ADS-B Tracking Aircraft at Home (Part 1)

With an interest radio and also in aircraft I soon found out that it was possible to receive the ADS-B signals from the aircraft and to plot them on a map.

Equipment

Getting started in ADS-B reception is very simple. All you need is a simple RTL Dongle and an antenna.

The RTL dongle can be very cheap and are usually designed as a TV receiver for your laptop or PC. SO long as they have the correct chip inside they can be used. This is an example of the TV Style Dongle. It is this sort of dongle that I used when I first started.

The dongle I use currently is one that has been designed to be used as an SDR receiver and is produced by RTL-SDR.com.

The second thing you need is something to decode the signals. I started of with using an old windows PC but have now switched to using a Raspberry Pi. This is used to run software called DUMP1090 to decode the ADS-B signal. This is available on MalcomRobbs Github.

The Setup

With the TV style dongles they usually come supplied with a small antenna. This antenna is obviously designed for receiving TV signals so needs to be cut down to about 68mm. This should then be mounted on top of something metal to act as a ground plane. An old tin can is a common option.

Stock ADS-B Antenna Splat

This is a splat of my first setup. This was a terrible setup but got me started. This was with the stock, untrimmed, antenna supplied with the dongle. about 10m of standard TV coax with multiple joints and an old windows 7 tower PC running 24/7. So not only was I using an untuned antenna and a very lossy coax run. But the PC running was very noisy and power hungry.

The first changes I made was to trim the stock antenna to 68mm. There are multiple pages and slightly different lengths quoted online but these are the instructions I followed.

Stock ADS-B antenna trimmed to 68mm Splat

As you can see this made a noticeable improvement to the received aircraft.

Soon after I upgraded the software running on the PC to the DUMP1090-mutability 0.15dev version. This was difficult to find for windows but I eventually found a copy. I will try and find this and either link to it of host it here.

Trimmed ADS-B Antenna & Upgraded to DUMP1090-Mutability Splat

Big change….

It was at this point I moved house, completed the build of a home built collinear from designs found online and upgraded to a Rpi.

The home built collinear was built using 8 segments inside of some PVC tube and then mounted in the loft of the house.

New House, ADS-B Collinear Antenna and moved to RPi Splat

As you can see this gave a boost in coverage over the trimmed stock antenna but the nulls north and south are due to the brickwork blocking the signal.

Since the increase in signal put more load on the RPi. During the summer months when the loft got rather warm, the temperature of the RPi got a bit higher then I wanted to a so invested in a heat sync and fan.

Added heat sync to RPi Graph

Here you can see the point at which I stuck the heat sync on and plugged the fan in.

A few months later the weather was finally good enough to get the mast mounted up onto the roof. the bast place I could find was to clamp it to the existing TV pole and then drill a hole through the wall back into the loft.

This created the best Improvement along with adding a filter and pre-amp.

ADS-B Antenna Mounted outside Splat

It was not until recently (early 2019) that i finally had an analyser that would tell me if the home built was anywhere near on frequency. I was very surprised to find I wasn’t that far off.

Graph showing VSWR curve of home built ADS-B antenna.

There must of been one or 2 segments slightly off as there was a couple more slight dips higher and lower down. But overall it was close enough.

Contributing data

The data i receive i also send out to other sites such as FR24. The main site I contribute to though is 360radar.co.uk (previously lowflyingwales.co.uk)

This page Provides an excelent setup guide for both Windows and RPi. the associated facebook group is also full of knowledge and help.

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