[Linrad] Re: Perseus with Linrad

[yo4aul <arrl.net; yo4aul@xxxxxxxxxxxxxxxx>]

Thanks for comments

Re:
> Also noticed that even if in Linrad baseband waterfall the  signal was
> still visible, you could not detect the signal audio output by ear...

YES:-)

why is that? Can this signal however be decoded by wsjt software?

re:
Something is wrong with your blanker observations. Otherwise
I think it is correct (but very limited.)

I admit that it is possible that my settings were not optimum

73 Corneliu




On Jul 2, 5:22 pm, Leif Asbrink <l...@xxxxxxxxxx> wrote:
> Hi Corneliu,
>
> > I guess that your calibration files for Perseus
> > will be useful to all Perseus owners.
>
> Yes:-)
>
> > I have tested Perseus plus a downconverter 144/28 with a signal
> > generator and a calibrated attenuator with 1 dB steps
> > for MDS and have discovered that Linrad and Winrad main waterfalls are
> > about 10 dB more sensitive than Perseus software.
>
> There is not really any limit. You can set the bandwith extremely
> narrow in Linrad and average over VERY long times so you can find
> signals that are very much weaker if you wish. That is really the problem
> with Linrad. Any setup I might suggest will be targeted to some
> particular usage and your interest could be something else. That
> is why I do not supply parameters for any particular hardware
> but rather for specific usages.http://www.sm5bsz.com/rf_library.htmhttp://www.sm5bsz.com/linuxdsp/usage/examples.htm
> There are many links here:http://www.sm5bsz.com/linuxdsp/linroot.htm
> Some of them give examples on various usages of Linrad.
>
> > also noticed that even if in the Perseus main waterfall you could not
> > see anymore the signal, in the extended window the signal was still
> > about 10 db above noise floor.
>
> This just depends on the parameters you have selected. Linrad allows
> you th have it the other way around in case that is what you want.
>
> > Also noticed that even if in Linrad baseband waterfall the  signal was
> > still visible, you could not detect the signal audio output by ear...
>
> YES:-)
>
> > I have noticed also that the dumb noiseblanker is quite effective
> > except in the condition when the signal is very close to the noise
> > floor when also the signal gets attenuated by blanker
>
> That is because you do not use the dumb blanker properly. (I think)
>
> > I would appreciate if you could supply the Linrad optimized settings
> > for Perseus week signal detection
>
> There is no such thing. Your local QRM/QRN situation might make
> it optimal to use a different calibration or different sizes
> for transforms. What you mean by weak signal is also a personal
> matter. Chasing weak EME signals is quite different from
> chasing weak SSB bursts in meteor scatter SSB. If you want to work
> weak signals in a terrestrial contest I guess you would not want
> the delay from antenna to loudspeaker to exceed 2 seconds or so.
> (In EME, 10 seconds is fine.)
>
> I have asked (many times) for recordings of situations where a signal
> is difficult to copy in order to use such examples here:http://www.sm5bsz.com/rf_library.htm
>
> There are many interesting aspects of interference fighting
> and signal detecting that I would like to demonstrate - but
> I want to do it on real signals not just simulations of mine.
>
> > Pls also advise if the a.m. findings are correct.
>
> Something is wrong with your blanker observations. Otherwise
> I think it is correct (but very limited.)
>
> 73
>
> Leif / SM5BSZ

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