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[aprssig] RE: [OZAPRS] Spread Spectrum APRS

Darryl Smith Darryl at radio-active.net.au
Fri Oct 15 20:12:44 UTC 2004

Well... Yes... And it is called "GPS tracking over CDMA 1x"

Seriously, CDMA and the APRS philosophy of no acknowledgements does not work
too well. Neither does collision avoidance.

The reason why 802.11 actually works is that mostly it is not Spread
Spectrum. Therefore you can to some extent carrier detect. And it has
RTS/CTS, but that is another matter.

When you have Spread Spectrum it is difficult to detect other users and
therefore you are likely to transmit over someone. Also you will only hear
the closest stations thanks to the way Spread Spectrum works. [You can
ignore the fact that NBFM which APRS uses normally also has the same issue
with only hearing the closest stations in this argument].

Having said all that... Do you have a proposal to put to us with some
hardware :-)


Darryl Smith, VK2TDS   POBox 169 Ingleburn NSW 2565 Australia
Mobile Number 0412 929 634 [+61 4 12 929 634 International] 
www.radio-active.net.au\blog\ - www.radio-active.net.au\web\tracking

-----Original Message-----
From: ozaprs-bounces at marconi.ics.mq.edu.au
[mailto:ozaprs-bounces at marconi.ics.mq.edu.au] On Behalf Of Andrew Rich
Sent: Saturday, 16 October 2004 12:12 AM
To: TAPR APRS Special Interest Group; Ozaprs at Marconi.Ics.Mq.Edu.Au
Subject: [OZAPRS] Spread Spectrum APRS

Has someone addressed this issue before ?

Has it been tested ?

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