[digitalradio] Re: Narrow SSTV contact
Question: what other modes are there in MMSSTV that will work in the narrow 500 Hz bandwidth? I think its limited to mp73-n, mp-110-n, mp140-n and the mc110-n, mc140-n, mc180-n modes. Unluckily i have never found a station qrv in those modes...
[digitalradio] Re: New release (4.7) of MULTIPSK
Any big fans of MULTIPSK that might like offer why they use it? I'm guessing you're using it for the ALE applications? I have made the test of running multipsk in parallel with winpsk and other psk31 software. The programs were set up to decode the same signals on 40m. Then i did compare the decoding success. Multipsk was clearly the winner. Im a multipsk fan !
[digitalradio] Re: RFSM 8000 Different pricing structure
I wonder how long we will have to read these sales pitches from the support group ?
[digitalradio] Re: Report on RFSM2400 vs. OFDM
How is what we tested somehow flawed in your mind? Compare it to testing psk31 against jt65 at snr's of -20db. psk31 wont work, jt65 will work. Flawed test. Your report of easypal only getting 1/6 of transmission is a clear indication that conditions or setup were not adequate. I could not even find what mode or qam type you were using. Flawed test. This is no weak signal mode. This mode is NOT automatic and needs quite some dedication. Comparing this (probably in default config) with an automatic mode is ... I do admit that I have done some calibration of my ICOM 756 Pro 2 S-meter and can give you at least some relative comparisons of dBm levels. S-meter and SNR have nothing in common. What does enrage me is the trashing of a well established free mode with the goal to hype up of an expensive software, which, you failed to mention, proved to be unusable for sstv in your own test (12 min for a 28kb picture is not acceptable).
[digitalradio] Re: Report on RFSM2400 vs. OFDM
I think i have expressed my point of view. Further discussions only per PM please. Andy does have my real email.
[digitalradio] Re: Report on RFSM2400 vs. OFDM
Unluckily i have to say that this comparison is quite flawed... using easypal which needs minimum 6db SNR in the lowest setting in conditions of less than 4db snr (1/6 throghput you say) is not a good idea. Comparing that to a mode which can adapt to lower snr's is BS at best. Your invited to repeat the test after having learned how to use easypal, and use it in suitable conditions. There are lots of experienced d-sstvers to get help from.
[digitalradio] Re: Setting up FDMDV
Both soundcards should also be qite precise at 48k sampling rate. If one or both cards are not able to precisely do 48k samples you will get bad audio quality, periodic interruptions, or bad SNR values. For vista users it's important to set the default audio rate to 48k, not 44100. I do not recommend vista at all, i have tested it and changed back to xp after a month.
[digitalradio] Re: Report on RFSM2400 vs. OFDM
I noticed that there are images that are sent with an RS 1 through 4 and then I think it converts them to jpg? The RSx files are additionally encoded. I dont remember the exact numbers but i think it allows 10% errors on rs1, 50% errors on rs4. You can actually decode an rs4 file when 50% of it is missing. I think easypal will do that automatically for you. There is an offline decoder the RS files, see KB4YZ site. BUT the efficiency of the offline decoder is only half as good as the easypal decoder because some info is missing in offline state. You will be able to rebuild an RS4 file with 25% missing offline, but 50% missing online (online is close to turbo-code performance !).
[digitalradio] Re: Opinions please...What is the best interface for PSK31?
If you spend a lot of money on an interface, it's because you wanted to, not because you need to. Right ! The main points of such an interface are to provide isolation between PC and Rig. This is normally done by audio-transformers for the mic and speaker lines, optoisolators for ptt line. The main problem i have seen in commercial interfaces is a bad frequency response for the audio. 50hz to 3khz should be flat. With some interfaces, it's not. The other problem are the cat-ptt devices. There is no point in having the audio isolated but running a ground-loop trough the cat-interface. I think the simple optoisolated single rts ptt devices are superior. If you have to use CAT for PTT you need a fully isolated CAT port ! The ideal solution would be to run the whole audio and ptt trough optical cables. Most soundcards do support optical, but i have never seen the Rig-counterpart for this. If you are a builder, it's a hand full of parts. If you have any old PC modem cards, you can steal the audio isolation transformers off of them and get past two important parts for free. Or buy something like the Rascal kit and build it. Comes with interface cables and everything shipped for under $50. It's not like it's some complicated piece of equipment.
