[aprssig] HF APRS Transceiver

[Ben Jackson]

On Fri, Mar 07, 2008 at 01:04:03PM -0800, Ev Tupis wrote:
> Not for nuthin, but I phoned MFJ a couple years ago
> asking if they'd consider a crystal controlled version
> of their SSB transceiver specifically for data-mode
> use.

Crystal control is not sufficient.  20ppm at 10MHz is 200Hz which is
an order of magnitude or more too high (consider that the shift of the
FSK is only 200Hz).  You probably need around 1ppm accuracy.  The
operator-free solution is a reference clock slaved to the GPS.  With
DDS it shouldn't be that hard.

-- 
Ben Jackson AD7GD
<ben at ben.com>
http://www.ben.com/