Tagged: GOES

Decoding EMWIN Weather Information VHF Rebroadcasts with an RTL-SDR

EMWIN is an acronym for Emergency Managers Weather Information Network, and is a service for emergency managers that provides weather forecasts, warnings, graphics and other information in real time. EMWIN is broadcast from geostationary NOAA GOES satellites, and if you have a GOES SDR receiver setup it is possible to receive and decode EMWIN data.

However, if you don't want to set up a GOES receiver, KD9IXX writes on his blog how he investigated EMWIN and found that 24/7 dedicated EMWIN VHF repeaters are common around the US. Having found an EMWIN repeater in his area at 163.37 MHz he used the TrueTTY decoder and was able to successfully decode the 1200 baud 8-bit ASCII encoded signal and receive weather text information. He notes that VHF EMWIN is an excellent source of non-internet based weather data that could be useful to anyone requiring weather data in emergency circumstances.

EMWIN VHF Repeater Decoded with TrueTTY
EMWIN VHF Repeater Decoded with TrueTTY

Weather Satellite Images from Geostationary COMS-1 Received

COMS-1 Geostationary Satellite Footprint
COMS-1 Geostationary Satellite Footprint https://www.wmo-sat.info/oscar/Satellites/view/33

COMS-1 is a geostationary weather satellited operated by the Korean Meteorological Agency (KMA) which was launched back in 2010. It is similar to NOAA GOES satellites as it is also geostationary orbit (@128.2°E - footprint covers all of Asia + AUS/NZ), and so is far away enough to image the entire disk of the Earth at once. Unfortunately, unlike the GOES satellites which have in the past few years become relatively easy for hobbyists to decode, the COMS-1 LRIT and HRIT downlink data is encrypted by KMA. KMA only appear to provide decryption keys to governments, research institutes and large organizations upon request.

However, recently Australian @sam210723 was able to successfully create code to decrypt the key message file and obtain the images. From a previous Twitter post of his, it appears that the encryption keys from the KMA example code are actually valid and can be used without needing to apply for a key.

Sam notes that he'll soon release a full blog post on his results, but for now he has an older post from last year that explains a bit about the satellite and decryption of the LRIT Key. His code is available on GitHub, and in a recent Twitter post he shows some example images that he's been able to receive using an Airspy SDR.

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.

USA-Satcom XRIT Decoder Updated

USA-Satcom is the programmer of XRIT Decoder (not to be confused with XRITDecoder by CM2ESP), which is a popular (paid) Windows decoding application for GOES weather satellites. Recently, over on the SDRplay forums RSP2user made a note about the latest update:

USA-Satcom has just released v2.1.0.0 of the XRIT Decoder. Along with enhancements for the XRIT Decoder, a new RSP Streamer X has been released and is operable with the RSP1A, RSP2, and RSPduo - new features include operation with two streams simultaneously (provided that the PC being used has sufficient processing power and an RSPduo or more than one compatible RSP are being used). Also new is the XRIT File manager which allows for improved operation with both LRIT and HRIT files, improved LUT for excellent false color images, user-selectable automated black filling of the white background on full disk visual and false color HRIT images, and country as well as state map overlays.

The new color enhancements are excellent:

GOES 16 Full Disk Weather Satellite Image. Received by RSP2user with V2.1.0.0 of XRIT Decoder.
GOES 16 Full Disk Weather Satellite Image. Received by RSP2user with V2.1.0.0 of XRIT Decoder.

If you are interested in receiving and decoding GOES images, we now have several previous blog posts on this topic which may be helpful.

Receiving GOES Weather Satellite Images with GNURadio and XRITDecoder in Windows

Thank you to ON7NDR as well as CM2ESP for submitting and figuring out a way to get GOES 16 decoding working with RTL-SDR using the free XRITDecoder, Xrit2Pic software and GNU Radio for Windows. 

ON7NDR's story is that he wanted to be able to receive GOES 16, but not being familiar with Linux he wanted a Windows based solution. He writes that the credit to finding the solution goes to CM2ESP who has written up a tutorial (pdf) explaining how to set everything up in Windows. ON7NDR has also written a separate complimentary tutorial (docx) that explains some steps in CM2ESPs tutorial a little further and provides a few tips on choosing correct the correct version of GNU Radio. He's also provided a screenshot showing what the correct config file looks like for an RTL-SDR dongle.

We note that for Windows there is also USA-Satcom's XRITDecoder, however this is closed source software which costs $100 USD.

