Tagged: satellite

IndiaRocketGirl Receives FengYun-2H S-VISSR Satellite Images

Over on her YouTube channel IndiaRocketGirl has posted a video showing how she was able to build a satellite dish and feed to receive FengYun-2H S-VISSR signals and get beautiful full disk images of the earth.

In the US and other countries RTL-SDR fans will be familiar with how to receive images from the GOES geostationary weather satellite. However from countries like India most GOES satellites will not be visible. Fortunately there are alternative satellites like the Chinese FengYun-2H satellite which is visible from India. FengYun-2H is a geostationary satellite that sends down a S-VISSR signal containing full disk images of the earth.

In her video IndiaRocketGirl uses a 1.8 meter diameter antenna, a homemade helical feed, an LNA+filter and an RTL-SDR as her hardware. For software she uses SatDump.

How to receive Real Time Images from Geostationary Satellites..? | India Rocket Girl

WXCorrector: Updating Keplers for Linux users of WXtoIMG

Thank you to Hamdy Abou El Anein for submitting news about the release of his software called "WXCorrector".  

WXCorrector is a dedicated solution designed specifically for Linux users who face challenges with the handling of Kepler elements in Wxtoimg. This tool addresses a critical issue where incorrect or outdated Keplerian elements can cause disruptions in tracking software, leading to inaccurate predictions and potential data loss.

It work on Linux, it needs sudo rights and Python3 installed.

https://github.com/hamdyaea/wxcorrector-for-linux

WXtoIMG is a commonly used piece of software for decoding images from NOAA APT weather satellites. However,  WXtoIMG is now considered abandonware as the original website has gone, and the main author has not updated the program in many years. The latest versions from 2017 can be downloaded from Archive.org. An alternative download site is https://www.wraase.de/wxtoimg, where they also provide a way to update Keplers for Windows machines.

Due to it's abandonment, certain features like Kepler updates from the internet appear to have broken over time with changes to the way Kepler files are served. Up to date Kepler files are required for the software to know exactly where satellites are in the sky for tracking and scheduling.

A modern alternative to WXtoIMG is SatDump, which now supports NOAA APT satellites.

WXtoIMG

Spacewalker LNA 434 MHz In Prelaunch at CrowdSupply

Thank you to Zoltan and team for submitting news of the prelaunch of their Spacewalker LNA 434 MHz. Spacewalker LNA is designed to improve reception of PocketSat and Cubesat satellite signals when received with SDR devices like the RTL-SDR. Often these relatively weak signals are drowned out by strong interfering terrestrial signals like DVB-T and GSM. To solve this the triple filter and dual amplification design used in the Spacewalker LNA can help to isolate the satellite signals.

The team write that prototype versions of the LNA are already successfully in use around the world with SatNOGS stations. The device uses two state of the art QPL9547 LNA with 0.2 dB noise figure and 25 dB gain at 434 MHz and three 434 MHz SAW filters. The design also uses an interesting coax stub for ESD protection. It can be powered with 5V USB-C or via bias tee.

The LNA is currently in the prelaunch stages with CrowdSupply, so it will likely be released for crowd funding within the next few months. If you are interested in being notified when the campaign launched, be sure to sign up on the Crowd Supply page for updates.

Spacewalker LNA 434 MHz. Designed for PocketSat and CubeSat signals amidst strong DVB-T, TETRA, FM, and LTE signals from densely packed transmitter towers.
Spacewalker LNA 434 MHz. Designed for PocketSat and CubeSat signals amidst strong DVB-T, TETRA, FM, and LTE signals from densely packed transmitter towers.

Multiple Comprehensive Tutorials on Weather Satellite Decoding

Over on his website "Jacopo's Lair" IU1QPR (@original_lego11) who is also a developer for SatDump has written up many tutorials about weather satellite decoding that involve the use of SatDump. SatDump is a popular piece of software often used with RTL-SDRs and other low cost SDRs for decoding weather satellite images.

