My Stats


#21

@sonic67 Then write receiver not Raspberry Pi please.

I’m not quite sure but yes i’ve also read somewhere the rtl-sdr chipset is indeed a limitation. Not quite sure why though :slight_smile:

You can also watch your local skyview, if some planes disappear relatively close to you or transmit less messages their signal is probably too strong. Before and after they disappear their signal would be somewhere between -3dBFS and 0dBFS.

Especially low flying aircraft can have a very strong signal as they can be close to your antenna while they are also in the optimum reception plane.


#22

It’s a low speed 8 bit ‘processor’.


#23

USB bandwidth and the RTL2832 are not a bottleneck - they’re always running at the same sampling rate & producing the same amount of data regardless of how much ADS-B traffic there is.

dump1090 CPU use is somewhat dependent on how much ADS-B traffic there is, but most of the CPU cost is independent of message rate and you’re not going to run out on a modern Pi anyway.

The ~1800 msg/sec soft limit is more of a limitation of ADS-B itself, you reach a point where message collisions mean you can’t get much more out of the radio signal. A sectorized antenna/receiver setup may help if you hit that limit.


#24

That’s what I meant. We had a discussion about that a while ago, with a link towards those calculations, but I was too lazy to try find it. The search function on the forum is not helpful (unless you know exactly some of the words used).
Also, I have a nagging suspicion that a receiver that can process more samples/sec will be able to discriminate between collisions better (temporal domain).
One that has more bits (ENOB) will also be able to process a wider dynamic.


#25

I find that too. ‘Good’ to see I’m not the only one.:wink:


#26

This may be the reason why the AirSpy is reported to have better performance, higher price not being a factor.


#27

Sure, but you need to rewrite the demodulator too to really take advantage of that; it’s not just a case of increasing the sampling rate.


#28

And this may also be the reason why the performance improvement with the AirSpy is only when using its own software.


#29

And by that you are meaning “I have to” :smiley:


#30

:rofl:

This is why I always try to write ‘one has to’, instead of ‘you have to’.:sweat_smile:


#31

Or is a royal “You” like the royal “We” :crown: ?
Oliver, after all, is kid of a king in that respect…


#32

“you” as in “someone who isn’t me” :wink:


#33

#34

Me too :slight_smile: :wink:


#35

By the way the dump1090 javascript is just wonderful.

Preparing a pull request with some cleanups / improvement.
Should probably do some whitespace fixing too because it is it’s a pain to work on.

Could you set a standard like 4 spaces as indentation? Could be 8 width tabs for all i care just want something i can set my vim to and not be surprised in the diff that it’s all kaputt!

edit: i wrote “because like” :frowning: gonna blame it on the javascript code that is real spaghetti


#36

Here is my graph for the last 20 hours, running gain of 42.1. Should I leave it running at 42.1 for a few days due to sunday being a quieter day than the rest of the week?


#37

Looks good i think. Try it for a week and see if you notice any difference.