JKCTech

My Radar Box Setup

Published 3 months ago13-07-2022 - 09:17

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As a person who is interested in radio signals and capturing data I technically should not be tuning in to, it was time for me to build a "proper" setup for capturing data from the air.

How It Works

Using a Raspberry Pi 3, some RTL-SDR USB dongles, (custom) software and some sysadmin skills, we are able to build a relatively simple computer that can receive, decode and process incoming data in a way we can visualize it.

For now, I will be focusing on these 3 subjects:

Frequency Protocol Description
169.65 Mhz FLEX Dutch Emergency Services paging network. (P2000)
172.45 Mhz POCSAG 1200 KPN Nationaal 3 - Only commerical paging network in The Netherlands.
1090 Mhz ADS-B Aviation tracking signals.

Preparations

I want this project to have a somewhat professional look so I gathered the best electrical box I could find in my pile of junk and decided to design the project around it.

Inside the box I will be using DIN rail which gives me a lot of freedom and mounting options.

I considered buying a DIN power-supply for the Raspberry but I figured that could give me more struggles than benifits so I replaced it by a DIN socket and it's usual powerbrick.

Of the 3 SDR devices, 2 will be used for paging signals. These signals are designed to penetrate walls and objects to prevent pagers from missing messages on day-to-day use. Because of this, the cheap and very basic antennas that come with the SDR devices will suffice.

For the flightdata however, this is another story. ADS-B signals are not made to penetrate obstacles and thus requires a direct line of sight between the sender and receiver. Because of this issue, my setup will be built on my balcony and have an antenna pole poke out above my rooftop. I decided to buy an SDR that is made specifically for ADS-B signals and has a filter built in.

Down here I drew a quick sketch to plan the layout and how to mount things inside the box.

Nice, we have a plan!

After an afternoon of online-shopping I ordered everything required to provide power on my balcony and mount everything in a semi professional way.

After waiting for waaaaay to long for my shipment to arrive (Thanks UPS...) I started putting everything together for a test fit.

Here you see the box containing the Raspberry Pi + SDR devices, a seperate box for the paging antennas and a pile of other junk to mount everything to the wall.

The Build

Now we are ready to start mounting everything on my balconay and see if we planned correctly...

In all fairness, I am a certified electrician who definetely knows the rules but I am also on a budget. Some of the decisions I made during this project are, to put it lightly, questionable... But since the balcony is hardly ever used and the box will be mounted out of sight behind the fence, I decided to throw some rules and regulations out of the window and make my life a little easier.

After mounting a double outlet and connecting it to my inside electricals I mounted the box directly below the outlet so I could connect it by just a cable and a plug. I specifically picked this over directly wiring the box directly to the socket so the box can be removed for maintenance without too much hassle. (You never know)

Next up is the smaller antenna box. This will house 2 SDR antennas and a WiFi antenna which is not yet connected, but might be used for later projects.

Now one of the most important this of this project: The ADS-B antenna.

Don't ask me how, but I happened to have a 4 meter long 32mm aluminium pipe laying around in my yard which was literally perfect for this purpose. Using some giant hose clamps I, once again, had laying around I strapped the pole to the fence and secured the antenna cable to the pole with some zip-ties every 30 centimeters or so.

I am very aware the antenna cable is too long and not the best of quality for this purpose but I got it with the antenna so to lower the cost for now I kept it. The cable is planned to be replaced by a custom length high quality cable once I feel the need for it.

The First Tests

By using the Rapsbery Pi Disk Imager I created a boot SD with my WiFi settings and more pre-configured, so as soon as the power got connected, the Raspberry came alive.

With the Juice SSH app for Android (Highly recommended) I connected to the RPI and installed all the required SDR drivers and tested all SDR's to see if they were behaving correctly.

It's a good thing I did this because one of the cheaper SDR's malfunctioned and had to be replaced. Now, everything is ready to be put to use!

P2000 & Open112

First off, I wanted to get P2000 working. For the past year I have been working on a software package (Open112) that can read the incoming alert messages and feed them to my Emergency Service tracking website 112Centraal.nl.

At this time [13th of july 2022] Open112 is in heavy development and not open to the public yet.

After a quick install and some configuration, the P2000 receiver was up!

Pocsag 1200 & Pagermon

For the commercial paging network I will be using some other software. Pagermon has it's issues and limitations but will work perfectly for a simple pager dashboard.

Sadly Pagermon is built on NodeJS which is a storage-nightmare but I will be running the Pagermon client on the RPI and the Pagermon server on a different machine which limits the pain.

After filling in some known capcodes from my own experience and configuring everything, the Pagermon server was up as well!

Note: I blurred some of the data below since KPN is know to cause trouble to people who share too much of the messages on the internet.

ADS-B & Tar1090

For the ADS-B data I will be using Readsb and tar1090 for a quick aviation radar.

After running both installers, configuring all systems and letting the auto gain controller look for a proper setting, I was able to receive data from over 200 Nautical Miles (230 Miles / 370 Kilometers) away.

This screenshot was taken at night, during the day I usually receive around 150-200 aircrafts

Feeding

Feeding my ADS-B data to platforms online can be useful to get benefits from said platforms or just to serve the community. Every platform has it's pros and cons and at this time, I am feeding the following platforms:

Platform Username / Stats Description
112Centraal - My own radar platform
Flightradar24 T-EHAM674 Filters traffic but had great tools.
Radarbox EXTRPI250497 Filters traffic but had good tools.
ADSBHub 112Centraal - JKCTech Provides (mediocre) worldwide ADS-B data for free.

Conclusion

This was an amazing project to learn more about radar, radio signals and capturing them using SDR. I will be using this radar box as a base for more future projects which will definetely be posted as well.