Category: Satellite

Using an RTL-SDR to Investigate GPS Interference Problems on Drones Caused By HD Cameras

Over on YouTube Drone and Model Aircraft enthusiast channel Paweł Spychalski has uploaded a video showing how he determined that cheap HD cameras that are commonly used on hobbyist drones can cause locking issues with the on board GPS. He writes:

You might believe it or not (today I will prove it, however) that HD cameras, especially cheap ones, can be responsible for GPS problems on your drones and model airplanes. The majority of HD cameras (RunCam Split, Runcam Split Mini, Foxeer Mix, Caddx Tarsier) generate RF noise on different frequencies. Some of them on 433MHz, some on 900MHz, but most of them also at around 1GHz. Just where one of the frequencies used by GPS signal sits. As a result, many GPS modules are reported to have problems getting a fix when the HD camera is running.

In the video he uses an RTL-SDR and SDR# to demonstrate the interference that shows up when a cheap HD camera is turned on. He shows how the interference is present at almost all frequencies from the ISM band frequencies commonly used for control and telemetry to the 1.5 GHz GPS frequencies.

GPS vs HD cameras - it's all about RF noise

SDR Makerspace Conference to be Held in Switzerland in November

SDR Makerspace is a community based in Greece that is run by the European Space Agency and Libre Space Foundation (who are responsible for the SatNOGS project). It provides funding and resources for Software Defined Radio based space communication projects.

On November 28-29 2019 they are holding the SDR Makerspace Conference in Payerne, Switzerland. The conference is free to register although spaces are limited.

The technical talks during the first day will be:

  • Open-Source SDR Software for Satellite Communications - Alexandru Csete
  • LimeSDR as an enabler for Satellite TV Transmissions - Dave Crump
  • How wide band data converters enable SDR in Satcoms - e2v
  • Teaching SDR: EPFL experience - Bixio Rimoldi
  • Xilinx’s adaptive solutions for SDR application - Georg Hanak
  • SDR Makerspace: Evaluation of SDR Boards and Toolchains - Sheila Christiansen
  • SDR and Amateur radio in space - Michel Burnand
  • SDR Makerspace lightning talks - Multiple Authors

The second day will consist of workshops on using SDRs for satellite communications, and on using the LimeNET Micro and LimeRFE for SDR satcom development.

Exhibitors who will be at the conference.
Exhibitors who will be at the conference.

L-Band Patch Antenna Set Preorder Sale Ending Soon – Shipping Begins Next Week

Just a heads up that the preorder sale on our new L-Band Patch antenna set will be ending October 21 as we are almost ready to ship the units out. After the preorder sale ends the pricing will rise from $34.95 to $39.95 USD.

PREORDER PRICING: 34.95 USD incl. free shipping.
PREORDER ENDS OCTOBER 21!

Please see our store to preorder the unit.

Preorder has now ended and shipping will begin shortly. Thank you!

The product is a ready to use active patch antenna set that is designed to receive L-Band satellites such as Inmarsat, Iridium and GPS. It is enclosed in a waterproof plastic case, and can easily be mounted to a window using the provided suction cup and 2M coax extension cable. It can also be mounted to almost anything else using the included flexible tripod legs, or if you prefer, use the standard 1/4" camera screw hole to connect it to any mount that you like.

The antenna is powered via 3.3V - 5V bias tee power, so any bias tee capable SDR such as our RTL-SDR Blog V3 can be used to power it.

In terms of performance see our previous post that announced the product for sample screenshots and reception tips.

The RTL-SDR Blog L-Band Satellite Patch Antenna Set
The RTL-SDR Blog L-Band Satellite Patch Antenna Set
Inmarsat Reception
Iridium Reception

International Space Station SSTV Event Scheduled for October 9 and 10

The International Space Station (ISS) periodically schedules radio events where they transmit Slow Scan Television (SSTV) images down to earth for listeners to receive and collect. This time they have scheduled SSTV images for October 9 09:50 - 14:00 GMT and October 10 08:55-15:15 GMT.

With an RTL-SDR and a simple V-Dipole from our RTL-SDR V3 antenna kit it is possible to receive these images when the ISS passes over. ISS passes for your city can be determined online, and the SSTV images can be decoded with a program like MMSSTV.

AMSAT-UK writes:

Russian cosmonauts are expected to activate Slow Scan Television (SSTV) image transmissions on 145.800 MHz FM from the International Space Station on Wednesday/Thursday, October 9/10.

This is the schedule for the planned activation of the MAI-75 SSTV activity from the ISS.
• Oct 9 09:50-14:00 GMT
• Oct 10 08:55-15:15 GMT

Transmissions will be sent on 145.800 MHz FM in the SSTV mode PD-120. Once received, images can be posted and viewed by the public at http://www.spaceflightsoftware.com/ARISS_SSTV/index.php

ISS SSTV uses a Kenwood TM D710E transceiver which is part of the amateur radio station located in the Russian ISS Service Module.

