Rebuilding and raising my ADS-B receiver

Earlier this year I replaced my Hexbeam (with another Hexbeam) and I wrote about it on this site. There was a gap of a couple of weeks when I was between aerials and to take advantage of that, I temporarily moved my ADS-B receiver to a temporary stub mast, effectively raising it 7ft from the original height.

Although this was only a small increase in height, the difference in performance was very noticeable and it germinated a seed that I’d planted in my head some months earlier. I’d been trying to work out if I would benefit from mounting my ADS-B aerial on top of the Hexbeam and even whether it would be possible or not.

Clearly the answer to the first part this was a huge “yes” but the next part was whether I could attach the aerial to the Hexbeam. I contacted the aerial manufacturer who suggested I could fix the 40m centre support pole to the Hexbeam and mount the ADS-B aerial on that.

You’ll remember that when I replaced my Hexbeam, the one I put up included the 40m element so after changing the aerial, I could see what I’d need to do regarding the ADS-B receiver.

For the last few years, I’ve been using a FlightAware 26″ 1090 MHz aerial and I’ve been very satisfied with it. I wanted to buy a new one and started looking around. Unfortunately there were none available in Europe whatsoever and all the suppliers I contacted in the USA either weren’t prepared to ship to the UK or wanted ridiculously high carriage. I contacted FlightAware direct and explained my situation. They were happy to ship me an aerial which sadly got lost by the courier and so they arranged for their European partner, Jetvision to send me an aerial. That arrived in early October while I was on holiday in the Channel Islands.

I also ordered 10m of Messi & Paoloni coax. After poring through the specifications, I decided to go with Hyperflex 10 as I figured it would give me an acceptable level of loss and be suitably flexible to go around the rotator. Incredibly, this was also lost by the courier (a different one) and a second shipment was arranged which arrived within a day of the aerial, while I was on holiday.

I’d also decided to rebuild the entire receiver system in the box as well. I was going from a Raspberry Pi 3B+ to the newer Pi4 and wanted to replace the slightly bodged power arrangements I’d used previously with an official Raspberry Pi PoE HAT.

With everything ready to go, all I had to do was wait for the weather to be decent enough. I needed a combination of a few days without rain and then not too cold with no wind. This took longer than expected and it wasn’t until the 24th November that I was able to lower the mast and do all the work.

I fitted the new aerial to the top of my Hexbeam and routed the coax down to the receiver box. I then stripped everything out of the box and rebuilt the receiver with the Pi4 and new PoE system. I cut the coax to length, installed the N-Type connector and fitted everything back together before raising the mast back up. The whole process took around three hours.

Because my new Hexbeam is taller than the old one, my ADS-B aerial is even higher than I’d hoped for. It’s now 11ft higher than it was and so is 44ft (13.4 metres) above the ground which is quite a substantial increase. However I’ve introduced some loss into the system which didn’t exist before due to the coax run. I’ve calculated this to be around 0.7dB which I consider to be acceptable.

A few days after I did this work, I went out for my morning walk and it was a typical autumn morning. Very chilly and bright, with a beautiful, cloudless, clear blue sky so I just had to take a picture. You can clearly see the Jetvision aerial on top of the Hexbeam and the box the equipment is all mounted in on the side of the mast. If you look closely, you can also see an aircraft in the background, although you might need to click the picture to zoom in.

Hexbeam with ADS-B aerial

In practical terms, it’s relatively easy to work out how much difference this upgrade has made. Taking into account the raised aerial and the change from the Pi3 to the Pi4, I’m seeing approximately 50% more messages per day, an increase of around 20% in the number of aircraft per day and I can see from the coverage graph on the FlightAware statistics page that I’m now receiving signals from aircraft out to 250+ miles in all directions. At time of writing, my message rate/second peaked at just over 2,900 on the 11th December.

I’ve done extensive testing while transmitting on all bands with high power through the Hexbeam and the RF doesn’t affect my ADS-B receiver at all.

You can see the live feed from this receiver and the two others I am responsible for on this page which also contains other links such as graphs, statistics and daily heatmaps.

I feed my data to a number of providers and also to Essex Radar which is my own consolidated Virtual Radar Server.

For completeness, here’s a list of every piece of equipment used in my installation from top to bottom:

Jetvision aerial
5.5m of Messi & Paoloni Hyperflex 10 coaxial cable
N-type female to SMA pigtail
RTL-SDR-LNA
Bias-Tee injector
SMA to SMA pigtail
Airspy Mini
Raspberry Pi 4 Model B (2Gb RAM)
Raspberry Pi PoE HAT
30m CAT 6 cable
TP-Link TL-PoE150S PoE injector

4 Comments

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  1. Hi, just been reading your post and viewing your live page, amazing stats! I’m not silly far from you and you are getitng over 100 more aircraft than me. I use a rasp pi 3, a flight aware pro plus dongle and a 5db gain antenna, do you think it’s just height that’s making such a difference, my antenna is conected to the dongle using around 3 metres of high performance coax and should be doing better. I’m in a remote location with no close neighbours but the ant is only attached to the house gable end which is approx 43 metres above sea level.

    Regards
    Richard

    link to my pi aware live
    http://81.133.74.90:444/dump1090-fa/

    1. Hi Richard,
      Thanks for the comment and the link to your Piaware live.
      There will be a number of factors and height is certainly one of them but it’s not just that. I’m in a very good location for receiving traffic as the CLN beacon is close by and that’s part of an airway in and out of the UK so I see all the traffic from there. I’m also well located for traffic in north west Europe that may be just beyond your reach. I’m also running a better receiver with an external LNA and a Pi4 which means I can run at a higher sample rate. I do have a very clear takeoff in all directions.
      It’s not just one thing, it’s a combination of all of the above really.
      73 Keith.

      1. Hi Keith and many thanks for the reply, I’m interested in changing the receiver and may upgrade to the one you’re using. I’m using a pi 3 and I have a friend who’s just installed a pi 4, do you think there will be a big improvement if he’s uses the software that will allow a higher sample rate? If so, I’ll upgrade to the 4 also.

        Regards
        Richard

        1. Hi Richard,
          I honestly can’t comment on what sort of improvement you’re likely to get. I’m not trying to avoid the question but without any knowledge of your location, your takeoff in all directions etc then it’s simply impossible to say.
          What I can say is that if you upgrade to a Pi 4, an AirSpy Mini and the external LNA I list in this post then you should see an increase in messages at the very least. Whether you’ll see an increase in range, I just can’t say. It’s worth having a look at this thread on the FlightAware forums to see what your theoretical maximum range is and then you’ll know what’s possible.
          Sorry if I’m coming across as non committal.
          73 Keith.

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