Thanks David, Where I was thinking was the SmallDV Raspberry. Which has COFDM, 4FDM, and OFDM. Maybe a filter that works with all, using a simple config. 48 k being the soundcard rate.
Steve On Wed, Dec 5, 2018 at 2:59 PM David Rowe <da...@rowetel.com> wrote: > > Hi Steve, > > Yes it's possible. Linear interpolation would probably work as well > from 48000 -> 7500. Good idea to measure the modem performance (BER at > a known Eb/No). > > However the OFDM modem is significantly better, and would be straight > fwd to port to different rates, just change the DFT expressions for w. > > Cheers, > > David > > On 06/12/18 03:01, Steve wrote: > > Question for filter experts: the Coherent FDM modem uses a conversion > > filter for 8000 to 7500 sample rate. I was wondering if it can be > > easily modified for 48000 to 7500 rates? > > > > For example it currently interpolates by 15 (8000 * 15 = 120,000) and > > then decimates (120,000 / 16 = 7500. > > > > Since the filter is basically a 120,000 Hz filter then, my simple > > brain says maybe I can interpolate by some number to use 48000 or > > 44100. Although neither of those divide into 120,000 evenly. So, > > obviously 120,000 has to go and 240,000 divided by 5 is 48000 and > > 240,000 / 32 = 7500. So I could interpolate by 5 and decimate by 32. > > > > Is this reasonable/impracticable? > > > > Steve > > > > > > _______________________________________________ > > Freetel-codec2 mailing list > > Freetel-codec2@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > > > > > _______________________________________________ > Freetel-codec2 mailing list > Freetel-codec2@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 _______________________________________________ Freetel-codec2 mailing list Freetel-codec2@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freetel-codec2
