Re: [digitalradio] RTTY decoding
Hi, I' ve searched the Internet for RTTY decoding methods and found the following: - frequency discriminator with IIR resonator. There's a IIR resonator for mark and one for space. A following mark/space detector try to find mark/space peaks in the spectrum and then a comparator decides if it's a "0" or "1" - frequency discriminator with FIR bandpass filter - analog or digital PLL - demodulation with Goertzel algorithm - zero crossing detector to identify the frequency of mark and space Are there other known methods and who knows something about or can explain the above decoders ? How do they perform in a noisy environment ? 73 Sven Are __ Do You Yahoo!? Sie sind Spam leid? Yahoo! Mail verfügt über einen herausragenden Schutz gegen Massenmails. http://mail.yahoo.com
Re: [digitalradio] RTTY decoding
> On Tue, 16 Feb 2010 04:53:04 -0800 (PST), Rick Westerfield > said: > Download MixW 2.19. It is easy to install, free and you do not need much of a > processor. It uses your soundcard as the modem and an HF radio to gather the > signals. Your computer processor is the microcontroller, so to speak. Yeah, because MixW will really help him understand RTTY decoding after he spends a couple of terms disassembling the binaries and reverse engineering the decoder. > There are numerous sources for the engineering behind RTTY digital signal > processing. Interesting stuff and it is a good place to start for young > electrical engineers. IEEE usually covers this topic very well and their > subscription rates for students are very low. IEEE publications cover many topics really well, but someone who wants to get a grasp on DSP will have better luck reading books (some of them freely avaialble online) or university course material. There are also at least two existing, actively developed, FOSS implementations of RTTY (pocketdigi and fldigi) that anyone can study, modify, improve and share. I don't speak for the authors of the RTTY modems in these programs but I imagine that they would be happy to help someone who has already spent some time trying to understand their design. -- 73, Stelios, M0GLD.
Re: [digitalradio] RTTY decoding
Rick, When did MixW become free? We, for years, have been able to download it for a trial period of no more than a couple of weeks, then it stopped working, until paid for. Its been a few years, but I think it was around $60.00 about 3-4 years ago, still a good bargin, since it works so well, and has many different modes. Its logbook though, cannot even start to compare with DXKeeper, nor its spotting section with SpotCollector. It does have an interface that works well with DXLabs, and I used that for a couple of days (checking out some digital modes) about a year ago. Danny Douglas N7DC ex WN5QMX ET2US WA5UKR ET3USA SV0WPP VS6DD N7DC/YV5 G5CTB All 2 years or more (except Novice). Short stints at: DA/PA/SU/HZ/7X/DU CR9/7Y/KH7/5A/GW/GM/F Pls QSL direct, buro, or LOTW preferred, I Do not use, but as a courtesy do upload to eQSL for those who do. Moderator DXandTALK http://groups.yahoo.com/group/DXandTalk Digital_modes http://groups.yahoo.com/group/digital_modes/?yguid=341090159 - Original Message - From: Rick Westerfield To: digitalradio@yahoogroups.com Sent: Tuesday, February 16, 2010 7:53 AM Subject: Re: [digitalradio] RTTY decoding Download MixW 2.19. It is easy to install, free and you do not need much of a processor. It uses your soundcard as the modem and an HF radio to gather the signals. Your computer processor is the microcontroller, so to speak. There are numerous sources for the engineering behind RTTY digital signal processing. Interesting stuff and it is a good place to start for young electrical engineers. IEEE usually covers this topic very well and their subscription rates for students are very low. What kind of HF radio do you have? Rick - KH2DF Sent from my iPhone On Feb 16, 2010, at 4:27 AM, "sven98de" wrote: Hi folks, I'm a student and interested in RTTY decoding principles. What methods/algorithms were used, what procedures has the best results ? Is it possible to implement a decoder with a microcontroller or does it have not enough resources ? 73 Sven
Re: [digitalradio] RTTY decoding
Download MixW 2.19. It is easy to install, free and you do not need much of a processor. It uses your soundcard as the modem and an HF radio to gather the signals. Your computer processor is the microcontroller, so to speak. There are numerous sources for the engineering behind RTTY digital signal processing. Interesting stuff and it is a good place to start for young electrical engineers. IEEE usually covers this topic very well and their subscription rates for students are very low. What kind of HF radio do you have? Rick - KH2DF Sent from my iPhone On Feb 16, 2010, at 4:27 AM, "sven98de" wrote: Hi folks, I'm a student and interested in RTTY decoding principles. What methods/algorithms were used, what procedures has the best results ? Is it possible to implement a decoder with a microcontroller or does it have not enough resources ? 73 Sven