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mhostetter / gr-adsb

GNU Radio OOT module for demodulating and decoding ADS-B packets
GNU General Public License v3.0
145 stars 44 forks source link

Static filename #2

Closed theforcedk closed 8 years ago

theforcedk commented 8 years ago

You're writing to a specific filename in:

./python/decoder.py:        self.fp_csv = open("/home/matt/adsb.csv", "a")

Make it configurable :)

mhostetter commented 8 years ago

Yes, definitely!

theforcedk commented 8 years ago

@mhostetter Is it worth adding a low pass/fir filter, or is it better to just grab all the signal and try and process it?

mhostetter commented 8 years ago

You're right. That would probably be beneficial because it would kill the out-of-band noise. I'm trying to write the code so it will support arbitrary sampling rates. I'm using a HackRF, so I'd like to support 2, 4, 8, 10, 16, 20 Msps (if the CPU can handle it!). So for the higher sampling rates, an FIR LPF would be beneficial I think. The question is what bandwidth filter. I don't want to filter the signal at all. I think the filter would need to be at least 2 MHz wide, but maybe slightly more. I'll play around with adding that! I'm sure the performance will improve.

mhostetter commented 8 years ago

What I'd really like to do is configure the HackRF in the osmocom source to reduce the ADC filter bandwidth. So I'm sampling at 4 Msps but I'd set the ADC anti-alias filter to ~2 MHz. That's a "free" filter that accomplishes the same goal. I don't think gr-osmosdr supports this though. Might have to add it!

theforcedk commented 8 years ago

@mhostetter That's actually a really nice idea, using ADC directly on the HackRF. It should be a bit faster than doing it in software (gnuradio), altho it's also doing it in software on the HackRF, but it should be faster as it's not hammering the USB with unnecessary traffic.

I'll play around with that too :)

I have very limited reception on 1090MHz with my Diamond SRH789, but I do get some traffic. Might need a new antenna (http://www.wa5vjb.com/)

Left = HackRF Right = RTL dongle

Look at "Messages" column.

screen shot 2016-04-13 at 13 29 39
mhostetter commented 8 years ago

Ok, that's cool. I'll have to play with it. I know about dump1090, but I thought it would be fun to write my own decoder.

I found the antenna to be very important. I have this one, but it appears to be out of stock. It has positive gain (in dBi) at 1090 MHz. http://www.amazon.com/dp/B00WZL6WPO?tag=fligh01-20

mhostetter commented 8 years ago

I added code to enable/disable CSV logging and configure the file name from the GNU Radio Companion GUI.