[digitalradio] Re: Redefining SSTV operations
a very powerful compression scheme, it's perhaps possible. The compression used is .jpg or .jp2 (jpeg-2000) For reasonybly sized pictures 10kb is minimum, 20kb is average size. The quality does deteriorate rapidly below 20kb/picture. The drm-modem (qam-16 mode b) has a raw troughput of 3600bps, 2400bps FEC'd. Means 66 sec for a 20kb picture. A 500hz wide FDM modem of 500hz BW would have 600bps raw, 400bps FEC'd, Means 6 minutes for a 20kb picture. I think this is not practical. btw you can test the quality/size tradeoff with irfanview.
[digitalradio] Bozo Guide for SVN (subversion)
Hi, Is there a bozo SVN guide for windows? The task is not to retreive anything, but to put a project into sourceforge or similar. The project is about 50 VC++ files and some libs. Any instructions would be appreciated. 73, Cesco, HB9TLK
[digitalradio] Re: Bozo Guide for SVN (subversion)
I also have a utility called Tortoise SVN that integrates with Windows Explorer. I have tried this and got extremely confused. I prefer the command line tool. I have not seen a bozos guide but can assist you. Offline from the group might be better... TNX. I will mail you directly, maybe you can remove some roadblocks for me. 73, Cesco, HB9TLK
[digitalradio] Re: PSKmail
I will think about it. It would be nice to have the pskmail functionality in a re-usable form. The actual code is not easy to run in windows, i did try and failed. The actual file-io message transfer system has the advantage to be universally usable. It's not linked to a specific psk31 soft, and its not even liked to psk31. That's an ideal situation for experiments. The code is complicated enough to need deep involvement to understand. It's not possible to quick-hack it into C. We need the help of the author !
[digitalradio] Re: 30 Meter digital
So, perhaps we can make more of an effort to use this band, Has anyone tried it for Digital Voice. ? Region 1 bandplan 30 m : 10100 - 10140 200 hz BW CW, QRP 10140 - 10150 500 hz BW digimodes No DV until someone makes a 500hz wide dv-mode for region 1.
[digitalradio] Re: MP3's of Amateur Radio Data Modes
Currently there are 25 MP3's on the BARTG website and they include ALE, DominoEX, Olivia and MT63. The DRM sound is messed-up. They got the feldhell-type text messages instead of a drm signal.
[digitalradio] Re: New Digital Voice Mode FDMDV
Hi Roland, O Arnaldo PY4BL, fez um ótimo contato hoje em FDMDV com IZ2GAF Doriano, com boa qualidade Wow. PY to IZ could be a record distance. você acrescentar em Settings, Sound, About a opção View, onde seriam colocadas as opções de Display (Waterfall, etc...) You are right. Tnx for the hint. 73, Cesco, HB9TLK
[digitalradio] Re: Digital high frame rate video via amateur radio
How far off are we from a day when we can do digital video and voice, video with perhaps a 5 frames a second rate ? Decades ? A highly jpg compressed 160*80 picture is about 1.2k At 5 frames/sec this is 6kb/sec. By using the P and I frames concept this could maybe be lowered to 3kb/sec. Adding voice results in 4.5 kb/sec. This is doable with today's modems, but snr requirement and BW will be high, picture resolution very low.
[digitalradio] Re: Digital high frame rate video via amateur radio
oops .. those numbers are wrong. I did mix up kbyte and kbit. The video may be limited to less than 1 frame / sec.
[digitalradio] Re: RS-ID
Hi Patrick, Signal to Noise ratio of -12 dB about 1.5 sec about 3 Hz WOW. This sounds excellent. The 1.5 sec is too long to use it before every transmission, but good for the initial transmission as you suggest. This would allow standby operation. Nice. I would be very intrested ! 73, Cesco
[digitalradio] Re: New Digital Voice Mode FDMDV
Hi Roland, Parabéns pelo FDMDV ! Obrigado. Muito feliz de ver seu mail ! Tenho uma sugestão: Seria melhor se a frequencia de transmissão fosse FIXA, A nova versao vai ter uma opcao a de voltar ao centro da banda. Tambem concertei o auto-tune. 73, Cesco, HB9TLK
[digitalradio] RS-ID
Hi Patrick, It will be perhaps interesting to have a specific RS ID which would permit to auto-tune automatically This would allow to drop the central carrier and get a 75hz narrower signal. It would loose the ability to transfer text, but gain 10% in robustness. Good idea. Questions: How long is the duration of the rs-id transmission ? How accurate is the tuning? 73, Cesco
[digitalradio] Re: New Digital Voice Mode FDMDV
Here is my XYL after encoding with MELP and FDMDV Are you trying to discredit the program by posting worst-case examples ?
