Note: This is an extended version of an article I wrote for the April 2012 issue of the Coastal Amateur Radio Society newsletter Groundwaves.
An ADS-B receiver is an excellent addition to the monitoring station of any aviation or military aviation scanning enthusiast but I really hadn’t considered purchasing one. At prices approaching or exceeding that of a good scanner, one really didn’t fit my budget. That changed recently when I was offered a used AirNav RadarBox for a bargain basement price. The decision to take up the offer wasn’t a difficult one and it soon became a part of my home station.
Many readers probably have two questions: What is ADS-B and what is a RadarBox? ADS-B, which stands for Automatic Dependent Surveillance-Broadcast, consists of signals from aircraft transmitted on 1090 MHz which includes aircraft identification data as well as altitude, heading, speed, and distance information which is used by the air traffic control system to help track flights. The RadarBox is a receiver for those transmissions; it is attached to a computer with a USB cable and uses software to decode the transmitted information. Currently, not all aircraft are equipped with ADS-B equipment but the FAA will require the majority of aircraft operating in the United States to have some sort of ADS-B capability by 2020. Many airliners are equipped with ADS-B equipment, but not all are transmitting position and heading information. As time goes on, more civilian and commercial flights will be transmitting position and heading information in addition to identification information. Many military aircraft are also ADS-B equipped, but they don’t transmit position and heading information for security reasons.
The Radar Box consists of the receiver, an antenna and supplied metal ground-plane disc, and software. The receiver connects to your computer via a USB cable (mini-USB connector on the receiver side). In addition to the data and control, the USB port also provides power to the receiver so there isn’t a wall wart or power supply to worry about. The antenna is normally placed as high as possible on the metal ground-plane disc (near a window if inside) but I found that the steel window frame by my radio desk works much better than the disc! The software is the key part of the whole thing as does the majority of the work.
What kind of range do you get out of the receiver? As with all things radio, it is dependent upon your antenna. In my case, the supplied mag-mount antenna is in a window facing south. I tend to get approximately 50-75 nautical miles to the south and 25-30 nautical miles to the north with 25-50 nautical miles to the east and west (see the range plot that the software can do below).
Naturally the range also depends upon the altitude at which the aircraft are flying; you’ll receive higher flying aircraft a longer range. Other antennas are available that can be mast mounted outside; these will provide much greater range, out to 100 nautical miles are more.
The AirNav RadarBox software takes the signals from the receiver and decodes the aircraft’s Mode-S identifier, aircraft type, registration/serial number, and callsign/flight ID. When position information is being transmitted, the software also decodes the latitude/longitude and altitude and plots the aircraft on a map and graphical display.
The screen shot above shows what you see on the software display. On the left side of the screen is a listing of aircraft being received including the time received, time of the last track changed (if tracking info is being received), the status (cruise, descend, climb, etc.), the Mode-S identifier, a flag showing nationality of the aircraft, registration/serial number, and aircraft type. On the bottom left of the screen, it will show airline name, and more detail aircraft information; if connected to the internet, it will also display a photograph of the aircraft if available. On the right side is the radar map display, each block of text is an aircraft whose position in being plotted and tracked with ADS-B information (if position information isn’t being transmitted by the aircraft it won’t display on the map).
So, of what use is the ADS-B receiver to the scanning and aviation enthusiast? For the aviation enthusiast, you can watch the flights that are transmitting position and heading information fly by on the map screen. You can see routing information and follow their track along the map as well as on a vertical display that shows their altitude. For plane spotters, it allows for easy identification of an aircraft by registration or serial number without being able to actually see the aircraft. For the scanning enthusiast, ADS-B also helps identify aircraft that you’re hearing on conventional voice radio. It isn’t unusual to hear an aircraft that you can’t identify by callsign. You can correlate what you’re hearing on the scanner to what you’re seeing on the RadarBox display and ID the flights. The software also keeps a history of what you’ve heard, so you can easily go box and research what you’ve heard. You do have to keep the GIGO factor (Garbage In, Garbage Out) in mind, though. Callsigns aren’t always programmed in and sometimes an old callsign might not be changed for a new flight.
Here is a list of what I received on the RadarBox on 19 March 2012. The ones in bold type are aircraft that showed up on the RadarBox and were heard on the scanners. In the case of an aircraft like LL 428, the ADS-B log helped identify the aircraft as one of the Navy’s new P-8A Poseidons; that aircraft just happens to be the first P-8A assigned to the Navy’s P-3 training unit at NAS Jacksonville, VP-30.
- 7386C5 – 4X-WSM, Israel Aircraft Industries, G280 (GULFTEST 280 out of KSAV)
- A4EA6F – N416AE, Bell 206, AirEvac (Brunswick)
- AB04F3 – N809SY, 737, SCX8900 (landing at Hunter AAF)
- ADFD7B – C-26D, 91-0511, MA ARNG (PAT 728)
- ADFEEF – C-9B, 160051, VR-52 (JT0384 on Box)
- AE025B – C-20D, 163692, VR-1 (VV102 on Box)
- AE038A – KC-135R, 62-3531, 121 ARW (SLUFF 41 on Box)
- AE049B – KC-135R, 61-0313, 916 ARW (BACKY 13)
- AE04AC – UC-35B, 99-0103, B/2-228 AVN
- AE04DA – C-40A, 165832,VR-58 (CONVOY 4927)
- AE053E – C-5M, 69-0024, 436 AW
- AE05FF – C-130H, 80-0320, 165 AW (DAWG 40)
- AE0603 – C-130H, 80-0324, 165 AW (REACH 140 on Box but using callsign DAWG 05)
- AE0606 – C-130H, 80-0332, 165 AW (DAWG 08 on Box)
- AE066A – KC-135R, 62-3549, 6 AMW (BLUE 83 on Box)
- AE06E4 – UC-12F (FOX 738?)
- AE07B7 – KC-135, 62-3528, 916 ARW (BACKY 14)
- AE10DF – RC-12X, 92-13120, 224 MI Bn (SUNNY 70)
- AE10E5 – RC-12P, 93-0700, 224 MI Bn (showed SUNNY 84, but c/s was SUNNY 39)
- AE1202 – RC-12N, 89-0270, 224 MI Bn (SUNNY 06)
- AE1238 – C-17A, 03-3127, 6 AS
- AE4EB2 – P-8A, 168428, VP-30, LL 428
Of particular interest to military aviation enthusiasts and MilAir monitors will be the Live Mode-S website. It provides a searchable database for Mode-S identifiers. The database is fed by the monitoring community. You can download a program that feeds the website’s database with what your ADS-B receiver is hearing. The website is an outstanding source of info and research tool for the MilAir hobbyist. Most of the time, even when I’m in Brunswick, I leave my RadarBox going to feed the database.
The RadarBox wasn’t a planned acquisition but it has been a good one. It is a tool that has benefited not only me as an individual but it helps the monitoring and spotter community at large through the online database and AirNav network. If you’re thinking about getting an ADS-B receiver, I strongly urge you to consider feeding the Live Mode-S database.