Categorie: Hackaday

As part of the payloads on the Firefly Blue Ghost Mission 1 (BGM1) that recently touched down on the Moon, the Lunar GNNS Receiver Experiment (LuGRE) has become the first practical demonstration of acquiring and tracking Earth orbital GNSS satellites. LuGRE consists of a weak-signal GNSS receiver, a high-gain L-band patch antenna the requisite amplification and filter circuits, designed to track a number of GPS and Galileo signals.

Designed by NASA and the Italian Space Agency (ISA), the LuGRE payload’s goal was to demonstrate GNSS-based positioning, navigation and timing at the Moon. This successful demonstration makes it plausible that future lunar missions, whether in orbit or on the surface, could use Earth’s GNSS satellites to navigate and position themselves with. On the way to the lunar surface, LuGRE confirmed being able to track GNSS at various distances from the Earth.

Both LuGRE and BGM1 are part of NASA’s Commercial Lunar Payload Services (CLPS) program, with BGM1 delivering a total of ten payloads to the Moon, each designed to study a different aspect of the lunar environment, as well as hardware and technologies relevant to future missions.

Saying farewell is hard, and in the case of the Voyager 1 & 2 spacecraft doubly so, seeing as how they have been with us for more than 47 years. From the highs of the 1970s and 1980s during their primary mission in our Solar System, to their journey into the unknown of Deep Space, every bit of information which their instruments record and send back is something unique that we could not obtain any other way. Yet with the shutting down of two more instruments, both spacecraft are now getting awfully close to the end of their extended missions.

Last February 25 the cosmic ray system (CRS) on Voyager 1 was disabled, with the Low Energy Charged Particle Instrument (LECP) on Voyager 2 to follow on March 24. With each spacecraft losing about 4 watts of available power per year from their RTGs, the next few instruments to be turned off are already known. Voyager 1’s LECP will be turned off next year, with that same year Voyager 2’s CRS also getting disabled.

This would leave both spacecraft with only their magnetometer (MAG) and plasma wave subsystem (PWS). These provide data on the local magnetic field and electron density, respectively, with at least one of these instruments on each spacecraft likely to remain active until the end of this decade, possibly into the next. With some luck both spacecraft will see their 50th birthday before humanity’s only presence in Deep Space falls silent.

Thanks to [Mark Stevens] for the tip.

We used to say that fixing something was easier than bringing up a design for the first time. After all, the thing you are fixing, presumably, worked at one time or another. These days, that’s not always true as fixing modern gear can be quite a challenge. Watching [Ken’s] repair of an old 1955 Silvertone radio reminded us of a simpler time. You can watch the action on the video below.

If you’ve never had the pleasure of working on an AM radio, you should definitely try it. Some people would use an amplifier to find where the signal dies out. Others will inject a signal into the radio to find where it stops. A good strategy is to start at the volume control and decide if it is before or after that. Then split the apparently bad section roughly in half and test that portion—sort of a hardware binary search. Of course, your first step should probably be to verify power, but after that, the hunt is on.

There’s something very satisfying about taking a dead radio and then hearing it come to life on your bench. In this case, some of the problems were from a previous repair.

Troubleshooting is an art all by itself. Restoring old radios is also great fun.

Single Sideband, or SSB, has been the predominant amateur radio voice mode for many decades now. It has bee traditionally generated by analogue means, generating a double sideband and filtering away the unwanted side, or generating 90 degree phase shifted quadrature signals and mixing them. More recent software-defined radios have taken this into the CPU, but here’s [Georg DG6RS] with another method. It uses SDR techniques and a combination of AM and FM to achieve polar modulation and generate SSB. He’s provided a fascinating in-depth technical explanation to help understand how it works.

The hardware is relatively straightforward; an SI5351 clock generator provides the reference for an ADF4351 PLL and VCO, which in turn feeds a PE4302 digital attenuator. It’s all driven from an STM32F103 microcontroller which handles the signal processing. Internally this means conventionally creating I and Q streams from the incoming audio, then an algorithm to generate the phase and amplitude for polar modulation. These are fed to the PLL and attenuator in turn for FM and AM modulation, and the result is SSB. It’s only suitable for narrow bandwidths, but it’s a novel and surprisingly simple deign.

We like being presented with new (to us at least) techniques, as it never pays to stand still. Meanwhile for more conventional designs, we’ve got you covered.

LoRa gear can be great for doing radio communications in a light-weight and low-power way. However, it can also work over great distances if you have the right hardware—and the right antennas in particular. [taste_the_code] has been experimenting in this regard, and whipped up a simple yagi antenna that can work at distances of up to 40 kilometers.

The basic mathematics behind the yagi antenna are well understood. To that end, [taste_the_code] used a simple online calculator to determine the correct dimensions to build a yagi out of 2 mm diameter wire that was tuned for the relevant frequency of 868 MHz. The build uses a 3D-printed boom a handle and holes for inserting each individual wire element in the right spot—with little measuring required once the wires are cut, since the print is dimensionally accurate. It was then just a matter of wiring it up to the right connector to suit the gear.