[digitalradio] Re: JT65A : DESDE URUGUAY CON PROBLEMAS
Pese al ajuste del reloj, las señales empìezan a aparecer en la cascada en cualquier momento y no en el punto del cambio de minuto como debería ser. He did adjust the clock, but signals are starting ramdomly, not at minute boundaries. I guess the clock adjustment went wrong.
[digitalradio] Re: FDMDV on 14.236
Hi Steinar, Anyone for digital voice qso 14.236? I have uploaded a recording of your CQ call audio in the files- digitalvoice section.
[digitalradio] Re: Technical Question: FDMDV
A 50 baud signal should have either a 50 Hz or a 100 Hz separation by my understanding. fdmdv modem is NOT OFDM. (would be called OFDMDV if it was) And even with ofdm, 50baud and 50hz will not work in real world. Try to googe ofdm and guard interval. What spacing would an ofdm systen with 50 baud and 1/3 guard interval, 2/3 symbol time have?
[digitalradio] Re: Technical Question: FDMDV / QPSK in PSK31
Modem description from Peter G3PLX (the modem author): --- The modem is based on a raised cosine shaped tone filter response which has the property of zero ISI and zero adjacent tone interference with no sidelobes. Half the channel filter is in the tx and the other half in the rx, so it's often called root raised cosine because the channel filters at each end have a response which is the square-root of the complete filter. ---
[digitalradio] Re: FDMDV - HF Frequency Division Multiplex Digital Voice
Hi Andy, FDMDV is the latest DRM digital voice mode on HF FDMDV does not use the DRM modem, but the FDM modem developed by a very well known digital mode expert. The FDM modem beats DRM in low- snr performance and qrm-robustness. 73, Cesco
[digitalradio] Re: The sorry state of VHF/UHF Packet
It's my understanding that 19.2k just isn't possible with a soundcard. Wrong. The main question is how much BW your radio provides. Having 10khz of BW 19.2k should be doable. Have a look at the DREAM software http://drm.sourceforge.net/ . It should get pretty close to 19.2 on 10khz BW, and exceed 19.2 on higher BW. DREAM has its own set of problems, mainly the long time to sync. You cant use that for packet out of the box.
[digitalradio] Re: digital voice within 100 Hz bandwidth
I would be plased to have a complete list of the phonemes and corresponding audio files from different speakers. I fear 44 phonemes will not be enough to do a context-free analisis. The data rate will be closer to 200pbs i think, since you will have to transfer a magnitude component along with the phoneme index, and maybe also a pitch component. Think of the pitch raise in a question, this feature is important for understanding. The main problem will be the fft to phoneme table correlation i think ... but to work on this there must be a phoneme table first.
[digitalradio] Re: digital voice within 100 Hz bandwidth
Very low bitrate algorithms exist now. There are a few that operate from 200 bps to 600 bps. The Navy has software called IVOX that gets in this range. Can you somehow lay hands on such a 200 to 600 bps codec? Im VERY intrested. The IVOX thing is based on 2400 bps lpc. With silence detection they bring it down to 1200bps average. Thats not the 200 to 600 bps codec.
[digitalradio] Re: digital voice within 100 Hz bandwidth
I did send you a PM.
[digitalradio] Re: 10 MHz Amateur Radio balloon to Cross the Atlantic
TNX for the info. I think you should post the message again when the baloon is on it's way. Or just a reminder so i wont forget to listen-in. I think it's a very intresting experiment lasting only a few days. So i personally dont understand the attitude of interpreting the national us band regulations against it...
