Over on his YouTube channel, "saveitforparts" has uploaded a video showing how he's modified an old wireless networking dish for L-band HRPT satellite reception. L-band satellites that transmit HRPT are polar orbiting, meaning that some sort of tracking solution is required to point the satellite dish at the sky as the satellite passes over. However, lacking any sort of motorized solution, saveitforparts simply removes the dish mount so that the dish can be manually held and tracked.
He notes that he uses the paid version of the Stellarium app for augmented reality tracking of the satellite. In the past there was a great app called "Satellite AR" which did this for free, however within the past few years it has unfortunately been removed from the Google Play store.
The modifications to the dish involve removing the feed from the satellite and installing a custom built helical feed. He also uses a small handheld PC with RTL-SDR on the rear. However in the end the handheld PC turns out to be problematic so he switches to a laptop.
The dish used in saveitforpart's project is quite similar to our upcoming Discovery Dish crowd funding project, so please check that out if you are interested.
For the past few years we have been working on finding the best way to help beginners get started with L-band weather satellite reception and basic radio astronomy. We have now come up with a solution that we're calling the 'Discovery Dish' - a lightweight 65 cm diameter dish and active filtered feed set.
Discovery Dish: Simplified system for weather satellite reception and hydrogen line radio astronomy
Discovery Dish is a 65-cm diameter aluminum satellite dish and active filtered feed designed for receiving GOES HRIT, GK-2A LRIT, FengYun LRIT, NOAA HRPT, Metop HRPT, Meteor M2 HRPT and other weather satellites that operate around 1.69 GHz. The dish is designed to weigh under one kilogram, and it splits into three petals, making it easier to ship worldwide. The 1.69 GHz feed contains a built-in LNA right at the feed point, as well as filtering, which means that there is almost no noise figure loss from cables or connectors.
Note that the prototype images show an early non-petalized prototype with rough laser cut wind holes. The production version will obviously be a lot neater looking!
In testing the 65 cm diameter Discovery Dish with it's highly optimized feed has proven effective at receiving the GOES HRIT satellite signal with SatDump. We typically achieve SNR values of 3-4 dB to GOES-18 at 24 deg elevation, and with SatDump an SNR of 1 dB is about the minimum required to receive images so there is plenty of margin. It can also easily receive LRIT from GK-2A and Fengyun, and also when combined with an antenna rotator (or manual hand rotating) can receive HRPT weather satellites too.
The feed on the Discovery Dish consists of a tuned dipole feed with two 5V bias tee powered low noise figure LNAs, and two SAW filters (centered at 1680 MHz with 69 MHz Bandwidth). The feeds are also easily swapped out, and we will also be selling a 1.42 GHz Hydrogen Line feed for those who want to use the dish to get started with radio astronomy. Because the LNA's are right by the feed there is are no losses from feed to LNA, so we can use thinner and easier to handle cabling like RG58 without any loss issues.
In the past we've recommended and relied on 60 x 100 cm WiFi dish antennas for L-Band geosynchronous satellites and Hydrogen Line reception, but at 1.6kg these are too heavy, wide and exert too much torque for light duty antenna rotators to handle. At about half the weight of an equivalent WiFi Dish, the Discovery Dish is much easier to handle.
In the future we hope to be able to provide a low cost light duty antenna rotator that compliments the Discovery Dish. Currently we have tested the Discovery Dish with the AntRunner antenna rotator and found it to be light enough for that rotator to handle, versus a WiFi dish which is far too heavy for it.
Also when compared to a WiFi dish, the Discovery Dish is much easier to optimally set the offset skew as you can simply rotate the feed, versus having to rotate the entire dish at 45 degree increments.
We will also be offering an outdoor electronics enclosure that can be used to house a Raspberry Pi, RTL-SDR and other components like POE splitters. In our tests we have been running an RTL-SDR Blog V4, Orange Pi 5 and POE splitter in the enclosure, and running the SatDump GUI directly on the Orange Pi 5. This results in a neat contained system where only one Ethernet cable needs to be run out to the enclosure.
As we are in pre-launch, pricing is not yet confirmed, but we expect the Discovery Dish to sell for less than US$200 with reasonable worldwide shipping costs. It will be a similar cost to what you would pay if you purchased a WiFi dish, filtered LNA and cabling yourself. Obviously please check what satellites can be seen in your region.
Over on the saveitforparts YouTube channel the creator has uploaded a video showing how he was able to image geosynchronous satellites with his modified motorized RV satellite dish. The idea is to scan the sky using the motorized dish, taking Ku-band RF power readings at each point in the sky. The result forms a heatmap image of satellite transmissions in the sky. For the most part, the satellites detected are TV satellites and they are at known positions in the sky.
However, in one of his recent scans saveitforparts appears to have detected an unknown satellite just outside of the geostationary plane. He goes on to discuss what it could have been, noting that it is most likely to be the AMSC 1 telecommunications satellite.
Recently I spotted a strange "UFO" with my homemade radio telescope / microwave imager. I've used this imager before to spot television satellites in geostationary orbit, but this unknown object was something new to me.
Spoiler Alert: I was able to determine that I'm probably seeing a geosynchronous (but not geostationary) satellite in an inclined / elliptical orbit. Specifically, I think this is the AMSC-1 telecom satellite, which is in a type of orbit designed to cover high latitudes like Northern Canada.
