Re: [linrad] RE: Using Linrad as a Diversity Receiver?

["w3sz" <w3sz@xxxxxxxxxxx>]

Thanks Leif and Bob for the informative, helpful posts.

I have a question.

What is the practical effect of feeding in 2 receivers with no common oscillators
which have a gradual frequency drift with respect to each other.

I understand that the phase of the signals will not be locked, and that the phase
will rotate at the frqeuency difference between the 2 receivers.  But with what I am
doing just feeding in 2 receivers and lining up the frequencies using the high
resolution display, things 'seem' to work OK.  Are they really?  I don't seem to get
any nulling of the signal, for example, due to out of phase interference.

I have a few other questions.

> Yes, The little box immediately to the right of the angle 
> value in the polarisation graph.

Do you mean the little green bar with the white [or yellow] line that I can move to
the left or the right?


> > I also noted that hitting "X+Y" in the baseband window with 
> > polarity fixed and at
> > zero does not send one input channel to one ear and the other 
> > input channel to the other ear as I expected it to.
> ????
> You get the green spectrum of the baseband graph into one ear and the
> magenta curve into the other.

Well, if I put it on 'fixed' polarity and turn on 'X + Y' and disconnect one input I
get almost no signal in either ear if I have pol on 90 degrees and good signal in
both ears if I have it on 0 degrees.  Things appear as expected on the baseband
display.  If I don't have X+Y turned on, then as expected I get NO signal at all if I
have one input disconnected and if I have the pol set to that vaule (0 or 90
degrees).  Thus what turning on "X+Y" does, is the equivalent of reducing the
'channel separation' to use a stereo hi fidelity term.



> 
> Then there is the pol default settings. For an X type cross yagi
> you set channel 1 at 45 degrees and for a + type yagi you
> set it at 0 degrees.
> 
> Do you get the baseband spectra right, but not the sound?

See above.

>  
> > I plan to put up another HF antenna to try diversity reception 
> > with 2 HF receivers and 2 antennas and Linrad.
> With common local oscillators;)
> The phase would rotate at the difference frequency so the
> frequency error should be below 0.05 Hz if the receivers are
> not locked;)

As at the top of  the email, I am wondering what the practical effect of this is. 
Things seem to work here.

>  
> > Has anyone else tried this?
> http://antennspecialisten.se/~sm5bsz/linuxdsp/demo/demhf2.htm

THIS IS VERY INTERESTING!  What were the 2 antennas or receive systems?

THanks again, and



73,
Roger Rehr
W3SZ
FN20ah
http://www.qsl.net/w3sz


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