[digitalradio] Re: OFDM Proposal
Could a higher higher success rate without the fill requests be achieved with some combination of better FEC, slower data rate, better spreading of the data over frequency and/or time? Try it. It's all there. FEC, data spreading and data rate can be selected in DRM, read the doc. Easypal has an additional FEC mode with much wider data spreading and another layer of high-efficiency FEC. By doubling the transmission time, you can recover up to 50% of the data ... Would it be feasible to use OFDM (or any other mode) with much longer ARQ cycle times (several seconds) to accomodate the computer timing limitations? This is already done. Find out how the bsr-stuff works. The limitation is that it's not automatic. This was an intentional design decision. We dont want a bunch of drm-robots on the qrg.
[digitalradio] Re: HF OFDM
Various sources I have read put typical maximum multipath at 10ms. If the symbol period is 25ms then there would not be a need for a guard interval since the critical part of the symbol is undistorted. Well, we want all of the symbol undistorted .. not only a part. So the 25ms symbol and the 10ms guard interval (your multipath time) adds up to a new 35ms symbol time. Note that carrier spacing is still based on 25ms to keep orthogonality intact.
[digitalradio] Re: Is D-Star a Viable Standard?
I think the DV part of dstar is somehow a dead-end... The intresting ability of d-star is the high-speed mode in the D1 units. Seems it's capable of something like 80kb/sec, but there is very few info on it. It could be 140khz wide .. does someone have documentation about ? This data rate allows not only DV, but DAV (Digital Audio Visual). That is live video and sound in very good quality. Only on 1.2 ghz now, but if it's 140khz wide i think 70cm may be an option too. Not only hear, but see your qso partner over the 70cm repeater,would that be intresting? I think yes. Lets hope icom doesent make a proprietary dead box, but only a modem, and use a PC for codec and camera/display stuff.
[digitalradio] Re: SCAMP?
Since RDFT was released under the GPL license, failure to release the source code for SCAMP may be violation of the GPL license. The rdft routines are not integrated into scamp, they are external exe's. Same trick is used by mixw, gpl-code is moved to an external library. While this seems to be legal in the scamp case, the mixw case could be different. To use GPL code in a library (.lib or .dll) the code must be released under lgpl (library gpl) i think. My personal thougths: It is very impolite to push a freeware developer to release his source with legal threats. The developper will get angry and stop working (for free) for the ham-community. This is an absolute NO-GO !
[digitalradio] Re: Most robust digi-mode with 200 to 600 bps ?
Are any minimum SNR numbers of those 2 modes known (375/300 bps)? The SNR for 8FSK can be about -5dB. The SNR for 8PSK at 75baud is about -10dB. Sorry, I don't remember the typical SNR for 300 or 600 baud 8PSK. I think we must start to specify SNR at Bandwidth, otherwise the numbers dont match well. Im no expert in the field... A non-standard type of OFDM could be designed for this slow DV, with only 2 amplitude levels, to achieve more robustness. I estimate -2dB SNR to 1dB SNR is easily possible, and probably much better. The drmdv ofdm is 1 amplitude level, 4 phase levels already. Going to only 2 phase levels could bring down the minimum snr to around +2db (at 600bps). That is at 2.4khz BW of signal, 2.7khz BW of snr measurement.
[digitalradio] Re: Most robust digi-mode with 200 to 600 bps ?
The 8FSK raw speed of ALE-mode provides 375baud, Try the 8PSK mode in PCALE, under the The increments are: 75, 150, 300, 600, 1200, 2400 baud. Thanks. ARQ makes no sense in DV, and FEC is easily adaptable to meet those 375 or 300 data rates of those 2 modes. Are any minimum SNR numbers of those 2 modes known (375/300 bps)? The problem with ofdm (windrm style) is that it's hard to go below SNR's of +5db. The current DRMDV program works down to +5db snr at 1400bps rate, so i expect a more robust mode to reach stable 350bps at -1db SNR. @rick: drm (ofdm) runs circles around scamp, and outperforms pactor3 in data rate at given snr as well besides that the robot-qrm mode is insanely expensive
[digitalradio] Re: Most robust digi-mode with 200 to 600 bps ?
don't think you can do much better than WinDRM type OFDM modes since you need the bps throughput to make it work adequately. you can. windrm uses 2400 bps at 8db snr min. drmdv uses 1200 bps at 5 db snr min. the new codec would use around 250 bps, wich givs an improvement of 6db in minimum snr compared to drmdv. That is in the future, the codec is not publicly available. (I would love to have it) I am not familiar with a robot-qrm mode, HI, it's not the pactor technology, but the way it's used. pactor pests is the name. They routinely destroy ongoing qso's.
