

8.3.5.4

Press <F4> again and enter your repeater callsign followed by <enter>.  
This will set the destination callsign that SETUP will use.

Now set the Logic Serial Number which should be supplied with the 
documentation.  There is no direct command to set the serial number, so it is 
done by using the WR (Write ROM) command 5 times.  The serial number 
digits have to entered in ASCII HEX, which basically means putting a '3' in 
front, i.e. the serial number 0123 would require 5 WR commands with data of  
30, 31, 32, 33 and the terminating NULL.  Enter the following commands.   
Each command should provoke an '-OK-' response:-

8.3.5.5

WR103w<enter>

8.3.5.6

WR113x<enter>

8.3.5.7

WR123y<enter>

8.3.5.8

WR133z<enter>


8.3.5.9

WR1400<enter>

Where w, x, y and z are the 4 digits of the serial number in order.  The 
'WR1400' at the end is the 'NULL termination' for the serial number string.

This can now be tested by entering a read serial number command:-

8.3.5.10

SN<enter>

Which should get a response with the serial number just entered:-

8.3.5.11

*GB3DI,G8CUL,0123xx*

Where 'GB3DI' and 'G8CUL' are the repeater and your callsigns respectively, 
and '0123' is the serial number.  The 'xx' at the end is the hex representation 
of the packet checksum.  The * and * are the packet start and end flags 
respectively.

8.3.6 Pre-set Adjustments

Having set the repeater callsign and serial number, the on-board adjustments 
can be made.  Within the command set, there are a number of 'test' 
commands which switch certain things on and off to allow on-board 
adjustments.  All commands should be followed by <enter>, and, with one 
exception, all should provoke an '-OK-' response  This should be done as 
follows:-

8.3.6.1

Set the audio signal generator to 1 kHz with the output level expected 
from the repeater receiver at full system deviation, and connect it to 
the audio input on P21 (0v) and P22.  Adjust R78 to give 340 mV rms 
(960 mV P:P) at TP7 using the oscilloscope.  If this cannot be 
achieved, the gain of the first stage can be varied by adjusting the 
R13/R35 combination.

8.3.6.2

Connect the oscilloscope to the output P28, and issue the TE 
command to open the audio gate and allow input audio through to the 
output.  Adjust R77 to give some nominal output level for full system 
deviation into the transmitter.  This is adjusted for correct output level 
later.  Issue the TF command to switch off the through audio.

8.3.6.3

Issue the SIc command to set the required CTCSS tone group to 'c', 
where 'c' is in the range 'A - J'.  Issue the EE command to enable 
CTCSS encode and then issue the TI command to enable the CTCSS 
tone, and adjust R70 to give the correct 	CTCSS output level.  This 
should be 0.16 of the required output level for full system deviation as 
set in 8.3.6.2 above.  This corresponds to 800 Hz deviation (for 5 kHz 
full system deviation), or 400 Hz deviation (for 2.5 kHz full system 
deviation) which is -16 dB.  Issue the TJ command to switch the 
CTCSS off.

8.3.6.4

Issue the TH command and adjust R69 to give the CW ident output 
level of 0.5 of full system deviation as set in 8.3.6.2 above.  Issue the 
TL command and the output level should drop to about 0.1 of full 
system deviation level.  Issue the TO command to switch it off again.

8.3.6.5

Issue the TH command again, and change LK5 to A-C.  This sets the 
auxiliary ident tone output, and adjust R67 to give full 	system deviation 
level output.  Issue the TO command, and change LK5 back to A-B.

8.3.6.6

Issue the TMA command and adjust R66 to give the computer data 
output at full system deviation.  Issue the TN command to switch it 
back off again.

8.3.6.7

Set the audio signal generator to 1750 Hz, and a level of  that 
expected from the receiver at full system deviation (i.e. -6 dB).  
Connect the oscilloscope to TP16, and adjust R65 to give a low logic 
level on the oscilloscope.  There will be a range of adjustment of R65 
where TP16 will be low.  Try to adjust R65 to the middle of this range.

8.3.6.8

Connect the oscilloscope to TP20, and issue the TMA command again.  
This will put the computer data ON at full system deviation.  Adjust R64 
to give the desired clipping level.  This clipping level is not very 'hard' 
and is only designed to guard against over-deviation of the repeater 
transmitter.  The best setting of this pre-set is probably just at or before 
the onset of clipping with full system deviation.  By not providing any 
audio tailoring, transmitted audio should be the same as received 
	audio.

8.3.6.9

Connect the oscilloscope to the audio output, P28, and re-adjust R77 
to give the required output level for full system deviation into the 
transmitter.  This pre-set may be adjusted later, in conjunction with any 
peak deviation control in the transmitter, to set the desired output level.  
This control adjusts the output level, leaving the relative amplitudes of 
all the individual signals onstant.  Issue the TN command to switch off 
the computer data.

This completes the setting-up of the presets on the board.  The next stage is 
probably to sit down and have a cup of tea (or coffee)!  Following this, the 
configurable parameters need to be set to the desired values.

 


8.4 Main Parameter Set-up

This section deals with the main set-up features within the logic.  There are a 
number of commands that need implementing.  These are split into 5 groups.  
These are:-

8.4.1 'Ack' Characters

The normal, main 'ack' character is set using the SAx command, where 'x' is 
the character required.  This is the normal 'end of over pip', and can be set to 
any normal CW character.  The SRx command sets the auxiliary 'ack' 
character, which is used in place of the main one if the logic is powered from 
P31 rather than P2, which would normally be connected to a standby battery 
supply.

Issue the following commands, remember all should be ended with <enter>, 
and the logic should respond with '-OK-' :-

8.4.1.1

SAx	sets the main 'ack' character to 'x'.
e.g. - SAK<enter>.

8.4.1.2

SRy	sets the auxiliary 'ack' character to 'y'.
e.g. - SRB<enter>.

8.4.2 Timings

There are a lot of timing settings that need configuring.  These are basically 
split into two groups, in-over timings, and end-of-over timings.  The in-over 
timings use ticks of 0.5 seconds each, while the end-of-over timings use ticks 
of 2ms each.  A 1 second timing is therefore 2 ticks for in-over and 500 ticks 
for end-of-over timers.

8.4.2.1

SWx	sets the minimum tone burst length before access is allowed.  
Typically this would be set to 125, giving a minimum tone burst for 
access of 250ms.  The maximum allowed is 255, giving 510ms.
e.g. - SW125<enter>.

8.4.2.2

S3x	sets the tone burst gate delay.  When a tone burst is detected, 
the through audio is gated out, after a delay, to remove the tone 
burst.  Some incoming audio can 'trip' the tone burst detector, thus 
removing some of the incoming audio if this delay is set too short.  
Setting this delay stops this 'chopping' of the incoming audio, but 
does allow a short tone burst to get through.  Typically this would be 
set to 50, giving a gate delay of 100ms.  This can be fine-tuned later 
when 'on-air' if desired.
e.g. - S350<enter>.

