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Message-ID: <002801c6671c$277e6d60$1fb06dcb@cobaltxp>
From: "Murray ZL1BPU" <zl1bpu@nzart.org.nz>
To: <rsgb_lf_group@blacksheep.org>
References: <444AF315.9020304@telus.net> <004001c6670a$22ff7a20$0300a8c0@LAPTOP>
Date: Mon, 24 Apr 2006 09:23:23 +1200
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Subject: LF: GPS Coherent EXciter - new
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Status: O

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