[digitalradio] Most robust digi-mode with 200 to 600 bps ?
Question to the experts: What is the most robust digi-mode with a 400 to 600 bps raw capacity (or 200 to 300 bps fec capacity) ? Is a boosted psk variant the best coice or is mfsk capable of such rates ? Other options ? Background: Seems someone has developed a 200bps voice codec. It's a phoneme coder. The data rate and the description sounds plausible. I dont know if this will ever be available as open source for amateurs, but it would be intresting to estimate the possibilities of such a codec for DV (digital voice). Such a coder could probably beat analog ssb in terms of robustness in marginal conditions.
[digitalradio] Re: the mislead about pactor and winlink in general
Its now clear why the two-year-old SCAMP busy frequency detector has never been incorporated into WinLink servers. How should they do it? One is a soundcard app, the other a proprietary microcontroller box. in the old days, when packet qrm was sometimes a problem we had a robot silencer to wipe a qrg clean. The program was listening to ongoing transfers, noting to, via and from adresses, and the sequence number. Then it would send a short disconnect with spoofed sender and seq.number to the robots. The qrg did always clean-up in a minute. I guess pactor would be sensitive to this type of busy indicator.
[digitalradio] Re: HF search text
This should do it, but untested with wsjt deep search yet. http://www.qslnet.de/member/hb9tlk/deepsearch.html
[digitalradio] Re: JT65A pile-up on 40M.
Double-click the trace you want decoded. Then double click another one. Works fine.
[digitalradio] Re: Deepsearch on JT65 HF --turn it off
How would one format an HF call3.txt example from file: ZS6GPM,KG33XU,,10/02 i think format is callsign,locator,,date additional entry would be: HB9TLK,JN47HJ,,3/07 Guess for HF the EME entries could be deleted to avoid false detects.
[digitalradio] Re: K3UK Bozo's Guide to HF JT65A update
The Bozo's Guide is excellent andy ! I would never have used JT65A on HF on my own, thanks to the group for making some hype around it.
[digitalradio] Re: JT65A and future of slow MFSK
The codebase appears to be GPL Yes, the source is there, but it's a mix of phyton, fortran and C. Not easy to see trough, or to build it. btw the intel fortran compiler is free for 30 days ...
[digitalradio] Re: ZS6WN JT65 14076
183900 1 6/8KT2Q ZS6WN KG46 1 0 seems he's stuck there. doesent stop calling you.
[digitalradio] Re: WSJT issue, recieve waterfall issue.
Try reducing the input level. I am using the creative mp3 usb for wsjt, and i have to set the input level slider near the botton for wsjt. Same slider is is in top position for psk31 or other modes. WSJT is too sensitive for normal position.
[digitalradio] Re: BIG DF OPERATING
Setting the freq. in the SpecJT window does change only rx freq, but tx stays the same? I did not know that. Thanks for info.
[digitalradio] Re: DV (Digital Voice) using PSK at 93 bps
HI, that one is good. I guess the Markov Model for DV would be 1 2 3 4 5 test, followed by a software crash.
[digitalradio] Re: DV (Digital Voice) using PSK at 93 bps
I could not follow and got messed up. You win Andy !
[digitalradio] DV (Digital Voice) using PSK at 93 bps
DV (Digital Voice) using PSK at 93 bps The new PSKDV Digital Voice soundcard mode allows acceptable voice quality over quite bad HF channels. It uses a new type of voice compressor with extremly high compression rates, and a transmission system very similar to psk31, but 3 times faster. The voice compressor does not try to extract sound parameters of a vocal cord / tuned pipe model like lpc or other low bitrate codecs. Instead it tries to extract harmonic magnitudes for vocals, and spectrum transitions for consonants. Then it tries to correlate those parameters with a table of 78 phonems. The extracted phonems and quantizized pitch and duration parameters are then sent over HF at 93bps. First tests have been very sucessful at SNR's down to -4 db. The mayor problem seems to be that the current phonem table is tuned to german language, and gives poor results in those strange foreign languages. Another issue is that you wont recocnize the voice of your qso partner. Individual voice aspects are lost in the compression process. Only pitch and talk-speed are preserved. The beta test program is downloadable in the usual place, but only today, 1. april.