8.4.2.3

SKx	sets the minimum post tone burst carrier latch time for the 
repeater to stay open.  Typically this would be set to 4, giving a 
carrier 'latch' time of 2 seconds.  The maximum allowed is 65535, 
giving a latch time of 32767.5 seconds!
e.g. - SK4<enter>.


8.4.2.4

S4x	sets the squelch delay.  No 'ack' will be given after an over 
which is shorter than this squelch delay.  Typically this would be set 
to 4, thus only giving 'acks' on overs longer than 2 seconds.
e.g. - S44<enter>.

8.4.2.5

STx	sets the repeater time-out time.  An over time longer than this 
time will have its incoming audio gated out (or not as selected in 
8.4.2.8), and replaced by 1 second 'pips'.  Typically this would be set 
to 600, giving a time-out of 300 seconds (5 minutes).  Note that this 
must be enabled with the ET command for the time-out to operate.
e.g. - ST600<enter>.

8.4.2.6

ES	to enable the 2 second carrier hang on access, or
DS	to disable the 2 second carrier hang on access,
e.g. - ES<enter>
    or - DS<enter>.


8.4.2.7

ET	to allow repeater time-outs, or
DT	to have no repeater time-out at all.
e.g. - ET<enter>
    or - DT<enter>.

8.4.2.8

EH	to allow through audio with time-out pips, or
DH	to only have time-out pips when in time-out.
e.g. - EH<enter>
    or - DH<enter>.

8.4.2.9

SZx	sets the time-out stop time (in seconds).  Typically this would be 
set to 10, giving 10 time-out 'pips' before shutdown.  If a time-out has 
occurred, time-out pips more than this will cause the repeater to issue 
its callsign and closedown.  Re-access with a tone burst is possible 
during the timeout 'PIP' phase or the shutdown phase, if the re-
access signal is strong enough.  After having shutdown, the repeater 
waits for the timed-out signal to go away, then will put its transmitter 
on, issue an 'OK' on CW and put its transmitter off again.  Normal 
access is then possible.  Note that this must be enabled with the EZ 
command for the timeout end to operate.
e.g. - SZ10<enter>.

8.4.2.10

EZ	to allow time-out end and closedown, or
DZ	to have continuous time-out until input signal goes away.
e.g. - EZ<enter>
    or - DZ<enter>.

8.4.2.11

SFx	sets the time from the end of an over to when the 'ack' character 
is sent.  Typically this would be set to 500, giving a time of 1 second.
e.g. - SF500<enter>.

8.4.2.12

SHx	set the 'ack' delay.  This is the time between double 'acks'.  
Typically it would be set to 2000, giving 4 seconds between 'acks'.  If 
set to 0, only a single 'ack' is given.
e.g. - SH2000<enter>.

8.4.2.13

SGx	sets the time from the end of an over to when the 'START' 
signal is given to the optional voice synthesiser board.  Typically this 
would be set to 5000, thus starting the synthesised voice at 10 
seconds after the over has finished   Note that while the voice is 
running, the end-of-over timer is NOT running, so subsequent 
timings, such at CTCSS off and shutdown times should not include 
the time taken for the voice to complete.  Note that this must be 
enabled with EV for the synthesised voice to operate.
e.g. - SG5000<enter>.

8.4.2.14

EV	to enable the synthesised voice on closedown, or
DV	to have no voice on closedown.
e.g. - EV<enter>
    or - DV<enter>.

8.4.2.15

SVx	sets the synthesised voice time-out.  Typically this would be set 
to 2500, giving a time-out of 5 seconds.  This is only used if the voice 
is enabled, but the voice board is not present, or does not work.
e.g. - SV2500<enter>.

When the voice synthesiser board has completed its replay, it issues a 
'VOICE_COMPLETE' signal.  This signal is used by the logic to re-enable the 
end-of-over timer and continue with normal operation.  If this voice complete 
signal does not occur, the logic will, in theory, wait for ever!  The voice time-
out will allow the logic to continue with normal operation without a voice 
complete signal on completion of the time-out period.

8.4.2.16

SXx	sets the CTCSS off time.  Typically this would be set to 7000, 
giving a time of 14 seconds from the end of over to when the CTCSS 
on transmit is switched off prior to the callsign and closedown.  This 
allows those of us lucky enough to have CTCSS in our radios not to 
hear the repeater callsign!
e.g. - SX7000<enter>.

8.4.2.17

SOx	sets the callsign and closedown time.  Typically this would be 
set to 7500, giving a time of 15 seconds from the end of over to when 
the repeater gives its callsign and closes down.
e.g. - SO7500<enter>.

8.4.3 Beacon

Beacons are sent every 'beacon-time'.  A beacon consists of a 'DE', (if 
enabled), the repeater callsign and CTCSS tone group, (if enabled).  If 
enabled, the locator, location and synthesised voice (the latter with transmit 
CTCSS ON) can also be sent.  These last three can be set so they are not 
sent every beacon, but every 'nth' beacon, where 'n' can be different for each.

8.4.3.1

SBx	set the time between beacons.  Typically this would be set to 
600, giving a beacon every 300 seconds (5 minutes).
e.g. - SB600<enter>.

8.4.3.2

EF	to have 'DE' on CW before the callsign, (de GB3DI for 
example), or
DF	to have just the callsign, (GB3DI for instance).
e.g. - EF<enter>
    or - DF<enter>.


8.4.3.3

EC	to not have CTCSS on when giving beacons, or
DC	to have CTCSS on for all beacons.
e.g. - EC<enter>
    or - DC<enter>.

8.4.3.4

SLs.s	set the text sent as a location to 's.s' when sending 
beacons.  This can be any normal text string up to 20 characters.
e.g. - SLOXFORD<enter>.

8.4.3.5

EL	to send the location text string with the beacon, or
DL	to not send any location text string.
e.g. - EL<enter>
    or - DL<enter>.

8.4.3.6

SSLn	sets the location to be sent every 'nth' beacon, if enabled.  
Typically this would be set to 12, giving a location sent every 12th 
beacon.
e.g. - SSL12<enter>.

8.4.3.7

SQiiiiii	sets the locator to 'iiiiii'.  Although this would normally be 
a 'Maidenhead' type locator, it can in fact be any text string up to a 
maximum length of 6 characters, even an old fashioned QRA if 
desired!
e.g. - SQIO91JO<enter>
or even SQZL33H <enter>!

8.4.3.8

EQ	to send the locator text string with the beacon, or
DQ to not send any locator text string.
e.g. - EQ<enter>
    or - DQ<enter>.

8.4.3.9

SSQn	sets the locator to be sent every 'nth' beacon if enabled.  
Typically this would be set to 4, giving a locator sent only every 4th 
beacon.
e.g. - SSQ4<enter>.

