Re: [digitalradio] Re: Path Simulations for PAX / HF Packet
Hello Tony, Glad you did measures for Pax. My figures are the following: Lowest S/N : - 10 dB for PAX and - 7 dB for PAX2 It corresponds to a Gaussian noise without any ionospheric distortion (your first case). In my figures, I accept an error rate of 2 % (2 characters false for 98 characters good). However with frames it is a bit more difficult to appreciate. Conditions of measure: the sampling speed of the sound card has been perfectly determined (Sampling freq button) and the sound level (as displayed in the Level box) is about 20 to 60 % (not critical). Normally there is a 3 dB difference between these 2 modes as there are strictly the same except that Pax2 is twice quicker than Pax. Note: Pax and Pax2 modulations are clones of Olivia, let's say very close on modulation to Contestia. For Pax and Packet there is no ARQ memory (contrary to ARQ FAE), so the minimum S/N in connected mode would be the same as in Unproto. Note: it could be theoritically possible to implement ARQ memory in Pax and Packet (which would give a sort of FEC (repetition) coding to these modes), but it would need time... 73 Patrick - Original Message - From: Tony [EMAIL PROTECTED] To: digitalradio@yahoogroups.com Sent: Sunday, August 24, 2008 11:05 PM Subject: [digitalradio] Re: Path Simulations for PAX / HF Packet Greetings Patrick, Hello Tony, TKS for the interesting tests. Did you test PAX or PAX2? with Unproto frames? 73 Patrick I used PAX2 with Unproto frames during the test. Haven't figured out how to test in the 'connect' mode yet. I just finished testing PAX 1 so please see below. PAX has a definite advantage in sensitivity over PAX-2 as well as the ability to print better when conditions are disturbed. There's a 3db advantage in sensitivity over PAX-2 when the criteria is based on 100% decode. But partial decodes at -6 and -10db vs. 0db and -2db would seem to indicated that PAX would do much better than PAX-2 in the ARQ connect mode. Would appreciate your thoughts on this Patrick... Tony, K2MO PAX: Sensitivity threshold for 100% decode: -11db (no ionospheric distortion) Ionospheric Simulations: High-Latitude Moderate.Complete decdoe @ -4db SNR. Partial decode -10db SNR High-Latitude DisturbedNO DECODE Mid-latitude Disturbed.Complete decode @ -4db SNR. Partial Decode @ -10db SNR Low-Latitude Disturbed.Complete decode @ 0db SNR. Partial decode @ -6db SNR PAX2: Sensitivity threshold for 100% decode: -2db (no ionospheric distortion) Ionospheric Simulations: High-Latitude Moderate.Complete decdoe @ +2db SNR. Partial decode 0db SNR High-Latitude DisturbedNO DECODE Mid-latitude Disturbed.Complete decode @ +1db SNR. Partial Decode @ -2db SNR Low-Latitude Disturbed.NO DECODE HFPAcket (300baud): Sensitivity threshold for 100% decode: +1db SNR (no ionospheric distortion) Ionospheric Simulations. NO DECODE* * Susceptible to slight multi-path timing delays and Doppler Spread; 1 Hz / 1msec Announce your digital presence via our Interactive Sked Page at http://www.obriensweb.com/sked Check our other Yahoo Groups http://groups.yahoo.com/group/dxlist/ http://groups.yahoo.com/group/contesting http://groups.yahoo.com/group/themixwgroup Yahoo! Groups Links
Re: [digitalradio] Re: Path Simulations for PAX / HF Packet
Patrick, Hello Tony, Glad you did measures for Pax. My pleasure; thanks for adding the mode to Multipsk! My figures are the following: Lowest S/N : - 10 dB for PAX and - 7 dB for PAX2. It corresponds to a Gaussian noise without any ionospheric distortion (your first case. Just tested PAX and PAX2 again for the lowest S/N (Gaussian noise only) and came up with -11db for PAX and -7db for PAX2. Very close. Normally there is a 3 dB difference between these 2 modes as there are strictly the same except that Pax2 is twice quicker than Pax. Understand Patrick. Ionospheric distortion seems to widen the gap between the two with PAX coming out ahead by 5db or so. I used the 100% decode criteria so that may be the difference. The PAX2 mode did not print at all (regardless of SNR) with the two most disturbing ionospheric simulations. Note: Pax and Pax2 modulations are clones of Olivia, let's say very close on modulation to Contestia. No wonder why they work so well! For Pax and Packet there is no ARQ memory (contrary to ARQ FAE), so the minimum S/N in connected mode would be the same as in Unproto. Thanks for clarifying that. Note: it could be theoritically possible to implement ARQ memory in Pax and Packet (which would give a sort of FEC (repetition)coding to these modes), but it would need time... Interesting. Thanks Patrick. Let me know if I can help with any mode simulations you haven't tried yet. Tony, K2MO
[digitalradio] Re: Path Simulations for PAX / HF Packet
Greetings Patrick, Hello Tony, TKS for the interesting tests. Did you test PAX or PAX2? with Unproto frames? 73 Patrick I used PAX2 with Unproto frames during the test. Haven't figured out how to test in the 'connect' mode yet. I just finished testing PAX 1 so please see below. PAX has a definite advantage in sensitivity over PAX-2 as well as the ability to print better when conditions are disturbed. There's a 3db advantage in sensitivity over PAX-2 when the criteria is based on 100% decode. But partial decodes at -6 and -10db vs. 0db and -2db would seem to indicated that PAX would do much better than PAX-2 in the ARQ connect mode. Would appreciate your thoughts on this Patrick... Tony, K2MO PAX: Sensitivity threshold for 100% decode: -11db (no ionospheric distortion) Ionospheric Simulations: High-Latitude Moderate.Complete decdoe @ -4db SNR. Partial decode -10db SNR High-Latitude DisturbedNO DECODE Mid-latitude Disturbed.Complete decode @ -4db SNR. Partial Decode @ -10db SNR Low-Latitude Disturbed.Complete decode @ 0db SNR. Partial decode @ -6db SNR PAX2: Sensitivity threshold for 100% decode: -2db (no ionospheric distortion) Ionospheric Simulations: High-Latitude Moderate.Complete decdoe @ +2db SNR. Partial decode 0db SNR High-Latitude DisturbedNO DECODE Mid-latitude Disturbed.Complete decode @ +1db SNR. Partial Decode @ -2db SNR Low-Latitude Disturbed.NO DECODE HFPAcket (300baud): Sensitivity threshold for 100% decode: +1db SNR (no ionospheric distortion) Ionospheric Simulations. NO DECODE* * Susceptible to slight multi-path timing delays and Doppler Spread; 1 Hz / 1msec
