(meteorobs) [radiometeoren] Re: Question about airplane and automatic counting Spectrum Lab
James Beauchamp
falcon99 at sbcglobal.net
Sat Sep 14 00:13:06 EDT 2013
Hi guys,
As someone who has been running a receiver with speclab for a few years now, but lacked the time to do the programming, I would suggest the following recommendation...
Since the doppler solution will be a bistatic one, aircraft reflections will slowly change compared to those of meteor hits. If you commonly get "head echo" hits prior to persistent echos from overdense events (sometimes you will get no persistence in small events, so it is the head echo only), you can use FFT bins from previous time slices to discriminate targets with long time constants from the short ones. Aircraft will slowly change in frequency over time compared to meteors that suddenly appear with HIGH doppler rate head echos.
It is a bit complicated on the code side, to which I am not experienced enough to help with recommended methods, but if i were a coding "god", i would average the bins in the time domain.
Aircraft will exhibit slow frequency change from a high abscissa to a lower one, but will be slowly changing compared to meteor reflections.
If, due to the lower base frequency, you get ONLY long-term reflections (no head echos) from the meteors, another discriminator could be the instantaneous appearance of an echo over several seconds. Again, the code could use time-based binning of previous FFT's to identify sudden appearances of consistent-doppler signals. This will be a bit more noisy, with a higher number of false targets from aircraft (due to fading as the reflections appear), but might be better value than nothing at all.
Just a couple of thoughts...
James
________________________________
From: "maarten.vanleenhove at telenet.be" <maarten.vanleenhove at telenet.be>
To: ernotp at gmail.com
Cc: radiometeoren at vvs.be; cm2esp at gmail.com; Meteor science and meteor observing <meteorobs at meteorobs.org>
Sent: Thursday, September 12, 2013 4:21 AM
Subject: Re: (meteorobs) [radiometeoren] Re: Question about airplane and automatic counting Spectrum Lab
If someone would find a solution for this, I 'd like to hear about it!
kind regards,
Maarten
________________________________
Van: "ernottp" <ernotp at gmail.com>
Aan: cm2esp at gmail.com
Cc: "Meteor science and meteor observing" <meteorobs at meteorobs.org>, radiometeoren at vvs.be
Verzonden: Donderdag 12 september 2013 10:58:45
Onderwerp: [radiometeoren] Re: Question about airplane and automatic counting Spectrum Lab
Hi,
Maarten Vanleenhove wrote a script for Spectrum Lab in which he it tries to avoid false detections due to aircrafts.
His url is:
http://www.supernovae.be/meteorcounting
However, errors occur.
Following him: "When two aircrafts reflections merge, the script will, due to the signal
width, assume a meteor was picked up. When large meteors appear,
sometimes the meteors will be double counted"
I do not use this script because we detect too many intersections of aircrafts (beacon at Dourbes in Belgium 49.97Mz)
Pierre Ernotte
2013/9/11 Raydel Abreu (CM2ESP) <cm2esp at gmail.com>
Hello all,
>
>Recently, by September 6th I was able to migrate my radio forward scatter system from 187 MHz TV to 61 MHz TV. Obviously as the frequency is lower a very high increment in rates is present.
>
>With the previous system a manual counting was performed so false positives by airplane traces were ignored. As my new system is peaking 150 meteor traces by hour as an average manual counting is impossible.
>
>A modified script for SpectrumLab based on the meteor_test distributed on the software installation package was written to track the weak but sporadic present direct signal carrier and it works very great.
>
>However, at least one or two times a day some airplanes gets into the working pass-band and produces a lot of false positives; producing false "hotspots" which difficult to identified as airplanes produced or real meteors outburst like the one recently detected by some members.
>
>Any advice or tips??? Or a recommended better script to deal with this "airplane outburst". The happening of this problem is very seldom, but still affecting data quality. See efficiency and the "hotspots" in the attached picture.
>
>Thanks and best wishes,
>
>Raydel, CM2ESP
>Havana, Cuba.
>
>
>
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