Thanks Steve, there was error in the spreadsheet calculations, I have checked in a corrected version with a total estimated bandwidth of 1575 Hz.
The spacing between carriers is nominally 1.5*Rs. Each carrier has a filter with 50% excess bandwidth, so each carrier is 1.5*Rs wide or 1.5*75 Hz = 112.5 Hz. On top of that I actually space them unequally, a little trick to reduce PAPR, so here are the actual frequencies, offset from the nominal centre: -731.250 -621.848 -513.585 -406.055 -299.068 -192.510 -86.309 19.588 125.220 230.617 335.803 440.797 545.617 650.275 So the last two are a bit closer than the first two carriers. Cheers, David On 04/02/17 09:36, Steve wrote: > I notice the cohpsk_frame_design.ods file has: > > Excess BW factor 1.5 > Carrier bandwidth 187.5 > Total signal bandwidth 1312.5 > Diversity factor 2 > Total BW with diversity 2625 > > > 187.5 Hz BW, but then in the software, a much narrower BW is produced. > Notch to notch looks like about 111 Hz. > > When you view the audio spectrum it is only about 1500 Hz BW total with > 14 carriers, and about 750 Hz without > diversity. It doesn't look crushed together though. Nice notches between > carriers. > > I would guess maybe .43 excess, and 111 Hz carrier bandwidths. > > Disclaimer: I have an art degree :-) > > > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, SlashDot.org! http://sdm.link/slashdot > > > > _______________________________________________ > Freetel-codec2 mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
