[aprssig] E Coast 9600 baud backbone 15W radios.

Stephen H. Smith wa8lmf2 at aol.com
Sun May 29 12:41:25 CDT 2016


On 5/29/2016 11:28 AM, Ev Tupis via aprssig wrote:
> From someone who has direct experience in this arena...the only reason is the cost of VHF SSB equipment.
>
> There is no issue with frequency stability as an SSB transceivers' passband is at least (grin) 2.5 kHz wide and decoder software can skim the entire waterfall looking for signals to decode.  It is the premise of ACDS^31 software used by http://www.PropNET.org.
>

Actually, I was thinking of G4HYG's "APRS Messenger" 
APRS-over-PSK63/GMSK250/PSK16 soundcard software which does NOT have any kind 
of scanning or AFC-like action. It implements VERY narrow audio "slots" for the 
incoming tones; i.e. less than 20 Hz. The program definitely depends on being 
able to keep an SSB radio on-frequency to within 10-20 Hz RF indefinitely.

Something that is quite trivial at 10.1 MHz (30 meters) with modern synthesized 
transceivers (My Kenwood TS-50 stays within 5 Hz indefinitely at 10.149 MHz 
with a temperate indoor climate.), but a challenge with ham-grade radios at 144 
MHz.

(The latest version of APRS Messenger does offer an option of multiple pairs of 
additional software modems at selectable intervals each side of the defined 
center audio frequency. This comes at the expense of greatly increased CPU 
loading.)


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Stephen H. Smith    wa8lmf (at) aol.com
Skype:        WA8LMF
EchoLink:  Node #  14400  [Think bottom of the 2-meter band]
Home Page:          http://wa8lmf.net

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