With a small satellite dish, feed, RTL-SDR and LNA+filter and the SatDump software it's possible and download beautiful images of the earth from many geostationary and polar orbiting weather satellites. We note that we are currently taking pre-orders on Crowd Supply for our Discovery Dish system, which is low cost hardware designed to help users get started with weather satellite reception.

Over on Reddit IU1QPR has created a listed summary of all the tutorials he's written. These are currently the most up to date and comprehensive tutorials that we have found on this topic. The tutorials cover everything from what satellites are available, what dish sizes you need, what SDRs can be used, what LNA+filter and other hardware you need, and how to use the SatDump software.

Satellite reception and decoding

Automated stations

SatDump usage

All have been moved to SatDump's documentation page

Satellite data processing and usage

From the HRPT tutorial: What various HRPT signals look like on the spectrum.
From IU1QPR's HRPT tutorial: What various HRPT signals look like on the spectrum.

Discovery Dish Updates and Some Cool Hi-Res Images

We have recently posted an update on our Discovery Dish crowd funding campaign over on Crowd Supply. Check it out on the update page, or on the repost down below.

Discovery Dish Teardown Session Livestream Recording

Thank you to Helen Leigh and Crowd Supply for featuring us on one of their Teardown Sessions live streams a few days ago. If you missed it, feel free to watch the recording below. On the livestream we discussed the Discovery Dish and talked a bit about the journey we took to get to the final product design.

Teardown Session 38: Discovery Dish

Enclosure Glands and Vents

We have decided to include a few cable glands and vents with the Discovery Dish Enclosure, as these will ensure that the bottom of the enclosure is protected against water jets and any splash back from the ground, as well as allowing the electronics inside to breathe a bit. Allowing waterproof enclosures to breathe is important in many environments to avoid condensation build up inside.

The glands and vents will be metal to ensure that RF tightness of the enclosure is maintained as much as possible.

The electronics inside can be passively cooled via thermal pads that sink all generated heat to the metal enclosure which acts as a large thermal mass and heatsink.

In the image below you can also see the mounting board. We are still planning to reduce the hole spacings on the board.

Rotator Timelapse

We’ve been testing an early prototype design of our upcoming antenna rotator for the Discovery Dish, and have created a quick preview timelapse of it running overnight. With mechanical designs like this it’s important to do some long-term testing, so we’re going to be running prototypes non-stop for several months while tracking many more satellites than would be typical.

DD Rotator Preview

 

Example Weather Satellite Images Downloaded

Some people have asked for high resolution examples of what can be received from satellites with the Discovery Dish. Below are a few samples.

GOES 18 Full Disk

Discovery Dish GOES 18 Full Disk Blend

 

GOES 18 Mesoscale

GOES 18 EMWINN

GOES 18 NWS

Metop AVHRR (Advanced Very High Resolution Radiometer)

Metop IASI (Infrared Atmospheric Sounding Interferometer)

GK-2A Full Disk

FengYun 4A Full Disk

Meteor MSU-MR (Multispectral Scanner Unit - Medium Resolution)

NOAA AVHRR (Advanced Very High Resolution Radiometer)

Crowdfunding Goals

We just wanted to clarify a point regarding how crowdfunding works. If the goal isn’t reached then everyone who ordered won’t be charged. We have had a few concerns from potential customers wondering if we will keep the money if the goal isn’t reached, but this is certainly not the case! In fact, credit cards will only be charged if we hit our funding goal. You can learn more in the Crowd Supply Guide.

The goal is set relatively high as this product requires a number of molds to be created for the dish and the various plastic parts, and molds typically have a high fixed initial cost. There is also a high minimum order quantity that we need to commit to in order to do a production run.

But the campaign is currently over 70% to its funding goal and we are expecting some large reseller orders to come in during the last few days of the campaign, so please don’t worry as the goal will almost certainly be reached with the help of just a few more individual supporters. If you have been on the edge, please consider supporting us to get this product started!

Customer Questions

In my environment temperatures get down to -20 to -30 degrees C. Will the electronics in the feed hold up?

