For anyone interested in making GPS coherent transmissions (for use with
G3PLX/VE7TIL/ZL2AFP Clicklock coherent software), the ZL1BPU LF Exciter now
has the capability.
The new Version D6b firmware provides two new modes:
- a fixed phase GPS locked mode (phase adjustable in 256 steps)
- an BPSK mode that switches between two arbitrary phases about 180�
apart at a predetermined rate
Synchronism is achieved with the leading edge of a GPS 1pps pulse, and can
be programmed to reset (or swap phase) every n seconds where n is 1 to
65536. (Best to keep n < 10 though). The GPS locked fixed phase mode can
have the phase changes remotely (by PC for example) and the existing EXC.EXE
program can be used to transmit phase encoded QRSS or ASK Morse.
The new code requires some simple hardware changes to replace the dot clock
output with GPS 1pps. The new code and hardware also has the following new
features:
- 32-bit synthesis for 0.3 milliHz resolution
- E/P mode transmitter control, where a separate 3-bit D-A converter
controls the transmitter power envelope, also keying the transmitter
- Eight adjustable and remote or beacon script controlled power levels
- 'Castle' mode - a new differential FSK QRSS mode which is 20% more
efficient and more readable than DFSKCW
The new version is described on my web site (assuming QSL.NET haven't done
another 'restore' of old data!). See
http://www.qsl.net/zl1bpu/MICRO/EXCITER/Index.htm . Look down at the bottom
of the page.
I use this Exciter to drive a 1kW Southern Avionics DGPS transmitter on 136
and 181kHz. Free upgrades of the firmware are available to all existing
users.
73,
Murray ZL1BPU
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