Tagged: satellites

Hystérésia: An Art Installation that Listens to Zombie Satellites

Thank you to Stéfane Perraud, Aram Kebabdjian and team for submitting news that they have recently launched an art project in Lausanne, Switzerland called "Hystérésia". The installation is technical art, which consists of an autonomous satellite receiving station designed to receive beacons from old "zombie" satellites, and then broadcast their signals audibly. A description of the ground station can be seen here.

Zombie or Dead satellites are satellites that are officially decommissioned and powered down, but have unintentionally reactivated. This often happens as over time the batteries on these satellites can undertake a chemical reaction from thousands of solar recharge cycles which eventually results in a short circuit. Hence the satellites reactivate when in sunlight. If you are interested we have an old post on this phenomena back from 2014.

The system is based on an antenna rotator with two Yagi's that tracks the zombie satellites as they pass over the sky. A QFH antenna has also been spotted in their images. Based on the waterfall images, an SDRplay RSP is used as the receiver, and some computing device is used to demodulate the signal into audio. Stefan adds:

Technically we are using a double yagi 137 and 145 plus a 777 antenna from diamond to catch 200 mHz

We developed a python based software that’s controlling a sdr software based on gnu radio.

We update TLE everyday, our azimuth and élévation rotor follow the satellites and we catch the signal with a sdr uno, plus a switch that choose antenna with the good satellite.

The machine is monitored by a bench of sensors , wind, humidity, temp. It can be control by internet via the website

The machine search for peaks around the chosen frequency,
Also the sound is processed by max/msp, we denoise it and we make music out of it

The 3 metallics pavillons blows the sound noise to the audience
Each time a satellite shows up, the machine sends a story told by one of our recording, a woman actors voice , it tells a specific history that’s tells a narrative about the satellite that’s on air … but in French

If you are unable to visit the installation in person, it appears that their website also broadcasts the last received satellite's sound. The website also shows photos of the history of the zombie satellites.

If you're interested in other art based on satellites and software defined radios, have a look at our previous post on the open weather project, and the "signs of life" project. Another SDR art project was 'Holypager', an art installation that continuously prints out pager messages received by a HackRF, and "ghosts in the air glow" project which used the HAARP antenna array to broadcast an art project.

Hysteresia montage (click for large version)
Hysteresia montage (click for large version)

SignalsEverywhere Podcast: Satcom Piracy Interview

Corrosive from the SignalsEverywhere YouTube channel has released a new episode of his podcast. In this episode Corrosive interviews an anonymous informant who has an interesting story about his involvement with the UHF Military SATCOM pirate radio scene in Brazil. Corrosive also explains a bit further about what SATCOM is and why it's so susceptible to piracy. He also notes that piracy on Inmarsat L-band frequencies is also becoming more common.

The UHF-SATCOM band is anywhere between 243 - 270 MHz and contains fairly strong signals from many several US satellites that can be received with a simple antenna and any UHF radio/SDR. Many of the satellites are simple repeaters without security, and pirates from Mexico and South America often hijack the satellite for their own personal use. In the past, and possibly even still today hijackers involved in drug trafficking and other illegal activities made use of these insecure military satellites for long range communications. Reception of these satellites is generally available in Canada, US, Mexico, South America, Europe and Africa.

Amazon AWS Satellite Ground Stations Now Available For Hire

Over on the AWS blog Jeff Barr has blogged about Amazon's new rentable ground station system called "AWS Ground Station". AWS, or Amazon Web Services is the server farm division of Amazon. They allow customers to rent out server capability on demand. In a similar sense, AWS Ground Station is aiming to allow customers to rent out satellite ground stations on demand.

Launching low cost micro/nano satellites has become very affordable in recent years and it's now common to see high schools, colleges, organizations and hobbyists designing, fabricating and launching their own satellites. Once launched, a ground station is required to receive the satellite's radio transmission as it passes over. Most low cost satellite owners will not have the budget to deploy ground stations all around the world for continuous monitoring of the satellite. This is where AWS Ground Station can take over, allowing a ground station on the other side of the world to be rented temporarily during a pass.

Currently the service is just starting, and only has 2 ground stations, but by 2019 they hope to have a total of 12. More information available on the official AWS Ground Station website.

Alternatively, there are other free open source services that could be utilized such as SATNOGS. SATNOGs relies on volunteer ground stations running antenna rotators that can be built with a 3D printer, some low cost motors and electronics, and an RTL-SDR. The antenna rotator carries a Yagi antenna and will automatically track, receive and upload satellite data to the internet for the public to access.