8.4.3.10

EA	to send the synthesised voice with the beacon, or
DA	to not send the synthesised voice with the beacon.
e.g. - EA<enter>
    or - DA<enter>.

8.4.3.11

SSVn	set the voice to be sent every 'nth' beacon if enabled.  
Typically this would be set to 12, giving a voice sent only every 12th 
beacon.
e.g. - SSV12<enter>.

8.4.4 Remote

Remote control can be with either a sequence of DTMF tones, or computer 
bitstream data.  The DTMF can be used to shutdown and startup the 
repeater, control the two digital outputs, or chop the incoming audio until the 
end of the current over .The computer bitstream data can provide quite 
extensive control and data read-out if desired.  The computer bitstream 
commands are protected by a password scheme, when 'on-air', to deter the 
'hacker'.  It can also be used via a second channel to avoid the use of the 
repeater main channel.  The use of this second control channel, for both 
DTMF and computer data is highly recommended.

8.4.4.1

SD1	to use the main repeater as the data input and output, or
SD2	to use the auxiliary channel as the data input and output.  See 
8.3.2 above for link setting associated with this selection.
e.g. - SD1<enter>
    or - SD2<enter>.

8.4.4.2

EM	to enable the 'on-air' use of DTMF tones, or
DM	to not use DTMF tones.
e.g. - EM<enter>
    or - DM<enter>.

8.4.4.3

SJn..n	sets the sequence of DTMF numbers to be used for 
remote repeater startup.  This can be any sequence of numbers 
including A - D, up to a maximum of 10 digits.
e.g. - SJ0123456789<enter>.

8.4.4.4

SYn..n	sets the sequence of DTMF numbers to be used for 
remote repeater shutdown.  This can be any sequence of numbers 
including A - D, up to a maximum of 10 digits.
e.g. - SY9876543210<enter>.

8.4.4.5

S51	sets the sequence of DTMF numbers to be used for control of 
digital output 1.  This can be any sequence of numbers including A - 
D, up to a maximum of 3 digits.
e.g. - S51123<enter>.

8.4.4.6

S52	sets the sequence of DTMF numbers to be used for control of 
digital output 2.  This can be any sequence of numbers including A - 
D, up to a maximum of 3 digits.
e.g. - S52456<enter>.

8.4.4.7

S53	sets the sequence of DTMF numbers to be used for the audio 
chop feature.  This can be any sequence of numbers including A - D, 
up to a maximum of 5 digits.
e.g. - S53456<enter>.

Two other keys on the DTMF keypad are also used, <*> for 'cancel', and <#> 
for 'complete'.  A typical sequence to use the DTMF control would be:-

*	Go to transmit
*	Press the '*' key, this will clear any numbers already received
*	Press the digit keys for the action required
*	Press the '#' key to indicate number sequence complete
*	Go to receive

For the digital output sequences, a '0' or '1' should be added to the end of the 
programmed sequence.  '0' will put the selected output LOW, and '1' will put it 
HIGH.

If the number sequence matches one of the set sequences, the repeater will 
come 'on-air' and send on CW either 'OFF' if the command was to shut the 
repeater down, or 'ON' if it was to start it up.  For the digital output DTMF 
commands, the repeater will send '1H', '1L', '2H' or '2L', signifying output 1 
high or low or output 2 high or low.  For the Audio chop feature, no positive 
response is given  just the through audio disappearing!

e.g. - to set digital out 1 HIGH, (using the above number sequence 
example):-

*	Go to transmit
*	Type '*' 
*	Type '1231'
*	Type '#' 
*	Go to receive

8.4.4.8

EB	to use 'on-air' computer bitstream control, or
DB	to not use 'on-air' computer bitstream control
e.g. - EB<enter>
    or - DB<enter>.

8.4.4.9

EP	if using a Plessey MV8870, or
DP	if using a MITEL MT8870 DTMF decoder
e.g. - EP<enter>
    or - DP<enter>.

8.4.4.10

ER	to enable the repeater - i.e. start-up, or
DR	to disable the repeater - i.e. shutdown.
e.g. - ER<enter>
    or - DR<enter>.

8.4.4.11

E1	to set digital output 1 HIGH, or
D1	to set digital output 1 LOW.
e.g. - E1<enter>
    or - D1<enter>.

8.4.4.12

E2	to set digital output 2 HIGH, or
D2	to set digital output 2 LOW.
e.g. - E2<enter>
    or - D2<enter>.


8.4.4.13

DO	to shut off the through audio for the remainer of the current 
over.  This can be used during a QSO to remove objectionable audio.  
Its use it transparent to the offender (he is on transmit after all!).  The 
ACK response is no different and subsequent overs are normal.

8.4.5 General Commands

8.4.5.1

S1H	if the main repeater squelch input is HIGH with signal, or
S1L	if the main repeater squelch input is LOW with signal.
e.g. - S1H<enter>
    or - S1L<enter>.

8.4.5.2

S2H	if the auxiliary squelch input is HIGH with signal, or
S2L	if the auxiliary squelch input is LOW with signal.
e.g. - S2H<enter>
    or - S2L<enter>.

8.4.5.3

SMx	sets the CW speed to x words per minute (WPM).   This may be 
in the range of 10 to 30 WPM.   Typically it would be set to 18.
e.g. - SM18<enter>.

8.4.5.4

SIc	set the CTCSS tone group to c, where c is A - J, as determined 
by the RSGB.
e.g. - SIJ<enter>.  Note, this may have been set in 8.3.6.4.

8.4.5.5

ED	to enable CTCSS decode, (i.e. repeater access), or
DD	to disable CTCSS decode.
e.g. - ED<enter>
    or - DD<enter>.

8.4.5.6

EE	to enable CTCSS encode, i.e. on transmit, or
DE	to disable CTCSS encode.
e.g. - EE<enter>
    or - DE<enter>.   Note, this may have been set in 8.3.6.4.

The toneburst access can be disabled, mainly for 6m repeater use.

8.4.5.7

EK	to enable Toneburst access, or
DK	to disable Toneburst access.
e.g. - EK<enter>
    or - DK<enter>.

The CTCSS decode system can also be set to require continuous CTCSS  
which is the normal PMR type use - .  This is a requirement for 6m repeaters.

8.4.5.8

EN	to enable continuous CTCSS on decode, or
DN	to disable continuous CTCSS decode.
e.g. - EN<enter>
    or - DN<enter>.

8.4.5.9

EG	to give the callsign on successful access, or
DG	to not give the callsign on access.
e.g. - EG<enter>
    or - DG<enter>.

8.4.5.10

EI	to give the callsign on shutdown, or
DI	to not give the callsign on shutdown.
e.g. - EI<enter>
    or - DI<enter>.

8.4.5.11

EW	to give time-out like 'pips' (actually 'T's) if a CTCSS tone is 
received during a QSO, but the tone is the wrong group, or
DW	to ignore any wrong CTCSS tone during a QSO.
e.g. - EW<enter>
    or - DW<enter>.

