ADS-B decoding

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ADS-B
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Joined: Mon Mar 05, 2018 5:24 pm

ADS-B decoding

Postby ADS-B » Mon Mar 05, 2018 5:49 pm

Hi

I got a RSP1A about a week ago and I am mainly going to use it for ADS-B decoding. I have been comparing it with a Flightaware dongle daily since I got it and the total range is about the same but the message rate is only 1/4 with the RSP and the low level aircraft is much fewer, so I am sure it is a gain problem.

Do I set the gain the same way in RSP Dump1090 as in the Dump1090 for Windows? --gain -10 for auto gain and max is --gain 49.6 or is it some other way to do it with the RSP?

It would be interesting to hear what other have in settings and what you think about the RSP for ADS-B decoding.
Last edited by ADS-B on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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RiverPatrol1
Posts: 13
Joined: Sat Mar 05, 2016 2:17 pm

Re: ADS-B decoding

Postby RiverPatrol1 » Wed Mar 21, 2018 9:45 pm

Good question @ADS-B. The gain values for the rtl-sdr are well known and I've had rsp's for several years but have never seen a published list of the gain or "gain reduction" values to use on the pi for gain other than -10 for auto-gain and --enable-agc. When using SDRUno and with it in the "gain" mode the IF gain shows from 24.8dB to 84.0dB on the RSP1 so that may be the way to set it up but I don't see any way to turn the LNA on which would be nice for 1090MHz.

Maybe one of the admins can jump in to shed some light on it.

I tried on the previous version and had problems on mlat getting errors for “Server status: clock unstable”, “Out-of-order timestamps” issues but after just trying out the newer Nov 2017 version it appears those issues are gone so I'm going to run this through the paces again and this time with the RSP1A.

I would think that the RSP would blow the rtl-sdr's out of the water for message count, range and planes tracked when set up correctly so with the mlat issues out of the way I'm going to find out.

As I'm just now seeing this post have you found out anything more on the performance of the rsp for ads-b?

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sdrplay
Posts: 783
Joined: Wed Jan 07, 2015 7:58 am

Re: ADS-B decoding

Postby sdrplay » Thu Mar 22, 2018 1:00 am

The optimum settings for the latest version of dump1090 that we put out are:

2MHz demod mode: --dev-sdrplay --interactive --net --normal

8MHz demod mode: --dev-sdrplay --interactive --net --oversample

Obviously remove --interactive if you don't want the terminal window to run in interactive mode

Best regards,

SDRplay Support

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RiverPatrol1
Posts: 13
Joined: Sat Mar 05, 2016 2:17 pm

Re: ADS-B decoding

Postby RiverPatrol1 » Sun Apr 01, 2018 1:59 pm

sdrplay wrote:The optimum settings for the latest version of dump1090 that we put out are:

2MHz demod mode: --dev-sdrplay --interactive --net --normal

8MHz demod mode: --dev-sdrplay --interactive --net --oversample

Obviously remove --interactive if you don't want the terminal window to run in interactive mode

Best regards,

SDRplay Support


Thx, I recently received that answer of the FB SDRplay page and have been testing that per Andy Play (FB Screen Name) statement of "We set the gain reduction to close to the limit and then have an algorithm that runs to assess the best gain reduction level to use." So far it has surpassed my use of "gain optimization scripts" that I have been using on the RTL-SDR versions of dump1090 so I am pretty impressed with it's performance.

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RiverPatrol1
Posts: 13
Joined: Sat Mar 05, 2016 2:17 pm

Re: ADS-B decoding

Postby RiverPatrol1 » Sun Apr 01, 2018 2:04 pm

@ADS-B

Use those commands listed above + any other port redirection if needed for your application. It was also stated that --gain wasn't supported at this time as well as agc because of the algorithm that they are currently using.

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