Hi, Have you seen the Ham Radio Mesh network:
http://usercontent.arednmesh.org/K/5/K5DLQ/livemap2.html So, there's quite a "market" out there for better solutions. Though, these are all built on mass produced affordable hardware and all that is modified (sorta) is the software. (basically just using the 1MHz and 5MHz modes the hardware can do) Alan VK2ZIW On Mon, 22 Jun 2020 07:39:54 +0930, David Rowe wrote > Some good progress on support for VHF/UHF data using Codec 2 modems: > > http://www.rowetel.com/?p=7207 > > - David > > On 22/6/20 7:24 am, David Rowe wrote: > > Hi Glen, > > > > Sounds like you are quite experienced and have had some fun times with > > LDPC work in the past. Thanks for your offer but I think we are good > > with LDPC in Codec 2. > > > > We currently have support for LDPC at the Octave simulation and C level > > using the CML library with great support on from Bill, VK5DSP. It's all > > running on the stm32 thanks to Don's fine work with the 700D port last year. > > > > Cheers, > > David > > > > On 21/6/20 9:19 pm, glen english wrote: > >> David, I have quite a bit of code in this area from modem stuff from > >> years ago. > >> > >> Mostly based on David Mackay's work from memory. I can dig it all out. > >> > >> I generated : > >> > >> LDPC matrix generator, parametizable. > >> > >> C++ encoder, C encoder, encoders with precalculated LUTs that I used on > >> STM32L0 at 16 MHz .. > >> > >> My decoder (soft) was all C/C++ for a processor with a bit of memory and > >> speed, mildly optimized. > >> > >> But, depending on the code size, and rate rate, might work in a STM32. > >> > >> It was all teamed up with a chirp + D^2-BPSK hybrid modem with an > >> optimized decoder ( and highly NEON optimized to run on an cortex A5 > >> and keep up. > >> > >> all is in a linux environment. I can dig out the LDPC stuff if ya like. > >> > >> -glen > >> > >> > >> > >> On 13/06/2020 3:31 pm, Bill Cowley wrote: > >>> Hi Jeroen, > >>> > >>> Further to David's reply, you might like to look at the AFF3CT > >>> sitehttps://aff3ct.github.io/ which provides comprehensive info on > >>> channel coding. David's codes have been Repeat Accumulate (RA) LDPC > >>> codes - we used them initially as encoding is very easy (eg well > >>> suited to a microController). Of course you probably don't need this > >>> - so you might get slightly better performance with other options. I > >>> haven't played with the AFF3CT software much, but it does cover RA. > >>> > >>> Cheers, Bill > >>> > >>> Cc: > >>> Bcc: > >>> Date: Thu, 11 Jun 2020 23:30:58 +0200 > >>> Subject: [Freetel-codec2] Generating LDPC code for 6000 mode > >>> Hi, > >>> > >>> The experiments with mode 6000 are going pretty well. > >>> Another local HAM (PE1ITR) even managed to work our repeater with > >>> just a > >>> HackRF. > >>> Compared to analog FM it seems to perform pretty well. > >>> > >>> But I would like to take it a bit further and try to introduce > >>> some FEC. > >>> Since the currently used codec2 mode only needs 3200bps there is > >>> still > >>> plenty of room. > >>> I was thinking about a rate 2/3 code (687 code bits for 458 data > >>> bits), > >>> but I am a bit puzzled with the ldpc octave code. > >>> How exactly do I generate the needed matrix (and ofcourse the C and > >>> header files)? > >>> > >>> Regards, > >>> Jeroen > >>> > >>> > >>> > >>> > >>> > >>> > >>> ---------- Forwarded message ---------- > >>> From: David Rowe <[email protected] <mailto:[email protected]>> > >>> To: [email protected] > >>> <mailto:[email protected]> > >>> Cc: > >>> Bcc: > >>> Date: Fri, 12 Jun 2020 07:29:34 +0930 > >>> Subject: Re: [Freetel-codec2] Generating LDPC code for 6000 mode > >>> Hi Jeroen, > >>> > >>> Hey that's great work with working the new mode on a HackRF, is that > >>> about 50mW max? > >>> > >>> Yes, FEC is a fine idea. > >>> > >>> A friend has been kind enough to generate the codes for me, > >>> however it's > >>> not a process that is automated or straight forward. Couple of > >>> options: > >>> > >>> 1/ Use an existing code. > >>> 2/ Use a code with more data bits than you require, and fill them > >>> with > >>> known bits at the encoder and decoder that you don't transmit. This > >>> effectively lowers the code rate a little. I do that for FreeDV > >>> 2020. > >>> 3/ Peruse the CML library codes and see if they have one that fits > >>> your > >>> use case, e.g. ldpcut.m > >>> > >>> There is an Octave utility to generate .[ch] files and run the > >>> codes in C. > >>> > >>> Cheers, > >>> David > >>> > >>> On 12/6/20 7:00 am, Jeroen Vreeken wrote: > >>> > Hi, > >>> > > >>> > The experiments with mode 6000 are going pretty well. > >>> > Another local HAM (PE1ITR) even managed to work our repeater > >>> with just a > >>> > HackRF. > >>> > Compared to analog FM it seems to perform pretty well. > >>> > > >>> > But I would like to take it a bit further and try to introduce > >>> some FEC. > >>> > Since the currently used codec2 mode only needs 3200bps there is > >>> still > >>> > plenty of room. > >>> > I was thinking about a rate 2/3 code (687 code bits for 458 data > >>> bits), > >>> > but I am a bit puzzled with the ldpc octave code. > >>> > How exactly do I generate the needed matrix (and ofcourse the C and > >>> > header files)? > >>> > > >>> > Regards, > >>> > Jeroen > >>> > > >>> > > >>> > > >>> > _______________________________________________ > >>> > Freetel-codec2 mailing list > >>> > [email protected] > >>> <mailto:[email protected]> > >>> > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > >>> > > >>> > >>> > >>> _______________________________________________ > >>> Freetel-codec2 mailing list > >>> [email protected] > >>> <mailto:[email protected]> > >>> https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > >>> > >>> > >>> > >>> _______________________________________________ > >>> Freetel-codec2 mailing list > >>> [email protected] > >>> https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > >> > > > > > > _______________________________________________ > > Freetel-codec2 mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > > > > _______________________________________________ > Freetel-codec2 mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 --------------------------------------------------- Alan Beard OpenWebMail 2.53 _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
