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[aprssig] I'm brainstorming, so don't beat me up!

Gerhard f5vag at nerim.net
Fri Jul 8 13:51:49 UTC 2005


The PSK31 server Roger Barker (G4IDE sk) had written, adds a CRC
to the frame and works very well on HF.

--
73 de Gerhard, F5VAG / DL7MW
APRS-IS Tier 2 server T2FRANCE:
Home: http://france.aprs2.net/
Status: http://france.aprs2.net:14501/

> -----Original Message-----
> From: aprssig-bounces at lists.tapr.org
> [mailto:aprssig-bounces at lists.tapr.org]On Behalf Of J. Lance Cotton
> Sent: Friday, July 08, 2005 3:41 PM
> To: TAPR APRS Mailing List
> Subject: Re: [aprssig] I'm brainstorming, so don't beat me up!
> 
> 
> Andrew Rich wrote:
> > psk31 for aprs ? on hf
> > 
> > -----Original Message-----
> > From: Wes Johnston [mailto:aprs at kd4rdb.com]
> > 
> > What about q15x25? mix32 (or is it mix-w) supports it... agwpe is
> > supposed to Real Soon Now. q15x25 is 15 PSK carriers with an aggregate
> > bit rate of 2500 baud on normal channels, and FEC. It's just a tweak
> > processor intensive to encode and decode.
> 
> PSK31 is an order of magnitude slower than HF 300 baud. Plus it has zero 
> error detection/correction. You definitely do not want mangled positional data!
> 
> I've played around (in a way) with q15x25, but at the time I had it up, I 
> didn't have a 2nd person to test with. It does look promising because it 
> ties in so well with AX.25 (but doesn't have to!).
> 
> The Linux q15x25 (also called newqpsk) modem is built into the soundcard 
> modem system and so any linux APRS or packet program that utilizes the ax25 
> network interface to the radio can use q15x25 instead of 1200 AFSK, 
> transparent to the program.
> 
> It does look promising and even holds the 2500 bps (raw) data rate on HF 
> channels. Though, of course, it was designed for SSB rigs, it may still work 
> with FM, but without the weak-signal performance.
> 
> Unlike some other robust digital modes, q15x25 does not have a long sync 
> time, which rules out so many for APRS use.
> 
> -- 
> J. Lance Cotton, KJ5O
> joe at lightningflash.net
> http://kj5o.lightningflash.net
> Three Step Plan: 1. Take over the world. 2. Get a lot of cookies. 3. Eat the 
> cookies.
> 
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