	Due to a 'feature' in the CTCSS integrated circuit used in the logic, this 
facility seems not to work very well.  It is suggested that it is left OFF (use the 
DW command), as it is likely to be removed in future firmware issues.


8.4.5.12

EJ	to allow CTCSS going away OR squelch closing to signify end 
of over, or
DJ	to only allow squelch closing to signify end of over.
e.g. - EJ<enter>
     or - DJ<enter>.

8.4.5.13

SEd..d	sets the set-up date.  This would normally be set to the 
date when the repeater logic was configured, or the 	configuration 
modified.  It is not used for anything, but can be read out later as a 
record.
e.g. - SE23/6/95<enter>.

8.4.6 Configuration Dump

The complete configuration set-up can be read out by pressing <F5> in the 
SETUP programme.  This will read the complete configuration, and display it 
on the PC screen.  This can then be printed locally, if desired, by using the 
<print screen> key, or saved to a file for later printing.

The configuration set-up screen shows the current settings of the 
configurable parameters, with timings converted from their 'tick' values to 
seconds, etc.  For each entry, the relevant command is also shown, together 
with the 'tick' value (either 0.5s or 2ms) for the timing values, as an aide-
memoir.  The <F7> key can be used to give a simple help screen.

8.5 Password Setup

Finally the Master Password should be set by pressing <F6>.  This will 
encrypt the 'From' callsign, (hopefully the repeater keepers!), and store it in 
the logic for later use with the SP command.

When using the computer bitstream data 'on-air', a password is needed for all 
commands.  This password is changed every time that it is used, so a method 
of initially setting it is required.  This is done with the SP command 
(automatically using <F2>).  The logic then checks that the Master Password 
received with the SP command matches that which was set previously with 
<F6> AND the encrypted 'From' callsign.  Note that the command for setting 
the master password (via <F6>) is only available locally, and so the master 
password cannot be changed 'on-air'.


8.6 Records Result Sheet

Test Record Result Sheet
G8CUL Repeater Logic

Serial Number		................................................................................

Repeater			................................................................................

Tester				................................................................................

Date			 	................................................................................

Inside Leg Measurement	................................................................................


Test Para Number
Actual Test
Measured Result
8.3.3
Supply Resistance

8.3.4
Supply current

8.3.4.1
Digital +5V

8.3.4.2
Analogue +5V

8.3.4.3
Analogue -5V

8.3.4.4
RS232 +10V

8.3.4.5
RS232 -10V

8.3.4.6
TP4 Waveform




9 Commands

This section gives a list of the commands which can be used to control the 
logic system.  It is intended as a reference and should be treated as such.  
The set-up implemented in section 8 uses these commands for the initial 
configuring of the logic.

9.1 Computer Commands

All variable parameters are modified by simple commands which are 
embedded within a 'packet' which contains a header (for source and 
destination callsigns), and a checksum to improve overall data integrity.

These 'packets' should not be confused with those used in 'packet radio', 
which are a completely different format!

		The packet format is as follows:-

	SOH				(byte value 1), (*)
	Source callsign		i.e. G8CUL
	Delimiter			Comma (,)
	Destination callsign		i.e. GB3DI
	Delimiter			Comma (,)
	Data field			Maximum of 20 characters (Packets IN)
					Maximum of 18 characters (Packets OUT)
	Checksum			2 HEX digits representing the modulo 256 
					algebraic sum of all the bytes in the packet, 
					NOT INCLUDING the checksum.
	EOM				(byte value 25), (*)

This packet format is used for all data transfers between the computer and 
the logic either via the RS232c port locally or the Bell 202 tones while 'on-air'.  
For commands from the computer to the logic, the first 2 or 3 characters in 
the data field are used for the command itself.

These commands consist of 2 or 3 UPPER-CASE characters, with optional 
extra parameters which are used as data for the command specified.

These commands allow setting up of the configurable parameters for 
individual repeater requirements, and are listed below.

For example, a packet containing a 'read serial number' command would be :-

	*G8CUL,GB3DI,SNBF*

Where * and * represent the SOH and EOM respectively.  These normally 
appear on a PC as a small face (SOH) and a down arrow (EOM).  The 'BF' 
after the SN command is the hex representation of the checksum.  In this 
example the source of the packet is G8CUL and the destination GB3DI.  The 
reply to this could be:-

	*GB3DI,G8CUL,0001DF*

The reply has the source and destination callsign 'swapped' and the data 
field just contains the reply, that is the serial number (0001) followed by the 
checksum (DF).

All commands will return some information or other.  A read command will 
return the requested information, while other commands will return a packet 
with '-OK-' in the data field.  In this way, a command issued which is either 
incorrect in itself, or has incorrect parameters associated with it will be 
ignored, and nothing will be returned to the computer.  If there is no answer to 
a command, then you have done something wrong!

All commands can be used locally, that is with the PC plugged directly into 
the logic unit, with LK1 removed.  Some commands may also be used 
remotely, that is via the radio while the repeater is 'on-air'.  These commands 
are referred to as global commands.  In the following list, each command is 
listed as being local (L) or global (G).  LK1 acts as a 'switch' to select local 
set-up or not.   Normal repeater operation is with LK1 IN.  To use local set-up, 
LK1 must be removed, this will also stop any repeater action while LK1 is 
OUT.

Commands used locally do not require the use of any passwords, but when 
used remotely, two 4 hex digit passwords are required for ALL global 
commands.  The first password is used for this command, and is tested 
against the password previously saved in the logic.  The second password, if 
the first was correct, is then saved and used for the next command.  This 
scheme gives a password which can change every time it is used.  There is, 
of course, an immediate flaw in this, how is the first password set the first 
time?  The SP command implements this, and uses for its first password a 
master password which does not change, and is held in the EEPROM in the 
logic unit.  The master password can be set by the S0 (zero not 'O') command 
(local only), and would normally be encrypted from the repeater keeper's 
callsign.  It cannot be read remotely, as the only command available to 
interrogate it is a local only command.

When using SETUP locally, there is no need for the use of any passwords.  
When used remotely, a password must be used for all commands.  This 
password can be automatically generated and inserted into the packet on 
pressing the <F1> key.  This key should be pressed between the command 
itself and any associated parameters.  It must therefore be used every time 
that any command is used remotely.

The freely available set-up PC programme implements all of this 
automatically, including the insertion of both 'to' and 'from' callsigns and the 
encryption of the master password from the repeater keeper's callsign, on 
pressing of the <F6> key.

9.1.1 Enable Commands

None of these commands require any extra parameters, and are used for 
ENABLING internal options.

