Re: [digitalradio] MT63 freq ?
Thanks for the return comments, Tony, and especially all your work in helping us understand these modes better. I have been looking at the data and comparing baud rate which directly relates to the length of symbol and I suspect that many of what we thought of as the most sensitive modes may, depending upon design, work poorly with anything other than calm ionospheric conditions. The MT-63 minimum S/N varies considerably depending upon the width of the signal which is how I came up with the comparison. Because of the redundancy in MT-63 you do get amazing ability to withstand what would otherwise be an obliterated signal. But the price is a very wide bandwidth mode that unfortunately causes QRM too. Imagine if everyone who is using PSK31 switched over to 1K or 2K MT-63. It would be very difficult to operate in the narrow area we have for text digital modes. I try and use only 500 Hz and narrower modes that I consider to be appropriate for HF use, unless the bands are severely disturbed and there are few other stations on at the time. Do you or any other group members have any experiences with comparing the lightning static abilities of MT-63 (various widths) to THOR and the new MFSK modes that are designed into the fldigi program? I did a recent comparison of MFSK16 on fldigi and Multipsk but found roughly the same results, even on very noisy circuits. I plan to do more testing. Does anyone know the difference between MFSK31 and MFSK32? THOR appears to be Domino EX with FEC. How does this compare to Multipsk's Domino EX/FEC? Are they similar but too different to intercommunicate? Finally, Tony, do you think that you could eventually do additional testing to measure what parameters are the cut off point for the various modes? I don't know enough about ionospheric disturbances to know if you can only have Doppler (such as polar flutter) without having multipath at the same time. I seems reasonable that you might have one or the other, but most times (as you have tested) you have some of each. This would be a rather large undertaking but it seems to me that it would be very valuable to know just how the modes drop off for various levels of Doppler and multipath. So you would know that 5 msec is the most you can handle for a given mode, or 3 Hz Doppler. And then to make it even more complicated, where is the drop off point for various combinations? Is this something you could do at some future time? That way, we would have even more revealing comparison of modes and what they can and can not do under increasing difficult conditions. 73, Rick, KV9U Tony wrote: Rick, The reason that I use various modes is to discover those that work the best for most conditions on a given band and maintain a reasonable throughput I agree. Knowing which modes perform well when conditions deteriorate is helpful. I complied the digital mode HF simulations for that reason. The MT-63 mode seems well suited for moderate speed (50 to 200 wpm) under conditions with periodic interference where a part of the data is obliterated The 1K mode does seem to recover well from lightning static and prints well when QRM'd. It doesn't seem to mind when other MT63 signals overlap by 25% or so either. That's something most digital modes can't do. It needs a much stronger signal than some other modes in order to do this by perhaps 5 to 10 dB The simulator says that MT63 has a minimum SNR of -8db for 100% throughput. That's about 2db less than PSK31 and about 6db less than MFSK16. If you place an RTTY signal over the top of MFSK16 or PSK31 signals, they will stop printing. MT63 will keep going. Of course, it's a much wider mode and has lots of redundancy. isn't it fair to say that MFSK16 is about the best choice for robustness, bandwidth, and speed for keyboarding? I think it is a well balanced mode. I also think it's hard to beat multi-tone FSK modes for robustness. They are much less susceptible to the effects of ionospheric Doppler and multi-path than other modes. They were the only mode types that withstood the 30Hz frequency spread during the high-latitude tests. That's about as brutal as it gets. Or do you find that with stronger signals, the slow version (50 Hz/50 wpm) of MT-63 gets through lightning static and QRM better than even the new MFSK versions designed into the fldigi program? Is there a way to simulate this with the software tests? I've tried to simulate lightning static by mixing real QRN with digital mode audio, but it did not work out well. I think a better approach might be to remove short segments of signal to simulate the type of heavy static crashes that would obliterate the signal entirely. It's still missing the AGC capture effect, but it should tell something about mode recovery after a drop-out. Tony, K2MO Simulation: High Latitude Disturbed Path delay: 7ms Frequency
Re: [digitalradio] MT63 freq ?
