Hello, I would like to ask the technicians among you. It is about the ADS-B and Mode S signal. I run 4 Pi Flightfeeder stations up here myself and I've often noticed that, e.g. Helicopters, Planes in mode S or even with ADS-B near the antenna (approx. 800 m - 0 m distance) can no longer be received or displayed. If these aircraft are further away, they will be displayed or received again. Possible causes ? Can someone explain this phenomenon to me? equipment I own 4 Raspi's , 1x flightaware stick+ antenna, radar box stick+antenna, 2x DVBt sticks. regards tom
Gain is too high. If you want to receive aircrafts really close by you'll need to reduce it quite a lot, likely losing some range.
Just use the search Forums button on the upper right "gain setting" I've found that different SDR dongles vary a lot. There is a script to automate finding optimum gain. You can also look at the 1090 graphs page to see RSSI signal levels. Just modify the gain setting in the config file until you get what you want.
Hey Guys , thank for your all helps . I have new created my complet raspi system inklude , fr24feed, rbfeeder, pfclient, adsbexchange I think this was easyer as search to the mistake for a newbe in raspberry theme New Dump1090 v.1.15 , before was 1.10 , and a new software , he called collectd Dump1090 , for statistic . now can i in a config data on the new dump config manuall or auto the gain . But I still don't really know how to read the statistics . I show the next times on automatic gain , hopefully it will be better with near planes . What I noticed is that the RISSI value for auto is low compared to manual mode . ( Auto (agc) ~ RISSI -20 to 2 , in manual mode more as 20 + . thanks at all for help ! regards
Go to a up to date decoder: https://github.com/wiedehopf/adsb-wiki/wiki/Raspbian-Lite:-ADS-B-receiver Easy to install readsb. https://github.com/wiedehopf/adsb-wiki/wiki/Optimizing-gain -30 is a weaker signal than -20 -20 is a weaker signal than -10
