Rob from Frugal Radio has recently uploaded the next video in his airband monitoring series. In this video Rob explains various airband communications that can be received from the airport, and explains about needing to be in the line of sight of an airport in order to receive them.
He goes on to explain signals and airport radio communications channels such as ATIS, Clearance Delivery, Tower, Arrivals (Approach), Departures, Radar and Terminal communications. The video provides various examples of these communications being received with an SDRplay software defined radio.
Monitoring VHF Airband Aviation Frequencies at the Airport
Over on their YouTube channel GNU Radio have uploaded a recent talk by Aaron Rossetto titled "A Look at Project 25 (P25) Digital Radio". The talk explains the North American public safety P25 system in great depth, and is a good watch for anyone looking into details on how the system works in a deeply technical way. He later shows some examples of his P25 decoding and recording setup. Slides can be found here, and the video is posted below.
Agenda: In this presentation, I will introduce Project 25 digital radio, with a strong emphasis on its use in North American public safety trunked radio systems, and to describe experiments monitoring and decoding P25 traffic using GNU Radio code.
Shortwave Radiogram's are digital broadcasts of images, text and sometimes HTML files that are regularly broadcast on two shortwave radio stations, WRMI in Florida and WINB in Pennsylvania. The transmissions are produced and presented by Dr. Kim Andrew Elliott, and a schedule can be found on the Shortwave Radiogram website.
Over on his blog Jeremy Clark has been experimenting with receiving shortwave radiograms with an RTL-SDR and upconverter. To do this he notes the transmission schedule on the shortwave radiogram website, and uses SDR# and MultiPSK in MFSK mode to receive and decode the data. Jeremy's post explains the MFSK transmission mode and shows a few examples of radiograms that he's received including a video posted below showing live reception and decoding.
Over on the Reddit /r/SpaceXLounge discussion board user /u/Xerbot has made an interesting post showing how u/derekcz was able to receive the telemetry signals from the latest SpaceX Falcon 9 rocket launch using a HackRF and a 1.2m prime focus dish with homebuilt feed designed for the 2232.5 MHz downlink frequency. Then after demodulating the signal with GNU Radio, /u/Xerbot was able to convert that signal into binary data, and then into plain text strings.
Another user /u/Origin_of_Mind then figured out that these strings are debug messages being sent by the software-defined GPS receiver, which amongst other data contains the GPS coordinates of the second stage. The GPS data indicates that the second stage was tracking over the north of Serbia at an altitude of 219 km and velocity of 7483m/s. /u/derekcz was able to then confirm that he was indeed recording the signal when the satellite would have been crossing Serbia, confirming the received telemetry was correct.
The entire thread is an interesting read, with multiple users dissecting the plaintext and finding out information about the launch. /u/Origin_of_Mind's post in particular explains the meaning of each of the data fields, which includes the system time, the XYZ coordinates in the earth-centered earth-fixed (ECEF) coordinate system, the loss of precision due to unfavorable GPS satellite positions and the number of GPS satellites currently received.
Another user /u/softwaresaur even notes that there was an "radiation_fdir_activation_guard" event. FDIR stands for Fault Detection, Isolation and Recovery (FDIR) and this event was triggered due to 0.06 s mission time discrepancy between the rocket and GPS true time.
Over on YouTube River's Educational Channel has uploaded a new video showing how he uses a Raspberry Pi to control a ceiling fan via it's wireless control signal. Back in January we posted about River's first video where he shows him using and RTL-SDR and Universal Radio Hacker (URH) to reverse engineer the control signal.
In this new video River uses the RPiTX software to generate the control signal without requiring any additional transmit hardware. He first explains how RPiTX can generate an arbitrary signal from a square wave and talks a bit about the harmonics this creates. To reduce harmonics he adds a simple low pass filter to the GPIO output.
Next to control the fan he uses the "sendook" program that is included with RPiTX to transmit the binary control string that he reverse engineered in his original video. Finally he creates a simple web server so that he can control his ceiling fans via his phone and integrate it into his smart home.
Abusing Raspberry Pi GPIO pins as a radio transmitter to control my ceiling fan
The Pinetab is a US$99.99 open source Ubuntu Linux Tablet based on a low power Pine64 singe board computer. The Pinetab can optionally support an internal RTL-SDR, which is essentially just a standard RTL-SDR PCB connected to the single board computer inside the tablet enclosure.
Over on YouTube channel Privacy & Tech Tips has uploaded a video where he takes the Pinetab apart and adds an external antenna port, allowing for external antennas to be connected. In the video we get a good look at the internals of the Pinetab, and after installing the external antenna port he shows us the Pinetab receiving a LoRa signal.
Opening Pinetab (Linux Tablet) back cover (+show tips for safer opening) on video and show how you can add an external threaded antenna port for your internal SDR. It makes for an amazingly compact SDR kit and smaller antennas like LoRa fit right inside the keyboard/tablet/laptop stand. Larger antennas such as a dipole, the antenna cord fits along the case/stand perfectly.
I show how to open the Pinetab safely, and install an external threaded antenna port. After this I take a Heltec LoRa ESP32 I have had laying around and use it to demo GQRX on the screen. I show LoRa packets coming over the radio waves at 915MHz. Series on SDR using Pinetab/Pinephone/Pine64 hardware. Linux makes for an amazing platform where the tools at hand leave the limits to what you can do to the power of your imagination.
Rob from Frugal Radio has recently started a new YouTube series all about monitoring aviation communications. In his first video Rob gives an overview on what can be aviation signals can monitored and recommends a few hardware scanners as well as software defined radios for monitoring.
This is an introductory video to my new series aimed about monitoring aviation communications. Throughout the series we will talk about:
Civil Airband (aka VHF airband)
Military Airband (aka UHF airband)
HF Aeronautical communications
Decoding aircraft data on HF and VHF
Decoding CPDLC transmissions and much more!
Good frequency scanners to use, like the Uniden BC125AT and BCT-15X
Thank you to Paolo Romani IZ1MLL for letting us know that he has updated his popular SDRSharp users guide that we posted about previously last December. The guide is available on the Airspy downloads page. SDR# (aka SDRSharp) from Airpsy.com is designed for Airspy SDRs, however it is one of the most popular SDR receiver programs that is used with RTL-SDRs as well. Paolo's guide covers all of the settings and features in SDR# as well as some third party plugins. Paolo writes:
In the last month I have completely rewritten the guide for other devices and for the latest radical changes to the software. From today, version 2.1 is available in Italian and English for all interested guys.
We note that the guide has also been translated in Spanish and Russian, although at the time of writing those translations are still only for the older guide.