GOES Full Disk Image of the Earth
GOES Full Disk Image of the Earth

A Step by Step Tutorial to Receiving GOES-16 Images with an RTL-SDR, Raspberry Pi and Goestools

Aleksey Smolenchuk (lxe) has recently uploaded a step-by-step guide to setting up a GOES weather satellite receiver with an RTL-SDR dongle, Raspberry Pi and the goestools software.  GOES 15/16/17 are geosynchronous weather satellites that beam high resolution weather  images and data. In particular they send beautiful 'full disk' images which show one side of the entire earth. Compared to the more familiar and easier to receive low earth orbit satellites such as NOAA APT and Meteor M2 LRPT, the geosynchronous GOES satellites require slightly more effort as you need to set up a dish antenna, use a special LNA, and install Linux software.

Aleksey's tutorial first shows where to purchase the required hardware and notes that the total cost of the system is around $185. Next he goes on to show the hardware connection order, and then how to install and configure the goestools decoding software onto a Raspberry Pi.

Aleksey's RTL-SDR Based GOES Receiver setup
Aleksey's RTL-SDR Based GOES Receiver setup

YouTube Video Demonstrates GOES Weather Satellite Reception

On The Thought Emporium YouTube channel a new video has been uploaded showing the full disk images of the earth that they've been able to receive from GOES geosynchronous weather satellites. Over the past couple of years GOES satellite reception has become much easier for hobbyists to achieve with the release of the NooElec SAWbird LNA+Filter, information on how to use a cheap 2.4 GHz WiFi grid antenna for reception and the release of free open source decoder software. It was also shown that an RTL-SDR dongle is sufficient for receiving these images as well. With all these new developments it is now possible to build a GOES receiving station for under $100.

The Thought Emporium video blurb reads:

In the fall of 2016 I saw my first rocket launch and little did I know that the satellite on that rocket would come to shape and fill my thoughts for many years. We're no strangers to getting data out of space on this channel, but GOES-16 is special, and not just because I was there when it left earth. Unlike the satellites we looked at in the past, GOES is in geostationary orbit and has an amazing suite of cameras and sensors on board. While it's a bit harder to receive data from GOES the extra effort is absolutely worth it, especially because it can see then entire globe all at once and send out those images in stunning high resolution. And it even comes with the added bonus of rebroadcast data from other satellites giving us a view of the opposite side of the planet as well.

In this video we go through the hardware and software needed to receive these gorgeous images and what is contained in the signals we receive.

How to Receive Beautiful Images of the Earth Directly From Space | GOES-15,16,17 and Himawari 8 HRIT

NooElec SAWBird: An LNA + Filter for GOES Weather Satellite Reception Now Available

NooElec has just released their new "SAWbird" GOES LNA for sale. This is an LNA and filter combination designed to help receive GOES weather satellite images. On the PCB is a 1688 MHz SAW filter and a low noise amplifier. It can be powered with 3V - 5.5V connected directly or via bias tee. The SAWbird is currently available on Amazon and their store for US$34.95. They also have a version for Inmarsat and Iridium, so make sure you choose the correct one.

GOES 15/16/17 are geosynchronous weather satellites that beam high resolution weather  images and data. In particular they send beautiful 'full disk' images which show one side of the entire earth. As GOES satellites are in a geosynchronous orbit, the satellite is in the same position in the sky all the time, so no tracking hardware is required and images can be constantly pulled down throughout the day without having to wait for a satellite to pass over. 

However, compared to the more familiar and easier to receive low earth orbit satellites such as NOAA APT and Meteor M2 LRPT, geosynchronous satellites like GOES are quite a bit further away, and transmit at 1.7 GHz. So to receive the signal you'll need a dish antenna that you can accurately point, a good low noise figure LNA and possibly a filter. So setting up a receiver is a bit more difficult when compared to receivers for NOAA and Meteor satellites. The SAWbird should help however, by providing a ready to use LNA+Filter combination.

Over the past few months several testers have already received engineering samples of the SAWbird and have been successful at receiving GOES images. From the results of several experimenters, it appears to be possible to use a cheap 2.4 GHz WiFi grid antenna with some minor modifications as a GOES satellite antenna. Get one with at least a one meter long width and bend the feed as described here or here to tune reception for the 1.7 GHz GOES frequency. Pieter Noordhuis has also shown that it's possible to use an RTL-SDR to receive GOES images, so an entire GOES system can be built on a budget.

NooElec SAWbird LNA + Filter for GOES reception.
NooElec SAWbird LNA + Filter for GOES reception.
GOES Full Disk Image of the Earth
GOES Full Disk Image of the Earth