Category: Satellite

Next International Space Station SSTV Event on April 11 – 14

Thank you to Alex Happysat for writing in and letting us know about the next upcoming ISS SSTV event which will begin on 11 April at about 18:00 UTC and end on 14 April 2019 18:00 UTC. If you were unaware, the International Space Station (ISS) transmits SSTV images several times a year to commemorate special space related events. SSTV or Slow Scan Television is an amateur radio mode which is used to transmit small images over radio signals.

The images will be transmitted constantly at 145.8 MHz over the active period and they are expected to be in the PD-120 SSTV format. To receive the images you can use a simple RTL-SDR dongle and the MMSSTV software. A tuned satellite antenna like a QFH, turnstile, or tracking Yagi would be preferred, but many people have had good success before using simpler antennas like a V-Dipole. Software like Orbitron, GPredict, various Android apps or NASA's Spot the Station website can be used to determine where the ISS is and predict when it will be over your location.

Over on the ARISS SSTV blog, they write:

The next big event will be the ARISS SSTV event that starts Thursday, April 11 about 18:00 UTC and will be operational until about 18:00 UTC on Sunday, April 14. Since this event will run continuously for 72 hours, folks in the higher latitudes should have a pretty good chance to receive all 12 of the images. Operators in the mid latitudes should be able to get most of them depending on location. Good Luck and Enjoy!

Alex also mentions that for this and other ISS events AMSAT Argentina is handing out ARISS-SSTV Diplomas to amateur radio operators who receive, record and upload at least 15 images received from the ISS, in at least two different radio operation with a month or more in between then.

If you cannot set up a receiver, it is possible to use R4UAB's WebSDR which will be available directly at However, note that internet reception is not valid for the AMSAT Diploma. An example of WebSDR SSTV reception and decoding from a smaller ISS SSTV event held a few days ago is shown below.

ISS SSTV R4UAB WEBSDR 12.04.2016 14:00 UTC

Othernet Dreamcatcher On Sale for Only $49

Over on the Othernet website the Dreamcatcher hardware is currently on sale for only US$49. This is the lowest we've ever seen it for sale.

If you weren't already aware, the Othernet project aims to bring live data such as news, weather, video, books, Wikipedia articles and audio broadcasts to the world via a free satellite service and cheap receivers. Although an internet connection provides the same data, Othernet's satellite broadcast is receivable in remote areas, will continue working in disasters, and costs nothing to continually receive roughly 200MB of data a day. The trade off is that the service is downlink only, so the data that you get is only what is curated by the Othernet team.

Currently the public service is in a test period and is only available in North America. Europe has come online recently too, however they write that the current version of Dreamcatcher that is for sale may not be optimal for receiving the EU signal.

While currently active, they write that the Othernet satellite service is not guaranteed to continue long term. However even if the service discontinues, the Dreamcatcher can still be used as a TX/RX capable LoRa radio. In a previous post we demonstrated a fun application with two Dreamcatchers and a LoRa chat application.

Othernet Dreamcatcher
Othernet Dreamcatcher

Receiving Voice Communications From the Soyuz MS-12 Expedition to the ISS

On March 14 the Soyuz MS-12 spacecraft mission was launched and this carried three astronauts to the International Space Station (ISS). Back on the ground, YouTube creator Tysonpower was able to receive the voice communications of Russian cosmonaut Alexey Ovchinin while the Soyuz spacecraft was approaching the ISS. To do this he used an Airspy SDR and home made QFH antenna, and he notes that reception could just have easily been achieved with an RTL-SDR.

Tysonpower has uploaded a video explaining what he received along with a subtitled and translated recording of the communication. More information also available on his blog post.

