[digitalradio] Contestia 1K vs MT63?
All, I was playing with the Contestia mode in an attempt to duplicate the wpm rate of MT63. I configured Contestia with 16 tones and a bandwidth of 1K. The sensitivity of the two seemed to be the same and the wpm rate appeared to be close. I then tested both modes with the HF path simulator dialed-in for selective fading with the SNR set a few db above the minimum decode threshold. As you can see below, print was better with MT63. The deep fades caused garbled characters with Contestia and it would appear the better copy with MT63 is a result of the redundancy built into the mode. I'm not sure if that's an accurate assessment as to why there is a difference, but it would seem so. Wonder if anyone can shed some light on this. Tony, K2MO Path Simulation : Selective Fading SNR : -3db / -6db Contestia 1K / 16 tone SNR -3db THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG THE QUICK BROWN FOS OVER TH- >G THE BROWN FOXMPS OVER THE LAZY DOG THE QUICRO,N FOX JUMPS OVELAZY DOG SNR -6db TE QUCK BROW FOX JUMPS OVER THE LAZY DOG THE QUG2NOWNS YVER THOEG THE BROWN FO#UBR OVER TE LAZY DOG THE QUIC^_^N FOX JUMPS OVELAZY DOG MT63 1K SNR -3db *DE K2MO* THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG *EOT* SNR -6db *DE K2M TH QUICK &AOWN FOX JUOP; OVrR THE LAZY ROG THE Q%ICK BROWN FOX JUMPS OVER THE LAZY DOG THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG THE QUICK BROWNFOX JUMPS OVER THE LAZY DOG *EOT*
[digitalradio] The Makrothen Contest RTTY Saturday 00:00-07:59 UTC and 16:00-23:59 UTC and Sunday
The Makrothen Contest TMC - The Rules - 2008 Last Update: 4-October-2008 TMC logo Date and Time: The contest takes place on the second full weekend of October each year. The next contest dates are Saturday 11th and Sunday 12th October 2008, with three separate periods: Saturday 00:00-07:59 UTC and 16:00-23:59 UTC and Sunday 08:00-15:59 UTC. Objective: The object of the contest is for amateurs around the world using RTTY to contact as many amateurs in other parts of the world as possible during the three contest periods. Terms of Competition for all classes: All entrants must operate within the limits of their chosen class when performing any activity that could impact their submitted score. Only the entrant's call sign can be used to aid the entrant's score. A station operating from a DXCC Entity different from that indicated by its call sign is required to sign portable. All antennas must be physically connected by wires to the transceiver/s, transmitter/s and receiver/s used by the entrant. All used transceivers, transmitters and receivers must be located within a 500 meter diameter area or within property limits of the station licensee, whichever is greater. All operation must take place from the same operating site. Any form of DX alerting assistance is permitted in all classes. Self spotting of any form on spotting nets is not permitted for any class. Self spotting is defined as generating packet radio or web site spots for your contest call sign, including - for example - this methods: using your own call sign; spotting your call sign while using another call sign; spotting of your call sign by other stations as a result of prearranged solicitation. To notify the locator of a station via any form of DX alerting assistance is unwanted and this unsportsmanlike behaviour can lead to a disqualification. Classes: Class 1: Single, All Band, Low Power * SO/Single Xcvr LP Class 2: Single, All Band, High Power * SO/Single Xcvr HP Class 3: Multi, All Band, Low Power * SO/Multi Xcvr LP (S/M) * MO/Single Xcvr LP (M/S) * MO/Multi Xcvr LP (M/M) Class 4: Multi, All Band, High Power * SO/Multi Xcvr HP (S/M) * MO/Single Xcvr HP (M/S) * MO/Multi Xcvr HP (M/M) Class 1 and 3: The output power shall not exceed 100 watts. Class 1 and 2: Single operator and single transceiver - or - single transmitter and single receiver. Class 3 and 4: S/M = Single operator and multiple transceivers, transmitters and receivers (see note). M/S = Multiple operator and single transceiver - or - single transmitter and single receiver. M/M = Multiple operator and multiple transceivers, transmitters and receivers (see note). Note: No limit to transceivers, transmitters and receivers, but only one signal and running station allowed per band. Bands: The 80, 40, 20, 15 and 10 meter bands may be used only. Exchange: No RST required. You have to send the first 4 characters of the "Maidenhead Grid Square Locator" (locator) at your QTH. (i.e.: FM19 or: JO41). Your log must show the correct locator sent and received for each contact. You must send the same locator in each QSO. Only portable "/p", mobile "/m", maritime mobile "/mm" and marine stations (example: "VEØ***", "HC9***") may change their locator every 60 minutes. QSO Points: A station may be worked once on each band for QSO points credit. The points for the QSO are equal to the distance in kilometer (rounded to an integer value) between the two stations exchanging their locator. IOW: one point is equal to one kilometer. Weighting of points on the lower bands: For a QSO on 40m you must multiply the "points per kilometer" with the factor 1.5 and for a QSO on 80m you must multiply the "points per kilometer" with the factor 2.0. The result must be rounded to an integer value. Special case - Exception: If both stations are located in the same square, then both stations - regardless of the band - get 100 points for this QSO finally. Don't multiply this 100 points with any weighting factor! Distance: The calculation of the distance should assume the earth is a perfect sphere with a radius of 6378.16 km. The base point for the distance calculation is the center of the Maidenhead Grid Square. The formula: distance = acos(cos(a1) x cos(b1) x cos(a2) x cos(b2) + cos(a1) x sin(b1) x cos(a2) x sin(b2) + sin(a1) x sin(a2)) x radius a1 = latitude of station-1 b1 = longitude of station-1 a2 = latitude of station-2 b2 = longitude of station-2 a1, b1, a2, b2 in radians radians = degrees x PI / 180 PI = 3.1415926535897932384626433832795 The distance must be rounded to an integer value. Multipliers: No multipliers. Scoring: Your total score is the total sum of total points of each band. For each valid QSO the distance and the points and the final total score will be calculated by the official log checker! You should have this in your mind, if your logging softwar
