Trial Run Results for Three Types of Whip Antennas

AnirbanSen

Member
Actually it doesn't look like it's working fine. It should look like the third one here:

View attachment 2977
(https://forum.planefinder.net/attachments/1569786921780-png.2977/)
I think i made the spectrum with lower gain, maybe 15 instead of the 30 given in the command from the thread.
But still you get the idea, yours is offset and just doesn't look right.
Check if making a spectrum with gain of 15 changes anything.
rtlsdr2.png

Pretty weird. Set at 1080Mhz. I've emailed rtlsdr admin. Let's see what he suggests.
 

AnirbanSen

Member
A replacement ticket has been created. Hopefully the new one will arrive in 3-4 weeks.
In the meantime, a new problem has emerged:
It appears that around 2am everyday, the signal falls off. The gain in dump1090-fa settings changes from -10 to 49.6.
It remains that way till I change the gain back to AGC and do a reboot.

Any idea what could be affecting this?
 

ab cd

Senior Member
Available in Planefinder forum also since Oct 28, 2017:
(Reminds me of Oblivian's comment. ;) )

 

AnirbanSen

Member
I think that was it. Wonder how it suddenly kicked it. Was a month ago I was testing that.
I also wonder why there is a huge difference between 49.6 and AGC. Signal is almost 4 times the strength at AGC.
 

ab cd

Senior Member
I think that was it. Wonder how it suddenly kicked it. Was a month ago I was testing that.
I also wonder why there is a huge difference between 49.6 and AGC. Signal is almost 4 times the strength at AGC.
For ADS-B signals, AGC does not act as Automatic Gain Control, it sets gain to almost 55.6 dB, which is 6 dB greater than 49.6 dB.
Every 3 dB increase doubles the signal, so 6 dB increase will double the signal twice, i.e. make it 2 x 2 = 4 times :)
 
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