Hi Bill, thanks for the extra info, I noticed the padding as I added extra padding to the nearest 32 bits as I do the parity generation in 32 bit chunks. 73 Alan M0NNB
On Wed, Feb 10, 2021 at 3:49 PM Bill Somerville <[email protected]> wrote: > On 10/02/2021 15:06, Bill Somerville wrote: > > On 10/02/2021 14:40, Alan Hopper wrote: > > Hi, > I'm trying to write a FST4 encoder without using the source, I'm most of > the way there using the excellent FT4_FT8_QEX and FST4_Quick_Start docs, > the latter mentions generator_fst4.dat and generator_fst4w.dat which I > can't find. Are these available or can I extract those tables from the > source without breaching the licence? Also what BT is used for the > Gaussian shaping. I see details of the 50 bit payload are 'in preparation', > If you want a proofreader, I'll very happily proof read by trying to > implement it:) > Thanks again for the great documentation and modes. > 73 Alan M0NNB > > > Hi Alan, > > I though there was a document describing the FST4 and FST4W protocols, but > I can find it right now. Yes you can use the parity generators as they are > part of the protocol. > > Here's the FST4 LDPC generator, a 139 by 26 matrix generating 139 parity > bits from 101 (77 + 24 bits CRC) message bits: > > > https://sourceforge.net/p/wsjt/wsjtx/ci/master/tree/lib/fst4/ldpc_240_101_generator.f90 > > and here's the FST4W LDPC generator, a 166 by 19 matrix generating 166 > parity bits from 74 (50 + 24 bits CRC) message bits: > > > https://sourceforge.net/p/wsjt/wsjtx/ci/master/tree/lib/fst4/ldpc_240_74_generator.f90 > > you will have to take my word for these two specific files being in the > public domain for now. > > BT for the WSJT-X FST4 and FST4W waveform Gaussian frequency smoothing is > 2.0. > > 73 > Bill > G4WJS. > > Hi Alan, > > note that the generator matrix widths above are for hex digits and contain > some excess zeros 26*4=101+3 excess and 19*4=74+2 excess respectively. > > We should have a more formal and complete document ready shortly. > > 73 > Bill > G4WJS. > _______________________________________________ > wsjt-devel mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/wsjt-devel >
_______________________________________________ wsjt-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/wsjt-devel
