Hi David Thank you very much for the quick answer. Since float would be good for you, I would be very happy with float-interface, since I now have always to convert my floats to short and v.v.
Even with shorts, the QSOs run very good! 73, hb9epu, Alfred On 17.10.2014 12:46, David Rowe wrote: > Hello Alfred, > > The use of 16 bit shorts was just due to convention. > > The fdmdv modem (and codec 2) uses floats underneath, converting to > shorts at the last moment in the API. We could perhaps create > freedv_api functions that have float interfaces. The demodulator isn't > level sensitive so should work down to very small amplitude input samples. > > Cheers, > > David > > On 17/10/14 18:10, wully wrote: >> Hi all >> >> In the last few days, I made an number of successfull QSOs with freeDV. >> It starts geting "standard use"! I am very happy about it working so >> good even under somewhat difficult conditions on 40m band. >> >> But I have seen a point: When using the function freedv_rx(...) I have >> to give the samples in short format. >> Since the TRX works over a wide range, lets say between -40dBm and >> -100dBm, one has to apply a reasonable conversion of the samples to give >> a good dynamic range in short format. The rx-data from HPSDR are >> 24bit-Numbers, which then are converted to float or double, so, that the >> filters can be applied seemlessly. Before going to freedv_rx(...), I >> filter and downconvert the samples to 8kHz. Then I apply a "AGC" to get >> the samples in reasonable short range. >> >> Why is the short format chosen in rx? Would float give more dynamic >> range to the demodulation? Or, why not? >> >> best regards, Alfred, hb9epu >> >> >> >> >> >> ------------------------------------------------------------------------------ >> Comprehensive Server Monitoring with Site24x7. >> Monitor 10 servers for $9/Month. >> Get alerted through email, SMS, voice calls or mobile push notifications. >> Take corrective actions from your mobile device. >> http://p.sf.net/sfu/Zoho >> _______________________________________________ >> Freetel-codec2 mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/freetel-codec2 >> > ------------------------------------------------------------------------------ > Comprehensive Server Monitoring with Site24x7. > Monitor 10 servers for $9/Month. > Get alerted through email, SMS, voice calls or mobile push notifications. > Take corrective actions from your mobile device. > http://p.sf.net/sfu/Zoho > _______________________________________________ > Freetel-codec2 mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 ------------------------------------------------------------------------------ Comprehensive Server Monitoring with Site24x7. Monitor 10 servers for $9/Month. Get alerted through email, SMS, voice calls or mobile push notifications. Take corrective actions from your mobile device. http://p.sf.net/sfu/Zoho _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
