RE: LF: <Tech>Re: A Question

[DL4YHF@aol.com]

Hi Alberto, Jim, and LF group,

As Jim already wrote, the amplitude measuring facility of Spectrum Lab uses a 
more or less arbitrarily chosen scale which is 0 dB for the lowest possible 
signal which can be detected (with a 16 bit ADC). However, I am not very 
happy with that choice myself. There is also the possibility of using Andy's 
CFAR noise detection algorithm (it is hidden somewhere in the spectrum alert 
function, works perfect except for the case when there is no input signal at 
all ;-).

Someone (was it Alberto ?) has already written about the problem that some 
soundcards seem to use a kind of AGC (no matter what the mixer settings say), 
 making absolute measurements inaccurate in the presence of static crashes 
etc.

IMO, a good solution is to display the difference (in dB) from the 'cursor 
position' to a definable 'reference area' where either the noise level or the 
amlitude of a reference generator can be measured. An optional "smoothing" 
(or averaging) of the displayed dB value can also help.

Alberto, if you find a good solution for this I would like to know how it 
works. Thanks...

Good luck for now,
73s Wolf (DL4YHF).