search

mutability / dump1090

Dump1090 is a simple Mode S decoder for RTLSDR devices
529 stars 137 forks source link

update librtlsdr/dump1090 to include new setting bandwidth option #50

Closed jester-xbmc closed 5 years ago

jester-xbmc commented 9 years ago

https://github.com/steve-m/librtlsdr/commit/d892279085491f9c610388da89bc701ef6ac632c

Allow setting bandwidth for R820T

This improves SDR performence for nearby channel interference. As a sideeffect also improves dynamic range becase ADC is not overloaded by unwanted singles.

mutability commented 9 years ago

Have you tried this? Given that ADS-B is a broad signal I can't see that reducing the IF bandwidth is particularly useful.

jester-xbmc commented 9 years ago

no, not yet, building a test environment right now, even with a broad signal as ADS-B i might help to cut down on nearby interference, every uDB helps ;-)

Mictronics commented 7 years ago

I know it's an old topic, but since I played with bandwidth settings you may interested in results. I'm running https://github.com/librtlsdr/librtlsdr v0.7.0 at the moment.

By default, bandwidth is set depending on sample frequency +/- 300KHz, so for dump1090 that will be 2.43MHz. Setting manually a lower BW will reduce noise, tracks/hour going down as well. A higher BW, up to 6MHz, will raise noise and mean level, tracks/hour going up, but not significantly, you may receive a few aircrafts more. A BW >6MHz increases noise significantly and therefore sensitivity suffers, noticeable higher CPU load but no real benefit for reception.

So I stick with default bandwidth as it seems to be a good trade-off for low noise, good sensitivity and acceptable CPU load.

As a side effect I learned: Never use auto-gain.