[EN subs] Empfang von Cosmonaut Alexey Ovchinin im Soyuz MS-12

Transferring Files via the BlockStream Satellite with Lightning Network Payments and RTL-SDR + Transacting Bitcoin over HF

The Blockstream satellite API is now live on the main Bitcoin network. Blockstream satellite is a project that aims to use geosynchronous satellites to strengthen the Bitcoin network by continuously broadcasting the Bitcoin blockchain all over the world. This allows people without internet access (or with censored internet) to receive Bitcoin. Setting up a Blockstream satellite receive station is a matter of building an RTL-SDR based receiver (or other GNU Radio compatible SDR) with a small satellite dish and LNB.

The API was also updated and this has enabled a feature that allows you to upload a file of up to 10 kB via the internet, which will then be transmitted via the satellites to anyone who is running a Blockstream RTL-SDR satellite receiver. Payment for the transmission is taken via the Bitcoin Lightning Network and transmissions appear to work on a priority basis, with larger payments receiving higher priority. The file is distributed to all receivers, so they note that private messages would need to be encrypted with public keys distributed to recipients in other ways. This service is similar to what the Othernet (prev. Outernet) network offered in the past with the ability to transmit data, tweets and APRS messages over their satellite network. We think that cheap small data satellite transmissions could have some interesting applications in remote control.

In related news on CryptoNewsZ it has been reported that a bitcoin lightning network transaction was completed over the 20M amateur radio band. The transaction was completed with the JS8 digital mode, which is similar to FT8 but designed for weak signal usage. The message was sent via the help of twitter, with @eiaine first sending money to @nvk via the internet. @nvk then sent the Lightning Network invoice over 21 JS8 messages via the 20M band to @eiaine who received it, thus confirming that the transaction was completed.

Demonstration of Two SatNOGS Rotators

Thank you to IZ5RZR for writing in and sharing his two SatNOGS rotator builds with usSatNOGS is an open source project that aims to make it easy for volunteers to build and run RTL-SDR or other SDR based RF ground stations that automatically monitor satellites, and upload that data to the internet for public access.

IZ5RZR writes that he's now made two rotators and one was modified to use a 5:18 stepper motor (which is upgradable to 50:1) to give more torque so that heavier antennas can be turned smoothly. His rotators are powered by a 12V battery charged by solar, and they can be controlled over WiFi with a PC/tablet/phone. He's also tested the rotators with a 24 dB parabolic grid antenna and found that the rotator could handle it even without a counterweight. He also notes that together with IK5XWA they've fixed a "Meridian Flip" bug in the firmware.

The video below shows the two rotators in action.

IZ5RZR Two SatNOGS Satellite Rotators

A Worldwide Map for HRPT Weather Satellite Receive Stations

Recently Manuel (DO5TY aka Tysonpower from YouTube) wrote in and wanted to share his website that shows HRPT weather satellite receive stations from around the world on a map, and links to their Twitter pages where you can see the latest images that have been uploaded. The database also describes the SDR and antenna equipment used by each station. Currently there are 10 stations on the map, and Manuel encourages other people to submit their stations to the map database too. If you are interested in contributing your station to the map, please see Manuel's blog post for more information.

Since the satellite broadcasts a live image of what is currently being seen by the weather camera, each receiver location receives a live view of their part of the earth only. The end goal of Manuel's HRPT station map is to crowd source and collect multiple images of different parts of the earth to create a large HRPT composite image. In a previous post, Manuel who is based in Germany was able to create a beautiful composite image covering Germany, the Atlantic Ocean and Canada with the help of a station in Canada. With more contributors larger and more complete composite images of the Earth could be created.

HRPT is a high resolution weather satellite image signal that is broadcast from the same NOAA satellites that provide the more commonly received low resolution APT images at 137 MHz. HRPT is also broadcast from the Feng Yun and Metop-A satellites. However, HRPT transmits at 1.7 GHz, so a high gain dish antenna with motorized tracking mount, LNA and high bandwidth SDR like an Airspy is required to receive it.

