[digitalradio] psk-125r
How does pak-125r work? Does it use the same varicode? Does it have error correcting code like QPSK-125? How many phases does it use? Would it work well for EME? n6ief
Re: [digitalradio] RSID Query
On Fri, Apr 09, 2010 at 07:18:48PM -0400, Tony wrote: All, I was just wondering if there's any confusion or misunderstanding among the group about RS-ID? We all know that it's not always easy to identify a mode by sight and sound yet I still see many calling CQ without any mode identification. The end result, no contacts. I'm sure most of the seasoned digital ops know what RS ID is and what it does, so what's the reasoning behind not using it? Tony -K2MO FLDIGI - Check RX ID / TX ID in upper right corner of program window. Click CONFIGURE / IDS to set preferences. MULTIPSK - Click RS ID / RX RS ID in main window. Click CONFIGURATION / MANAGMENT OF ID's. Check CONTINUOUS DETECTION. Ham Radio Deluxe / DM780 Version 5 Open DM780. Click OPTIONS / MODES + IDs / REED SOLOMON TAB. Check: ENABLE RSID DETECTION / SHOW IN QSO WINDOW AS HYPERLINK SHOW POPUP WINDOW / SHOW RSID BUTTON ON QSO TRANSMIT TOOLBAR MixW: I _like_ RSID. I like it a lot, especially since lots of the multitone modes (OLIVIA, Contestia, THOR, and the like) sound and look alike to me, and I spend a lot of time trying to identify the particular submode and copy what's being sent. WIthout RSID, it sometimes takes enough time that the station on the other end quits. I've switched to HRD+DM780 precisely because they do offer RSID, even though I have a paid-up license for MixW. I vastly prefer MixW because it suits my operating style and its interface is IMHO better designed. I'm getting to the point of being less uncomfortable with HRD and DM780, but still prefer MixW. I also like having a text-mode log file with ;-separated items per line, as I can read it directly and bang it right out to my website. That *DOES* *NOT* in any mean that I have anything other than the most lively respect and admiration for HRD, DM780, and Simon's other works, or for him. It's just a matter of personal preference. C'mon, Yuri and company! Add RSID (and video ID) to MixW! -- Mike Andrews, W5EGO mi...@mikea.ath.cx Tired old sysadmin
Re: [digitalradio] RSID Query
Mike, I asked the Mixw team about RSID some time ago. Nick replied and seemed enthusiastic; I haven't heard anything from him since then. Tony -K2MO On 4/12/2010 12:23 PM, mikea wrote: On Fri, Apr 09, 2010 at 07:18:48PM -0400, Tony wrote: All, I was just wondering if there's any confusion or misunderstanding among the group about RS-ID? We all know that it's not always easy to identify a mode by sight and sound yet I still see many calling CQ without any mode identification. The end result, no contacts. I'm sure most of the seasoned digital ops know what RS ID is and what it does, so what's the reasoning behind not using it? Tony -K2MO FLDIGI - Check RX ID / TX ID in upper right corner of program window. Click CONFIGURE / IDS to set preferences. MULTIPSK - Click RS ID / RX RS ID in main window. Click CONFIGURATION / MANAGMENT OF ID's. Check CONTINUOUS DETECTION. Ham Radio Deluxe / DM780 Version 5 Open DM780. Click OPTIONS / MODES + IDs / REED SOLOMON TAB. Check: ENABLE RSID DETECTION / SHOW IN QSO WINDOW AS HYPERLINK SHOW POPUP WINDOW / SHOW RSID BUTTON ON QSO TRANSMIT TOOLBAR MixW: I _like_ RSID. I like it a lot, especially since lots of the multitone modes (OLIVIA, Contestia, THOR, and the like) sound and look alike to me, and I spend a lot of time trying to identify the particular submode and copy what's being sent. WIthout RSID, it sometimes takes enough time that the station on the other end quits. I've switched to HRD+DM780 precisely because they do offer RSID, even though I have a paid-up license for MixW. I vastly prefer MixW because it suits my operating style and its interface is IMHO better designed. I'm getting to the point of being less uncomfortable with HRD and DM780, but still prefer MixW. I also like having a text-mode log file with ;-separated items per line, as I can read it directly and bang it right out to my website. That *DOES* *NOT* in any mean that I have anything other than the most lively respect and admiration for HRD, DM780, and Simon's other works, or for him. It's just a matter of personal preference. C'mon, Yuri and company! Add RSID (and video ID) to MixW! -- Mike Andrews, W5EGO mi...@mikea.ath.cx mailto:mikea%40mikea.ath.cx Tired old sysadmin __ Information from ESET NOD32 Antivirus, version of virus signature database 5022 (20100412) __ The message was checked by ESET NOD32 Antivirus. http://www.eset.com
[digitalradio] Re: psk-125r
Hi Mike, Psk125r (and the other r psk modes for that matter) are simply a standard bpsk mode with the following changes: 1. FEC with a rate of 1/2 which means that we send two bits for every bit of data. This redundancy is what provides most of it's extra robustness but of course at the cost of the effective data speed. So psk125r is about (more on this later) the same typing rate as psk63. 2. Convolutional encoder to spread the bits around so that noise has less effect 3. Soft-decoder which takes into account the phase and amplitude of the signal received to decide if it is a strong 1 or 0 or a weak one. Since we send two bits per data bit, the decoder on the receiver end can than decide which one is of better quality and has more chances to be the real thing rather than noise. 4. MFSK varicode for the simple reason that is has for some patterns of characters about 13% speed gain on the standard psk varicode. So in conclusion you may ask why bother with double the bandwidth (and therefore a 3dB power handicap)? The coding gain from all the above is theoretically 5dB and the tests performed in the lab show that this is pretty right and therefore +5 -3 = +2dB of advantage in white noise conditions. But also (and probably more importantly) the spreading of the bits in time allows for the impact of noise bursts to be reduced since it is less probable to have two noise bursts at exactly the same time for the first bit and it's redundant counterpart which is sent later on. This set of modes was created mainly for ARQ applications like Pskmail and Flarq as we wanted to close a gap between the MFSK/IFSK modes which are robust but slow (while remaining below 500Hz bandwidth) and the psk125,250 and 500 modes which are fast but can be more easily disturbed by QRM and need good s/n ratios. Remembering that for ARQ applications, one bad bit is most likely one bad frame that needs to be retransmitted. Regarding QPSK modes: they have also FEC but the spreading of bit is more limited and the 90 degree instead of 180 degree spreading of the phase changes make it only marginally better than bpsk in my experience. In some cases they can be worse in fact. Now for your third question: I doubt that this would be a good mode for EME due to it's level of sensitivity. I am no expert in EME but the little I know it that you need to have a mode that has a very low minimum s/n as the path losses are very high. The JT65A mode has a minimum s/n of -23dB versus something around -13 or -14dB for psk125r. Even the slowest psk mode that I know of, PSK10AM (in Patrick's Multipsk) has a -19.5 minimum s/n, so still a few dBs below JT65A. If these king of modes had any chance in EME then it would need to be slowed down even further, plus I don't know what the EME path is like regarding phase distortion which is a major negative for these modes since they rely and a phase change to encode a 1 or 0. Hope this helps. Best 73s, John (VK2ETA) --- In digitalradio@yahoogroups.com, Mike Lebo mike-l...@... wrote: How does pak-125r work? Does it use the same varicode? Does it have error correcting code like QPSK-125? How many phases does it use? Would it work well for EME? n6ief
