Perseus with Linrad
yo4aul
Is it necessary to calibrate Perseus to use the smart blanker?
73 Corneliu
Leif Asbrink
> Is anyone using Perseus with Linrad?
> Is it necessary to calibrate Perseus to use the smart blanker?
collect the pulse shapes for your hardware. The calibration
procedure gives some freedom to the user to optimise his system
for different purposes, but for the Perseus I do not think it
is very interesting to go much above 80% bandwidth usage because
of the aliasing that would then become visible so for the Perseus
it would be possible to supply a calibration file for each sampling
rate.
I have been on travel for a couple of days and I have some other
things to attend to, but with time I will give whatever support
needed to make you, and anyone else who might be interested, able
to use Perseus in an optimal way with Linrad:-)
In the meantime, use the dumb blanker. It is far more clever
than any conventional blanker you might find in other receivers.
Analog or SDRs.
Regards
Leif / SM5BSZ
yo4aul
Thanks for your attention. I guess that your calibration files for
Perseus
will be useful to all Perseus owners.
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.
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.
Also noticed that even if in Linrad baseband waterfall the signal was
still visible, you could not detect the signal audio output by ear...
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
I would appreciate if you could supply the Linrad optimized settings
for Perseus week signal detection
Pls also advise if the a.m. findings are correct.
73 Corneliu
Leif Asbrink
> 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.htm
http://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
yo4aul
Re:
> still visible, you could not detect the signal audio output by ear...
YES:-)
re:
I think it is correct (but very limited.)
73 Corneliu
On Jul 2, 5:22 pm, Leif Asbrink <l...@sm5bsz.com> 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