[OZAPRS] Low cost HF Modem

[Richter, Mike W]

Horses for courses

a) HF APRS Black-box 100Watt tracker
 - TT3 puts out MIC-E data as unmodulated binary data at 300 baud that
FSK's the oscillator.

b) HF APRS from existing SSB HF Tx which is used primarily for voice
 - TT3 puts out MIC-E data as 200Hz-shifted tones keyed at 300 baud that
goes to Microphone input.

Byon needs to add TWO more configuration options !

Mike VK2bmm



-----Original Message-----
From: Bob Bruninga [mailto:bruninga at usna.edu]
Sent: Wednesday, 22 October 2003 12:10 am
To: ozaprs at marconi.ics.mq.edu.au
Subject: Re: [OZAPRS] Low cost HF Modem


On Tue, 21 Oct 2003, Richter, Mike W wrote:

> To get more people operating on HF, it would help to have low cost APRS
> encoder and Modulator.
>  Byon is currently looking at reviewing the TinyTrak 3 design. It
> wouldn't be hard to have a configuration option to send the data at
> 300baud rather than the usual 1200 baud.

My recommendation would be to NOT output the APRS to 300 baud TONES (which
needs an SSB transmitter) but convert it to simply digital TTL levels to
drive a crystal and generate FSK directly!  Then only 5 more transistors
will result in a black-box 100Watt HF tracker that should fit in a
cracker-jax size box, since it needs no heat sink (it only TX's for 1
second out of every 300!)..

That has alway s been my dream for APRS HF mobile long-haul operators.  I
wrote this all up somewhere.  Probably in my APRSdos README\HF.txt file?

Someone forward this to Byon... thanks.

de WB4APR at amsat.org, Bob

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