Hi Bill, > Steve, I am unsure about a couple of the changes I have made, particularly > the limited slice of the cdat complex array used when applying the Rayleigh > fading model on line 275 (necessary to avoid an array bounds violation when > using 11025 Hz rate), and whether I should apply clipping to 16-bit full > scale after applying the gain offset at line 288. I also don't understand > what line 287 is doing as it seems to apply a normalization factor 'fac' that > I would expect to be applied on line 288 yet that line used a fixed factor of > 100.0 (`rms`). Perhaps you can review my changes and advise?
I think that jt65sim is working properly in r8391. The fac vs rms thing was taking care of a hidden feature, whereby the simulator generates a noiseless signal whenever the requested SNR exceeds 90 dB. That wasn’t working properly with nonzero Doppler spread, even in the original version, because the peak amplitude is random - so I made some changes that will cause a noiseless (SNR>90 dB) signal to be scaled so that the (random) peak magnitude is 32767. I also changed the hardwired Nyquist frequency from 6000.0 to (fsample/2) so that the noise should be scaled properly for either sampling rate. With the new option for an arbitrary “gain offset", I decided that it would also be worthwhile to print a warning if the simulated data is clipped in the wav file. The user should probably re-run with a smaller gain value if clipping is detected. Steve k9an ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ wsjt-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/wsjt-devel