Rick W wrote: I don't know enough about ionospheric disturbances to know if you can only have Doppler (such as polar flutter) without having multipath at the same time. The only way that comes to my mind that you can get rid of multipath is by just receiving a single ray. To achieve it, a working frequency for a given path geometry between two stations might be chosen for a limited period. That is tricky and sadly, not practical, being a moving target. The practical solution is to use the Optimum Working Frequency, conventionally 85% of the MUF, but that might allow some multipath to propagate. When you must reach more than one station, at different distances, you certainly must allow multipath to exist as well. I seems reasonable that you might have one or the other, but most times (as you have tested) you have some of each. The boundaries between ionospheric regions are always shaky, and contracting or expanding around the planet, so, most of the time, some Doppler, even slight and slow, is unavoidable. 73, Jose, CO2JA
Re: [digitalradio] MT63 freq ?
Tony, last week there was MT63 activity on 14109 but 14106 also seems to have been used. Andy K3UK Thanks for passing that along Andy. Spot history does seem to be a pretty good indicator of mode activity. I guess it's safe to assume that only a small percentage of MT63 activity gets spotted so there's still hope ; ) Seems a shame to waste the work Mr. Jalocha put into the mode. Not exactly spectrum friendly, but it does have it's place. It's certainly more effective than other modes when static crashes and multipath become a problem. Tony, K2MO
Re: [digitalradio] MT63 freq ?
Hi Tony Well I am still around and when we get some conditions back again so that a qso is possible you will find me on mt63 again on the old frequency. Les VK2DSG That would be nice Les. I've been hearing VK occasionally on 20 meters around 2200z on both the long and short path. Wonder if that's about the time the digital SSTV was reported? I have more free time these days so I'll be monitoring. Thanks, Tony, K2MO - Original Message - From: Leskep [EMAIL PROTECTED] To: digitalradio@yahoogroups.com Sent: Saturday, September 13, 2008 6:54 AM Subject: Re: [digitalradio] MT63 freq ? Hi Tony Well I am still around and when we get some conditions back again so that a qso is possible you will find me on mt63 again on the old frequency - I see the sun spot number has been up to 12 over the last day or so so there could at last be an upward trend Was some reports here today of some transmissions copied on EasyPal from the US so maybe things will look up soon Regards Les VK2DSG From: Tony Sent: Saturday, September 13, 2008 7:03 PM To: digitalradio@yahoogroups.com Subject: Re: [digitalradio] MT63 freq ? John, 14,109.5 still being used for MT63? Activity is not what it once was, but I still catch the occasional QSO now and then. I used to have regular QSO's with VK2DSG on 20 meters around the time IZ8BLY released his MT63 software. The mode had a good following for several years. Let me know when you're QRV John. Can sked with you this weekend. The mode is certainly robust; does very well with static crashes and QRM. Tony -K2MO - Original Message - From: John Becker, WØJAB [EMAIL PROTECTED] To: digitalradio@yahoogroups.com Sent: Friday, September 12, 2008 2:37 PM Subject: [digitalradio] MT63 freq ? 14,109.5 still being used for MT63?
Re: [digitalradio] MT63 freq ?
John, 14,109.5 still being used for MT63? Activity is not what it once was, but I still catch the occasional QSO now and then. I used to have regular QSO's with VK2DSG on 20 meters around the time IZ8BLY released his MT63 software. The mode had a good following for several years. Let me know when you're QRV John. Can sked with you this weekend. The mode is certainly robust; does very well with static crashes and QRM. Tony -K2MO - Original Message - From: John Becker, WØJAB [EMAIL PROTECTED] To: digitalradio@yahoogroups.com Sent: Friday, September 12, 2008 2:37 PM Subject: [digitalradio] MT63 freq ? 14,109.5 still being used for MT63?
Re: [digitalradio] MT63 freq ?
