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LF: DF0WD decoded/ External ADC/ Wolf Beacon sigs

To: [email protected]
Subject: LF: DF0WD decoded/ External ADC/ Wolf Beacon sigs
From: "James Moritz" <[email protected]>
Date: Wed, 18 Apr 2001 12:56:52 +0000
Organization: University of Hertfordshire
Reply-to: [email protected]
Sender: <[email protected]>
Dear LF Group,

Based on DL4YHF's description of his BPSK TX, and measuring the frequency of the DF0WD WOLF-mode signal, I was able to re- calculate the command line parameters for WOLF, and decode the recorded signal from last Sunday as "M0BMU WD TNX 73". The power level Wolf was using produced decoding within the first frame of data, so lower power could easily be used.
Rik's idea of an external ADC board for DSP software is nice -
however, some interface circuitry would be needed to connect the
ADC to the COM port. In practice, this interface might as well be a
DSP processor, which could then pre-process the high-speed ADC
data to alleviate the bottleneck caused by the COM port. Different
software could be downloaded to the DSP from the PC via the
COM port. In fact, the overall arrangement would be much the
same as the DSP evaluation boards offered by people like
Motorola, Analog Devices and Texas, the main difference would be
the provision of a high accuracy clock source. It might be possible
to identify an existing board which could be easily modified.
I hope to run a WOLF - mode signal this evening from about
2000utc. I will start at 300mW ERP, then after an hour reduce to
30mW ERP and leave it running for a couple of hours. As before, I
will transmit a carrier for a few minutes at the start of each 1/2
hour. I will transmit on 137.4400kHz for a change, in case anyone
is trying to use 137.5kHz.
Cheers, Jim Moritz
73 de M0BMU


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