Over on YouTube Adam 9A4QV has uploaded a video showing how to build a DIY bandpass filter for 137 MHz. This can help improve the reception of NOAA and Meteor M weather satellites, by blocking strong out of band signals. Adams design is a 132 MHz – 142 MHz Butterworth bandpass filter which gives about 35 dB attenuation outside of the pass band. He’s also posted a write up documenting the filter design on his website.
Lucas Teske recently went ahead and built the 137 MHz filter suggested by Adam. Lucas didn’t have the correct capacitor values so he ended up cascading several in series. His results showed that the filter did improve his reception significantly.
A few days ago we reported that the Outernet L-band satellite service had just upgraded their software to make it available for receiving APRS and weather updates. Back then it wasn’t clear what the weather updates would entail. Today weather updates starting being transmitted. They are using NOAA data and displaying it on a live weather app (which can also be viewed online here).
The app can be used to view weather data such as wind vectors, temperatures, relative humidity, total precipitable water, total cloud water, mean sea level pressure and ocean currents. Outernet writes that the global weather data will be updated via their satellite system once per day, and that each update also provides 24h, 48h and 72h predictions.
We also see that grib files for mariners are now coming in as well as several Wikipedia articles and regular APRS broadcasts from the ISS.
It looks like the Outernet service is becoming more and more useful over time. If you are interested in receiving Outernet with an RTL-SDR see our tutorial post here.
Over on Reddit user merg_flerg has uploaded an imgur post that carefully details a step by step guide for building a double cross antenna. A double cross antenna is great for reception of satellites like NOAA and Meteor since it has a sky oriented radiation pattern with very few nulls. This means that it can receive satellite signals coming from the sky well. Alternative antennas for NOAA/Meteor include turnstiles and QFH antennas, although the double cross antenna seems to have the least nulls, meaning that the signal is less likely to fade in and out as the satellite moves across the sky.
merg_flerg’s design is also modified from the standard design slightly, allowing it to become easily disassembled and carried within a backpack. At the end of his tutorial he writes that he gets much better reception with his double cross antenna than he does with his QFH.
In the post he demonstrates the final constructed antenna decoding a NOAA APT weather satellite image with an RTL-SDR and the WXtoIMG software. See our tutorial for information on decoding NOAA weather satellite images.
It is well known that the NOAA satellites broadcast weather satellite images which can be received and displayed with an RTL-SDR and computer. What is less known is that there is a telemetry beacon that is also transmitted by the same satellites. The telemetry not only contains data such as the current spacecraft time, day and ID, but also contains scientific data from on board instruments such as:
The HIRS/3 and HIRS/4 instruments which is a high resolution infrared sounder which can be used to create a low resolution multi-spectral scan of the earth. (more info)
The Space Environment Monitor (SEM-2) which has a Medium Energy Proton and Electron Detector (MEPED), and a Total Energy Detector (TED). This experiment is used to measure the effect of the sun on satellite communications. (more info)
The experimental DCS/2 transmitter which retransmits signals from 401.65 MHz sea buoys, arctic fox collars, sea ice monitors, weather balloons and more. (more info pdf)
The ARGOS Advanced Data Collection System (ADCS) which amongst other uses is used in research for tracking animal GPS collars around the world.
According to various reports the Russian Meteor M-N2 satellite appears to be active again once more. The Meteor M N-2 is a polar orbiting Russian weather satellite that was launched in July 2014. It transmits with the LRPT protocol which allows us to receive weather satellite images with an RTL-SDR that are of a much higher resolution than the NOAA APT satellites.
Unfortunately late last year Meteor M N-2 had some problems and LRPT transmissions were turned off for the time being. During this downtime the Russian space agency switched the LRPT transmitter on the older Meteor M N-1 satellite back on, even though the satellite was tumbling in orbit. Currently people are not reporting any signal from Meteor M N-1, so this may have been turned off, perhaps temporarily.
Now however, it seems that Meteor M N-2 has been switched back on again and various people have already successfully received its signal. If you want to receive these Meteor M N-2 weather images with an RTL-SDR dongle or other SDR then you can view the tutorial written by Happysat here.
In order to optimally receive NOAA weather satellite images a special satellite antenna tuned for 137 MHz should to be built. Generally either a QFH or turnstile antenna is recommended as these receive signals coming from the sky very well. If you are interested in receiving weather satellite images from NOAA satellites with an RTL-SDR dongle then we have a tutorial available here.
While QFH and turnstile antennas are not difficult or expensive to build, they still do require a small amount of electrical and construction skills. Over on YouTube user Wanderlinse shows us a possible alternative NOAA antenna that is simply made out of an old umbrella (the video is narrated in German, but it is easy to understand from the visuals). He uses a short BNC cable with crocodile clips, and connects one clip to the spines of the umbrella, and the other to the central metal shaft. For some reason this seems to create a good antenna that receives NOAA APT signals very well. To prevent wind issues he also cuts out some holes in the umbrella fabric.
Wanderlinse also shows that he can receive other signals with this umbrella antenna too, such as long wave, medium wave, shortwave, aircraft radio and ham radio.
The Meteor M N-2 is a polar orbiting Russian weather satellite that was launched in July 2014. It transmits with the LRPT protocol which allows us to receive weather satellite images that are of a much higher resolution than the NOAA APT satellites. For a while since the launch RTL-SDR users had a good time receiving beautiful images from Meteor M-N2, but unfortunately since late last year the N2 LRPT transmitter has been turned off, due to technical problems with the IR sensors as cited by Russian meteorologists.
Fortunately for Meteor N2 enthusiasts the old Meteor M N1 satellite which was thought to be dead sprung back into life around November 2015. Recently Matthew A., a reader of our blog wrote in to let us know that while N2 is still not transmitting, N1 is still transmitting, albeit with somewhat distorted images. Matthew also mentions this link: http://homepage.ntlworld.com/phqfh1/status.htm, which contains up to date info on the status of all weather satellites. He also writes:
While transmissions are readily detectable and decodable at night, it seems that M N-1’s infrared sensors are not functioning. Yielding only black, with the typical noise bars of Red, Green, or Blue
As has been previously mentioned, Meteor MN-1’s stabilization system has obviously failed, and the horizon is clearly visible. Perhaps not of scientific value, but certainly beautiful.
Recently a reader of our blog, Initrd, wrote in to let us know about a new tutorial he created that shows how to set up a dual NOAA APT and Meteor LRPT weather satellite monitoring station with an RTL-SDR dongle. These weather satellites transmit a live image of the portion of the earth that they are currently over, providing a valuable tool for weather analysis. APT transmissions are analogue and are transmitted by the American NOAA satellites, and the newer Meteor M2 satellite transmits a higher resolution image in the LRPT format. We also have posted separate tutorials that show how to set up NOAA APT and Meteor M2 LRPT decoding with an RTL-SDR, but Initrd’s tutorial appears to be a good all in one guide.
His tutorial takes you step by step through a process that involves setting up the satellite tracking software Orbitron, all the required SDR# plugins, the APT decoder WXtoIMG and the LRPT decoder. The tutorial also shows how to connect them all together and set them up so that APT and LRPT decoding can coexist.