GreenCube is a CubeSat by the Sapienza University of Rome, and it is designed to demonstrate an autonomous biological laboratory for cultivating plants onboard a CubeSat.
While this is an interesting mission in itself, for amateur radio operators there is another interesting facet to the satellite. Unlike most CubeSats which are launched in Low Earth Orbit (LEO), GreenCube was launched higher in Medium Earth Orbit (MEO) which provides a larger radio reception footprint over the earth. The satellite also contains a digital repeater (digipeater) at 435.310 MHz, which allows amateur radio operators to transmit digital radio packets up, and have the satellite repeat the packet back over a wide area footprint on earth.
Over on his latest video, Matt, from the TechMinds YouTube channel shows us how to receive and decode the packets from the GreenCube digipeater. In his demonstration Matt uses an SDRPlay RSPdx as the receiver, SDR++ as the receiver software, SoundModem as the packet decoder, GreenCube Terminal for displaying the messages, and GPredict for tracking the satellite and compensating for the doppler effect. He also notes that while a directional antenna on a motorized tracker is recommended, he was able to still receive packets with his omnidirectional terrestrial antennas without much issue.
The "RFinder Android Radio 10 Inch Tablet - 136-174mhz, 400-490mhz DMR/FM - Embedded RTL-SDR" is able to be pre-ordered for $1,499.95 USD + shipping. It is a ruggedized 10 inch Android tablet with a built in two way 4W VHF/UHF DMR/RF radio as well as an additional built in RTL-SDR. In terms of computing hardware, it comes with an Octa-Core 2.3 GHz CPU, 4GB RAM, 64GB ROM, and it supports cellular connectivity.
In their manual they share the following slide showing the built in RTL-SDR running the RF Analyzer Android app.
Various reviews of the RFinder P10 have been showing up on YouTube. Here is one review by Ham Radio 2.0 where the RFinder P10 is demonstrated at the Huntsville Hamfest.
New RFinder P10 Tablet with Dual Band DMR and RTL-SDR Receiver - Huntsville Hamfest
One part of the amateur radio hobby is 'EME', or Earth-Moon-Earth. The idea is to bounce radio signals off the surface of the moon, and have them received over a vast distance. Typically weak signal amateur radio modulation schemes such as JT65 are used due to their ability to be decoded even with the very weak signals that come back from the moon bounce.
Recently a group of students from the College of New Jersey are attempting to bounce signals off the moon using the LoRa modulation scheme. LoRa is a modulation scheme designed to be used with IoT devices, however it also has great performance when signals are weak so it's a good candidate for moon bounce.
The students are using a HackRF and the SDR-Angel software with the signal being transmitted in the amateur radio bands at 1296 MHz. The antenna hardware consists of an 1296 MHz feedhorn attached to an 8-meter dish. They hope that the use of LoRa modulation can reduce the power requirements for EME.
The main goal of this project is to establish Earth-Moon-Earth communication with LoRa modulated signals. There are three main goals that this project is trying to accomplish. The three goals of our project are to reflect a signal off the Moon and receive it back here in New Jersey, transmit a signal from here in New Jersey, bounce it off of the Moon, and then receive the signal on a dish located in Alaska, and our final goal for this project is to establish two way communication between New Jersey and Alaska.
Our initial approach to this project is to use SDRAngel to modulate and demodulate our signal. SDRAngel is a free, open-source software that we can use to transmit and receive signals via SDR (Software Defined Radio).
Our modulation technique, LoRa, uses Chirp Spread Spectrum modulation that allows for low power, long range transmissions at the cost of a low data rate.
The peripheral of choice for this project is the HackRF One, a SDR peripheral that allows us to send and receive signals.
It was to be a US$149 FT8 receiver based on an open source RF chip design, capable of acquiring signals between 7 MHz and 70 MHz (technically 1 MHz to 100 MHz). Shipments were expected to begin in April 2023.
Unfortunately the Maverick team just released today that the project will be suspended indefinitely due to logistical issues. Backers of the project will receive a full refund.
