[digitalradio] MFTTY - HF Path Simulations
All, I was able to take some time to test MFTTY with the HF path simulator this evening. I added a few commonly use modes for comparison. As expected, the slower / narrow MFTTY modes seemed to have a definite weak signal advantage over the faster ones. The minimum SNR test showed a wide 12db gap in sensitivity between 1/8 speed and double speed modes. This should show when testing the different MFTTY modes on the air. In the HF simulator tests, each mode was subjected to same HF path distortion. The less tolerable a mode is to this distortion, the greater the throughput errors. It would seem that MFTTY would compare well with other more robust modes if the character speed is kept down using the half and quarter speed modes. At least that's what the HF simulator seemed to indicate. I'd appreciate hearing about on-air tests from you all so I can compare some real data to the simulators. Thanks, Tony -K2MO Minimum SNR MFTTY Double Speed -5db Normal Speed -7db 1/2 Speed-9db 1/4 Speed -13db 1/8 Speed -17db MFSK16 -14db Olivia 500/16 -13db PSK31-10db RTTY -dab Path Simulations Path Simulation: Mid Latitude Disturbed SNR -8db Mode Throughput Double Speed 10% Normal Speed10% 1/2 Speed25% 1/4 Speed50% 1/8 Speed85% MFSK16 100% Olivia 500/16 100% PSK31 70% RTTY 4520% ___ Selective Fading SNR -8db Double Speed 10% Normal Speed 30% Half Speed45% Quarter Speed 60% Eighth Speed70% MFSK1690% Olivia 500/15 100% PSK31 65% RTTY 45 25%
Re: [digitalradio] MFTTY - HF Path Simulations
Thanks for the tests, Tony. The numbers confirm what NC5O and I found yesterday with our on-the-air comparisons between MFTTY, PSK31, PSK63, PSK125, and MFSK16 over a period of four hours and changing band conditions. We could communicate on PSK31 long after MFTTY had quit decoding, and solid copy using MFSK16 (but with a wider bandwidth, of course) when PSK31 started producing errors. 73, Skip KH6TY - Original Message - From: Tony d...@optonline.net To: digitalradio@yahoogroups.com Sent: Saturday, January 17, 2009 3:59 AM Subject: [digitalradio] MFTTY - HF Path Simulations All, I was able to take some time to test MFTTY with the HF path simulator this evening. I added a few commonly use modes for comparison. As expected, the slower / narrow MFTTY modes seemed to have a definite weak signal advantage over the faster ones. The minimum SNR test showed a wide 12db gap in sensitivity between 1/8 speed and double speed modes. This should show when testing the different MFTTY modes on the air. In the HF simulator tests, each mode was subjected to same HF path distortion. The less tolerable a mode is to this distortion, the greater the throughput errors. It would seem that MFTTY would compare well with other more robust modes if the character speed is kept down using the half and quarter speed modes. At least that's what the HF simulator seemed to indicate. I'd appreciate hearing about on-air tests from you all so I can compare some real data to the simulators. Thanks, Tony -K2MO Minimum SNR MFTTY Double Speed -5db Normal Speed -7db 1/2 Speed-9db 1/4 Speed -13db 1/8 Speed -17db MFSK16 -14db Olivia 500/16 -13db PSK31-10db RTTY -dab Path Simulations Path Simulation: Mid Latitude Disturbed SNR -8db Mode Throughput Double Speed 10% Normal Speed10% 1/2 Speed25% 1/4 Speed50% 1/8 Speed85% MFSK16 100% Olivia 500/16 100% PSK31 70% RTTY 4520% ___ Selective Fading SNR -8db Double Speed 10% Normal Speed 30% Half Speed45% Quarter Speed 60% Eighth Speed70% MFSK1690% Olivia 500/15 100% PSK31 65% RTTY 45 25% No virus found in this incoming message. Checked by AVG - http://www.avg.com Version: 8.0.138 / Virus Database: 270.10.8/1898 - Release Date: 1/16/2009 3:09 PM
Re: [digitalradio] MFTTY - HF Path Simulations
Selective Fading SNR -8db MFSK1690% Olivia 500/15 100% PSK31 65% RTTY 45 25% Although MFSK16 produced 10% errors when Olivia produced no errors, Olivia 16-500 (20 wpm) takes twice as long to send the same information as MFSK16 (42 wpm), so it is exposed to QRM and QSB over a much longer time. If you are only interested in exchanging name, qth, and signal report, Olivia will usually do that better than MFSK16, but for ragchewing, over a longer time period, using IMHO MFSK16 will probably be as good as Olivia without having to wait as long for the text to appear. 73, Skip KH6TY
[digitalradio] Re: AX.25 modem as an infrastructure?
