Category: Satellite

Receiving X-Band Images from the Arktika-M1 Arctic Monitoring Satellite

Recently on Twitter @arvedviehweger (Arved) has tweeted that he has successfully received images from the Russian Arctic monitoring satellite known as ARKTIKA-M1, via it's X-band downlink at 7865 MHz. We've reached out to Arved and he's provided the following information on his setup and how he's receiving and decoding the images.

 

The Arktika-M1 satellite is a Russian weather satellite which operates in a HEO orbit. It was launched in February 2021 and has downlinks on multiple bands. The main payload downlink for the imagery is on 7865 MHz (which is also known as the lower X-Band). The satellite only transmits imagery on the X-Band at the moment, it is currently unknown whether it will ever transmit any image data on L-Band.

For Amateur reception that means having access to X-Band RF gear. It usually consists of a low noise pre-amplifier and a downconverter to convert 7865 MHz down to a lower frequency for easier reception with a high bandwidth SDR such as the LimeSDR, a USRP etc.

In my personal setup I use a surplus pre-amplifier made by MITEQ (around 36dB of gain, 1dB NF), my own self-made DK5AV compact X-Band downconverter and a LimeSDR-USB.

The L-Band gear is mounted on top (helix and the pre-amp behind it) and the X-Band gear is right below. From left to right you can see the feed, the downconverter (silver box) and the LNA (mounted to a heatsink and a fan). Recording is done with a LimeSDR-USB running at a sample rate of 50 MSPS. The satellite transmits every 15 minutes once it reaches its apogee, each transmission including the idle period lasts for about 10 minutes. Some pictures of the idle transmission and the actual data transmission can be found in this Tweet, [noting that Idle = more spikes, actual data looks weaker]:

Depending on the geographical location a rather large satellite dish is also required for Arktika-M1. Reception reports all over Europe clearly show that the satellite has a beamed antenna (similar to ELEKTRO-L2).

In my setup I can get away with a 2.4m prime focus dish (made by Channel Master) in North Eastern Germany. It produces around 9 - 10 dB of SNR in the demod of @aang254’s excellent SatDump software. Anything above 5dB will usually result in a decode but since the satellite does not have any FEC you will need more than that for a clean picture. (Image of SNR in Satdump)

A Comprehensive Beginners Guide to HRPT Weather Satellite Reception

Over on his blog Derek (OK9SGC) has recently uploaded a very comprehensive beginners guide to receiving HRPT weather satellite images. HRPT reception can be a little daunting as it requires a good L-Band dish setup which involves choosing and building a feed, and importantly, a way to track the satellite with the dish as it moves across the sky. Tracking can be achieved manually by hand, but that can be very difficult and so a motorized tracking mount is recommended.  

This is unlike the much easier to receive NOAA APT or Meteor LRPT satellite signals in the VHF band which can be received by a V-dipole antenna, or the geostationary GOES HRIT satellites that can be received with a WiFi grid dish and LNA. Both of which do not require tracking.

The advantage of HRPT however, is that you end up with high resolution, close-up, and uncompressed images of the earth. For example Derek notes that NOAA APT gives 4km/px resolution, and Meteor LRPT gives much better 1km/px resolution but it is heavily compressed. Whereas HRPT gives peak resolutions of 1km/px uncompressed. There are also nine satellites in operation sending HRPT, so there are more opportunities to receive.

Derek has created a very comprehensive beginners guide that covers almost everything from purchasing and building the hardware, to finding and tracking the satellites, to setting up the software and decoding images. He notes that an RTL-SDR can be used as the receiver, and that a WiFi dish with GOES SAWBird LNA can work, although the difficult tracking requirements are still there so a smaller offset dish with custom helix feed might be preferred. Derek also provides useful tips, like the fact that the NOAA15 HRPT signal is quite a lot weaker than others.

Images from Dereks HRPT Guide

Nils Reviews our RTL-SDR Blog L-Band Active Patch Antenna

Over on his blog Nils Schiffhauer (DK8OK) has recently uploaded a review of our RTL-SDR Blog Active L-Band Patch Antenna. This is a satellite patch antenna designed for experimenters who want to receive Inmarsat, Iridium, GPS and other GNSS signals. It covers 1525 - 1660 MHz. (Please note it does not cover GOES or other L-band weather satellites as these are much weaker signals that require a dish). The antenna comes as a set with mounting hardware and extension cable and can be purchased on our store for $49.95 including free worldwide shipping to most countries.