The Maverick-603 project has been indefinitely suspended due to unforeseen logistical obstacles. No funds have yet been spent and all backers will receive full refunds. If you backed this project, your refund will be issued within the next week to the credit card you originally used. If your credit card is no longer valid, please contact Crowd Supply support before midnight UTC on Friday, April 28, 2023 to arrange your refund. If the Maverick-603 project is revived, we will post another update. Thank you for your support and patience.
Since the famous takedown of a suspected Chinese spy balloon, US jets have shot down a total of three more unidentified balloon objects, now suspected by officials to be 'commercial or benign'. There is speculation that at least one these three objects may have been an amateur radio 'pico' balloon.
One part of the amateur radio hobby is launching high altitude balloons with various radio and other payloads. Larger amateur radio balloons launched in the USA require FAA clearance, need a radar reflector attached, and usually continually transmit APRS telemetry before naturally popping and falling back to earth after a few hours, just like a weather balloon.
However there is also the simpler 'pico' ballooning hobby, which involves the use of mylar helium party balloons to launch small solar powered payloads that are only a few grams in weight. They typically transmit low power WSPR at HF frequencies and can only transmit whenever there is sufficient solar power available. Amateur radio or SDR hobbyist stations around the world can pick up these transmissions, and report them on amateur.sondehub.org and/or wsprnet.org. Well built balloons can totally circumnavigate the globe several times over several months before degrading.
While termed 'pico', the party balloons used can still be roughly a meter in diameter on the ground, with some latex balloons potentially expanding further at high altitudes due to the low atmospheric pressure. These balloons can be legally launched from almost anywhere in the world. In particular in the USA there is no FAA clearance required to launch them due to their payload being much less than the limit of 4 lbs (1.8kg).
There is speculation that at least one of the objects shot down over Canada, Yukon by a US Air Force jet may have been amateur radio pico balloon K9YO-15 which was launched from Illinois on October 10 2022. It was on it's seventh circumnavigation of the globe after being aloft for 123 days.
The launch blog post indicates that the K9YO-15 balloon was flying a silver mylar 32" sphere SAG balloon which appears to be this one from balloons.online. Unlike latex or rubber weather balloons which inflate and stretch as they rise into lower atmospheric pressures, these mylar balloons can't stretch, so their fully inflated ground size will be the same as their size at high altitudes, meaning the pico balloon won't get much bigger than 32". The payload was a GPS module, Arduino, SI5351 used as a WSPR and APRS transmitter and a solar panel, all together weighing 16.4 grams. A pentagon memo notes that the object shot down over Canada was a "small metallic balloon with a tethered payload" which fits the description of the pico balloon exactly.
The K9YO-15 balloon ceased all WSPR telemetry transmissions while flying just below Alaska since Feb 11 00:18 UTC (just before sunset in Alaska when the solar panels would stop working).
By using NOAA wind models and the last known location by Alaska, K9YO-15 was projected to have been over Yukon when the US Air Force shot down the unknown balloon object at Feb 11 20:41 UTC (3:41 PM EST / 1:41 PM Yukon time according to Canadian Defense Minister Anand). Reports put the altitude of the shot down object at approximately 40,000ft (~12000 meters), which matches the projected ~11500 meters of K9YO-15. Based on the previous days transmission times, it is suspected that if it were operational, the balloon would have begun transmitting again sometime later in the Yukon afternoon when the sun was stronger, but no transmissions have been seen.
The search area for the fallen balloon debris is reported to be in difficult to access terrain between Dawson City and Mayo. If we do a rough overlay of the predicted trajectory over a Google map, we can see that the predicted location of KY9O-15 at the reported time of the missile impact matches this description very well.
Over on Twitter @ikluft (KO6YQ) has been reporting on this speculation, and has been keeping an eye on K9YO-15, awaiting telemetry transmission. We recommend following his account for further updates.
NIBBB #HamRadio club of Illinois🇺🇸 declared K9YO #balloon "missing in action" after no telemetry was received for 5 days. It was projected to be over Yukon Saturday when NORAD🇺🇸🇨🇦 shot down an "unknown object", close enough to raise questions. https://t.co/9ZkRqkc6Zr#aviation
I see you're all talking about my tweet. Yes, we are still watching to see if K9YO-15 transmits any telemetry today.