Hi Misko. I strongly believe before going to actually implement something one shall explore existing systems first and if it is possible, try to simulate a new system using the existing one. I propose that you and your friends try to set up a flexnet system using fixed links at single frequency. You may try to add and remove a link and see how fast the change will be redistributed around the other nodes using shared frequency and very low bandwidth channel and how much of the shared bandwidth will be used just for protocol overhead. When you setup your test, try to make sure only two transmitters will hear each other. I believe the probability of packet clashes will be so high, that the network will not work. 73, Vojtech OK1IAK
[digitalradio] Re: New to the Group
--- In digitalradio@yahoogroups.com, clarkmvimi clarkmv...@... wrote: Good day. I am new to the group and digital modes. My name is Steve Clark V73CS and I am located in the Marshall Islands. I am wanting to setup a digital station here. I have someone sending me an AEA 232 MBX for my station here. I was wondering about software for it and what other TNC/interface would be recomended for a beginner to setup a digital station. Thanks in advance for the bandwidth and have a great day. 73 Steve Clark V73CS/N4TKP Majuro, Marshall Islands Welcome Steve, I would recommend any of the following FLdigi, Multipsk, DM780, and DXLab Suite with Winwarbler. For an interface, take a look at the Microham line of interfaces. Andy K3UK
[digitalradio] New fldigi 3.10
The latest fldigi 3.10 is now available on the w1hkj.com web site.
Re: [digitalradio] MFTTY - HF Path Simulations
Skip, Glad to hear that the path simulations coincide with your on-air tests. I agree with your take on Olivia 500/16 and MFSK16. There are times when I'd rather sacrifice some throughput and go twice as fast. The throughput gap between the two does increase under severe ionospheric distortion as you can see in the high latitude tests below. We'll have to wait for another ionospheric storm and work over the pole to confirm what the simulator indicates. Thanks Skip... Tony -K2MO Simulation: High Latitude DisturbedPath delay: 7msFrequency spread: 30Hz SNR: -3db (weak signal)Mode ThroughputContestia 500/16.100% CW 20 WPM100%Olivia 1000/32...100% Olivia 500/16100% Olivia 500/8.100% Olivia 500/4..95% RTTYM**...95%Voice (Multipsk)..95% MFSK31... 90% MFSK1675% RTTY..40%Chip-64...10% Chip-128**no copyDominoEX-4no copy FEC-31no copyJason Turbo (Fa...no copyMT631Kno copyPSK10.no copy PSKAM10...no copyPSK31.no copy PSK63.no copyThor-11...no copy ThrobX-4..no copy Feld HellReadable - Original Message - From: kh6ty kh...@comcast.net To: digitalradio@yahoogroups.com Sent: Saturday, January 17, 2009 5:21 AM Subject: Re: [digitalradio] MFTTY - HF Path Simulations Thanks for the tests, Tony. The numbers confirm what NC5O and I found yesterday with our on-the-air comparisons between MFTTY, PSK31, PSK63, PSK125, and MFSK16 over a period of four hours and changing band conditions. We could communicate on PSK31 long after MFTTY had quit decoding, and solid copy using MFSK16 (but with a wider bandwidth, of course) when PSK31 started producing errors. 73, Skip KH6TY - Original Message - From: Tony d...@optonline.net To: digitalradio@yahoogroups.com Sent: Saturday, January 17, 2009 3:59 AM Subject: [digitalradio] MFTTY - HF Path Simulations All, I was able to take some time to test MFTTY with the HF path simulator this evening. I added a few commonly use modes for comparison. As expected, the slower / narrow MFTTY modes seemed to have a definite weak signal advantage over the faster ones. The minimum SNR test showed a wide 12db gap in sensitivity between 1/8 speed and double speed modes. This should show when testing the different MFTTY modes on the air. In the HF simulator tests, each mode was subjected to same HF path distortion. The less tolerable a mode is to this distortion, the greater the throughput errors. It would seem that MFTTY would compare well with other more robust modes if the character speed is kept down using the half and quarter speed modes. At least that's what the HF simulator seemed to indicate. I'd appreciate hearing about on-air tests from you all so I can compare some real data to the simulators. Thanks, Tony -K2MO Minimum SNR MFTTY Double Speed -5db Normal Speed -7db 1/2 Speed-9db 1/4 Speed -13db 1/8 Speed -17db MFSK16 -14db Olivia 500/16 -13db PSK31-10db RTTY -dab Path Simulations Path Simulation: Mid Latitude Disturbed SNR -8db Mode Throughput Double Speed 10% Normal Speed10% 1/2 Speed25% 1/4 Speed50% 1/8 Speed85% MFSK16 100% Olivia 500/16 100% PSK31 70% RTTY 4520% ___ Selective Fading SNR -8db Double Speed 10% Normal Speed 30% Half Speed45% Quarter Speed 60% Eighth Speed70% MFSK1690% Olivia 500/15 100% PSK31 65% RTTY 45 25% No virus found in this incoming message. Checked by AVG - http://www.avg.com Version: 8.0.138 / Virus Database: 270.10.8/1898 - Release Date: 1/16/2009 3:09 PM
