fredag den 27. januar 2017

When were you squawking last?

Did you ever lye on the beach in the sunshine, looking up in the sky....? suddenly you see the white trace of a plane drawing a fluffy line in the blue sky. And perhaps wondering where it comes from, or where it goes. It's in the air....

With this RaspberryPi 2-construction you will be able to get the information immediately. All civil aircrafts use transponders of diffrent types, some send continous ID and simple info about the flight, some SQUAWK when hit by radars. The signals are transmitted at a frequency of 978 or 1090 MHz and can be reached within a line of sight, depending, of course, on the antenna.

You may find several variants of this construction on the internet and it can be presented in different ways, often using Internet, therefore it can be an IOT variant. The equipment is fairly simple, no soldering or GPIO wiring. The role of Raspberry Pi is to manage the receiver, to receive and translate the packed signals, and to present the data locally or via HTTP on another device as for example a laptop. A job suited for the ARM-processor.

                                                                     You recognize a flight number in the terminal stream

The receiver is a simple 50dkk TV/DAB/SDR-USB-dongle with a smal local antenna. It needs to run a receiver like E4000 or Rafael. And tuning via SDR-RTL 2832 chipset. The Software Defined Radio can be set to tune at any frequency within a wide range, in this case 1040 MHZ (Se my other posting about SDR and RPi). For streaming purposes the signal is output as TCP.

                                                                       Screendump from my laptop with google maps

As you see from the above pictures, the raw data is quite readable in the RPi Terminal, but rolling all the time. But if you open the RPi IP adress and the Port of the data with an HTTP option, the server calls Google Maps and shows the plane and the continous movement of the flight. And at the same time a list of flights and hights.  There are surely more flights but even if we live on a hill, the small antenna only captures the signal in the direction of my window, and with a small antenna a short range. A bigger one is needed.

You may say it is the same as in FlightRadar24, and yes, but it illustrates some of the many signals available in traffic, and yes, FlightRadar24 also uses some RaspberryPis as source in their database. And you will see them faster.

As RaspberryPi project it is useful, It involves external communication, networking, compiling, streaming, file handling and many other aspects and as other IoT-projects it involves few data, which RPi handles perfectly.