9.1.1.1 Timings

EH	(G)	Enable through audio when in time-out
ET	(G)	Enable repeater time-out
EV	(G)	Enable the repeater 'Voice' on closedown
EZ	(G)	Enable repeater time-out 'End'

9.1.1.2 Beacon

EA	(G)	Enable the 'Voice' when giving beacons
EC	(G)	Enable CTCSS encode inhibit when giving callsigns.
EF	(G)	Enable 'DE' before callsign
EL	(G)	Enable the sending of the location when giving beacons
EQ	(G)	Enable the sending of the locator when giving beacons

9.1.1.3 Remote

EB	(G)	Enable the remote bit stream data control
EM	(G)	Enable DTMF commands
EP	(G)	Enable the use of the PLESSEY MV8870

9.1.1.4 General

ED	(G)	Enable CTCSS decode, i.e. on receive
EE	(G)	Enable CTCSS encode, i.e. on transmit
EG	(G)	Enable sending the callsign on initial access
EJ	(G)	Allow CTCSS or squelch to signify end of over
EI	(G)	Enable sending the callsign on closedown
EK	(G)	Enable tone burst access
EN	(G)	Enable continuous CTCSS operation
ER	(G)	Enable the repeater - i.e. startup
*EW	(G)	Enable 'time-out' pips when wrong CTCSS received
E1	(G)	Put digital output 1 HIGH
E2	(G)	Put digital output 2 HIGH


9.1.2 Disable Commands

As above, none of these commands require any extra parameters.   They are 
all used for DISABLING internal options.

9.1.2.1 Timings

DH	(G)	Disable through audio when in time-out
DT	(G)	Disable repeater time-out
DV	(G)	Disable the repeater 'Voice' on closedown
DZ	(G)	Disable repeater time-out 'End'

9.1.2.2 Beacon

DA	(G)	Disable the 'Voice' when giving beacons
DC	(G)	Disable CTCSS encode inhibit when giving callsigns.
DF	(G)	Disable 'DE' before callsign
DL	(G)	Disable the sending of the location when giving beacons
DQ	(G)	Disable the sending of the locator when giving beacons

9.1.2.3 Remote

DB	(G)	Disable the remote bit stream data control
DM	(G)	Disable DTMF commands
DP	(G)	Disable the use of the PLESSEY MV8870, i.e., use the MITEL 
		MT8870

	BEWARE! 	If you use the DB command remotely to disable the 
computer bit stream data control, the only way of re-enabling it would 
be to take a visit to the repeater site with a PC computer and re-enable it 
locally!

9.1.2.4 General

DD	(G)	Disable CTCSS decode
DE	(G)	Disable CTCSS encode
DG	(G)	Disable sending the callsign on initial access
DI	(G)	Disable sending the callsign on closedown
DJ	(G)	Allow squelch only to signify end of over
DK	(G)	Disable tone burst access
DN	(G)	Disable continuous CTCSS operation
DR	(G)	Disable the repeater - i.e. shutdown
*DW	(G)	Disable 'time-out' pips when wrong CTCSS received
D1	(G)	Put digital output 1 LOW
D2	(G)	Put digital output 2 LOW

* These commands are likely to be removed in future firmware issues.

Notes:

EV/DV enable/disable the control of an external voice synthesiser unit.

ER/DR enable/disable the repeater itself, i.e. remote shutdown etc.

EW/DW enable/disable time-out like pips on receipt of incorrect CTCSS.   
See the note in 8.4.5.11.  They are likely to be removed in future firmware 
issues.

EZ/DZ enable/disable a time-out time-out, that is whether to switch the 
repeater off after a given time of time-out 'pips'.

EN/DN enable/disable the use of continuous CTCSS operation.  When 
enabled (EN), only received signals with the correct CTCSS will be passed to 
the transmitter.

EK/DK and EN/DN are for firmware version V2.0a onwards only!  Their 
intended use is for 6m repeaters.

9.1.3 Read Commands

Some of these commands require extra parameters, while others do not.

RD (G)	Read diagnostics.  Two numbers are returned, followed 
by the firmware version number.  The numbers are 
counters which correspond to the number of packets 
received with a bad checksum and bad length 
respectively.

RMaaaa (L)	Read the contents of processor memory aaaa (in HEX).  
Processor addresses lie in the range 0000 to 1FFF.

RRaa (L)	Read the contents of EEPROM address aa (in HEX).  
EEPROM addresses lie in the range 00 to 7F.

RS (G)	Dump EEPROM, all 128 bytes are read.  Note that this is 
normally implemented using <F5>.

RV (G)	Read variables.  Two 8 digit HEX numbers are 	returned.  
These are the oncount and offcount counters, which 
correspond to the time the repeater has been in use and 
'idle' (in beacon mode) respectively.  Each counter counts 
0.5 second 'ticks'.  i.e. the time in seconds is the counter 
* 2.  The SETUP programme will convert these numbers 
to total time and in-use time as a percentage of total time.

SN (G)	Read the serial number of the logic unit.

9.1.4 Write Commands

These are only included to give very low level control.  In normal use they 
should NOT be used.  If they are, they must be used with EXTREME care.  
Failure to do so could easily end up with a non-functioning logic system.

WMaaaadd (L)	Write byte value dd to processor memory address aaaa, 
(both in HEX).

WRaadd (L)	Write byte value dd to EEPROM address aa, (both in 
HEX).

In fact, the only time I can visualise the use of WR is the initial setting up of 
the logic serial number.  I can not think of any need for the WM command at 
all!

9.1.5 Set Commands

These are the main commands for setting up the repeater logic configurable 
parameters.  They all need extra parameters, the format of which depends 
upon the command in question.

9.1.5.1 'Ack'

SAx (G)	Set the 'Ack' character to x.  This is used for the end of 
over 'pip'.  For example, an 'E' gives a short pip, a 'T' 
	gives a longer one!  Any normal CW character can be 
used.

SRx (G)	Set the 'Ack' character used when on battery supply to x.  
This character is used in place of the normal one (set by 
the SA command) when the logic is running on battery 
supply.

9.1.5.2 Timings

SFxx (G)	Set the 'Ack' time to xx * 2ms.  This is the time from the 
end of 'over' to the 'Ack'.

SGxx (G)	Set the 'Voice' time to xx * 2ms.  This is the time from the 
end of the 'over' to the start of the 'Voice'.

SHxx (G)	Set the pip delay to xx * 2ms.  This is the time between 
double 'Acks'.  If set to 0, a single 'Ack' is used.

SKxx (G)	Set the access 'latch' time to xx * 0.5 seconds.  This is the 
minimum carrier ON time required (after tone burst time) 
to get the repeater to latch on.  It may be set to 0.

SOxx (G)	Set the time to callsign and closedown to xx * 2ms.  This 
is the time from the end of the 'over' to the start of the 
callsign and closedown.

STxx (G)	Set the repeater time-out time to xx * 0.5 seconds.  This 
is the 'over' time before the audio input is shut-off (if 
selected) and time-out starts.  See ET/DT above for 
enabling/disabling the time-out feature and EH/DH.  See 
also SZ below.