The antenna was tested with a Reyas RYLR998 module acting as a base station, with the DIY yagi hooked up to a RYLR993 module in the field. In testing, [taste_the_code] was able to communicate reliably from 40 kilometers away.

We’ve featured some other unique LoRa antenna builds before, too. Video after the break.

We’ve seen a lot of interest in Meshtastic, the license-free mesh network for small amounts of data over the airwaves. [Ham Radio Rookie] was disappointed with his Meshtastic node’s small and inefficient antennas. So he decided to make what we suspect is the world’s first Meshtastic necktie.

We assume the power is low enough that having it across your thorax is probably not terrible. Probably. The tie is a product of a Cricut, Faraday cloth, and tiny hardware (the Xiao ESP32S3 and the WIO SX1262 board). The biggest problem was the RF connector, which needed something smaller than the normal BNC connector.

Of course, ideally, you’d like to have a very tiny battery. We can handle tying the knot, but you might prefer using a clip-on. Besides, then you could clip it to anything handy, too.

The tie antenna is probably going to outperform the rubber duckies. Still, we don’t expect it to get super long range. If you press a USB battery into service, you might find the low power electronics keep letting the battery shut off. There is an easy fix for this, but it will up your power consumption.

When the first artificial satellite, Sputnik, was put into orbit around Earth, anyone in the path of the satellite could receive the beeps transmitted by the satellite provided they had some simple radio equipment. Of course, there was no two-way communication with this satellite, and it only lasted a few weeks before its batteries died. Here in the future, though, there are many more satellites in orbit and a few are specifically meant for ham radio operators. And, like the ’50s, it doesn’t take too much specialized equipment to communicate with them, although now that communication can be two-way.

The first step in this guide by [W2PAK] is to know where these satellites are in the sky. The simplest way to do that is to use a smartphone app called GoSatWatch and, when configured for a specific location, shows the satellites currently overhead. After that it’s time to break out the radio gear, which can be surprisingly inexpensive. A dual-band handheld is required since satellite uplink and downlink can be on different bands, and the antenna can be made from simple parts as well as [W2PAK] demonstrates in a separate video. Combined, this can easily be done for less than $100. [W2PAK] also goes over the proper format and etiquette for a satellite contact as well, so a new operator can pick it up quickly.

Using satellites as repeaters opens up a lot of capabilities when compared to terrestrial communications. Especially for operators with entry-level licenses who are restricted to mostly VHF and UHF, it adds a challenge as well as significantly increased range compared to ground-based repeaters and line-of-sight communications. There are plenty of activities around satellites that don’t require a license at all, too, like this project which downloads weather imagery from weather satellites.

Crystal oscillators are incredibly useful components, but they come with one little snag: their oscillation is temperature-dependent. For many applications the relatively small deviation is not a problem, but especially for precision instruments this is a deal breaker. Enter the oven controlled crystal oscillator, or OCXO. These do basically what it says on the tin, but what’s inside them? [Kerry Wong] took apart a vintage Toyocom TCO-627VC 10 MHz OCXO, revealing a lot more complexity than one might assume.

Inside the insulated enclosure there is of course the crystal oscillator itself, which has a heating coil wrapped around it. Of note is that other OCXOs that [Kerry] took apart had more insulation, as well as other ways of providing the thermal energy. In this particular unit a thermistor is attached to the crystal’s metal case to measure its temperature and provide feedback to the heating circuit. The ICs on the PCB are hard to identify due to the conformal coating, but at least one appears to be a 74LS00, alongside a 78L05 voltage regulator which reduces the 12V input voltage.

As an older OCXO it probably is a lot chunkier than newer units, but the basic principle remains the same, with a heating loop that ensures that the crystal inside the unit remains at the same temperature.

[Stephen] recently wrote in to share his experiments with using the LimeSDR mini to conduct a bit of piracy on the airwaves, and though we can’t immediately think of a legitimate application for spamming the full FM broadcast band simultaneously, we can’t help but be fascinated by the technique. Called the Taylorator, as it was originally intended to carpet bomb the dial with the collected works of Taylor Swift on every channel, the code makes for some interesting reading if you’re interested in the transmission-side of software defined radio (SDR).

The write-up talks about the logistics of FM modulation, and how quickly the computational demands stack up when you’re trying to push out 100 different audio streams at once. It takes a desktop-class CPU to pull it off in real-time, and eats up nearly 4 GB of RAM.

You could use this project to play a different episode of the Hackaday Podcast on every FM channel at once, but we wouldn’t recommend it. As [Stephen] touches on at the end of the post, this is almost certainly illegal no matter where you happen to live. That said, if you keep the power low enough so as not to broadcast anything beyond your home lab, it’s unlikely anyone will ever find out.