. . .and in cases like UHF operation, where band noise may not be the limiting factor, in a properly-designed receiver the noise of the LNA is the determining factor. The LNA noise, multiplied by the gain of the receiver front end, should always exceed the LSB of the sound card. For higher-resolution sound cards, with smaller LSBs, one is able to employ less front-end gain which, as Bill points out, does not aid sensitivity but instead adds extra headroom for strong signals.
If one adds resolution to a sound card and gets improved sensitivity at UHF, I would suspect insufficient receiver front-end gain in the original design. 73, Ed N4II. -----Original Message----- From: Bill Somerville <g4...@classdesign.com> Sent: Wednesday, January 8, 2020 9:34 AM To: wsjt-devel@lists.sourceforge.net Subject: Re: [wsjt-devel] jt9 bin on 32 bit audio file On 08/01/2020 14:08, Olivier SCHMITT wrote: > Hi every one, > > A short question to ask if jt9 is able to decode deep in 24 or 32 bit > audio file instead of 16bit? > Why 24 or 32 bit? Beacause most of soundcard can use minimum 24 bits > and when you maximise the precision, your more able to détermine weak > signals in deeper? > > Thanks in advance. 73 F4HTB Hi Olivier, the maximum usable bit depth on a typical high end sound card is about 18-bit, those extra two bits of resolution would provide almost nothing in terms of real sensitivity. The band noise is the limiting factor, not the sampling bit depth. All that could be gained is a small amount of extra headroom for strong signals. 73 Bill G4WJS. _______________________________________________ wsjt-devel mailing list wsjt-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/wsjt-devel _______________________________________________ wsjt-devel mailing list wsjt-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/wsjt-devel