[digitalradio] Information Please re Reading the Radio for Digital Modes
G'Day All, I am trying to get more to grips with all the digital modes to operate. I currently run HRD w DM780 and MFTTY software on my computer (Love HRD) I have used DM780 in the past but it was just plug-in and see if it ran, which it did and was able to make some contacts. I have since moved into a new house and have not had the time to set the radio shack up. This is now coming together and hopefully should be back on the air in a week or two. I want to understand the digital operation more so I can understand what is happening and how to make contacts correctly. Let me start with what I am seeing when starting. DM780 through the sound card to Kenwood TS-480S/AT, in the data socket. When I start DM780 and look at the screen, waterfall I see the data mode, in this case PSK31 on 14.081.5, but the radio is showing 14.080. I remember when I first was using PSK31 I could see other stations within the window of the waterfall, they could of been on 14.082.5 or 14.080.6 and that I was able to leave the radio freq alone and just click on the other station and then make a contact. What I was interested in, is, should I have moved the radio freq. to pull the station onto the 1.5Khz above the. (Don't know if I explained that correctly) Also there is heaps mentioned about NO ALC, I have set my TS-480S/AT to the requirements for digital mode, and even dropped the input down further. I was still getting some ALC when in TX. No-body said I was producing a bad signal so I don't know if I was TXing right. Should I set the radio up as stated and then drop back the audio out from the soundcard? Think that is about it, thanks in advance for any responces. Regards Kevin, ZL1KFM. Get Skype and call me for free. sparc_nz Description: Binary data
Re: [digitalradio] Information Please re Reading the Radio for Digital Modes
Kevin, What I was interested in, is, should I have moved the radio freq. to pull the station onto the 1.5Khz No need to move the VFO unless you decide to search outside the 2.5 KHz window of your radios pass band. Most of the PSK31 activity, for example, falls within that window. Should I set the radio up as stated and then drop back the audio out from the soundcard? You might have to fiddle with both the rig and sound card to minimize the ALC. GL Tony -K2MO - Original Message - From: Gmail - Kevin, Natalia, Stacey Rochelle spar...@gmail.com To: digitalradio@yahoogroups.com Sent: Saturday, January 17, 2009 7:10 PM Subject: [digitalradio] Information Please re Reading the Radio for Digital Modes G'Day All, I am trying to get more to grips with all the digital modes to operate. I currently run HRD w DM780 and MFTTY software on my computer (Love HRD) I have used DM780 in the past but it was just plug-in and see if it ran, which it did and was able to make some contacts. I have since moved into a new house and have not had the time to set the radio shack up. This is now coming together and hopefully should be back on the air in a week or two. I want to understand the digital operation more so I can understand what is happening and how to make contacts correctly. Let me start with what I am seeing when starting. DM780 through the sound card to Kenwood TS-480S/AT, in the data socket. When I start DM780 and look at the screen, waterfall I see the data mode, in this case PSK31 on 14.081.5, but the radio is showing 14.080. I remember when I first was using PSK31 I could see other stations within the window of the waterfall, they could of been on 14.082.5 or 14.080.6 and that I was able to leave the radio freq alone and just click on the other station and then make a contact. What I was interested in, is, should I have moved the radio freq. to pull the station onto the 1.5Khz above the. (Don't know if I explained that correctly) Also there is heaps mentioned about NO ALC, I have set my TS-480S/AT to the requirements for digital mode, and even dropped the input down further. I was still getting some ALC when in TX. No-body said I was producing a bad signal so I don't know if I was TXing right. Should I set the radio up as stated and then drop back the audio out from the soundcard? Think that is about it, thanks in advance for any responces. Regards Kevin, ZL1KFM. Get Skype and call me for free.
