Building an aircraft observer based on Raspberry Pi

This project uses Raspberry Pi with ultra-low-cost software radio (SDR) hardware to receive tracking information sent from an airborne S-mode transponder outside millions of miles. The Raspberry Pi is equipped with a smart 3.5-inch TFT display to provide a convenient overview of aircraft activities.

Hardware

The rtl2832u-based small SDR receiver (124-5461) is designed for DVB-T reception and is on the market for the first time. However, due to the efforts of the Linux kernel hackers over the past few years, the original sample of the device can be acquired, not just a demodulated DVB signal. This means that the wireless system can then be applied to the software, enabling great flexibility.

The RTL2832U chip is usually mating with a tuner IC. Specifically to the Adafruit USB receiver, it is a r820t that can receive signals from 24MHz to 1,850mhz. It should be noted that the RTL-SDR hardware has a 8-bit ADC resolution and a 7-bit significant number of digits (ENOB), with no competitive advantage over the dynamic range of the more expensive SDR platforms. But for many purposes it is enough and has a very high price/performance ratio.

The software for receiving and decoding S-mode signals provides a site interface based on Google maps and a local display that is not particularly needed. However, the addition of the Adafruit PITFT 3.5-inch display (124-5487) provides a concise overview of the "at-a-glance" aerial activity. In addition, the combination of the Raspberry Pi, SDR receiver and TFT display can also be configured as a very cool, independent scanner for spectral visualization.

The TFT display simply plugs into the Pi P1 headers, and the SDR receiver simply plugs into a USB port.

Raspbian

There are two options for installing Raspbian: Download a kernel-supported image from Adafruit for the configured TFT display, or write a Raspbian built-in image and configure it accordingly. I chose the latter because I usually prefer to use the official O/S installation image and then perform the desired custom action. However, the former contains fewer steps and is less prone to error. Adafruit provides guidance for two different methods.

After writing the Micro SD card with "DD", I changed the hostname from the default "Raspberrypi" to "Planepi" by editing the file to make it easier to find the network:

etc/hostnameetc/hosts

Notice the missing slash at the beginning because you don't want to edit the file in/etc on the computer that is writing the SD card-so you need to add the root file system under the SD card, no matter what path is installed on your PC.

If you prefer to configure your system with the accompanying keyboard, monitor, and mouse, you do not have to start SSH. However, if you prefer to configure over an SSH connection as I do, you need to do the following:

sudo touch boot/ssh

Replace "boot" with whatever you want. The full path is to boot the system files on the SD card.

If the pi is connected to a wired network, you can remove the Micro SD card, insert the PI and boot. However, if you are using a wireless network connection, you will also need to edit:

etc/wpa_supplicant/wpa_supplicant.conf

Again, this is not the configuration file in/etc/wpa_supplicant on the computer where you are writing the SD card, and the configuration file is located in the Etc/wpa_supplicant directory on the SD card root file system.

For more information on configuring your wireless network manually, refer to the Raspberry Pi documentation.

Pitft settings

Since I use the Raspbian built-in image and need to configure the kernel support for this image for the TFT display, I follow the DIY installer script instructions provided by Adafruit: Easy installation for installation. However, the "sudo apt-get Install" line appears with the error shown above because the built-in image has an updated version of the software, so you need to run the following script to force the downgrade:

$ sudo apt-get install -y --force-yes raspberrypi-bootloader adafruit-pitft-helper raspberrypi-kernel

The secondary script is then run to install the 3.5-inch resistive Pitft.

$ sudo adafruit-pitft-helper -t 35r

It is generally recommended to use the pre-configured Raspbian image provided by Adafruit. However, the information above is only useful for beginners who use the Raspbian built-in image, regardless of whether they add these features to an existing system running other applications for any reason.

Finally, if the image at the top of this article shows that the USB power lead is facing the Pi downward, you need to update the configuration to rotate the display 180 degrees. You can do this by editing the/boot/config.txt file and changing the rotate=270 to rotate=90.

dump1090

There are a variety of software available to receive and decode S-mode transmissions, which was achieved 5 years ago, when I wrote about the GNU Radio-based surface-to-air model. This time, however, we intend to use the software called dump1090, which is named after 1090MHz usage frequency in S mode.

Compared to the GNU Radio, the benefits of dump1090 include: having the lowest external dependency; It is also particularly robust and adept at decoding weak signals. When working in interactive mode, it prints an overview of the activity to the console, and the branch that is shared on GitHub is slightly modified to accommodate the 3.5-inch TFT display.

To build, we need to run the following script:

$ sudo apt-get install libusb-1.0-< Span class= "Hljs-number" >0-dev librtlsdr-dev rtl-sdr$ git clone https://github.com/ Designsparkrs/dump1090$ CD dump109 0$ make         

Then edit the/etc/rc.local file and add the following line before" Exit 0 ":

cd ~pi/dump1090; ./dump1090 --net --net-http-port 80 --interactive &

Run

Now that we need to reboot to configure the kernel for the TFT display, the configuration will be blocked if the default TV tuner support is not loaded for the RTL-SDR hardware. If all goes well, dump1090 will start with the line we just added to/etc/rc.local. The TFT display should then start displaying the content when the signal is received.

If the browser is connected to raspberry Pi, we will get a simple Web application. The program is based on Google maps, with data such as aircraft location markings and elevation of the beef plate surface.

Please note that the antenna supplied with the SDR receiver is not optimal for 1090MHz, but in most areas the antenna can be used at least for certain aircraft signals. Make sure that you place it near the window or window. If you are unlucky enough to receive a signal, the plan for a simple DIY antenna online can be tuned to 1090MHz for higher gain.

Other software and services

dump1090 also allows the original S-mode information to be available on the network, which can be used with software such as planeplotter for more complex displays. In addition, data can be sent from receivers to online services that provide access to crowdsourcing flight data, such as OpenSky Network and FlightAware.

Building an aircraft observer based on Raspberry Pi