Tony, last week there was MT63 activity on 14109 but 14106 also seems to have been used this northern hemisphere summer . SP9MRP 14109.0 SP9MRP CQ MT63 1625 07 Sep YL2CA 14109.5 E73BLMT63 NEBOJSA PRIJEDOR 1319 12 Aug F5JQF 14105.5 F5JQFMT63 1859 25 Jun UA0AV 7035.0 RA3ZSE MT63 ANATOLY 1713 01 Jun VE3OIJ 10143.5 VE3OIJ MT63 500 Hz 0015 24 May F5JQF-@14106.0 F5JQFMT63 CQ CQ CQ . 1613 18 May F5JQF 14106.0 F5JQFMT63 CQ CQ CQ .. 1613 18 May SP3AMZ 14106.0 SP3AMZ MT63 CQ 0812 15 May SP3AMZ-@ 14106.0 SP3AMZ MT63 CQ 0812 15 May F5JQF 14106.0 UR5WCQ MT63 Pavel 0804 15 May F5JQF-@14106.0 UR5WCQ MT63 Pavel 0804 15 May F5JQF 14106.0 F5JQFMT63 CQ CQ CQ CQ ... 0754 15 May F5JQF-@14106.0 F5JQFMT63 CQ CQ CQ CQ 0754 15 May F5JQF 14108.5 F5JQFMT63 CQ CQ CQ ... 0828 12 May F5JQF-@14108.5 F5JQFMT63 CQ CQ CQ ... 0827 12 May RV6HO 14107.5 F5JQFMT63 1747 11 May RV6HO-@14107.5 F5JQFMT63 1747 11 May F5JQF 14106.7 F5JQFMT63 CQ CQ CQ CQ ... 1723 11 May F5JQF-@14106.7 F5JQFMT63 CQ CQ CQ CQ ... 1723 11 May F5JQF 14106.6 F5JQFMT63 CQ CQ CQ CQ ... 0704 11 May F5JQF-@14106.6 F5JQFMT63 CQ CQ CQ CQ .. 0704 11 May F5JQF 14106.7 F5JQFMT63 CQ CQ CQ .. 0648 10 May F5JQF-@14106.7 F5JQFMT63 CQ CQ CQ .. 0648 10 May F5JQF 14108.0 F5JQFMT63 CQ CQ CQ 1818 09 May F5JQF-@14108.0 F5JQFMT63 CQ CQ CQ 1818 09 May F5JQF 14106.6 F5JQFMT63 CQ CQ CQ ... 1229 09 May F5JQF-@14106.6 F5JQFMT63 CQ CQ CQ ... 1228 09 May F5JQF 14106.0 F5JQFMT63 CQ CQ CQ ... 1828 08 May F5JQF-@14106.0 F5JQFMT63 CQ CQ CQ ... 1828 08 May F5JQF 14106.2 F5JQFMT63 CQ CQ CQ . 0708 08 May F5JQF-@14106.2 F5JQFMT63 CQ CQ CQ . 0708 08 May F5JQF-@14107.6 F5JQFMT63 1922 07 May F5JQF 14107.6 F5JQFMT63 1922 07 May VE3PDC 10143.2 VE3OIJ CQ MT63 2237 01 May F5JQF-@14107.0 F5JQFMT63 CQ CQ 0850 01 May SWL-@ 14106.5 ON3ADMT63 CQ Calling 1340 25 Apr EC1AEU 14109.5 OZ1PMX MT63 599 1805 13 Apr MW3WFF-@ 14088.0 S56EPX good qso Franjo MT63 1000 1640 08 Mar NK7Z-@ 7019.9 TEST SPOTMT63 0431 28 Jan SWL-@ 14108.5 I1VPJMT63 1550 19 Jan SWL-@ 14108.5 I1VPJMT63 1110 19 Jan SWL-@ 14108.5 I1VPJMT63 1419 18 Jan OZ1PMX-@3582.1 RA6FCU MT63 1000/long 0254 15 Jan SWL-@ 28129.5 I1VPJMT63 1109 13 Jan SWL-@ 14109.5 I1VPJMT63 0633 13 Jan SP3AMZ-@ 14109.5 SP3AMZ MT63 1000 Hz 1017 12 Jan SWL-@ 14109.5 I1VPJMT63 0951 12 Jan RW9SZ-@14110.5 RW9SZCQ MT63 0913 12 Jan SWL-@ 14109.5 I1VPJMT63 0713 12 Jan UA0AV 14071.1 JT1KAA Pse don`t used MT63 this freq 0616 07 Jan UA0AV 14071.5 JT1KAA ENK u know MT63 FRQ? 0441 07 Jan CT1EUB 14066.0 CQ mt63 1015 06 Jan LU8EKC 14106.5 LU8EKC calling cq mt63 1655 05 Jan UA0AV 14071.0 JT1DAMT63 ENKHBAYAR ULAANBAATAR 0428 04 Jan On Sat, Sep 13, 2008 at 5:03 AM, Tony [EMAIL PROTECTED] wrote: John, 14,109.5 still being used for MT63? Activity is not what it once was, but I still catch the occasional QSO now and then. I used to have regular QSO's with VK2DSG on 20 meters around the time IZ8BLY released his MT63 software. The mode had a good following for several years. Let me know when you're QRV John. Can sked with you this weekend. The mode is certainly robust; does very well with static crashes and QRM. Tony -K2MO - Original Message - From: John Becker, WØJAB [EMAIL PROTECTED] To: digitalradio@yahoogroups.com Sent: Friday, September 12, 2008 2:37 PM Subject: [digitalradio] MT63 freq ? 14,109.5 still being used for MT63? -- Andy K3UK
Re: [digitalradio] MT63 freq ?
