He's now begun a new series on his channel where he will be exploring the world of software defined radio in more depth. The first video that he's uploaded today is an overview where he overviews EMS communications, aircraft signals, military air signals, maritime signals, space signals, as well as other interesting signals he's received like wireless earpieces for musicians at concerts and TV studio talkback links. He writes:
The 2020 SDR Guide Episode 1 has just been released. It serves as an introduction to the incredible world of Software Defined Radio and will be of interest to both beginners and more advanced users.
Over the next few weeks, Frugal Radio will be exploring various aspects of using SDRs within the hobby. These include :
DragonOS is a ready to use Linux OS image that includes various SDR programs preinstalled and ready to use. The creator Aaron also runs a YouTube channel that has multiple tutorial videos demonstrating software built into DragonOS.
In his latest video Aaron explores Iridium reception with an RTL-SDR Blog V3, RTL-SDR Blog Active L-Band Patch Antenna and Iridium Toolkit/gr-iridium. Iridium is a satellite constellation that provides services such as global paging, satellite phones, tracking and fleet management services, as well as services for emergency, aircraft, maritime and covert operations too.
In the video he shows how to edit the config file to turn the bias tee on, how to record Iridium data, how to install the AMBE voice decoder, and finally how to decode the Iridum data with Iridium toolkit and play voice recordings.
DragonOS LTS Decoding Iridium satellites with the Iridium toolkit (gr-iridium, RTL-SDR)
Just after our post a few days ago about an art project involving weather satellite reception with SDRs, we received a story submission about an artistic performance with similar weather satellite and SDR themes. The submission from Sasha Engelmann reads:
Open Work, Second Body asks: From the climate crisis to coronavirus: what are the tools we need to make sense of events unfolding on vastly disparate scales? Through spoken word, field recordings and live radio reception of two NOAA satellite images, the work probes the porous boundaries between our bodies, local atmospheres and weather systems.
Due to lockdown constraints in London, Sophie and Sasha were not able to be in the same place or to leave their apartments, so they performed the work via simultaneous streams from their respective balconies in South East and North West London. Using RTL-SDRs, Turnstile antennas, Open Broadcast Software and collaborating with two NOAA satellite passes, Sophie and Sasha shared the process of decoding NOAA satellite images with hundreds of viewers around the world, employing spoken word poetry and field recordings to complicate relationships of local and global, weather and climate, the individual and the collective.
Recordings of the performances can be found at the links below.
Open Work, Second Body is part of Sophie and Sasha's larger artistic research and design project Open Weather, which employs ham radio, open data and feminist theories and approaches to build new and diverse communities around satellite image decoding and weather sensing. The Open Weather web platform will be launched in Summer 2020 and will host an archive of SDR-generated weather images, visually rich how-to guides for those with no radio and engineering experience, and material about Sophie and Sasha's collaborative artistic practice.
For Open Work, Second Body, Sophie and Sasha would like to thank the Soundcamp Team: Grant Smith, Dawn Scarfe, Christine Bramwell, Maria Papadomanolaki and Ciara Drew. They are grateful to Daisy Hildyard for her willingness to be in conversation with them, Bill Liles NQ6Zfor technical advice, Jol Thoms for sound design, Rachel Dedman, Laure Selys and Arjuna Neuman (Radio Earth Hold) for early curatorial input, Akademie Schloss Solitude for the support of a residency, the satellites NOAA 18 and NOAA 19 and the RTL-SDR and wider ham radio community.
As part of his Masters in Design Studies studies Daniel Tompkins created an art installation called "signs of life" which was focused around his interest in weather satellite reception with an SDR.
FM radio headphones were given out at the door. Each set was tuned beforehand to receive a broadcast from my pre-programmed station.
Visitors were then invited to walk around the room, contemplating the artifacts of the exhibit. A V-dipole at one end of the room captures the broadcast and displays a real-time spectrogram of the radio waves on a small display.
Across the room, a satellite dish points back, creating an alignment across the projected GOES-16 "full-disk" image animation of the Earth. Along the back wall, a few dozen images show demodulated signals from the NOAA 15/18/19 satellites as they passed over Cambridge, Massachusetts in the months of October and November 2018.
The experience demonstrated my interest in tapping into an invisible (wireless) environment of digital information. A USB, software-defined radio (SDR) dongle helped me reach the satellites.
In listening to the transmission, the visitors are engaging in a shared experience, but are somehow still alone and unable to communicate while wearing their headphones. The performance of the exhibition is designed to be a place which simulates the real disconnection of techno-humanity. The "reﬂecting pool" of the earth spinning on the ﬂoor might provide a metaphorical reﬂection of humanity and progress.
This installation reminds us of the "Holypager" live art piece which used a HackRF to receive and print out live pager messages with an aim to demonstrate the amount of personal data being sent publicly over pagers. Another related art piece was the "Ghosts in the Air Glow" project by Amanda Dawn Christie, which saw the HAARP Auroral research facility used to transmit various art pieces to be received from all over the world by people with HF radios.
[@aang254] made a custom HRPT decoder and ported HRPT blocks for NOAA, METEOR and MetOp to work with gnuradio 3.8 on Linux. Right now it is the only free and open source decoder for MetOp (that works), and he also thinks about implementing FengYun support. I tested the decoder and it works great.