SVxx (G)	Set the 'Voice' time-out to xx * 2ms.  i.e. 2500 gives 5 
	seconds.  This is used if the 'Voice' is enabled, but is not 
connected or does not work!  This time-out will allow the 
repeater to continue functioning.

SWxx (G)	Set the tone burst length required for access to xx * 2ms.  
The maximum is 510ms, (xx = 255!).  This sets the 
minimum tone-burst length that will allow access.

SXxx (G)	Set the CTCSS off time to xx * 2ms.  This is the time from 
the end of the 'over' when the CTCSS encode is inhibited.  
Also see EC/DC.

SZxx (G)	Set the time-out stop time in seconds.  This is used to 
determine the time for which time-out pips are given.  At 
the end of this time, the repeater will go into a normal 
closedown procedure.  See the EZ/DZ commands for 
enabling/disabling this feature.

S3xx (G)	Set the tone burst delay time to xx * 2ms.  This is the 
length of tone burst required before incoming audio will 
be gated out.  Setting this too low may cause slight 
breaks in normal speech.

S4xx (G)	Set the squelch delay time to xx * 0.5 seconds.  This is 
the minimum 'over' time that will give an 'ack'.  Times 
shorter than this will not produce an 'ack', thus deterring 
the insistent 'bleeper'!


9.1.5.3 Beacon

SBxx (G)	Set the beacon time interval to xx *0.5 seconds.  For 
example, 600 gives 300 seconds (5 minutes).

SLcccc (L)	Set the location to the string cccc.  The maximum string 
length is 20 characters, and can be anything you want!  It 
is used when sending beacons.

SQxxxx (L)	Set the locator to xxxx.  The locator is used when sending 
beacons.  The maximum length is 6 characters.

SSLxx (G)	Set how often the location is sent with the beacon.  For 
example, if the location is enabled with the EL command, 
setting this command to 3 will give a location every 3rd 
beacon.  The allowed range is 0-255.  BEWARE - a value 
of 0 will have the effect of 256!  A value of 1 will send the 
location with every beacon.

SSQxx (G)	Set how often the locator is sent with the beacon.  For 
example, if the locator is enabled with the EQ command, 
setting this command to 2 will give a locator every 2nd 
beacon.  The allowed range is 0-255.  BEWARE - a value 
of 0 will have the effect of 256!  A value of 1 will send the 
location with every beacon.

SSVxx (G)	Set how often the voice is sent with the beacon.  For 
example, if the voice is enabled with the EA command, 
setting this command to 6 will give a voice every 6th 
beacon.  The allowed range is 0-255.  BEWARE - a value 
of 0 will have the effect of 256!  A value of 1 will send the 
location with every beacon.

9.1.5.4 Remote

SDn (L)	Set main (n = 1), or auxiliary (n = 2) for the data channel.  
This also requires LK3, LK4 and LK5 to be set to A-C on 
the logic board.  See the set-up instructions for more 
details.

SJx...x (L)	Set the DTMF sequence for remote repeater startup.  The 
maximum length is ten digits.

SYx...x (L)	Set the DTMF sequence for remote repeater shutdown.  
The maximum length is ten digits.

S5nxxx (L)	Set the DTMF sequence for remote control of output 1 or 
output 2.  n must be either 1 or 2, and the maximum 
length for xxx is 3 digits.

S53xxx (L)	Set the DTMF sequence for the audio chop.  The 
maximum length for xxx is 5 digits.

9.1.5.5 General

SCccccc (L)	Set the repeater callsign to ccccc.  The maximum callsign 
length is 6 characters.

SEddddd (L)	Set the set-up date.  This would normally be of the form 
dd/mm/yy.  This has a maximum length of 8 characters, 
and is only held in EEPROM for later perusal.  It is 
recommended that it is set when any configuration is 
changed, for future reference.

SIc (L)	Set the CTCSS group to use.  'c' should be in the range 
'A' - 'J'.  Note that 'I' is not used, and is treated as though 
it were 'J'.  The sub-audio tone then used is as decided 
by the RSGB!

SMxx (G)	Set the CW speed to xx WPM.  It can be in the range of 
10 to 30 WPM.  This speed is used for all characters sent 
on CW, 'Ack' characters, beacon etc.

SPoonn (G)	Set the new password number to nn.  See below for use.

S0xxxx (L)	Set the master password to the 4 hex digit number xxxx.  
This is implemented by the <F6> key when in local set 
up.

S1x (L)	Set the squelch polarity of the main receive input .  'x' 
should be either 'H' or 'L', meaning an incoming signal 
giving a HIGH or LOW level on the squelch line.  Note 
that this is on input to the logic board itself, not any prior 
level shifters!

S2x (L)	Set the squelch polarity of the auxiliary receive input.  As 
above, 'x' should be either 'H' or 'L'.

9.1.6 Test Commands

These commands can only be accessed locally, and give test features to 
enable setting up of the various level adjustments etc.


TA	(L)	Put the main transmitter ON.
TB	(L)	Put the main transmitter OFF.
TC	(L)	Put the auxiliary transmitter ON.
TD	(L)	Put the auxiliary transmitter OFF.
TE	(L)	Open the audio gate (put RX audio through to TX input).
TF	(L)	Shut the audio gate.
TH	(L)	Switch on tone oscillator at HIGH level.
TL	(L)	Switch on tone oscillator at LOW level.
TO	(L)	Switch off tone oscillator.
TI	(L)	Switch on currently selected CTCSS tone.
TJ	(L)	Switch off CTCSS tone.
TMA	(L)	Switch on bitstream data tone from FX614.
TMC	(L)	Switch on bitstream test data from FX614.   Note .
TN	(L)	Switch off bitstream data tone.

 Note  - This command will send a continuous 10101010 bitstream to the 
	FX614 The only exit from this state is to reset the logic, either by 
	turning power off and on, or by using LK2.

Some commands can be used all the time, (whether local or remote), while 
others may only be used locally, that is when the computer is plugged into the 
RS232c port directly.  When a command is used remotely, the use of a 
password is mandatory to access the command.  The password must occur 
BETWEEN the 2 character command and its parameters (if any).  The 
password should consist of a 4 digit HEX number, followed by another 4 digit 
HEX number.  The first number is used as the password for THIS command, 
and the second number is used as the password for the NEXT command.  In 
this way the password will change every time that any command is accessed 
remotely.  There is no need for any password action when any command is 
accessed locally.

The only exception to the above is the Set Password (SP) command itself.  
The first password must match both the master password held in the 
EEPROM and the encrypted 'from' callsign in the packet header.  The second 
password is then used to set the password for the NEXT command.  This 
allows forgetful repeater keepers to set a new password number when they 
have forgotten the old one!

The master password is set by the S0 command, which can only be used 
locally.  This master password would normally be encrypted from the repeater 
keeper's callsign.