[digitalradio] Re: Report of the ARRL Ad Hoc HF Digital Committee Dissenting Recommendation
The only other known use for voice-bandwidth data modes is for image transfers, which can send an SSTV-size picture, with a very low error rate, in 30 seconds, using a bandwidth of 2400 Hz. the same image, at the same low error rate, can be sent in less than 2 minutes, using a bandwidth under 500 Hz. SSTV has traditionally uesed 2.4khz BW since the analog days. There will be quite some resistance from sstv operators to change this to 500hz and extend the waiting time from 1 min average to more than five min. (30 sec to 2 min numbers are incorrect) Everyone actually operating sstv will confirm ! Digital SSTV concentrates on one frequency per band. That is 2.4khz per band. There are no full automatic stations for digi-sstv, there is NO software to allow full auto operation. THERE ARE NO DIGI-SSTV ROBOTS ! Usually the digi-sstv arq operations are operator-initiated and NOT automatic. You can't compare that to pactor, you are behaving incorrectly to the bunch of digi-sstv operators. In other words, just by accepting to wait longer for an image to arrive, as is the current practice in SSTV, it is not necessary to use a voice-bandwidth transmission mode. WRONG. 5 min for a single picture will kill the mode. Recommendation: Voice-bandwidth data modes SHOULD NOT be introduced on the HF bands. Automatic (Robot operated) Voice-bandwidth data modes SHOULD NOT be introduced on the HF bands. 73, Cesco, HB9TLK
[digitalradio] Re: MPSK vs OFDM vs MFSK for HF High Speed Data
So using multimulticarrier soundmodem with a YaeComWood + 1kW PA will only heat your ham shack without other useful effect. Negative. The grounded-grid PA's have no negative effect on SNR if tuned right (tuned for peak power). Those PA's have better lineariy than the 100W push-pull transistors in your rig.
[digitalradio] Re: MPSK vs OFDM vs MFSK for HF High Speed Data
when n becomes big, the ratio tends to 1/square(n) For example, for MT63 where you have 64 carriers in parallel, You transmit only 12.5 watts with a 100 watts maximum XCVR. The same applies to the digi-sstv hamdrm/windrm modes. 30 to 60 carriers, crest factor (average to peak power) is about 10db. On a 100w tx im running 10W to 15W average power. Most hams use PA's with this mode. A 1kw pep amp runs an average power of only 60W for best SNR's. Increasing the average power will make the signal less readable due to peak-clipping. It usually takes some time for beginners with those modes to realize and believe this. The advantage of the mode is speed. 2400 bps with +10db snr, 1200 bps with +6db snr.
[digitalradio] Re: Anyone using DigiTRX (Ver 3.11) for ditigal TV?`
As I understand it, DigiTRX won't run on less than WIN XP.. No. Digtrx runs happily on win98. But you need 1ghz or better.
[digitalradio] Re: Morphing Dave, Simon, and Patrick.
In my point of view: TCP is complicated ! Its easy to build a client (maybe), its more complicated to build a server, and it's hard to build a server which reliably can accept and handle multiple connections on one port ! The solution could be to have a common DLL with an easy interface for C,C++ and delphi (C# anyone ?, hope not). The dll handles all communication issues, TCP or direct. The dll comes with example programs in C,C++ and delphi. The software creators then only have to include the dll and get full interoperability with other programs, without caring about sockets and similar things. I am not intrested in rig-remote control or logbook stuff, only in audio-data exchange. The dll i'm actually using to interface kgk- transceiver,iqfft,winpsk,hamdrm and multipsk has a very simple interface. It transfers data trough common memory, except for multipsk which uses tcp/ip. It's in the basic form of: initRX(samplerate,buffersize); readRX(buffer); initTX(samplerate,buffersize); writeTX(buffer) Every program can use it's own buffersize, and in the future it's own samplerate. Timing is implicit, some procedures are blocking, others not.
[digitalradio] Re: Vista emphasizes security over compatibility
When I get my soundcard DLL written for VISTA I'll make the source available. This would be great ! btw, where did you get the new sound API from ?
[digitalradio] Re: Using IQ for digital modes.
So far there's no IQ software for digital mode reception (please prove me wrong!) I hope so: DREAM is IQ capable. Start it with dream.exe -c 3 (see dream's help) and feed it with your IQ signal. More, since dream is open-source, and dreams iq-capability is a modular phase-shift hilbert filter this method can easily be copied to other open source apps.