Please note that SSTV events are dependent on other activities, schedules and crew responsibilities on the ISS and subject to change at any time. You can check for updates regarding planned operation at:
ISS Ham https://twitter.com/RF2Space
ARISS Status https://twitter.com/ARISS_status
ARISS SSTV Blog https://ariss-sstv.blogspot.com/
AMSAT Bulletin Board http://www.amsat.org/mailman/listinfo/amsat-bb

Read the MagPi article Pictures from space via ham radio
https://www.raspberrypi.org/magpi/pictures-from-space-via-ham-radio/

ISS SSTV info and links https://amsat-uk.org/beginners/iss-sstv/

A Wall Mounted SatNOGS Ground Station Monitor

If you weren't already aware,  SatNOGS is an open source project that aims to make it easy for volunteers to build and run RF ground stations (typically based on RTL-SDR hardware) that automatically monitor satellite data, and upload that data to the internet for public access. This is very useful for low budget cubesats launched by schools/small organizations that don't have the resources for a worldwide monitoring network as data can be collected from all over the world no matter where the satellite is.

Over on the SatNOGS Libre Space forums, user cshields have posted about his near wall mounted SatNOGS monitoring station. With the station he's able to monitor the status of his SatNOGS station via an LCD screen and see the location of satellites that next in the queue to be received. There are also some status lights and LCD text screen for monitoring the SatNOGS rotator hardware.

The station consists of a Raspberry Pi 4, 7" LCD display, 500 GB SSD, RTL-SDR Blog V3, and an Arduino with 16x2 LCD and NeoPixel. cshields post covers the full details of the build.

[Also seen on Hackaday]

SatNOGS Ground Station Monitor
SatNOGS Ground Station Monitor

Hacking Iridium Satellites With Iridium Toolkit

Over on YouTube TechMinds has uploaded a video showing how to use the Iridium Toolkit software to receive data and audio from Iridium satellites with an Airspy. Iridium is a global satellite service that provides various services such as global paging, satellite phones, tracking and fleet management services, as well as services for emergency, aircraft, maritime and covert operations too. It consists of multiple low earth orbit satellites where there is at least one visible in the sky at any point in time, at most locations on the Earth.

The frequencies used by the older generation Iridium satellites are in the L-band, and the data is completely unencrypted. That allows anyone with an RTL-SDR or other SDR radio to decode the data with the open source Iridium Toolkit. If you're interested in how Iridium Toolkit was developed, see this previous post about Stefan "Sec" Zehl and Schneider's 2016 talk.

In the video Tech Minds shows decoding of various data, including an audio call and the satellite tracks and heat map of Iridium satellites.

Hacking Iridium Satellites With Iridium Toolkit

Transmitting WSPR on QO-100 with a moRFeus and less than 4 mW Power

Thank you to Zoltan for submitting a short post about using a moRFeus to uplink WSPR to the Es'Hail-2 (QO-100) geostationary satellite with amateur radio repeater. moRFeus is a versatile US$99 signal generator and frequency mixer that can be controlled either by it's built in LCD screen, or via software on a Windows or Linux PC. It can generate a clean low phase noise tone anywhere between 85 to 5400 MHz, and can be used as a mixer for upconverting or downconverting signals. We have discussed moRFeus a few times before on this blog as we think it's a useful tool.

In his setup, Zoltan uses a QRP Labs U3S WSPR transmitter kit that was configured to transmit WSPR at 2m (144 MHz). It is not designed for transmitting the 2.4 GHz QO-100 uplink frequency. To get around that limitation, the moRFeus is used to upconvert the 144 MHz frequency into the QO-100 uplink band by mixing it with a 2,255,634.309 kHz signal. The resulting 2.4 GHz output signal from moRFeus is sent to an amplifier, 2.4 GHz band pass filter, and finally into a 5-turn LHCP helical feed mounted on a 1m parabolic dish.

Successful uplink was confirmed by a UK based WebSDR receiving the QO-100 downlink. Zoltan estimates that the total output power was only 4mW, and actually more like 1-2 mW due to losses in the coax feed.

WSPR uplink with moRFeus
WSPR uplink with moRFeus

Mike Tests out L-Band STD-C and AERO with a Low Cost Modified GPS Antenna

SDR-Kits.net have begun selling low cost GPS antennas that are modified to receive the Inmarsat satellite frequencies between 1535 MHz to 1550 MHz. They also have a version for Iridium satellites that receives 1610 MHz to 1630 MHz. The antennas are powered by a 3-5V bias tee, so they should work fine with SDRplay, Airspy and RTL-SDR Blog V3 units.

Mike Ladd from SDRplay has recently sent us a guide to receiving AERO and STD-C messages on L-band with the SDR-Kits antenna and an SDRPlay unit running SDRUno (Megaupload link).

AERO messages are a form of satellite ACARS, and typically contain short messages from aircraft. It is also possible to receive AERO audio calls. STD-C aka FleetNET and SafetyNET is a marine service that broadcasts messages that typically contain text information such as search and rescue (SAR) and coast guard messages as well as news, weather and incident reports. Some private messages are also seen. To decode AERO Mike uses JAERO, and for STD-C he uses the Tekmanoid STD-C decoder.

Mike has also created a very handy bank of frequencies for the SDRUno frequency manager which can be downloaded from here.

We note that if you're interested in waiting, at the end of September we will have an L-band patch antenna set available too. Our antenna will work from 1525 up to 1637 MHz. Prototypes have shown have shown good Inmarsat, Iridium and GPS reception. More details coming next month when manufacturing gets closer to finishing up.

Screenshot of the Tekmanoid Decoder from Mikes Tutorial
Screenshot of the Tekmanoid Decoder from Mikes Tutorial