He's also working on extracting the full data from HRPT, not just the AVHRR/MSU-GS imagery but also all the telemetry and other instrument data.
HRPT is a high resolution weather satellite image signal that is broadcast from the same NOAA satellites that provide the more commonly received low resolution APT images at 137 MHz. HRPT is also broadcast by the FengYun-3, Metop and Meteor satellites. However, HRPT transmits at 1.7 GHz, so a high gain dish antenna with motorized tracking mount (or hand guided tracking), LNA and a high bandwidth SDR like an Airspy is required to receive it.
Apart from APT there is also the HIRS instrument data which is transmitted in the Direct Sounding Broadcast (DSB) telemetry signal that is spaced at a slight offset from the APT frequency. According to NOAA, the HIRS instrument is "a discrete stepping, line-scan instrument designed to measure scene radiance in 20 spectral bands to permit the calculation of the vertical temperature profile from the Earth's surface to about 40 km". The SDR# screenshot below shows what the HIRS signal looks like, and to the sides you can see NOAA APT signals.
NOAA-HIRS-decoder makes use of the Project-Dessert-Tortoise NOAA satellite telemetry decoder that we posted about previously which can be used to decode data from most of the other scientific instruments on the NOAA satellites. The HIRS decoder by Zbigniew uses the raw text data produced by the Project-Dessert-Tortoise decoder and converts it into images. Full instructions on setting up the decoder on Windows is provided on the NOAA-HIRS-decoder website, just click the menu icon on the top right of the page, and go to "usage".
The received data contains 10 channels of long wave infrared, 9 channels of medium wave infrared, and one visible light measurement. The software will plot the 20 channels as images that are 56 pixels wide. This is not a high resolution picture, but it is nevertheless valuable data that can be used for scientific or weather prediction purposes.
A new video showing how to build a V-dipole for weather satellite reception has been uploaded over on the Tech Minds YouTube channel. A V-dipole isa dipole antenna arranged in a 120 degrees "vee" shape, and mounted horizontally. It was first popularized by Adam 9A4QV who realized that such a simple antenna would work well for low earth orbit satellites like the NOAA and Meteor weather sats.
The video shows how to use some steel rods, a plastic pipe and terminal block to build the v-dipole. After building and mounting the antenna in the required North-South orientation he shows how he's using Gpredict with SDR# and WxToImg to decode the NOAA satellite image.
How To Build A V Dipole For Receiving Weather Satellites
Back in March we posted about Othernet's release of their "Bullseye" TCXO ultra stable LNB for receiving QO-100 and other Ku-Band satellites. We have decided to now offer these for sale on our store as well.
They cost US$29.95 with free shipping to most countries. We are currently selling it over on our blog store and on our Aliexpress store. The Aliexpress store uses Aliexpress Standard Shipping which may be better for some countries like Poland, Ukraine, etc. As usual, please expect that there could be shipping delays at the moment due to the ongoing global pandemic. Since the US is not covered by QO-100 we will not be stocking Amazon USA.
QO-100 / Es'hail-2 is a geostationary satellite at at 25.5°E (covering Africa, Europe, the Middle East, India, eastern Brazil and the west half of Russia/Asia) providing broadcasting services. However, as a bonus it has allowed amateur radio operators to use a spare transponder. Uplink is at 2.4 GHz and downlink is at 10.5 GHz. Most SDRs do not tune all the way up to 10.5 GHz, so an LNB (low noise block) is typically used, which contains the feed, an LNA, and a downconverter which converts the 10.5 GHz frequency into a much lower one that can be received by most SDRs.
In order to properly monitor signals on QO-100 an LNB with a Temperature Compensated Oscillator (TCXO) or other stabilization method is required. Most LNBs have non-stabilized crystals which will drift over time with temperature changes. This means that the narrowband signals used on QO-100 can easily drift out of the receive band or cause distorted reception. It is possible to hand modify a standard Ku-band LNB by soldering on a replacement TCXO or hacking in connections to a GPSDO, but the Bullseye LNB is ready to use and cheap.
The official product details read:
The Bullseye LNB is the world's most precise and stable DTH/consumer Ku-band down converter. Even a VSAT LNBF costing hundreds of dollars more is no match for the performance of the Bullseye 10K LNB. Each unit is calibrated at the factory to within 1 kHz of absolute precision against a GPS-locked spectrum analyzer. Under outdoor conditions, the stability of the LNB is well within 10 kHz of offset. As a bonus feature, the Bullseye 10K provides access to its internal 25 MHz TCXO through the secondary F-connector. This reference output can be used to directly monitor the performance of the TCXO over time.
Bullseye 10 kHz BE01
Universal single output LNB
Frequency stability within 10 kHz in normal outdoor environment
Phase locked loop with 2 PPM TCXO
Factory calibration within 1 kHz utilizing GPS-locked spectrum analyzers
Ultra high precision PLL employing proprietary frequency control system (patent pending)
Digitally controlled carrier offset with optional programmer
25 MHz output reference available on secondary F-connector (red)
Return loss of 8 dB (739 - 1950 MHz) and 10 dB (1100 - 2150 MHz)
Noise figure: 0.5 dB
We note that an external bias tee power injector is required to power the LNB as it requires 11.5V - 14V to operate in vertical polarization and 16V - 19V to operate with horizontal polarization. The bias tee on the RTL-SDR Blog V3 outputs 4.5V so it is not suitable.