So far K9YO-15 has not sent any new telemetry since Friday before sunset over Alaska. Some have misread confusing data presentation on Sondehub which lists last known telemetry as covering a time range from then to now. Currently the last we've heard from K9YO-15 was Friday Feb 10 before sunset over Alaska (00:48 GMT Feb 11). But the map on Sondehub does show the last reported position.
These floater balloons often use only solar panels, no batteries. Batteries were dropped from the projects early on because they have limited charging cycles before they stop accepting a charge, especially in the harsh temps at altitude, -40F/-40C or worse. When the battery stops accepting a charge, it ends telemetry from the mission. So they only report telemetry during daylight, when the sun is at a high enough angle to illuminate the tiny solar panels. In the Arctic winter, the days are short and the sun might not get high enough to wake up the electronics. So it stays dormant for one or more days until it drifts back down to lower latitudes where there's more sunlight. So K9YO-15 was in a period where watchers didn't expect to hear from it for a few days. But we expected it today. So far nothing. As I write this, daylight is almost done way up there for Tuesday, Feb 14.
We (the Amateur Radio balloon community) only expect any telemetry from it today would be via WSPR, none via APRS. WSPR uses HF and can be received at long distances, where it's relayed to Internet map sites. APRS is (usually) on VHF and UHF, only received by line of sight. There are no relay stations in range of today's projected flight course in northern Ontario and James Bay, Canada. So APRS-fed sites wouldn't show updates today anyway.
For an introduction, I'm Ian KO6YQ. I was involved in the first Ham Radio balloons that circumnavigated the globe starting in 2016, launched from San Jose, California. I had roles on them including tracking analyst and social media spokesman. I also organized and led the Ham Radio tracking teams which recovered the Civilian Space eXploration Team (CSXT) first amateur rocket to (suborbital) space in 2004.
Explaining a discrepancy with time reporting on Sondehub, KO6YQ notes:
Since this story has gone viral and now entered the mainstream media, we thought we'd answer a few common questions that we're seeing in the media and comments.
Who is launching pico balloons and why?
Pico balloons are typically launched by ham/amateur radio hobbyists, universities, researchers, schools or kids STEM programs. The idea of launching a low cost balloon that can be tracked while travelling the world is a fun project for hobbyists and a great STEM learning experience for kids.
You might also be interested in tracking regular weather balloons which are launched by meteorological agencies around the world usually twice per day. These are designed to only last a few hours in the air before popping. They can be tracked at https://sondehub.org. A popular hobby of radio enthusiasts is chasing these weather balloons and being the first to recover the fallen sensor package called a radiosonde.
A pico balloon is essentially a kids party balloon. Why aren't there thousands of kids party balloons circumnavigating the globe?
Balloons will inflate more as they rise into the atmosphere, since higher altitudes have lower pressure. A kids party balloon would typically be inflated fully on the ground. If a careless child released a balloon it would rise up, and pop within a few hours, as it reaches an altitude of around 5000ft - 30,000ft (1500m - 9000m) or higher where the internal pressure of the balloon is too great for the balloon's material to hold it.
Pico balloons are weighted by their payloads, and are only partially inflated on the ground. The goal is to inflate with enough Helium or Hydrogen to get the payload to rise at ground level, but allow enough internal space for the balloon to expand without popping as it rises. The weighted balloon will eventually reach an equilibrium point at some altitude where it's fully inflated, but can't rise any higher due to the weighting. This is called being 'neutrally buoyant'. The balloon launcher can use a calculator (such as this one) to determine the right amount of helium to use based on the balloon size and payload weight.
Mylar balloons are used because helium atoms will leak out of the walls of latex/rubber balloons, and they will be flat within a few days. With Mylar balloons the leakage is much slower and they can stay inflated for months.
How can a pico balloon circumnavigate the globe?
As mentioned in the previous question, it's possible to engineer the height that the balloon will fly at by only partially inflating the balloon on the ground. Once at the desired altitude, winds will eventually pull the balloon into global jet streams that take the balloon all around the earth at an average speed of 80 - 140 mph (129 - 225 km/h).
