PreTalen SDR Challenge

Joshua DeWeese

Feb 28 2020

Goals

  • Show how I approach problems/tasks
    • Research
    • Plan
    • Execute
    • Iterate

Research

  • No HW yet
  • What is an SDR?
  • What is GNU Radio?
  • What is GRC?
  • What is my game plan?

Game Plan

  • Explore GNU Radio
  • HW bring-up
  • HW + GNU Radio (hello world)
  • Decode something
  • Make presentation

Explore GNU Radio

  • Check repos: "apt search gnu radio"
  • Install: "sudo apt install gnuradio"
  • Run through some simulation tutorials

HW bring-up

rtl_fm -f 99.1M -M fm -s 170k -A fast -l 0 -E deemp | \
play -r 170k -t raw -e s -b 16 -c 1 -V1 -

HW + GNU Radio

YN560

  • 2.4HGz FSK - Nope!

APRS

  • 144.390MHz - Yes....
  • Gqrx - nada
  • Baofeng - no problem
  • Antenna?
  • Miss-information?
    • 24MHz - 1850MHz
    • 87.5MHz - 108 MHZ ?!
    • 25MHz - 1700MHz ?!?!
  • Confirmation: 147.045MHz (W8DGN) static!!!!

RDS

Lamp remote

Learned

  • Modulation AM, FM, FSK, ASK
  • IF
  • GRC, GNU Radio, Gqrx
  • Some reverse engineering
  • Little smarter each attempt
  • Easy to get discouraged
    • Experience has taught me this usually precedes the breakthrough

Going Forward

  • Grok it!
  • Better antenna
  • Better placement (remote control via Beaglebone)
  • Local repeater activity tracker?
  • Spy water, gas, electric meter?
  • Garage door remote extra buttons?

Code Samples

Demo

Questions