[digitalradio] ALE141 and ALE400 mail
Note: for the file ALE_and_ALE400_easy_with_Multipsk.doc: http://f6cte.free.fr/ALE_and_ALE400_easy_with_Multipsk.doc http://f6cte.free.fr/ALE_and_ALE400_easy_with_Multipsk.doc add some store and forward ability. Do you mean: receive a text or a file and, on detection of a specific call sign, forward the text or the file to another specific addressee? I really like the way in which you can send a file and/or to another station more or less automatically. Taking this one step further, if this file was addressed to a specific station, how great would it be for the receiving station to forward the file to the addressee if it detects the addressee station. Many times station A can hear station B and station C can hear station B , but A cannot hear C, and it wouid be a way to get traffic from A to C, if that makes any sense. VE5GPM is sitting on 14,111.0 and VE5MU is sitting on 7103.0 , both USB , Both running 141A, both programmed to respond to HFN or QRZ calls. They will be on these frequencies until 0400Z Sunday 18th January, so please try a sounding or a connect. John VE5MU
[digitalradio] Re: Information Please re Reading the Radio for Digital Modes
--- In digitalradio@yahoogroups.com, Gmail - Kevin, Natalia, Stacey Rochelle spar...@... wrote: DM780 through the sound card to Kenwood TS-480S/AT, in the data socket. When I start DM780 and look at the screen, waterfall I see the data mode, in this case PSK31 on 14.081.5, but the radio is showing 14.080. I remember when I first was using PSK31 I could see other stations within the window of the waterfall, they could of been on 14.082.5 or 14.080.6 and that I was able to leave the radio freq alone and just click on the other station and then make a contact. What I was interested in, is, should I have moved the radio freq. to pull the station onto the 1.5Khz above the. (Don't know if I explained that correctly) Unfamiliar as I am with the TS-480, when you are using the data mode I guess it is choosing a particular bandpass filter, and probably setting the transceiver to lower sideband as well. That bandpass filter might be narrow, like 500 Hz. So what you see on the waterfall is 500 Hz of spectrum that is centered maybe 1.5 KHz below the dial frequency. Or maybe not. It is more usual in the digital modes to always use USB, and to use SSB mode so you get the filter that is about 2.8 Khz wide. Then if the transceiver dial is set to 14.080 you will see on the waterfall frequencies above that by the amount indicated on the waterfall frequency scale: maybe 500 to 2500 Hz, meaning actual frequencies of 14.080500 to 14.08300 And you point and click with the mouse to choose a PSK signal in that range. One problem then is that if you are trying to copy a weaker signal and a very strong signal comes on nearby the strong signal will cause the receiver AGC to cut down the gain of the receiver, so that the weaker signal is cut down also to where you can barely see it. Hence you would rather have a narrower filter, such as the one you use for data mode, to separate the signal you are trying to copy from the nearby strong signal. And you could tune the main tuning so as to push the strong signal off the edge of the filter, one side or the other, while keeping the desired signal in the passband. Also there is heaps mentioned about NO ALC, I have set my TS-480S/AT to the requirements for digital mode, and even dropped the input down further. I was still getting some ALC when in TX. No-body said I was producing a bad signal so I don't know if I was TXing right. Should I set the radio up as stated and then drop back the audio out from the soundcard? There are two potential problems with transmit audio level. One is that there might be an amplifier ahead of the gain control in the radio - this is very typical if you are going in through the mike connector rather than through the back panel connector. If you overdrive this amplifier it creates distortion products, and since it is ahead of the gain control knob there is nothing you can do with that knob to eliminated the distortion. The remedy is to cut down the sound card output from the computer, either with the computer volume control or with an attenuator between the computer output and the radio input. The other problem is that PSK requires no ALC. Many other digital modes such as RTTY and MFSK do not have this problem as they transmit only one tone at a time; but PSK is effectively a two-tone signal. This one you can control using the gain control on the radio, just turn it down until the ALC goes to zero. Also you want to be sure that any speech processor is turned off, as this distorts the waveform too. Jim W6JVE
