Categories
ADS-B SDR

Receiving aircraft ADS-B (position) signals

If you came from the SDR (software defined radio) introduction post, you already have an idea of what these devices can do. If you came from somewhere else and want a brief introduction, head on over to SDRs (or how I pull radio signals out of the air).

The SDR topic that provides me the most entertainment is picking up aircraft ADS-B (Automatic Dependent Surveillance-Broadcast) position signals. As of 2020, all civilian aircraft in the United States are required to transmit their position continuously. I am not sure of the specifics but they are transmitted at least once per second, sometimes more with different messages. The idea is if every aircraft has both a ADS-B transmitter and receiver, there will be less crashes because the position of every nearby aircraft is known. There is also a Federal Aviation Administration (FAA) component where they will be able to better direct aircraft in the national airspace.

What this means for those of us here on the ground is we can be constantly receiving position data from planes flying in the air above us, or taxiing around airports around us.

Below is a screenshot of what the Denver airspace looks like during a typical Tuesday evening:

aircraft positions around enver
ADS-B positions on a Tuesday evening

There are 33 aircraft with data being received by my stations in the above screenshot, of which 25 are showing a location. Green colors are low altitude, blues are medium, and purple is high altitude. The farthest plane away from my house (station) is 100.9 nautical miles away, or 115 “normal” miles away. The highest altitude is actually being shared by two planes: N499RK and ICAO identifier A66618, both of which are business jets, at 45,000 ft. The lowest plane is N735CF at 6,700 ft, which is a training aircraft doing pattern work (repeated take offs and landings) at KBJC.

It is pretty straight-forward to get this data, assuming you have the right equipment. Most people get started with a Raspberry Pi. If you already have one, great! It is super easy to flash the SD card with Piaware, plug in your SDR, attach the antenna and start watching the positions stream in.

If you don’t have a Raspberry Pi, they’re pretty reasonably priced. The Raspberry Pi 4 is the newest version. Any size memory will work. Raspberry Pi 3 will also work! If you want some information on getting started with a Raspberry Pi, check out my Getting Started with a Raspberry Pi YouTube video.

The most basic setup will run you about $110 to get started. This includes a Raspberry Pi 3B+ starter kit (with SD card and everything needed to run the Pi) as well as a RTL-SDR with a basic antenna. You can check the current prices here on Amazon:

CanaKit Raspberry Pi 3 B+ Starter Kit (32 GB EVO+ Edition)

Nooelec NESDR Mini USB RTL-SDR RTL2832U & R820T Tuner for ADS-B

These are the exact items I used to get started and they’re still up and running. I repurposed the Nooelec SDR for around the house stuff because I got a different SDR for ADS-B reception. As I was testing these links, Amazon kindly reminded me how long ago I got into this hobby – more than five years ago!

nooelec RTL-SDR purchased from Amazon in 2016
nooelec RTL-SDR purchased from Amazon in 2016

This post got long quick so I’ll stop here for now. The two links are enough for everything you need to get started. I’ll continue with a part two for how to set everything up, as well as upgrades to increase reception.

Continued at Receiving aircraft ADS-B (position) signals – part 2!

Austin’s Nerdy Things is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com.

Categories
SDR

SDRs (or how I pull radio signals out of the air)

I figured I’ll be posting things based on how frequently I used them, at least to start. Eventually, I’d like to post based on your requests! Out of all the topics listed in the Introduction post, I use (or at least have various systems & automations using) SDRs to pull data out of radio signals the most frequently. In fact, most of what I have set up runs 24×7.

First off – what is a SDR? SDR stands for software defined radio. It means you can plug in one of these USB-based devices into your computer, and instantly be able to pull radio signals out of the air. Previously, like from whenever radio became a thing, until recently, radios were analog devices made up of resistors, transistors, and other things like that. They were bought tuned to a specific frequency and further, only listening to a certain type of signal on that specific frequency.

