Software Defined Radio, Chapter 1: The Beginning (for me)
Sometime in 2003, my boss handed me a textbook about Software Defined Radio and told me I should learn about it. The company was SAMSys Technologies, an RFID industry pioneer. I had written the firmware for many of the company's products, but they always used hardware based radios. I was a hard working professional at the top of my game, but SDR didn't click for me. At the time it was too theoretical. Without something real to poke, I got lost real fast.
Another thing that happened at SAMSys was that a coworker made a sniffer for UHF RFID that allowed me to view the air interface on an o'scope (I vastly prefer the Agilent MSO with MegaZoom, which lets me capture an entire transaction and zoom in to each bit without recapturing). That tool was crazy valuable in my RFID reader development at SAMSys because it showed me both forward and reverse link traffic, and even let me see if a tag was responding. I've tried to duplicate it a few times, but never got very far with it. This is a typical effort:
Even with AC coupling, the signal wandered too much to support any kind of automated parsing.
Working in the RFID industry ever since, the subject of SDR has come up often enough. In 2017, I bought an RTL-SDR and made my first attempt to sniff UHF Gen2 traffic with Cubic SDR:
That's definitely RFID data in the top right Audio box. This 2017 thread at rtl-sdr.com put me onto GNU Radio to decode it:
https://www.rtl-sdr.com/forum/viewtopic.php?f=1&t=1862&sid=be28646ed918f03afca2356c5887723d#unread
Within a few days, I had a laptop set up for FC23 and GnuRadio loaded. Couldn't make it work quickly, even after following all the instructions. My day work took over for a while and the whole project sat until 2019...
Another thing that happened at SAMSys was that a coworker made a sniffer for UHF RFID that allowed me to view the air interface on an o'scope (I vastly prefer the Agilent MSO with MegaZoom, which lets me capture an entire transaction and zoom in to each bit without recapturing). That tool was crazy valuable in my RFID reader development at SAMSys because it showed me both forward and reverse link traffic, and even let me see if a tag was responding. I've tried to duplicate it a few times, but never got very far with it. This is a typical effort:
Working in the RFID industry ever since, the subject of SDR has come up often enough. In 2017, I bought an RTL-SDR and made my first attempt to sniff UHF Gen2 traffic with Cubic SDR:
That's definitely RFID data in the top right Audio box. This 2017 thread at rtl-sdr.com put me onto GNU Radio to decode it:
https://www.rtl-sdr.com/forum/viewtopic.php?f=1&t=1862&sid=be28646ed918f03afca2356c5887723d#unread
Within a few days, I had a laptop set up for FC23 and GnuRadio loaded. Couldn't make it work quickly, even after following all the instructions. My day work took over for a while and the whole project sat until 2019...
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