User Manual

STTRS DOCUMENTATION
Document Number 80-330501HBKM – Issue A - Draft Page 393 of 500
21.3.1.9. Channel Control Module (17-011501)
The operating frequency for each channel in each repeater is programmed by 16 DIL (Dual In Line)
switches. The programming switches are mounted in the Channel Control Module. The Channel
Selectivity Modules are connected to the Channel Control Module via multi-way ribbon cables.
Adjacent to the DIL switches for each channel is a toggle switch to turn on and off individual channels
as required. A green LED indicates the power status of each channel.
A red LED shows the alarm condition for each channel. An illuminated alarm LED indicates that the
synthesiser has not achieved phase lock and that the module is disabled. There is a problem which
requires investigation, often a frequency programmed outside the operating frequency range.
The following information is necessary before attempting the programming procedure.
1. operating frequency
2. synthesiser channel spacing (step size)
3. synthesiser offset (IF)
Programming Procedure
Check that the required frequency falls within the operational frequency limits of the Cell Enhancer.
For each channel required, subtract the synthesiser offset from the required operating frequency and
record the resulting local oscillator frequency.
Divide each local oscillator frequency by the channel spacing and check that the result is an integer
(i.e: no remainder).
If the synthesiser division ratio is not an integer value, check the required operational frequency and
repeat the calculation checking for mistakes.
Convert the required local oscillator frequency to synthesiser programming switch state patterns
according to the following table. Note: the frequency of the passband will dictate the switch steps
used.
Switch Functions
Switch Number Synthesiser offset added when switch in UP position
12.5kHz step size 25kHz step size
1 +12.5kHz +25kHz
2 +25kHz +50kHz
3 +50kHz +100kHz
4 +100kHz +200kHz
5 +200kHz +400kHz
6 +400kHz +800kHz
7 +800kHz +1.6MHz
8 +1.6MHz +3.2MHz
9 +3.2MHz +6.4MHz
10 +6.4MHz +12.8MHz
11 +12.8MHz +25.6MHz
12 +25.6MHz +51.2MHz
13 +51.2MHz +102.4MHz
14 +102.4MHz +204.8MHz
15 +204.8MHz +409.6MHz
16 +409.6MHz +819.2MHz