Feature Request - Linrad

Message from discussion Feature Request
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Date: Wed, 3 Jun 2009 01:00:49 +0200
From: Leif Asbrink <l...@sm5bsz.com>
To: linrad@googlegroups.com
Subject: Re: Feature Request
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Hi Thomas,

> I am looking in VLF, up to 30KHz.  I want to see SID, tweeks, etc.
Hmmm, SID and tweaks require quite different displays and etc might
be yet another different thing;-)

> The VLF stations are in the range of 10 to 25KHz.  So I would use 9KHz
> as the lower frequency and 26KHz as the upper.
For SID?

I would suggest you monitor 9 to 180 kHz or perhaps a little more.
Enable the network and run half a dozen of instances of Linrad.
Select half a dozen of stations at suitable distances over the
frequency range, place the S-meter graph in the upper left part of 
the windoe and reduce the window sizes so you see only the S-meter 
graphs for all the different stations.

You might have the signal level of the carriers of half a dozen stations
for the latest 12 hours on screen and a SID should show a sudden change
on all of them.

Another thing could be to monitor the frequency at extreme resolution.
I would guess a SID would cause a doppler shift.

For tweeks I think what I wrote previously would apply. If you
want better time resoultion you might want a higher power of
sin for the fft1 window. (Transfoems would overlap a little more.)

Previously I suggested that you should set the fft1 bandwidth
to 15 Hz. That was incorrect. Set 30 Hz if you use a sine squared 
window.

> The other mode is 100Hz to 15KHz.  Depending on activity, I would choose
> a subset of this, e.g. 7KHz as the lower frequency and 14KHz as the
> upper.
> 
> I will play with this.
Yes. There are several parameters to play with. Record raw data so you
can look at the same sequence with different processinmg parameters
to learn whar effects different parameter settings will have.

> I have not been able to reliably replicate the failure mode.  I can get
> it to happen at random times.  I ran xlinrad several hours while doing
> other things, editing, switching windows, moving windows, starting
> applications, using gdb, etc.  I had some ft245 entries in
> var/log/messages the first time I started xlinrad, but, nothing after.
> And, no overrun errors.  I stopped and started xlinrad several times in
> this period with no additional entries in var/log/messages.  I will poke
> at it now and then.  I keep a log of par* files, so I can capture the
> setup if I can reproduce the errors.
Very good. If you find something that seems reproducible I might be able
to reproduce it here. Then I might be able to prevent the problem or
perhaps to make Linrad exit with an error message that would help to
eliminate the problem. ("Make sure that chron is not running" or similar...)

Leif / SM5BSZ