A website like Ventusky can be used to view the current jet streams at 40,000ft (12,000m), the altitude that KY9O-15 was neutrally buoyant at.
In California helium balloons in general have been banned, to stop pollution, damage to wildlife, and to protect power lines.
The transmission of the WSPR and APRS telemetry radio signals would be allowed under amateur radio rules. UK, Yemen and North Korea are countries that prohibit transmissions from balloons, and compliance can be achieved via geofencing the transmissions in the software.
All information suggests that the NIBBB hobby club and KY9O's balloon were operating perfectly legally.
What exactly was the payload on the KY9O-15 pico balloon?
The payload was a GPS receiver, an Arduino microcontroller, a radio transmitter and some solar panels. The solar panels power the electronics when in sun, and the GPS receiver determines the global coordinates of the balloon. The microcontroller is the 'brain' of the payload which reads the GPS coordinates from the GPS receiver, and tells the transmitter to send out a WSPR radio signal advertising the balloons ID and coordinates.
These are all common off the shelf, small components that could all fit in the palm of a hand. They would in total cost under $100. K9YO's payload in total only weighed 16.4g (0.58 oz).
An F22 with all it's radio sensors should have picked up the transmissions from the pico balloon. Why didn't it?
Pico balloons usually don't carry batteries because they are heavy and degrade over time. So instead they carry paper thin solar panels. So the balloon circuits and transmitter are only active when in strong sunlight, any other time it is completely quiet and powered down. It's possible that in the weak Yukon sun at high latitude wouldn't have been strong enough to power the WSPR transmitter until later in the day.
How could a tiny 32" balloon be spotted by radar? How could a sidewinder missile lock onto it?
The pico balloon was made out of metallic mylar material which would easily show up on a modern radar system. It's possible that in the past before the Chinese spy balloon incident, radar operators would ignore or filter out slow moving small objects like insects/birds/balloons that pose no threat.
The sidewinder has a fragmentation warhead, so an explosion near the balloon would easily take it out. The metallic mylar material would easily reflect the sun's infrared, and against the cold background of the sky/space it would be easy for the IR heat seeker sensor on the sidewinder missile to track it.
The K9YO balloon was flying at altitudes used by commercial airliners. Is there any risk to them?
A jet coming across a pico balloon in the first place would be very unlikely, and even more unlikely for it to make it's way in to an engine even if an aircraft flew directly at it. But there is some risk that a balloon ingested by an jet engine could cause issues. However given their lightweight nature it seems unlikely that there would be any massive damage, if any at all.
What is WSPR and APRS?
WSPR (pronounced as 'whisper') stands for Weak Signal Propagation Reporter. It is a type of radio signal protocol used by amateur radio hobbyists. Because of the way it is designed, it is possible for WSPR to be transmitted with very low power (such as the tiny amount of power possible from small solar panels), and still be received by amateur radio ground stations all over the world. The WSPR signal encodes it's callsign ID, and the transmitters GPS location. Amateur ground stations will upload received WSPR data to sites like wsprnet.org.
APRS or "Automatic Packet Reporting System" is another protocol used by amateur radio hobbyists. However, these signals don't travel globally, rather they can only be received locally with line of sight. The advantage is that APRS signal can be transmitted much faster (assuming sufficient power).
Are we 100% certain that the object was the K9YO pico balloon?
No, despite the circumstantial evidence, there is still some doubt. The balloon was already old and probably near the end of it's life. The sun in the high Yukon latitudes is also weaker, meaning that the solar panels might not be getting sufficient sun to power the circuits. The balloon had previously gone missing for 30 days before reappearing. And the transmitter was showing signs of drifting in frequency.
Are there any other globe trotting radio projects?
Yes, there are small autonomous boats or 'drift buoys' travelling the seas through natural currents. These also use WSPR and APRS to report their location. hitchBOT was a hitchhiking robot that relied on travelling strangers to find and carry it around the world. It had a GPS receiver and 3G radio.