Re: [digitalradio] Re: Sound card question
Hello John, As said by Vojtech the big problem is the synchronization. As there is no specific synchro signal, you must synchronize of the signal itself (using some non-linear function). The synchronization is primarily done for the theoritical modulation speed with the hypothesis of a pefect sound card speed. If there is a difference in sound card speed, the synchro must make up for the difference. If this one is too much important (let's say 1 %), it is difficult (or let's say not possible) to synchronize. A bad synchronisation means some noise in the moment when one need to do the bit estimation, and hence some noise on the phasemeter. The more sensitive modes are the modes with a lot of carriers as MT63 (because the relative difference between carriers become weaker and weaker and finally you can mix two carriers). The degradation of the decoding versus the difference with the nominal sound card speed varies from one mode to another. It is a slow function in PSK31 but a quick function in Olivia. As said by Votjech, CW and RTTY as not so sensitive because there is no synchronization done (they are asynchronous modes), but reversely the minimum S/N cannot be so good as a synchronous mode (as PSK31 for example). 73 Patrick - Original Message - From: "vk2eta" <[EMAIL PROTECTED]> To: Sent: Friday, October 10, 2008 3:48 AM Subject: [digitalradio] Re: Sound card question > While we are on this interesting subject of sound card calibration I > have a question in regards to the effect of the calibration itself on > the capability of properly decoding the signals.So two questions: > > 1. I noticed that although most PSK31 signals I receive are showing > the two phase positions as displayed on the scope at 180 degrees, > some are consistently at less angle than that, typically down to > about 135 degrees. When I say consistently I mean it is obviously not > just a momentary shift due to propagation as one can see with DX or > QRMed signals. Is this related to the difference in calibration > between the sound cards? > > 2. In the case of PSK31 how much does mis-calibration really affects > the reception? Does it result in a simple an increase percentage of > mis-decoded characters when propagation/QRM creates unwanted phase > shifts? > > 2. Which modes are the most / least sensitive to sound cards > calibration differences? My guest is that in the least category we > should find the psk and ifsk (e.g. Domino) modes and in the most > sensitive category MFSK modes. Is that a correct assesment? > > Thanks, John (VK2ETA) > > > > > Announce your digital presence via our Interactive Sked Page at > http://www.obriensweb.com/sked > > 30M digital activity at http://www.projectsandparts.com/30m > > Recommended software : DM780, Multipsk, FLDIGI, Winwarbler ,MMVARI. > Yahoo! Groups Links > > > > >
[digitalradio] QRV MT63 14106
All, I'll be QRV MT63 this evening starting 2200z -- 14106.0 USB. Tony, K2MO
[digitalradio] Re: Sound card question
Hi John. > 1. I noticed that although most PSK31 signals I receive are showing > the two phase positions as displayed on the scope at 180 degrees, > some are consistently at less angle than that, typically down to > about 135 degrees. When I say consistently I mean it is obviously not > just a momentary shift due to propagation as one can see with DX or > QRMed signals. Is this related to the difference in calibration > between the sound cards? Yes > 2. In the case of PSK31 how much does mis-calibration really affects > the reception? Does it result in a simple an increase percentage of > mis-decoded characters when propagation/QRM creates unwanted phase > shifts? In case of PSK31 it depends on the implementation of the decoder algorithm. Uncalibrated clock will cause phase shift to be different from 180 grades, which adds some uncertainity to decoded bit value. But uncalibrated clock will also negatively influence decoder ability to bit synchronize. I remember optimizing PocketDigi PSK31 decoder for best SNR. One of my optimizations was decreasing speed of PSK31 decoder clock synchronization. One does not want a single noise spike to have much influence. I was very surprised, when I found that my decoder did not work at all when the sound card clock was 1% off. > 3. Which modes are the most / least sensitive to sound cards > calibration differences? My guest is that in the least category we > should find the psk and ifsk (e.g. Domino) modes and in the most > sensitive category MFSK modes. Is that a correct assesment? Least sensitive will be CW and RTTY, which are asynchronous modes. Narrow spaced multitone modes (MFSK, Olivia, Contestia, Throb, Domino) will have problems if the tone scale is stretched or shrinked against the decoder bins caused by sound card clock error. Also the same applies here as at 2). Ability to bit synchronize if the sound card clock is off depends on the implementation of the decoder algorithm and is usually a compromise between SNR ability, time to synchronize and sensitivity to clock difference between modulator and demodulator. 73, Vojtech OK1IAK