The components used in the feed all have ratings down to at least -40 degrees C. In very cold environments, the one thing we would suggest considering is if a dish heater is required. These are heating strips that can be placed on the dish and can help melt snow/ice buildup.

What is the hole pattern on the dish?

The hole pattern on the dish has no specific function, the holes are simply used for reducing wind loading and weight. The manufacture of the prototype dish requires that the holes be cut by laser cutter, but the laser cutter we have available was not large enough to do the entire dish at once. So it was manually rotated around, and this caused an uneven pattern.

The production version of the dish will split into three petals, and each petal will be manufactured via a stamping process. Stamping is when a sheet of metal is placed under a heavy molded block of metal, and then that block of metal is pressed down on the sheet metal to create a desired shape. With this stamping process we will have perfectly neat hole patterns.

I suggest that the S-band version of the feed not use a downconverter, and just use an SDR that can receive S-band instead.

We currently have a similar opinion.

To explain this customer question/comment, we note that as mentioned in the previous update, we are planning to soon test an S-band version of the feed which should be able to receive S-band satellites.

However, the typical software defined radio used is an RTL-SDR, which cannot reach S-band frequencies like 2.2 GHz where most S-band satellites transmit. To get around this, we could add downconversion circuitry to the S-band feed, which would increase complexity and cost. This would convert the 2.2 GHz frequencies down to a frequency that the RTL-SDR can receive (below 1.766 GHz). Alternatively, we could simply recommend that customers interested in S-band reception instead use another SDR such as the HackRF, PlutoSDR, or LimeSDR Mini 2.0.

Once we have tested the S-band version of the feed, we will make a decision on if we should add a downconverter or just recommend the use of other SDRs that can reach the S-band.

Can any of the feeds be used for 1296 MHz EME (earth-moon-earth bounce communications)?

Sorry no, the feeds will not be suitable for EME, as that requires transmission which our feeds do not support.

I would like to use the dish on an astronomical mount. What is the expected weight of the dish and feed?

The dish itself weighs less than 1 kg (2.2 lbs). Together with the feed and mount we expect it to weigh a total of less than 1.5 kg. This is significantly lighter than a Wi-Fi dish which is already 1.6 - 2 kg (depending on the brand) for just the dish by itself.

Are weather satellites encrypted?

No, most weather satellites like this are not encrypted. Although these satellites come from various countries’ governmental space and/or military agencies, weather satellite data is generally considered public science. If it’s not necessary, adding encryption is undesired as it adds complexity to the system and increases the amount of data that needs to be transferred.

Obviously high-end military and commercial satellites are encrypted and we cannot receive data from those. It’s possible that future weather satellites could be encrypted, but given the current trend of new weather satellites being unencrypted this seems unlikely.

 

Crowd Supply Discovery Dish Teardown Session: Thursday 30 November Noon PST

Crowd Supply is hosting Teardown Session 38 on Thursday 3- November at Noon PST time which will feature the Discovery Dish. Join us for this livestream where I will be talking about and showing the Discovery Dish prototype.

Discovery Dish is currently being crowd funded over on Crowd Supply. It is designed to be an easy entry to the world of L-band weather satellites, hydrogen line radio astronomy, and Inmarsat reception. The Discovery Dish aims to be the start of an ecosystem of hardware designed to get users set up with satellite reception, including a planned companion light-duty antenna rotator.

Remember to click on the “Notify me” button on the YouTube link in order to be reminded about the stream!

Teardown Session 38: Discovery Dish

Modifying a 2.4 GHz WiFi Grid Antenna for Improved 1.7 GHz Reception + DIY Rotator Instructions

People have had much success in receiving L-band weather satellites like GOES and polar orbiting HRPT satellites using 2.4 GHz WiFi grid dishes, even though their 1.7 GHz signals are considered out of band for the WiFi grid dish feed. While this works most of the time, reception can be sometimes weak and borderline.