These types of satellites don't seem to show up too often on my telescope / imager setup, since they're not as common and aren't usually aimed directly at my location. This is the first time I've managed to spot one (if that's what I'm seeing), so it seems kind of rare to catch it with this particular equipment!
Folks might also ask if this "UFO" could be the sun or moon producing microwave signals, but those were both off to the left of the scan, not where the mystery signal showed up. It's also probably not a reflection / side lobe / "lens flare", I do get those, but they show up as rings around the main signals, and in fact this mystery signal has its own faint ring around it. Since my dish takes 3-4hrs to do a full scan, this also isn't something fast like a plane or low-orbit satellite as those don't show up on my imager (I'm essentially taking a very long time exposure).
I'm still planning to upgrade / rebuild this mini radiotelescope device in the future, hopefully with more flexibility to pick up different frequencies. That should let me see even more satellites (and maybe other space stuff!).
Mysterious Space Object Detected With DIY Radio Telescope
Over on his YouTube channel dereksgc has uploaded the next video in his series on satellite reception. In this video he shows how to build a Yagi antenna tuned for 137 MHz, which is great for receiving NOAA APT and Meteor M2-3 LRPT. Note that a Yagi antenna will give you stronger reception compared to a turnstile, QFH or V-Dipole, but as it is a directional antenna you will need to manually point it towards the satellite as it passes over your location.
For Meteor M2-3 LRPT, a Yagi antenna may be beneficial, as it appears this satellite is having some issues with signal strength, due to a possibly defective antenna that did not fully unfold on the satellite.
The Yagi antenna design is a four element design, with one reflector, two directors and one driven dipole element. The physical construction consists of a piece of wood for the boom, brass welding rods for the elements, and a terminal block for the active dipole element. 3D printed handles are added for easy holding and the RTL-SDR and LNA sit directly on top of the boom.
STEREO-A is a satellite launched in 2006 which is orbiting the sun and used for making solar observations. Usually it is so far away that massive deep space satellite dish's are required to receive this satellite. However for the first time since it's launch, STEREO-A's orbit is taking it close enough to Earth for small home satellite ground stations to be able to receive the data and download some images of the sun.
Scott's blog post explains the orbit, how the satellite transmits at 8.443.579 GHz, and shows his feed and hardware setup which involves a few filters, LNAs, GPS reference clock, a mixer and an Ettus B200 SDR. He also notes how he uses a modified motorized telescope mount to automatically track the satellite as it moves through space.
The rest of Scott's post explains how to use the "CCSDS Turbo R6 K8920" Decoder in SatDump to decode the signal and recover images, noting that some tuning of parameters was required and that because of the slow data rate it can take hours to get even one megabyte of data. He goes on to acknowledge everyone who figured out how to decode the image and telemetry data from the satellite, some observations on the STEREO-A beacon and finally some amazing images and animations he's received.
A weak signal from STEREO-A received back in mid June 2023Image of the sun from STEREO-A
Over on dereksgc's YouTube channel another recent video from his satellite decoding series shows how to download images from the Coriolis satellite, a US Department of Defense satellite launched in 2003, that is among other uses designed to measure wind speed and direction from space using a radiometer.
The entire history of an orbit is only downlinked in the S-band when over an official ground station, however it also has a 'tactical' downlink for live data that the US Navy uses. As the data is unencrypted, with a satellite dish, 2.2 GHz feed, LNA and a software defined radio like the HackRF, anyone can receive the data.
In his video dereksgc explains the satellite, shows his hardware, and demonstrates reception. He then passes the recording into SatDump which results in the images. The images themselves are nothing interesting to look at, as they are produced by a sensor designed to measure wind. But dereksgc shows how multiple images can be composited into something a little more interesting.
Receiving images from a US DoD satellite (Coriolis) || Satellite reception pt.9
Over on YouTube dereksgc has another video on Meteor M2-3 reception. In the video Derek goes over the history of Meteor M launches and then goes on to test reception of the 3.4 GHz telemetry signal which he recorded early after the satellites launch.
The next day he sets up 1.7 GHz HRPT reception using a hand tracked satellite dish and is successful as receiving it. He then goes on to test 137 MHz LRPT reception with a V-dipole antenna and RTL-SDR and is also successful. Finally he decodes the recordings using SatDump and is able to get some great images.
Derek also notes that there might be a problem with the LRPT antenna which could explain some reports of poor reception at some elevations of the satellite. He notes that it seems likely that the QFH antenna extension process on the satellite didn't extend fully or at all.
Receiving Meteor-M N2-3 LRPT and HRPT || Satellite reception pt.11
A few days ago we posted about the successful launch and deployment of the latest Russian Meteor M2-3 weather satellite. The satellite is currently actively transmitting LRPT weather images.
Over on his YouTube channel, "saveitforparts" has uploaded a video showing how he received images from the new satellite using his RTL-SDR. His method involves first recording the signal pass on a Raspberry Pi with rtl_fm, and then passing that wav file into SatDump for decoding and image generation.
We note that it is also possible to directly live decode the pass using SatDump, however a Raspberry Pi may be a little too slow to run the GUI version of SatDump. Instead you could use rtl_tcp on the Pi and run SatDump on a networked PC, or simply run the RTL-SDR and SatDump on the PC or a more powerful device like an Orange Pi 5.
Ultimately he experiences some unresolved problems with the decoding process, but is able to end up with a decent image.
Grabbing Images From New Russian Satellite (Meteor M2-3)