[digitalradio] Re: SDRs Open Possibility for 18kHz Bandwidth HF Data?
So, , what digital modes exist that are in the 12 to 20 kHz range could I use if I when and bought a SDR today ? DRM. 9, 10, 18 and 20khz wide. Really good bitrate. and it's free. google DREAM drm receiver. DREAM does transmit too, DV (cd-quality) or data. If this would be legal we would already have wide-digital-sstv with 18 kbit/sec or even streaming video (low quality) on HF.
[digitalradio] Re: Movement toward open digital software?
I often wonder if there is even one ham working on adapting the existing ham DRM type protocol to a pipelined ARQ connected mode that has adaptability to conditions. I think no. The main problem of arq-drm is the very long turnaround time. It's in the 20sec range. This makes normal arq like in pskmail or packet a very lame thing. The only work-around is the thing digital sstv does. keep the number of arq cycles as low as possible. This is done by sending out all data at once (20kb or more), and then getting the not-ack's (there are no ack's) for all the lost segments (packets, 400ms data chunks) at once. This does work very well for large amounts of data, but is not good for small (less 5k) data transfers.
[digitalradio] Re: Movement toward open digital software?
How do you determine your specific 20 second turnaround time? Couldn't it be any reasonable number from say 1 second up to maybe 20 seconds? The time from start of transmission until receiving the first data segment is 10s to 15s. That's the sync-zone, the lead-in. 20 sec is not to be taken pedantically, it may be 15.2135 sec, HI but the magnitute is NOT in the 2 sec range.
[digitalradio] Re: Digital Sound Cards -- What IS the best?
While using a sound card with a wide frequency response, and using high sampling rates, might intuitively appear to be a good idea, I'd suggest this is not likely to be the case. Thoughts? What am I missing in this logic? my thoughts (not veryfied) : You should use the max. sample rate the card is capable of. Normally, this is 48khz. The reason behind is microsofts audio resampler. i.e. if you request 11025 samplerate, the soundcard may still be working at 48khz, and the driver resamples the audio to 11025. Now, the MS resampler is not that good, and may produce quite some wow and flutter. This is no issue listening to music, etc, but it does heavily affect some modulation types. Other possible rates are 24khz, 12khz, 8khz, etc. Those can be directly derived from 48khz without passing the windows resampler.
[digitalradio] Re: USA: No Advanced Digital HF Data Comms
Near the equator, there is little frequency spread ( 4 Hz), but it is larger in near-polar paths and can be very large (up to 40 Hz) under disturbed conditions. A question: where does the frequency spread come from ? Is this a doppler effect of a moving ionosphere, or are there other causes ? why is the effect bigger in polar regions ?
[digitalradio] Fast HF Modem Development Re: OFDM data D1D
is that dynamic variable, does it increment amplitude level symbols based upon updating ARQ feedback, No Or fixed symbol based upon manual operator setting, or a link initialization routine? Yes. The transmitter sets the mode, the rx will adapt automatically Which modem is it? The DRM modem used in easypal/hampal/digtrx/windrm snr values are about +5db for qam-4 (qbpsk) and +9db for qam-16 (the one with amplitude part)
[digitalradio] Re: CPU performance ?
All LCD or TFT monitors produce severe picture distortion at any but the default monitor resolution. I would not care about picture distorsion, but at any but the default monitor resolution the text becomes blurry (not sharp). The cause is that any resolution has to be up or downscaled to the monitors native resolution for display. At uneven up or downscaling, some aliasing occurs, which is visible and disturbing (especially reading text). Personally i have used a 1600x1200 21' lcd monitor until last year. Then i swapped it for a 19' lcd with 1280x1024 resolution because i could not see the small pixels on the 1600x1200 monitor any more ! As we get older, we might focus on pixel size, not on resolution. Big screens are nice, but only at low-res. If you need more screen size, a dual low-res monitor setup is nicer than a single hi-res screen. This dual-screen thing works excellently in winXP, give it a try !
