The PCGM (Programmable Clock Generator Module) is a device used
for some configurations
of simulcast with the RTCM. For transmitters that can "swallow"
a 10 MHz external reference clock source
(such as the Motorola Quantar, etc), all you need is the output
of the RTCM driving the direct
modulation of the transmitter. For radios that do not have an
external reference clock source
(or have one, but not at 10MHz), the PCGM will take the 10Mhz
reference from the GPSDO (generally
a Trimble Thunderbolt) and "make" whatever frequency your
transmitter needs for a reference
(at least one of 17988 frequencies possible). Transmitters that
do not have an external reference
clock input at all generally need to be modified to disconnect
the normal internal reference oscillator
and make provisions to allow injection of the reference clock
frequency from the PCGM.
In addition the PCGM also generates the voltages (3 of them, I
believe) to run the Trimble
Thunderbolt, with a single (generally 12 volt) input to the
PCGM.
These devices are available for sale from the Micro-Node.Com
site.
There was also a question on the list about the ClockSynth
project. This was merely an initial prototype
to prove the base design of the PCGM. There were only 2 boards
of this type built. They worked and
demonstrated the validity of the general concept from which the
PCGM was then based.
Jim WB6NIL