In his review Nils tests the patch antenna with his wideband BladeRF software defined radio showing a wide 60 MHz of bandwidth being received. He then goes on to show it being used to receive AERO, via the JAERO decoder, and STD-C via the Tekmanoid decoder.

We want to take this opportunity to pre-announce that due to rising shipping costs the price of this antenna set will be going up by $10 in early 2022. Before the price raise we will put out another post, but if you are interested in one we'd recommend picking one up soon.

Nils tests the water resistance of the antenna.

SDRAngel Features Overview: ADS-B, APT, DVB-S, DAB+, AIS, VOR, APRS, and many more built-in apps

SDRAngel is a general purpose software defined radio program that is compatible with most SDRs including the RTL-SDR. We've posted about it several times before on the blog, however we did not realize how much progress has occurred with developing various built in plugins and decoders for it.

Thanks to Jon for writing in and sharing with us a demonstration video that the SDRAngel team have released on their YouTube channel. From the video we can see that SDRAngel now comes stock with a whole host of built in decoders and apps for various radio applications making it close to an all-in-one SDR platform. The built in applications include:

  • ADS-B Decoder: Decodes aircraft ADS-B data and plots aircraft positions on a map
  • NOAA APT Decoder: Decodes NOAA weather satellite images (in black and white only)
  • DVB-S: Decodes and plays Digital TV DVB-S and DVB-S2 video
  • AIS: Decodes marine AIS data and plots vessel positions on a map
  • VOR: Decodes VOR aircraft navigational beacons, and plots bearing lines on a map, allowing you to determine your receivers position.
  • DAB+: Decodes and plays DAB digital audio signals
  • Radio Astronomy Hydrogen Line: With an appropriate radio telescope connected to the SDR, integrates and displays the Hydrogen Line FFT with various settings, and a map of the galaxy showing where your dish is pointing. Can also control a dish rotator.
  • Radio Astronomy Solar Observations: Similar to the Hydrogen line app, allows you to make solar measurements.
  • Broadcast FM: Decoding and playback. Includes RDS decoding.
  • Noise Figure Measurements: Together with a noise source you can measure the noise figure of a SDR.
  • Airband Voice: Receive multiple Airband channels simultaneously
  • Graves Radar Tracker: For Europeans, track a satellite and watch for reflections in the spectrum from the French Graves space radar. 
  • Radio Clocks: Receive and decode accurate time from radio clocks such as MSF, DCF77, TDF and WWVB.
  • APRS: Decode APRS data, and plot APRS locations and moving APRS enabled vehicles on a map with speed plot.
  • Pagers: Decode POCSAG pagers
  • APRS/AX.25 Satellite: Decode APRS messages from the ISS and NO-84 satellites, via the built in decoder and satellite tracker.
  • Channel Analyzer: Analyze signals in the frequency and time domains
  • QSO Digital and Analog Voice: Decode digital and analog voice. Digital voice handled by the built in DSD demodulator, and includes DMR, dPMR and D-Star.
  • Beacons: Monitor propagation via amateur radio beacons, and plot them on a map.

We note that the video doesn't show the following additional features such as an analog TV decoder, the SDRAngel "ChirpChat" text mode, a FreeDV decoder and several other features.

Technical Details on an SDR Supercluster with Eight HackRFs

A few weeks ago we posted about Reddit member u/OlegKutkov who used his HackRF supercluster to receive Starlink beacons, but details on the HackRF supercluster project itself were a little sparse. Now Oleg has posted a full description about the HackRF supercluster, noting that the 8 HackRF's in the system can provide up to 160 MHz of live monitoring bandwidth.

Oleg shows how each of the boards are connected to the same GPS disciplined 10 MHz clock source, how it uses an RF splitter with LNA and how it requires 8 separate host controllers connected to individual PCIe lines in his computer system to overcome the USB2.0 data bandwidth limits. He also shows the GNU Radio script he's created that combines the 8 sources into one.

Oleg writes how he's using the HackRF supercluster together with a TV Ku-Band LNB and satellite dish for wideband satellite monitoring.

HackRF Supercluster Block Diagram
The HackRF Supercluster

Receiving Starlink Beacons with an RTL-SDR and LNB

Derek OK9SGC has recently posted a write-up of how they’ve been able to receive the Ku-band beacon signals from the Starlink constellation of communication satellites continually launched by SpaceX since 2015. While we recently covered Starlink Beacons being captured with a HackRF Supercluster Derek has noted that receiving the beacons requires little more than an LNB, a low-cost SDR such as the RTL-SDR V3 and a power injector to provide 12V DC to the LNB. Derek notes that a dish is not even required as the beacons transmit with high power.

