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rtlsdrblog / rtl-sdr-blog

Modified Osmocom drivers with enhancements for RTL-SDR Blog V3 and V4 units.
https://www.rtl-sdr.com
GNU General Public License v2.0
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Required gain for fixed dynamic range decreases for ADS-B #46

Open by opened 8 months ago

by commented 8 months ago

Since one of the latest commits (https://github.com/rtlsdrblog/rtl-sdr-blog/commit/e47685ebf0aea2cb0fefaf5afd4427c0dfc5a5e7 and ff.), the sensitivity for ADS-B use of my v4 dongle decreased dramatically: I'm running dump1090-fa with automatic adaptive gain settings (i.e., https://github.com/flightaware/dump1090/blob/dev/README.adaptive-gain.md); to have 30 dB dynamic range, automatic gain set itself to a max. of ~45 dB, now it is only ~30 dB, which impacts sensitivity for more distant signals dramatically. dump1090-localhost-misc-48h-2

hdtvspace commented 7 months ago

For ADS-B with 1090 MHz the V3 has an better performance and with an LNA near the antenna and an cavity filter a dream team. https://www.tuxrunner.de/2022/06/29/ads-b-luftraumueberwachung-mit-raspberry-pi/

But for e.g. AIS marine ship tracking the V4 is the better choice. –––––––––––––––––––––––– The V4 however does come with some disadvantages compared to the V3 that need to be noted: Due to the increased filtering there can be an average of 2-3 dB less sensitivity on some bands. …

More info at the release page from rtl-sdr.

by commented 7 months ago

Sure; my point is that the challenge came only with said commit and the loss is on the very same V4 (no V3 involved), meaning performance was lost due to the latest software patch.

by commented 5 months ago

See also https://github.com/rtlsdrblog/rtl-sdr-blog/issues/51