The intention of this rather complicated changing password scheme is to give 
some limited security if the repeater is to use the remote bit stream data 
control.


9.2 DTMF Control

The use of DTMF tones while 'on-air' gives some remote control.  This limited 
control allows the repeater to be shut down and re-started, the setting high or 
low of 2 digital output signals and the chopping of through audio.  Having set 
the DTMF digits required for the various functions, the use of this control is 
the same for all of the DTMF remote control functions.  Two other keys on the 
DTMF keypad are also used, <*> for 'cancel', and <#> for 'complete'.  The 
DTMF keys 'A' to 'D' may also be used, but if the MITEL DTMF decoder is 
used, a minor wiring modification is required to the PCB.  This modification 
requires pin 5 of IC2 ('SEL') to be connected to 0V rather than +5V.

A typical sequence to use the DTMF control would be:-

*	Go to transmit
*	Press the <*> key, this will clear any numbers already received
*	Press the digit keys for the action required
*	Press the <#> key to indicate number sequence complete
*	Go to receive

For the digital output sequences, a '0' or '1' should be added to the end of the 
programmed sequence.  '0' will put the selected output LOW, and '1' will put it 
HIGH.

If the received number sequence matches one of the set sequences, after the 
input squelch has closed (or 2 seconds, whichever is first), the repeater will 
come 'on-air', and send on CW either 'OFF' if the command was to shut the 
repeater down, or 'ON' if it was to start it up.  For the digital output DTMF 
commands, the repeater will send '1H', '1L', '2H' or '2L', signifying output 1 
high or low or output 2 high or low.  The audio chop feature gives no reply, 
but will remove the through audio until the end of that over.

e.g. - to set digital out 1 HIGH, (using the number sequence example shown 
before):-

*	Go to transmit
*	Type '*' 
*	Type '1231'
*	Type '#' 
*	Go to receive

10 PC Setup Programme

A SETUP.EXE programme is freely available which, when run on a PC 
compatible computer, encodes the packets described above, and controls the 
use of passwords etc.  This setup programme is capable of using either 
COM1 or COM2 as an RS232c port to communicate with the repeater logic 
either locally in SETUP mode, or remotely while the repeater is 'ON-AIR'.  
When used remotely, a normal BayComm type modem (with a suitable 9-pin 
adapter, as shown in section 15) connected to radio equipment capable of 
communicating with the repeater, is required to control all the 'remote' 
commands.

10.1 Setup Invocation

Setup can be used with either COM1 or COM2.  To invoke setup type:

	SETUP or SETUP 1, to use COM1.

	SETUP 2, to use COM2.

SETUP requires a configuration file to operate, which, if not present, will be 
generated by SETUP itself, after suitable prompting.  This SETUP.CFG file 
contains the repeater callsign, the repeater keeper's callsign and the next 
password number to be used.  When SETUP is invoked, SETUP.CFG is read 
and the callsigns and the password number set accordingly.  When setup is 
exited, the current values are written to SETUP.CFG.

10.2 SETUP Function Keys

Setup uses a number of function keys to control various things.  These 
function keys and their uses are described below.

F1 - Send the NEXT password number - this automatically changes each time 
it is used.

F2 - Set password number.  This probably needs to be used each time a 
remote control session is started.  It will set the password number in the PC 
AND send it to the logic.  A 4 figure HEX number should be typed in response 
to the request.  This number will be used the next time <F1> is pressed.

F3 - Set the 'FROM' callsign.  The callsign put in here and in F4 below set the 
callsigns used for every transaction from then on.  This and the 'TO' call are 
saved in the SETUP.CFG file when the programme is exited, so will appear 
automatically next time.  (As does the next password number!).

F4 - Set the 'TO' callsign.  See F3 above.  Must be the repeater callsign.

F5 - Dumps the contents of the EEPROM out to the PC.  This is then 
displayed in tabular form for simple (!) perusal.  Options are then available to 
save and/or print the setup information.

F6 - Set Master Password.  This encrypts the 'FROM' callsign and sends it to 
the logic.  This command (in the logic) only works in local mode, so the 
master password can't be changed unless you are actually connected directly 
to the logic. 

F7 - Gives a help screen.  This is in the same format as the screen produced 
by the F5 key, but just gives the commands.  No data is read from the logic, 
so this operation is faster than using the F5 key!

X  - (UPPER CASE) to exit the programme.

NOTE - ALL COMMANDS AND ALL PARAMETERS MUST BE IN UPPER 
CASE.  HIT THE 'CAPS LOCK' KEY ON THE KEYBOARD!

After each command, a key press will normally get command prompt back 
again and be the first character of the next command.  Due to the rather large 
'TXDELAY' built in each end of the communications link, the response is not 
immediate!

During remote operation, each command requires the use of the <F1> key to 
insert the password numbers into the packet.  The current password, (i.e. the 
next one to be used) is thus held in the logic and in the SETUP programme.  
If for any reason these two passwords get out of synchronisation with each 
other, by the mis-typing of a wrong command for example, the logic will no 
longer respond to commands, as it is checking for a different password than 
that being sent by the SETUP programme.  The <F2> key can then be used 
to re-synchronisation the passwords, by telling the logic what the next 
password will be.  As described elsewhere, this requires the use of the 
master password and the repeater keepers callsign.

11 Hardware and Circuit Description

11.1 Introduction

The hardware design is based around a single-chip micro-controller from 
Motorola, the MC68HC705.  This device contains up to 32 Input/Output lines, 
a timer, a serial port, RAM and about 7 kbytes of EPROM to contain the 
programme.  The processor is interfaced to other devices within the circuit 
design to provide the required functions.

Other features incorporated are implemented by the usual NE567 for tone 
burst detection, an FX805 for CTCSS, MT8870 for DTMF decoding and 
FX614 for serial data input and output.  Non-volatile parameter storage is 
provided by a 128byte EEPROM.


11.2 Analogue Sheet

Incoming audio from the receiver is amplified by one half of IC19 (TLC272).  
The level at the input of this amplifier may be adjusted by R78 (fine gain), or 
by changing the ratio of R13/R35.  This signal is then split to feed all the 
devices which require it.  These are IC10, the NE567 tone burst detector, 
IC2, the MV8870 DTMF decoder and IC9, the FX614 data decoder.  The 
remote control signals to IC2 and IC9 may be routed from a separate 
receiver, by changing LK3 from A-B to A-C.  This would then necessitate the 
use of a separate transmitter, changing LK4 from A-B to A-C, LK5 from A-B to 
A-C and using the SD command to inform the control programme of the use 
of a separate receiver/transmitter combination.

