Quite understandable. But my only frustration is that I admire how on Linux one could create a AX25 port with soundmodem (A software packet modem), then mount on top of this, a TCP/IP interface.
At this moment, you can use any TCP/IP program on top of your rig: Everything works without change. I really find that great but unfortunately it works only on Linux and, as you point out, the performance of AX25 in HF does not seem fantastic (Although there are enhancements apparently, like https://lists.develer.com/pipermail/bertos/2010-December/002949.html or http://en.wikipedia.org/wiki/FX.25_Forward_Error_Correction ) This does not mean that I criticize your solution of course, because indeed it works well. It is simply that I loved the technical simplicity and elegance of the AX25 implementation on Linux, and I always hoped this would be possible to have the same but with PSK or any other modem. Thanks Remi On Sat, Jul 27, 2013 at 1:53 PM, Rein Couperus <[email protected]> wrote: > First, AX25 is not the protocol you would develop for use on HF. Its > headers are killing your > throughput. That´s why the pskmail protocol was developed by K9PS, and > empirically optimized an extended by PA0R. > Also, the TCP protocol is unfit for use at HF, because of its speed > requirements. > The PSKmail servers act as a gateway between the air interface protocol > and TCP/IP, > taking care of timing requirements of both networks and ARQ on the air > interface > protocol. Because some of the modes used (PSK, PSKxxR, MFSK and THOR) > use varicode, the timing requirement of the air interface is non-trivial. > Also, because of the difficult channel conditions on HF and the QRM > genereated > by the fact that we use shared frequencies, it was necessary to develop > adaptive, asymmetrical > mode switching. Try this with TCP. > > It is very easy to add services to the servers, they are progrtammed in > PERL. > > Rein PA0R > > > > -- > > > "Available services are POP, SMTP, web access" > > Simply based on TCP/IP or is there a dedicated socket for each protocol ? > > Thanks > > R > > On Sat, Jul 27, 2013 at 11:41 AM, Rein Couperus <[email protected]>wrote: >> >> Yes, it is working with HF transceivers as well. >> Tested with a FT857... of course you will need a frquency with 2.5 kHz >> bandwidth. >> (does not work on 30m in Region 1). We prefer staying within 500 Hz bw on >> HF, >> to be a ´good citizen´ on these shared frequencies... We reach 32 >> characters/second >> ARQ with PSK500 on a clear channel, sending 512 bytes per frame in 500 Hz >> bw >> (52 cps compressed). >> >> Available services are POP, SMTP, web access (text, forms), grib files, >> NOAA wx charts, >> Twitter, full APRS compatibility (with socket for Xastir an UIview), file >> up/download and telnet. >> >> Rein PA0R >> (Info: http://pskmail.org) >> >> Will it be usable on a "normal" radio such as FT817 ? >> Also, at 2400 bauds, it might be nice to add a Hayes-compatible >> pseudo-tty interface. It is fast enough to do a telnet connection. >> >> Remi >> >> On Sat, Jul 27, 2013 at 7:06 AM, Guy Story KC5GOI <[email protected]>wrote: >>> >>> John, we have been using the multi-carrier PSK modes in Denton County >>> on our bi-weekly net with good results for roughly a year. I have to go >>> looking for it but we found on our repeater that lower frequency audio get >>> more emphasis and gradually rolls off the higher in frequency you go. I >>> have graphs of the data but I need to dig for it. I can to that tomorrow >>> during the VOA Radiogram. >>> >>> 73 >>> >>> Guy >>> KC5GOI >>> >>> On Fri, Jul 26, 2013 at 12:47 PM, John Phelps <[email protected]> wrote: >>> >>>> Hello all, >>>> Apologies for the number of mailing-lists this touches, but am taking a >>>> bit of a survey: >>>> >>>> Want see how many people would be interested in using, developing, >>>> and/or testing Fldigi for "high speed" data over FM audio and/or FM-audio >>>> repeaters. In my testing so far, it appears the speed would be somewhere in >>>> the 3 Kb/s to 4 Kb/s range, possibly higher. >>>> >>>> Since the goal is fast data, audio coupling is out: faster speeds >>>> simply require a direct-audio connection. My inexpensive solution here was >>>> to interface a Baofeng UV-5R to a soundcard: see attached file for details >>>> (for good engineering practice, 1:1 isolation transformers should be added >>>> to isolate the radio form the soundcard). >>>> Conveniently, Baofeng and other radios contain an inbuilt VOX circuit >>>> to control PTT. No additional interface needed (I recently purchased 3 for >>>> this project, hihi) >>>> >>>> I saw some testing months ago for a mode that could be used over FM >>>> repeaters. >>>> Here I am proposing a new digital mode: NBEMS-FM >>>> This not a mode that I am making, but rather one I think we all should >>>> contribute to and discuss together. This will result in a better overall >>>> design. >>>> >>>> The details of the NBEMS-FM mode should be, in my opinion: >>>> * 2 Speeds: one for Uplink / Reliability, one for Downlink / Backhaul >>>> * No options to accidentally mis-configure >>>> * Modem uses a set-frequency (no AFC to be mis-adjusted) >>>> * Little-to-no FEC overhead >>>> * Use PSK instead of QAM, to better allow for drastic audio-level >>>> mis-adjustments to still decode >>>> * Common-sense balance of speed and reliability >>>> >>>> >>>> In my testing here, it appears 8PSK is the highest constellation that >>>> is reliable over FM audio. I have tested on-air patches for fldigi that >>>> reliably transmitted data using two 8PSK carriers at 500 Baud, for a >>>> datarate (raw and net) of 3Kbps. Will work on porting those patches forward >>>> to the recent Fldigi versions. >>>> >>>> First thing that is required is the common audio upper and lower >>>> "cutoff frequencies" of amateur repeaters and radios. >>>> From the previous testing, what was the consensus? >>>> >>>> Responses and opinions appreciated at: [email protected], or on the >>>> mailing list. >>>> >>>> John >>>> KL4YFD >>>> >>>> _______________________________________________ >>>> fldigi-alpha mailing list >>>> [email protected] >>>> https://lists.berlios.de/mailman/listinfo/fldigi-alpha >>>> >>> >>> >>> >>> -- >>> 73 >>> >>> Guy Story KC5GOI >>> [email protected] >>> >>> _______________________________________________ >>> fldigi-alpha mailing list >>> [email protected] >>> https://lists.berlios.de/mailman/listinfo/fldigi-alpha >> >>
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