Software defined radio (SDR) changes all of that. It can be tuned to a wide range of frequencies and just passes along the data it gets to whatever program you use to decode the signals. Luckily for us, there are many open-source programs written by very smart people that already decode these signals!

This is the broad post for SDRs. I’ll write more posts for what I’m doing with the specifics. You may also see them called RTL-SDRs. RTL is the shortened name of the chipset (RealTek). There are other, more expensive SDRs not based on RealTek chipsets that can work better in some situations. For me, the $15-25 RTL SDRs do great. RTL-SDRs were originally intended to receive over-the-air TV signals. I’m sure they do fine with that but I’ve never tried to utilize them for their intended use.

Here are some of the things I’m doing with SDRs:

  1. ADS-B aircraft signal reception. As of the beginning of 2020, all civilian aircraft within US airspace must constantly broadcast their position. With a decently positioned antenna, these signals can be received up to 250 miles away from the aircraft! Link to part one of ADS-B reception.
  2. AMR – automated meter reading. Where I live, the electric and gas utility has meters installed at my house that broadcast their usage at least once a minute. I can receive these signals from my (and my neighbors!) meters and plot them to determine electricity/natural gas usage.
  3. Temperature sensor reading. You know those basic temperature sensor kits that most dads have sitting near the kitchen sink? The ones with a screen showing temperature/humidity inside and outside? Those are very easily decoded. I have one hanging outside and a few others around the house. They can also be placed in the freezer for advanced warning if a freezer goes out!

Some other thing I’m not currently doing but have thought about:

  1. Satellite reception for weather satellites (US GOES, Russian Meteor M2, and others). They transmit when overhead for the non-geosynchronous satellites and all the time for the geosynchronous satellites. The antenna required is quite a bit bigger than the around-the-house SDR stuff but still perfectly reasonable.
  2. General amateur radio reception
  3. Police radio scanning
  4. Aviation frequency reception

This post will be much better with pictures! I’ll add them soon.

Categories
Blog Admin

Introduction / Table of Contents

The most recent post is the next post down!

I intend to use this site to document my journey down the path of nerdiness (past, present, and future). I’ve been learning over the years from various sites like what I hope this one becomes, and want to give back. I have a wide variety of topics I’d like to cover. At a minimum, posting about my activities will help me document what I learned to refer back in the future. I’ll also post about projects we do ourselves around the house instead of hiring professionals, saving big $$$$ in the process. Hope you enjoy the journey with me!

Below are some topic I plan on covering (I’ve already done something with every one of these and plan on documenting it):

  1. RTL-SDRs (receiving signals from your electric meter, ADS-B, general radio stuff)
  2. Virtual machines and my homelab setup
  3. Home automation / smart home (Home Assistant, Tasmota, Phillips Hue bulbs, automating various tasks throughout the house)
  4. My mini solar setup (2x300W panels) and not-so-mini battery backup (8x272Ah LiFePO4 batteries – should yield 7ish kWh of storage)
  5. Remote control aircraft running Arduplane with video downlink and two-way telemetry
  6. General computer stuff (building them, what I use mine for, Hyper-V)
  7. Home network (Ubiquiti setup, VLANs, wiring the house with CAT6, IP security cameras on Blue Iris)
  8. Formation of my LLC if anyone wants to hear about that
  9. The wheel options trading strategy
  10. Cryptocurrency (mining focus)
  11. SCADA (my day job)
  12. 3D printing
  13. Engine tuning (for my old WRX and new F-150)
  14. All the cool things you can do with a Raspberry pi and other SBCs
  15. Arduino/ESP32/ESP8266 automation devices
  16. My electric bikes
  17. Microsecond accurate Raspberry Pi NTP appliance using GPS pulse per second (PPS) timing signals
  18. DIY multi-zone sprinkler system install
  19. Drone survey of property
  20. Securing this WordPress site from hackers (Fail2Ban at both WordPress and system service level)
  21. Backing up WordPress sites
  22. General Linux tips/tricks
  23. VPNs (openvpn and wireguard)