The received audio signal is also fed to IC3, an FX805, onto pin 10 for the 
audio path and pin 16 for the CTCSS tone.  The audio path within IC3 also 
contains the through audio gate and a 300Hz high pass filter to remove the 
incoming CTCSS tone.  The audio out from pin 11 is then added to the 
outgoing CTCSS tone from pin 9, as well as all other outgoing audio signals.  
This outgoing information consists of through audio, CTCSS transmit tone 
(generated by the FX805), CW ident and data tones.  This combined audio is 
then peak clipped by IC19, to guard against over-deviation of the transmitted 
signal, and filtered by a 40dB per decade low-pass filter (IC20).  The output 
of this filter is fed to the repeater transmitter via an output level control, R77.

No de-emphasis or pre-emphasis is included in the logic.  In fact the repeater 
transmitter must have its pre-emphasis removed to avoid attenuation of the 
outgoing CTCSS tone.  Likewise on receive, any de-emphasis in the repeater 
receiver must also be removed, to give neutral audio tailoring and avoid 
excessive received CTCSS amplitude.  The overall effect of not having any 
in-built audio tailoring is that signals are transmitted as they are received, 
with the exception of the peak clipping and subsequent low pass filtering.

The tone burst detect frequency is set by R65, and has a nominal bandwidth 
of about 100Hz.

When IC2, an MT8870 (or MV8870) detects a valid DTMF tone it produces 
an interrupt signal to the processor, and puts the DTMF tone binary code on 
its output for the processor to read.

IC9, an FX614, detects the standard Bell 202 tones, producing the decoded 
serial data into the processor serial input.  The serial output from the 
processor is routed to IC9, which gives either a 1200Hz or 2200Hz tone on its 
analogue output on pin 7, which is switched on and off into the transmitter 
input under processor control. 

The 'ack' and CW ident tones are produced by the usual phase shift 
oscillator, using TR4.  TR3 buffers the oscillator output, and TR5 is used to 
vary the gain of TR4 under processor control, which has the effect of stopping 
and starting the oscillating action.  The tone output level can be switched 
between a high and low level, (depending upon input signal presence) by 
TR6.  The tone frequency is set to a nominal 1700Hz by C37, C40 and C41 
(0.01uF).  Changing these values to 0.015uF or 0.022uF should give nominal 
frequencies of 1200Hz and 850Hz respectively.

11.3 Digital Sheet

At the heart of the logic is the micro-controller, or processor, IC1, an 
MC68HC705C8.  This contains all the usual micro-processor hardware 
elements, CPU, clock, timer, I/O, EPROM (for the control programme), RAM 
and serial interface.  All these features are used by the control programme.

Two squelch signals are buffered by IC17, 74HCT14, and fed to the 
processor.  These are for the main and (optional) auxiliary receivers.

Another squelch input is available for an extra link receiver, which may be 
used for repeater linking.  An extra audio input to the transmitter summing 
amplifier is also provided for link receiver use, (or synthesised voice).  
However, the current control programme does not yet support repeater 
linking, but a beta version is undergoing tests.  This requires the use of 
external linking hardware.  The protocols involved are not yet sufficiently 
defined to allow full implementation - yet.  Watch this space, however, as 
both our repeaters (GB3DI and GB3OX) are due to be linked in the near 
future.    GB3TE and GB3CL, at Clacton-on-Sea, are currently operating as a 
co-sited linked pair.

The RS232c interface is connected via PL1, a 9 pin 'D' type SOCKET, via the 
RS232c interface device, IC7, an LT1080, to the serial in and out of the 
processor on pins 29 and 30.   These signals are fed via 2 'gates' of an 
analogue multiplexer, IC8, 74HCT4053.  This allows the serial input and 
output of the processor to be switched between the RS232c interface and the 
MODEM IC, IC9.  The control for this switching is the link LK1, which is also 
applied to the processor so the control programme can also 'know' when LK1 
is removed for set-up.  IC7 generates its own 10V (ish) for the RS232c 
interface levels by a simple internal charge-pump system.  LED1 indicates 
when the logic is in set-up mode (with LK1 removed), AND a PC is present 
with the correct handshake signal.

Outputs to the two PTT signals, for the main and (optional) auxiliary 
transmitters, is via open collector transistors to operate conventional PTT 
type controls.  These signals also drive two LED's, LED3 and LED4 via two 
inverters of IC16, to give indication when the transmitter(s) are on.

The repeater may be shut down by the remote commands described above, 
or by shorting P8 to P7 locally.  Another LED, LED2, is used to indicate when 
the repeater is 'on-air' or shut down/in set-up mode.

Incoming power at a nominal +12V is applied to a 3 terminal regulator, IC4 
from either the main, P2, or auxiliary, P31, power .  The application of +12V 
on the main power inputs is sensed by the processor via R74, D10, R73 and 
IC16, and is used to select the main or backup 'ack' character.  If a battery 
supply system is used, this facility will give indication of mains failure.

Power for the analogue circuitry, at 5V is generated by IC5, an NMA0505S, 
which is a low power isolating switching power converter.  Inputs and output 
from IC5 are filtered to reduce interference from the digital to the analogue 
circuitry.

IC6, XLS93C46P, is a 128byte EEPROM connected to the processor by a 
serial data link.  The DATA_OUT and SER_CLK signals are shared by the 
CTCSS IC, IC3, each having separate Chip Select (CS) and DATA_IN 
signals.  All the configuration data is held in this EEPROM, which does not 
forget its contents when power is switched off.

12 Block Diagram

 

Figure 1 Control Logic Block Diagram

13 Board Layout

The PCB layout is shown on this page, and is given for reference only!


14 Circuit Diagrams

The two circuit diagrams, the analogue and digital sheets, are provided on 
the next two pages in fold-out A3 fashion.

15 BayComm Adapter

To use the remote computer control, a simple pin-swapping adapter is 
needed between the PC and the BayComm modem.  This swaps the data 
in/out pins from those used by BayComm to the normal asynchronous data 
in/out pins, and the PTT control.

The adapter is made up using a 9 pin 'D' plug and a 9 pin 'D' socket. The pins 
should be connected as follows:-

Signal Function
PC 9 pin Socket
BayComm 9 pin Plug
Receive Data
2
8
Transmit Data
3
4
Signal Ground
5
5
PTT
7
7
Control Lines
4, 6 & 8
3

This adapter can be made by bolting a plug and socket together, and then 
wiring between them.  This assembly is then put on the end of the cable 
between the PC and the BayComm modem, at either end.

16 Current Installations

The G8CUL Repeater Logic has been successfully running the GB3CL 
(70cms) and GB3TE (2m) repeaters in Essex since May 1994 and October 
1994 respectively.  Tony Horsman (G0MBA), who has been responsible for 
installing the new logic, would be happy to talk to you about it, and about me!  
He can be contacted on 01255 822265 or QTHR.  Of our own repeaters, for 
which the logic was originally designed, GB3DI has been running since 
September 1995, GB3OX since 1997 and GB3WO since 1999  There are an 
increasing number of other repeater installations in the UK currently using the 
G8CUL Repeater Logic.

The G8CUL Repeater Logic
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