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
