Essex Radar

I’ve been running an instance of Virtual Radar Server (VRS) for some time and recently decided that this is something I can easily share to anyone who is interested.

What is VRS though?

VRS is a server running on my network that can take a feed from multiple ADS-B receivers, consolidate them together and provide a decent graphical interface showing all the aircraft tracked. Unlike most of the commercial services, this is unfiltered and real-time. Of course, it only shows aircraft that I’m actually receiving signals from but I do have a pretty decent setup here so the coverage is good.

Essex Radar

A project like this needed its own website and so Essex Radar was born at http://essexradar.co.uk.

I have two receivers feeding aircraft to Essex Radar – One is in my loft and is using a Raspberry Pi 3 Model B, a FlightAware Pro Stick Plus SDR dongle and a homebrew two element J-Pole collinear. The second is outside on top of my mast and is a Pi 3 Model B+, an Airspy Mini SDR dongle, LNA and FlightAware 26″ aerial.

Essex Radar was used to create this 24 hour timelapse video of Boeing 747s.

Monitoring aircraft is something I find quite fascinating and it combines two of my interests, radio and aviation and is something you can do quite cheaply. Although I’ve briefly described my two receivers above, I’d like to give a few more details and options as to what you need.

Be aware, this is going to contain a lot of links to various products.

No matter what you choose to do, you’ll need to start with a single board computer and in my opinion the best one to use will be a Raspberry Pi. There are others on the market but the Pi is the simplest to get hold of and appears to have the best support.

At time of writing, the current Pi is the Raspberry Pi 3 Model B+ and if you don’t own a Pi, this is the version I recommend you buy. If you already have a Pi then it will almost certainly work as an ADS-B receiver although I’m not sure I’d want to use anything older than a 2B. There are many different suppliers and they’re all around the same price.

You’ll need a power supply for your Pi. This must be a good, stable PSU capable of at least a couple of amps at 5 volts. My recommendation is the official Raspberry Pi Universal Power Supply but another option is to run a less stable PSU at higher voltage and drop it down using an LM2596 DC-DC converter. I know from bitter experience that some power sources are particularly bad. My ADS-B receiver which is mounted on top of my mast was originally running from PoE but continually gave me under voltage warnings. To resolve this, I switched the output from my PoE device to 9 volts and used an LM2596 converter to drop it to 5 volts. I no longer have any power problems.

The other essential item is a memory card. Not all SD cards are built equally and some are significantly slower than others. I’ve had great success with SanDisk Ultra 16 GB MicroSDHC UHS-I cards and use them in all my Pis.

A Pi, PSU and memory card will cost around £40-£45 depending on where you buy them from. I’m not going to recommend anywhere specific for these three items because prices change regularly so just shop around for the best deal.

The next thing you need is a receiver. If you want to do this the cheapest way possible then you can get an RTL SDR dongle from eBay for less than a tenner and it will work but it won’t be very good.

There are other receivers available that cost a little more but in my opinion, the one that will give you the best value for money is the FlightAware Pro Stick Plus. This dongle comes with a built in amplifier (LNA) and 1090MHz filter and is what I’m currently using for the receiver located in my loft. It’s available from various UK suppliers for around £30, works really well and is perfectly good for most people.

If you want more performance then you’re starting to get a bit more expensive and the law of diminishing returns comes into effect. The next step up is to buy a separate receiver and amplifier. If you want to do this then my recommendation is the RTL-SDR V3 dongle and the RTL-SDR 1090MHz LNA at $21.95 and $26.95 respectively and available from the RTL-SDR shop. These will take a couple of weeks to be delivered to the UK and you’ll also need to buy a bias-tee module as well which will add another tenner or so to the cost and further complicate the build.

I think that the next upgrade from this setup would be to replace the receiver with an Airspy Mini SDR dongle but at around £120, that’s not going to appeal to many people. If you really want to squeeze the maximum performance then you should consider a Mode-S Beast receiver but that’s getting extravagant as one of those will cost you around €240 in kit form.

Next, you’ll need an aerial. There have been many aerial designs posted on the internet and I’m not going to link to all of them but I do suggest looking at this thread on the FlightAware forums for some simple and easy to build antennas. The first aerial I built was the spider which is effectively a quarter wave groundplane and you can see a picture of it here. It works but it doesn’t work as well as the next aerial I built which is a two element J-Pole collinear. That collinear is still in use on my receiver in the loft. It’s a superb aerial and it works far better than I ever expected. It was easy to build and as I already had the wire and the connector, it didn’t cost me a penny.

If you would rather buy a cheap aerial then look for an ADS-B PCB aerial but be warned, it may arrive unsoldered and you’ll have to fix it yourself.

If you want a good solid weatherproof aerial to use outside, then I have experience of two different types. Search eBay for COL1090/5-H and you’ll find the same aerial we use for the receiver at the Martello Tower Group site. This isn’t always available but when it’s there, it’s a good buy at around £30 including shipping. These aerials are all built by hand so be aware that performance between them may vary slightly (I know this from experience).

A little more expensive at around £54 but of more consistent quality is the FlightAware 26″ aerial. I use one of these on my receiver here and I can’t fault it. The build quality is very good and mine has been mounted outside at 10m AGL in all weather conditions for nearly two years with no noticeable problems. Apart from being a bit faded, it’s just as good as when it was new.

I will mention one more commercial aerial but I have no experience of using it and can only go by the reports I’ve read. The ADS-B Vertical Outdoor Base Antenna is $149 from DPD Productions and is very highly rated.

Finally – Coax. Buy the best you can afford and use as short a run as possible. Cheap cable is very lossy and this is one area where you mustn’t cut corners. For example, 10m of RG58 will give you around 5.5dB loss, 10m of RG213 will give you roughly 2.8dB loss and 10m of Messi & Paoloni HyperFlex 10 has around 1.4dB loss. Don’t skimp on your coaxial cable.

Once you’ve collected all your hardware, you’ll need to set up the software. That’s pretty straightforward as there are a number of pre-built images available which do all the hard work for you so I’m not going to go into long winded instructions.
I suggest using the FlightAware image and full details can be found here. Because I’ve already gone through the hardware, you just need to jump forward to the second section “Install PiAware on your SD card”. You should be able to set the software up from start to finish in about half an hour. The guide linked above covers absolutely everything.

I appreciate that there’s a lot to take in here and I congratulate you if you’ve read this far! If you have an interest in radio and aviation then setting up your own aircraft tracker is neither difficult or expensive and it’s really fun to be able to see aircraft in the sky near you. If you do decide to do this and would like to be included as part of Essex Radar then please contact me.

The day after I put Essex Radar online was the day of the historic D-Day Flypast where a number of DC-3 aircraft flew from Duxford, over Colchester and Southend on their way to Normandy. Essex Ham were monitoring the flight and they used Essex Radar to track it. You can read more about this and see a video including Essex Radar here. I’m very pleased to have been able to provide this service.

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