Hi Tony Well I am still around and when we get some conditions back again so that a qso is possible you will find me on mt63 again on the old frequency - I see the sun spot number has been up to 12 over the last day or so so there could at last be an upward trend Was some reports here today of some transmissions copied on EasyPal from the US so maybe things will look up soon Regards Les VK2DSG From: Tony Sent: Saturday, September 13, 2008 7:03 PM To: digitalradio@yahoogroups.com Subject: Re: [digitalradio] MT63 freq ? John, 14,109.5 still being used for MT63? Activity is not what it once was, but I still catch the occasional QSO now and then. I used to have regular QSO's with VK2DSG on 20 meters around the time IZ8BLY released his MT63 software. The mode had a good following for several years. Let me know when you're QRV John. Can sked with you this weekend. The mode is certainly robust; does very well with static crashes and QRM. Tony -K2MO - Original Message - From: John Becker, WØJAB [EMAIL PROTECTED] To: digitalradio@yahoogroups.com Sent: Friday, September 12, 2008 2:37 PM Subject: [digitalradio] MT63 freq ? 14,109.5 still being used for MT63?
Re: [digitalradio] MT63 freq ?
The reason that I use various modes is to discover those that work the best for most conditions on a given band and maintain a reasonable throughput for a specific use. The MT-63 mode seems well suited for moderate speed (50 to 200 wpm) under conditions with periodic interference where a part of the data is obliterated, but enough gets through for solid printing. It needs a much stronger signal than some other modes in order to do this by perhaps 5 to 10 dB and to get the higher speed (200 wpm) it needs a much wider footprint (2000 Hz) than most other digital modes. Tuning can be difficult as signals get weaker because the waterfall pattern starts to look like background noise. For casual QSO use, it seems to me that a speed of around 40 wpm, which is a common speed for the narrow (PSK31) and relatively narrow (MFSK16) modes works well for most hams. When conditions get more difficult, as long as the signals are not too weak, some of the Olivia modes may be the best choice if you can tolerate the slower throughput. Based on K2MO's tests and other hams practical on air experience, isn't it fair to say that MFSK16 is about the best choice for robustness, bandwidth, and speed for keyboarding? When conditions allow there are now a number of additional MFSK baud rates, such as used with NBEMS. The main difficulty is accurate tuning, but MFSK does have a mark position during idle, that you can line your cursor with to get close to the lock in frequency. Or do you find that with stronger signals, the slow version (50 Hz/50 wpm) of MT-63 gets through lightning static and QRM better than even the new MFSK versions designed into the fldigi program? Is there a way to simulate this with the software tests? 73, Rick, KV9U
Re: [digitalradio] MT63 freq ?
Good deal Tony. I will be in out of the shack all weekend but can park the rig on say 14,106.00 1KZ long and see what happens. Trying to get ready for a DOWNPOUR from IKE. They said on last nights news that we very well may get 6.5 + inches of rain. John, W0JAB