[digitalradio] Re: OFDM data is Emission Designator D1D
OFDM squeezes more carriers into the same space by making the carriers orthogonal to their next door neighbors. Its not only the next door neighbors but ALL the carriers. If you look at the the ofdm signal with a correctly timed FFT with exactly a symbol time length, there is NO overlap of the carriers. That is how domodualtion is done. But if you look at the the ofdm signal with an fft of incorrect length, or not proprly timed (including phase-change symbol boundaries) the carriers will overlap quite a bit ! Your waterfall display is such a randomly timed fft of incorrect lenght. The advantage of this system ? each subcarrier can change it's phase (and amplitude) much faster than a carrier of limited bandwidth could do, but during symbol integration time there is no carrier overlap, the orthogonality remains perfect. One example of a bandwidth limited subcarrier system is RDFT. in contrast OFDM does NOT limit the subcarrier bandwidth !
[digitalradio] Fast HF Modem Development Re: OFDM data D1D
I foresee and recommend this variable OFDM symbol approach as the best next step in fast HF modems for hams. Those systems are actually very sucessful in high data rate applications like digital sstv. Appearing 2 years ago they have become mainstream in a very short time. Its not the next step, it's already old stuff, HI
[digitalradio] Re: RFSM-2400 on 14.109,5
I am QRV on 14.109,5 USB (VFO) and Wait connection... Calling you, 18:32 utc (i think) 14.109.5 vfo, 14.111 center. No answer till now.
[digitalradio] Re: OFDM data is Emission Designator D1D
relevant to its classification to OFDM. Which it is NOT. The carriers are on 120 Hz centers and the baud times are 100 Hz. Because the baud time is not commensurate with angular frequency of the carriers, the dot products are not zero and therefore, they are NOT orthogonal in PACTOR-III. I do not agree. 100 baud means 10ms/symbol, of which 8.33ms symbol time, 1.66ms guard interval. Carrier spacing is 1000ms/8.33ms = 120hz. The carrier spacing is orthogonal to the integration time, and not to integration time + guard intervall. It's exacly like all the other ofdm systems.
[digitalradio] Re: Rigexpert SD and WinDRM
Is anyone in the grouping using the Rigexpert SD for the WinDRM DV mode? The Rigexpert SD is essentially an expensive usb-soundcard with the correct cables already installed. I dont have one, but there should be no problem at all. Direct the voice audio inout to your PC's normal soundcard, and the TX-RX inout at the Rigexpert. Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[digitalradio] Re: Digital Voice: Some thoughts after one week.
The WinDRM specification is very sketchy .. Well,... you are invited to provide a better one. but the FEC is not described. The interleaving of the pilots and overhead data is described but not the interleaving of the voice data. It says This document describes the DIFFERENCE of mode HAM to the official broadcast DRM standard. That means everithing not described is like the official broadcast DRM standard. FEC and interleave is exactly like broadcast. More, its the same code used in the DREAM DRM software. I will have to have a conversation with one of the speech codec designers I work with. A codec withh 1000bit/sec would allow qam-4 modulation, and improve the robustness to useful levels. Tests with a 1200 bit/sec LPC codec have been negative (bad intellegibility). Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[digitalradio] Re: Digital Voice: Some thoughts after one week.
It was my understanding that the QAM-4 modulation was used for the text transmission Negative. Text and data can be anything from qam-4 to qam-64 FAC data (the callsign) is the only thing which is always qam-4 and you needed to use at least QAM-16 for the voice. Since the codecs used have 2400bps data rate, qam-16 is necessary. But if you find a decent 1200bps codec, data rate is lower, and qam-4 could be enough. How many bps can you get through with QAM-4? See the list on the windrm spec page. http://www.qslnet.de/member/hb9tlk/drm_h.html If LPC doesn't work at 1200 bps, And apparently it works OK at 1000 bps? I dont understand. Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[digitalradio] Re: Digital Voice: Some thoughts after one week.
The only solution to do voice exchange with a low S/N would be to translate all the pronounced words in symbols Exactly what i am thinking! We need to establish a phoneme alphabet. Then, a correlator is needed to extract those phonems from the voice input. Each phonem should have duration and pitch indicators to allow a more individual reconstruction of the voice. This would result in a robust, low-bitrate and somewhat robotic DV system. Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[digitalradio] Re: Digital Voice: Some thoughts after one week.
From my understanding of the documentation for WinDRM, MELP does work if the speed is at least 1,000 bps. No. 1000 bp400ms (bit per 400 ms) or 2400 bps This per second / per 400 millisecond mixture is confusing ! Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