AWS Ground Station Web Site
AWS Ground Station Web Site

SDR# GPredict Satellite Tracking Plugin

Thanks to Alex for submitting news about his new SDR# plugin called "SDRSharp.GpredictConnector". This plugin allows SDR# to interface with GPredict which is a tool used for tracking the orbit of satellites. Just like with the DDE Tracking plugin and the Orbitron satellite tracking program this plugin could be used to automatically tune SDR# to the frequency of a passing satellite using GPredict. It should also be able to compensate for any doppler shift frequency offset.

To use with SDR# simply download the zip file and move the .dll file into the SDR# folder. Then add the 'magicline' to the plugins.xml file using a text editor. In GPredict you can then add a radio interface from the preferences, and then use the 'Radio Connect' interface to connect to the plugin.

Connecting to GPredict using the GPredictConnector SDR# Plugin
Connecting to GPredict using the GPredictConnector SDR# Plugin

Talks from the AMSAT-UK RSGB 2017 Convention

The Radio Society of Great Britain (RSGB) and AMSAT-UK recently presented a number of talks at their latest convention held in October of this year. Some of the talks are SDR related and are interesting for those interested in satellite reception. A couple of interesting SDR related talks are presented below, and the rest of the talks can be accessed on their YouTube page.

Software defined radio for the satellite geek - Alex Csete OZ9AEC

In this talk Alex Csete (Oz9AEC) who is the programmer behind the popular GQRX software that is often used with RTL-SDRs discusses his latest work and some of his experiences with writing software for SDRs.

2017: Software defined radio for the satellite geek - Alex Csete OZ9AEC

Going to space the libre way - Pierros Papadeas, Libre Space Foundation

In this talk Pierros Papadeas who is the founder of the Libre Space Foundation discusses their SatNOGS project. SatNOGS is a project that uses RTL-SDRs in custom 3D printed home made satellite tracking ground stations. It aims to enable easy access to live satellite data online by significantly increasing ground station coverage.

2017: Going to space the libre way - Pierros Papadeas, Libre Space Foundation

Testing a 16x RTL-SDR V3 WebSDR System for the Satcom Band

Over on Twitter Denis (@uhfsatcom) has recently been teasing us with photos of his 16 dongle RTL-SDR V3 setup. The system looks like it's designed to be a satcom band WebSDR receiver. 

The satcom band is around 240 - 270 MHz and mostly consists of various military satellites that act as simple repeaters which are often hijacked by pirates. WebSDR is a piece of software that allows for online web streaming of SDR radios. Users from all over the world can listen in if made public. Denis has also uploaded a short video showing a test of 8 dongles running and receiving the satcom band on his WebSDR system.

We look forward to hearing more updates on this project!

8 rtlsdr websdr test

Modded SUP-2400 Downconverters now Available at RXTXDX.com for $25

Last week we posted about KD0CQ’s interest check on his ready to go modded SUP-2400 downconverter. Interest was strong so the unit is now available for sale on a store he’s just set up at RXTXDX.com. The ready to go unit costs $25 USD including a 9V battery plug and F->SMA or MCX adapter.

Last year KD0CQ discovered that the SUP-2400 is a cheap $5 – $10 DirecTV (US satellite TV) module which can be hand modded into a downconverter for the RTL-SDR. A downconverter allows you to listen to frequencies above the maximum frequency range of the RTL-SDR by converting frequencies down into a range receivable by the RTL-SDR (or of course any other SDR). The modified SUP-2400 allows to you listen up to just over 4 GHz.

The SUP-2400 modification is moderately involved and requires soldering and desoldering SMD pieces, so this product is great for anyone who just wants a cheap and low cost downconverter which is ready to go. And at $25 USD it’s still very good value. Shipping within the USA is $7.75, and internationally it is about $13.50.

The modified SUP-2400 Downconverter
The modified SUP-2400 Downconverter

Potentially Receiving up to 10 GHz with an RTL-SDR and Multiple SUP-24000 Downconverters

Back in 2016 KD0CQ discovered that a $5 DirectTV device with model name SUP-2400 could be used as a downconverter with an RTL-SDR for receiving frequencies of up to 4.5 GHz. A downconverter is a device that converts high frequencies such as 4.5 GHz down into a frequency actually receivable by the RTL-SDR. The SUP-2400 is able to be modified into a useful downconverter by opening it up and manually removing some mixing harmonic filters.

In his latest post KD0CQ shows how you could combine four modified SUP-2400 downconverters to create a quarduple conversion mixer which allows you to receive up to 10 GHz. The post goes into the mixing math and practicalities of this idea. KD0CQ writes that some amplification will most likely be required to push the signal through, and in the past he’s managed to receive up to 7.5 GHz.

The SUP-2400 Directv upconverter that can be converted into a downconverter.
The SUP-2400 DirecTV device that can be converted into a downconverter.