HRPT Station Map
HRPT Station Map

XRIT Decoder Updated: Improved Image Quality and IR Enhancements

USA-Satcom is the programmer of XRIT Decoder, which is a popular (paid) Windows decoding application for GOES weather satellites. With a WiFi grid dish antenna, LNA and SDRplay, Airspy or even an RTL-SDR, high resolution full disk images of the earth can be downloaded from these geosynchronous satellites. Browse through our previous GOES posts for ideas and various tutorials about setting up a receiver.

Recently, XRIT decoder has been updated and now has improved image quality and an antenna alignment helper tool. A further update also adds improved processing for IR images. Over on the SDRplay forums RSP2user has been testing the updates and writes:

USA- Satcom has just released version 1.4.6985 of the XRIT Decoder software package. New features include:

1) Improved image clarity.

2) An antenna Align Mode feature.
3) And a Viterbi and Eb/No (Energy per Bit to Noise Power Spectral Density Ratio akanormalized SNR) graph over time feature. 

The improved image clarity reduces image artifacts at the Earth-space boundary of the image and improves the overall aesthetics of the colorization of the full disk images. The images are quite amazing. The resolution is far better than what can be shown here due to image size limitations for this site. Below is a full disk GOES 16 image from February 17, 2019 and a corresponding zoomed in portion to get an idea of the resolution and clarity (the actual full disk images are approximately 40MB PNG images each which are much greater resolution than the below image)

The antenna Align Mode is a great new feature that allows users to view the Signal Quality, Viterbi FEC, and Eb/No from a distance using large numeric values. This mode enables users to better view these values when fine tuning adjustments to GOES receiving antennas. The Eb/No and Viterbi graphing enables users to see how well their receiving system is doing throughout the day (e.g., over temperature and while the sun is in alignment with the receiving path).

GOES 16 Received by RSP2User
GOES 16 Received by RSP2User

More updates from USA-Satcom to the XRIT Decoder software with a new patch from today. The XRIT file manager now provides IR image enhancements for GOES Bands 8 and 13. Here are some examples:

G16 CH13 & G16 Band8 Enhancements . Images received by RSP2user.
G16 CH13 & G16 Band8 Enhancements . Images received by RSP2user.

See the post on the SDRplay forums for further details, higher res images and the full update history.

Es’hail-2 Amateur Transponder Now Active

Es'Hail 2 Coverage
Es'Hail 2 Coverage from Amsat-UK

Es'hail 2 was launched last November and it is the first geostationary satellite to contain an amateur radio transponder. The satellite is positioned at 25.5°E which is over Africa. It's reception footprint covers Africa, Europe, the Middle East, India, eastern Brazil and the west half of Russia/Asia. There are two amateur transponders on the satellite. One is a narrow band linear transponder which uplinks from  2400.050 - 2400.300 MHz and downlinks from 10489.550 - 10489.800 MHz. Another is a wide band digital transponder for amateur digital TV which uplinks from 2401.500 - 2409.500 MHz and downlinks from 10491.000 - 10499.000 MHz.

Although it launched last year it takes several months for the engineers to test and qualify the transponder for use. Over the last few weeks the transponder was intermittently active during the testing, but now since Feb 13 2019 the amateur transponder has finally been fully activated for amateur radio use.

To receive it with an RTL-SDR or most other SDRs an LNB is required to receive the 10 GHz signal and downconvert it into a frequency range that most SDRs support. Typically an Octagon LNB is used, and these are easy to find and cheap as they are often used for satellite TV.

From various reports seen on Twitter, it seems that the signal is strong enough that a satellite dish is not required for receiving - simply pointing the LNB directly at the satellite is enough.

If you can't set up a receiver, there is an OpenWebRX livestream of the Es'hail 2 narrowband channel that has been set up by Zoltan/RFSparkling which is available at (note the server can only handle 8 users at a time, so try again later if it's busy). Also as pointed out by KD9IXX on Twitter, there are also several servers receiving and streaming Es'hail2 including an Airspy based one run officially by AMSAT-DL.