ADS-B reception again

Its been some time since I played with receiving ADS-B signals from aircraft, but with the prospect of being able to track military flights in return for contributing data, I looked again at the 360radar website.

In order to contribute, you of course need to be able to receive, decode, and upload the ADS-B 'squitters'. The easiest way to do this for us was to make use of one of the RTL SDR dongles I have, plus Sams Raspberry Pi 2B single board computer

The 360radar website contains all the instructions needed to install the necessary software and get the system working, so between me and Sam we followed this and soon had decoded signals from a slack handful of aircraft using the dongles crappy stock magmount antenna stuck to the top of a Horlicks tin.

The next job then was to improve the antenna. I decided on  a simple 1/4 wave ground-plane design, but utilised twelve radials over the normal four, the resulting ground-plane at the frequency in question, 1.09GHz, being to RF all but solid. This antenna was built around a spare panel mount BNC socket

What was awkward was soldering the elements on! A 45W iron is not quite powerful enough for the job! It worked, but was hard to do. Ive ordered a 150W iron for any future heavy tasks like this!

With the new antenna just held close to vertical temporarily the resulting increase in received aircraft was astounding! from around 5-8 to 50-60!

However, since all this was rigged on Sams windowsill, it couldnt stay this way. So I had to create a stand to mount the antenna on, so that it can remain in use for some time, until we get the system compact and contained for mast-head mounting.

Theres nothing flash about this mount. Its literally a bit of PVC conduit, rammed into a hole in a block of wood, with a BNC to BNC patch lead in it!

And here it is with the antenna mounted and the receiver connected. It keeps it vertical, and more to the point tidy. The screenshot below shows a moment in the decoded aircraft signals using this antenna.

More work is required, for a start I need to let Sam have his R-Pi back!  So the software will need to be installed on another R-Pi that im arranging to obtain, and the whole thing - antenna, receiver and computer, mounted into a weatherproof radome for installing on the roof apex mast. I plan on running another length of external grade CAT5 cable for this, and making use of PoEt (Power over Ethernet), so I also have some PoEt adapters on order.

Ive received the amplifiers that I intend to use with the HB100 radar modules as well, so will need to fit that experiment in soon.


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