Over on Facebook and usradioguy.com, António Pereira has been sharing his mod which optimizes a 2.4 GHz feed for 1.7 GHz instead. The mod involves removing the enclosure of the feed which requires a heat gun to remove the glue, extending the feed's dipole by soldering on copper extension strips, tuning the dipole with a VNA, and finally tweaking the focal point. This results in an optimized L-band weather satellite antenna.

António Pereira has also shared instructions for creating an antenna rotator from an ESP32, Arduino Nano, two NEMA 23 stepper motors, two stepper controllers, two 50:1 worm gearboxes, and two optical homing switches, as well as power supplies for the motors and circuits. He also shares the Arduino code that he's written.

We also note that we currently are crowd funding for our Discovery Dish, which will be a ready to use satellite dish system for L-band weather satellites, as well as Inmarsat and hydrogen line radio astronomy. Check it out on Crowd Supply.

Modified dipole feed on a 2.4 GHz WiFi grid antenna feed
A DIY antenna rotator for the modified 1.7 GHz WiFi grid dish.
A DIY antenna rotator for the modified 1.7 GHz WiFi grid dish.

Discovery Dish Now Available for Crowd Funding! A Lightweight Dish and Feed for L-Band Weather Satellites, Hydrogen Line and Inmarsat

Today our Crowd Funding campaign for the Discovery Dish has gone live! Thank you to anyone who supports this project and our goal of bringing affordable products that make getting into various radio projects easier.

Our launch announcement reads:

We decided to develop Discovery Dish because we were disappointed by the lack of ready-to-use, low-cost, lightweight dish antennas on the market that are suitable for software-defined radio projects like receiving L-Band geostationary and polar-orbiting weather satellites, as well as for 1.5 GHz Inmarsat reception and 1.42 GHz hydrogen line radio astronomy. With excellent open source weather satellite decoding software, like SatDump, now available, it’s time for a complementary, easy-to-use hardware solution.

Through testing over several years, we chose 65 cm as the diameter, as we found that 60 cm is close to the minimum diameter required for perfect GOES weather satellite reception at 24° elevation, so this size should be suitable for most of the world that has GOES reception available. For LRPT satellites like GK-2A, and HRPT polar-orbiting satellites, it is more than large enough. We combined the dish with a carefully tuned feed that has a built-in low-noise amplifier (LNA) and dual filtering, which means there is no loss from feed to LNA. This also means we can use thinner and less stiff coax cable, which is a lot easier to handle and route. Finally we ensured that the entire dish and feed system is waterproof.

The only other ready-to-use dish offering we found is based on a modified 2.4 GHz grid Wi-Fi dish, which is still in our opinion too big and heavy. Size and weight is especially the important if you want to be able to use a low-cost, light-duty antenna rotator, which typically can only handle less than 1 kg in weight. We found that the grid Wi-Fi dish offering also has no solution for waterproofing the LNA, so the LNA needs to be placed indoors and very thick and unwieldy coax is used to avoid feed to LNA losses.

Other ways to receive these weather satellites and carry out hydrogen line experiments typically involve modifying a 2.4 GHz Wi-Fi grid antenna, or an old satellite TV dish. But these modifications can be time-consuming and difficult to get right, and even 60 cm satellite TV dishes are too heavy for light-duty antenna rotators.

Finally, we developed Discovery Dish with an eye toward it being used with a low-cost antenna rotator, and we are in the process of prototyping our own rotator design. Our antenna rotator is not ready for crowdfunding yet, as there are still some things to work out and long-term stress testing to be done, but please keep an eye out for it in 2024! An antenna rotator is a great addition if you want to use a dish antenna to decode images from the polar-orbiting HRPT weather satellites.

Note that you don’t need an antenna rotator to receive geostationary satellites like GOES, or to do drift hydrogen line observations. For polar-orbiting HRPT satellites, the lightweight nature of Discovery Dish also makes tracking the satellites by hand a much easier prospect.

Learn more about Discovery Dish on our main campaign page. Thank you to everyone who supports the Discovery Dish project in any way!

Discovery Dish: Simplified system for weather satellite reception and hydrogen line radio astronomy