Starlink Beacon Receiver Setup

Due to the low earth orbit and thus high speed of travel of the Starlink constellation you’ll notice strong Doppler effect drifts in your received signal. Derek notes that it may be interesting to perform Doppler analysis on the satellites with the satellite tracking toolkit for radio observations (strf) software. He also noted that in the 30 minutes he was receiving for, there was almost no point in time where a beacon was not being received, indicating that the Starlink constellation is close to achieving 100% sky coverage. 

Derek has made the process easy to understand and illustrates just how easy it is to listen to these beacon signals. Of course we note that these are just the beacons, and they carry no data. Still they are fun signal to receive, and doppler analysis could reveal interesting information about orbits. 

Starlink beacons shown in a fast FFT (LEFT), and slow FFT (RIGHT)

LeanHRPT – A set of tools for the manipulation of HRPT data

Over on Reddit u/Xerbot has posted about the release of his new software called "LeanHRPT". When combined with a software defined radio, this software can be used to decode and view HRPT weather satellite images received from satellites such as NOAA, Meteor, MetOp and FengYun. We note that unlike APT and LRPT weather satellite signals which transmit in the VHF bands, HRPT signals are generally at ~1.70 GHz and require a motorized or hand tracked satellite dish to receive. u/Xerbot writes:

LeanHRPT is a flexible, easy to use and powerful set of tools for the manipulation of HRPT data (maybe I could be convinced to add LRPT support).

When used properly LeanHRPT Decode can generate (almost) L1B data usable in actual land/weather observation, or just pretty images :)

You can get it here: https://github.com/Xerbo/LeanHRPT-Decode

The LeanHRPT project also contains LeanHRPT Demod, as you probably guessed, a HRPT demodulator. It features an incredibly high sensitivity as well as being able to do both realtime (through SoapySDR) and offline demodulation (baseband).

You can get it here: https://github.com/Xerbo/LeanHRPT-Demod

LeanHRPT Applying a map overlay on FengYun

Receiving Starlink Beacons with a HackRF Supercluster

Over on Reddit member u/OlegKutkov has recently posted about his success at receiving Starlink beacons at 11.325 GHz with his HackRF "supercluster". Starlink is an Elon Musk / SpaceX venture that aims to provide fast global satellite internet access for low cost. The venture is advanced enough that in most locations the service is now operational, and there will be Starlink satellites in the local sky at any given time.

Oleg's setup to receive the satellite beacons consists of a small hand tracked satellite dish with LNB feed connected to his HackRF "supercluster". The supercluster is 8 HackRFs connected to the same antenna via a splitter, resulting in 160 MHz of bandwidth. Oleg's blog post from last year appears to contain a bit more information about the start of the supercluster. The 11.325 GHz beacon frequency is out of range for the HackRF which covers up to 6 GHz, so a standard satellite TV LNB is used to downconvert the frequency. The LNB had to first be converted to circular polarization, and is fed via an 'invacom' feedhorn.

Update Notes: Thank you to @dereksgc for pointing out that the HackRF supercluster and modified LNBs aren't actually required to receive Starlink beacons. Derek notes that the Starlink beacons are actually very easy to receive. All you need is an RTL-SDR V3 and a stock "astra" LNB (or the Bullseye LNB) which will convert the 11325 MHz beacon frequency to 1575 MHz which is in the range of the RTL-SDR. The bandwidth of the beacons including doppler shift is also small enough for the RTL-SDR. The beacons are circularly polarized, but strong enough to be received with an unmodified linear LNB and small offset TV dish. So receiving the beacons is possible with modest hardware, provided you have a way to power the LNB. Oleg's setup appears to be gearing up to receive the actual wideband data from Starlink, or some other wideband satellite signals.

In the spectrum waterfall image, the doppler shift of the beacons is clearly visible due to the speed at which the satellites orbit.

More information about his setup is available from his followup Reddit comment and the Twitter links he provides there. You can also visit his Twitter directly at @olegkutkov where he shows more images of his HackRF supercluster and the hardware he' using.

In the past we've posted about how IU2EFA and Jan de Jong were able to track the Starlink satellites via an alternative means involving reception of the European GRAVES space radar being reflected off the satellite body.

Oleg's HackRF Supercluster
Starlink Beacons Received. Doppler shift clearly visible.