Monday, September 1, 2014

Software Defined Radio

I figured I'd spend more time reverse engineering and trying to build a custom SPI boot image, but then I came across the Quark SoC X1000 Board Support Package Build Guide which basically documents exactly what I was trying to do.  Good news is that the firmware update image (document calls it the capsule file) format was pretty much what I had found.  Well, next time, I'll try to RTFM harder. :-)

Lately, I've been tinkering with Software Defined Radio (SDR) based on Realtek RTL2832u part.  The chip seems to have an interesting backstory - originally designed for digital TV, someone found a debug raw output mode and reverse engineered it to make it a very low cost SDR platform.  I bought mine from Amazon for less than 9 dollars including shipping though it did take a while to get here from China.

Galileo board (with standoffs!) and the RTL2832u USB Stick
So far, I've been messing with individual tools from the rtl-sdr package and feeding airplane ADS-B data to FlightRadar24.  Airplanes equipped with the proper transponders will broadcast various data including the altitude, heading, ground speed, and GPS coordinates on 1090MHz.  It's been interesting to see the data captured by the radio as I see the planes fly by to land at SFO.

My short term goal is to get the ADS-B feed fully running on the Galileo - the rtl-sdr package relies on libusb package, so there shouldn't be any Linux kernel modules or changes required.  Ideally, I'd be able to basically take the 386 binary and run it on the Galileo, but we'll see how that works out. :-)  It also seems like the antenna that ships with the module is pretty crappy, so that'll eventually have to be resolved somehow.  Tuning to a local radio stations gives mostly muffled sound, though that might also be because I'm messing something up in the software.

RF and radios are something that I have very little experience with, and it's pretty exciting to jump into a field where everything is new and amazing!

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