In January we posted about the AntRunner, which is a $325 (incl. shipping) satellite antenna rotator shipped from China. Recently we've come across another low cost satellite rotator from Australia called the "SARCTRAC Mk3b" which was developed as part of a school amateur radio educational program. This rotator fully assembled comes in at AU$400 + AU$50 worldwide shipping (US$290 + US$40 = US$330), making it's price comparable with the AntRunner. SARCTRAC can be purchased from the sarcnet products page. Currently only the fully built unit is available, but in the future they plan to offer a cheaper kit option.
We're yet to test the SARCTRAC Mk3b, but based on an overall review of it's advertising, it appears that the SARCTRAC has some superior specifications and a superior design when compared to the AntRunner.
Unlike the AntRunner, SARCTRAC comes with all its components enclosed in a waterproof IP65 rated enclosure. Its design also makes use of a 3D position sensor with magnetometer, allowing the unit to know its orientation at all times, meaning that it should be able to automatically position itself from startup. The design also makes use of DC motors with a built in worm gear drive, so the the motors back driving is not possible.
The system is controlled via a built in Raspberry Pi 3B+ and can communicate with the controlling PC via WiFi. Raspberry Pi's have stable WiFi connections, so we shouldn't see the connection problems that we had with the ESP32 based AntRunner.
Just like the AntRunner, SARCTRAC is only a lightweight rotator with torque specs of 50kg.cm static and 25kg.cm dynamic. So it should be able to handle counterbalanced Yagi beams, and lightweight dish antennas.
SARCTRAC Mk3 Satellite Antenna Rotator Controller and TRACker
Over on YouTubem channel NotaRubicon Productions has uploaded a video describing how a KrakenSDR was used to find the location of a person jamming a repeater site. Amateur radio enthusiasts can utilize VHF or UHF repeater towers, which receive signals from lower power handheld or other radios, and retransmit that signal at high power on a slightly different frequency over a much wider area. Unfortunately malicious people can jam these repeaters by transmitting at the same time as other users, effectively denying use of the repeater by legitimate users.
If you weren't already aware, KrakenSDR is our 5-channel coherent radio based on RTL-SDRs, and it can be used for applications like radio direction finding. We successfully crowd funded the device on Crowd Supply, and the device is currently available for sale on Crowd Supply, Mouser and direct from our website krakenrf.com.
In this video I read the story of how we caught the jammer that had been jamming our GMRS repeater for months, and how by using the KrakenSDR Radio Direction Finder (RF locator), we were at his house in 1 hour.
The KrakenSDR can track a signal being transmitted from 100Mhz to 1Ghz - so I can track ham repeater jammers, GMRS repeater jammers, ham-radio transmitters, GMRS radios - pretty much any transmitter with a signal strong enough for you to receive.
How The KrakenSDR Located Our Repeater Jammer In 1 Hour. Overview of the KrakenRF Inc. RF Locator
The Maverick-603 is a US$149 FT8 receiver based on an open source RF chip design which is capable of acquiring signals between 7 MHz and 70 MHz (technically 1 MHz to 100 MHz). It is currently undergoing Crowd Funding on Crowd Supply with 7 days left in the campaign. Shipping is expected to begin in April 2023.
FT8 is a popular weak signal propagation digital mode used by ham radio enthusiasts. FT8 signals can be received and decoded all over the world even with low transmit power and poor propagation conditions thanks to its highly error tolerant encoding. A dedicated FT8 receiver allows enthusiasts to set up a 24/7 FT8 monitor without dedicating more expensive ham radio equipment to the task. Note that a computing device like a PC or possibly a Raspberry Pi 4 will still be required to run the FT8 decoding software as this is a software defined radio.
The Maverick-603 is based on a custom open source RF chip design made possible by the company eFabless. It is now possible to cheaply design and produce custom ASIC chips (at least at the lower end of the technology scale), replacing more costly FPGA designs. The technical specs of the Maverick-603 are:
Power Supply: 3.3 V / 10 mA
Operating Frequency Range: 1 to 100 MHz
Minimum Signal Strength: -25 dBm
Input Antenna Impedance: 50 Ohm
Data Interface: SPI
Board Size: 2" x 1.75"
Capable of receiving FT8 signals
7 - 70 MHZ frequency range
Low-power operation (1.8 Volts) means no battery or outlet is required