Re: [digitalradio] Re: Reed Solomon Identifier
Vojtech, Thank you for figuring this out. I had thought that the mode ID was sent in the mode, and that all modes were decoded in parallel to see which one resulted in the ECC-protected key codeword. The advantage of senfing the mode ID using the mode itseld is that propagation characteristics that favor one mode over another will not cause failure to ID or the converse (copy of ID but failure to copy the actual transmission). All my questions had been with this belief in mind. 73, Leigh/WA5ZNU On Wed, 4 Apr 2007 8:24 pm, Vojtech Bubnik wrote: Hi Patrick. On Wed, 4 Apr 2007 8:24 pm, Vojtech Bubnik wrote: Hi Patrick. you send a heavily FEC protected keyword in the desired mode. you do a parallel decode of all modes, de-FEC all and look which one matches the the codeword ? Yes it is. But it is not only done for one frequency, it is done for all frequencies in the band. I played with MultiPSK and listened to the generated RS sequence. In my opinion it is always the same modulation. According to my ears and spectrogram it seems to be some kind of MFSK modulation, always the same number of tones and symbol speed. Please correct me, but I think there is a misunderstanding on the list. I suppose that the RS ID is very similar to Olivia, there are three differences though and I thing we have discussed it by personal e-mails. - Olivia uses Hadamard/Welsh transformation, RS uses Reed Solomon block code - Olivia is decoded parallel on a constraned band, RS is decoded parallel on the whole sound card spectrum. The channel separation is half tone. - RS code sends just one block with the mode ID. Olivia and RS decode both a lot of channels in parallel (at least the original Olivia code from Pawel Jalocha does that) and it selects the one, which gives highest correlation. This automatically gives the answer for other party frequency. I received the RS code from Patrick, but I did not add it to PocketDigi yet. I am busy now with firmware programming of ATS-3A, I hope to teach it to modulate the single tone modes by programming its DDS. It will be the ultimate portable digital set, hi. 73, Vojtech OK1IAK
[digitalradio] Re: Reed Solomon Identifier
Hi Patrick. you send a heavily FEC protected keyword in the desired mode. you do a parallel decode of all modes, de-FEC all and look which one matches the the codeword ? Yes it is. But it is not only done for one frequency, it is done for all frequencies in the band. I played with MultiPSK and listened to the generated RS sequence. In my opinion it is always the same modulation. According to my ears and spectrogram it seems to be some kind of MFSK modulation, always the same number of tones and symbol speed. Please correct me, but I think there is a misunderstanding on the list. I suppose that the RS ID is very similar to Olivia, there are three differences though and I thing we have discussed it by personal e-mails. - Olivia uses Hadamard/Welsh transformation, RS uses Reed Solomon block code - Olivia is decoded parallel on a constraned band, RS is decoded parallel on the whole sound card spectrum. The channel separation is half tone. - RS code sends just one block with the mode ID. Olivia and RS decode both a lot of channels in parallel (at least the original Olivia code from Pawel Jalocha does that) and it selects the one, which gives highest correlation. This automatically gives the answer for other party frequency. I received the RS code from Patrick, but I did not add it to PocketDigi yet. I am busy now with firmware programming of ATS-3A, I hope to teach it to modulate the single tone modes by programming its DDS. It will be the ultimate portable digital set, hi. 73, Vojtech OK1IAK
Re: [digitalradio] Re: Reed Solomon Identifier
Hello Votjech, spectrogram it seems to be some kind of MFSK modulation, always the Yes it is. list. I suppose that the RS ID is very similar to Olivia, there are It is very similar to JT65A in fact. - Olivia uses Hadamard/Welsh transformation, RS uses Reed Solomon block code Yes it does - Olivia is decoded parallel on a constraned band, RS is decoded parallel on the whole sound card spectrum. The channel separation is half tone. No, when searching for an Olivia or RS ID transmission, the goal is to find the best correlation with a possible code. Half tone after half tone, you calculate the functions and see if the result fits with a possible transmission of code. The big advantage of these functions (Hadamard or RS) is that the correlation function is extremely sharp. - RS code sends just one block with the mode ID. Yes it does. 73 Patrick - Original Message - From: Vojtech Bubnik To: digitalradio@yahoogroups.com Sent: Thursday, April 05, 2007 8:24 AM Subject: [digitalradio] Re: Reed Solomon Identifier Hi Patrick. you send a heavily FEC protected keyword in the desired mode. you do a parallel decode of all modes, de-FEC all and look which one matches the the codeword ? Yes it is. But it is not only done for one frequency, it is done for all frequencies in the band. I played with MultiPSK and listened to the generated RS sequence. In my opinion it is always the same modulation. According to my ears and spectrogram it seems to be some kind of MFSK modulation, always the same number of tones and symbol speed. Please correct me, but I think there is a misunderstanding on the list. I suppose that the RS ID is very similar to Olivia, there are three differences though and I thing we have discussed it by personal e-mails. - Olivia uses Hadamard/Welsh transformation, RS uses Reed Solomon block code - Olivia is decoded parallel on a constraned band, RS is decoded parallel on the whole sound card spectrum. The channel separation is half tone. - RS code sends just one block with the mode ID. Olivia and RS decode both a lot of channels in parallel (at least the original Olivia code from Pawel Jalocha does that) and it selects the one, which gives highest correlation. This automatically gives the answer for other party frequency. I received the RS code from Patrick, but I did not add it to PocketDigi yet. I am busy now with firmware programming of ATS-3A, I hope to teach it to modulate the single tone modes by programming its DDS. It will be the ultimate portable digital set, hi. 73, Vojtech OK1IAK
[digitalradio] Re: Reed-Solomon identifier for automatic detection of the digital mode
Yes Andy, so far it is very very encouragingwith limited usage it seems to address the what mode it that question...more trials are needed though... 73 and be well, Bill N9DSJ --- In digitalradio@yahoogroups.com, Andrew O'Brien [EMAIL PROTECTED] wrote: Has anyone played around with this new Multipsk feature yet ? Andy K3Uk 3) Reed-Solomon identifier for automatic detection of the digital mode and the frequency (automatic tuning). This identifier permits to, automatically, locate, any digital transmission done in one of the RX/TX modes handled by Multipsk (91 modes and sub-modes in 4.1.1 version). It is detected, in one hand, the used mode and, in the other hand, the central frequency of the identifier (which is also the central frequency of the transmission), with a precision of +/- 2.7 Hz. As soon as this identifier is received, Multipsk switches on the received mode and frequency and decodes immediatly the QSO in progress or the call (CQ). This identifier is transmitted in 1.4 sec and has a bandwidth of 172 Hz. Its detection is done down to a Signal to Noise ratio of -14 dB (without missing at -12 dB), so with a sensitivity equal or better than the one of the majority of the digital modes (RTTY, PSK31...). Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
