APRS ..yms. radioamatööritoimintaa

Sleeper_agent

Luutnantti
Venäläinen E07 numeroasema luettelemassa "Six, Zero, Three, One" ja OTH (tai rannikko) tutka "vesiputouksessa".Six, zero, three, one  + OTH radar.png
 

ctg

Greatest Leader
Demonstrating what engineers and scientists get up to when they are riding out the current pandemic in their homes, the ESA team has put out a series of tutorials for Windows 7 and 10, macOS, iOS and Android, Ubuntu, and, of course, the Raspberry Pi, on how to pick up and decode Slow Scan Television (SSTV) transmissions from the orbiting outpost.

Those hoping for the latest and greatest HD video should look away now: think more ZX Spectrum loading screen than Netflix 4K cinematics.

Naturally, we had a crack at making it work (using the Windows 10 instructions) and succeeded in viewing the test image after delving into the dark arts of the Windows sound mixer. Pay close attention to the instructional video on setting up the Stereo Mixer (we didn't).
 

ctg

Greatest Leader
Amateur radio operators have always been at the top of their game when they’ve been hacking radios. A ham license gives you permission to open up a radio and modify it, or even to build a radio from scratch. True, as technology has advanced the opportunities for old school radio hacking have diminished, but that doesn’t mean that the new computerized radios aren’t vulnerable to the diligent ham’s tender ministrations.

A case in point: the Kenwood TH-D74A’s firmware has been dumped and partially decoded. A somewhat informal collaboration between [Hash (AG5OW)] and [Travis Goodspeed (KK4VCZ)], the process that started with [Hash]’s teardown of his radio, seen in the video below. The radio, a tri-band handy talkie with capabilities miles beyond even the most complex of the cheap imports and with a price tag to match, had a serial port and JTAG connector. A JTAGulator allowed him to probe some of the secrets, but a full exploration required spending $140 on a spare PCB for the radio and some deft work removing the BGA-packaged Flash ROM and dumping its image to disk.

[Travis] picked up the analysis from there. He found three programs within the image, including the radio’s firmware and a bunch of strings used in the radio’s UI, in both English and Japanese. The work is far from complete, but the foundation is there for further exploration and potential future firmware patches to give the radio a different feature set.

This is a great case study in reverse engineering, and it’s really worth a trip down the rabbit hole to learn more. If you’re looking for a more formal exploration of reverse engineering, you could do a lot worse than HackadayU’s “Reverse Engineering with Ghidra” course, which just wrapping up.
 

ctg

Greatest Leader
Todella hieno

radioglobe-large.jpg


There’s no denying that the reach and variety of internet radio is super cool. The problem is that none of the available interfaces really give the enormity of the thing the justice it deserves. We long for a more physical and satisfying interface for tuning in stations from around the globe, and [Jude] has made just the thing.

RadioGlobe lets the user tune in over 2000 stations from around the world by spinning a real globe. It works by using two absolute rotary encoders that each have a whopping 1024 positions available. One encoder is stuck into the South Pole, and it reads the lines of longitude as the user spins the globe.

The other encoder is on the left side of the globe, and reads whatever latitude is focused in the reticle. Both encoder are connected to a Raspberry Pi 4, though if you want to replicate this open-source project using the incredibly detailed instructions, he says a Raspberry Pi 3 B+ will work, too.

In the base there’s an LCD that shows the coordinates, the city, and the station ID. Other stations in the area are tune-able with the jog wheel on the base. There’s also an RGB LED that blinks red while the station is being tuned in, and turns green when it’s done. We totally dig the clean and minimalist look of this build — especially the surprise transparent bottom panel that lets you see all the guts.

There are three videos after the break – a short demo that gives you the gist of how it works, a longer demonstration, and a nice explanation of absolute rotary encoders. Those are just the tip of the iceberg, because [Jude] kept a daily vlog of the build.

Maybe you just long for a web radio that dials in vintage appeal. This antique internet radio has a lot of features, but you wouldn’t know it from the outside.
https://hackaday.com/2020/07/27/radioglobe-takes-the-world-of-internet-radio-for-a-spin/
 

Sleeper_agent

Luutnantti
Onkohan venäläiset herättäneet tikan uudestaan henkiin? Eilen kuuntelin ja tallensin joutessani puolalaista S11a numeroaseman lähetystä, niin muutama minuutti lähetyksen alkamisesta alkoi kuulua vaimeaa naputtavaa ääntä joka nopeasti voimistui takovaksi paukutukseksi ja siirtyi kokonaan tuon numeroita lähettävän taajuuden päälle ja sitä kesti noin puoli minuuttia.
 

ctg

Greatest Leader
Mzg0ODc5Nw.jpeg


Ultimately, when NASA’s Jet Propulsion Laboratory (JPL), where I am a senior antenna engineer, began to seriously consider a Europa lander mission, we realized that the antenna was the limiting factor. The antenna needs to maintain a direct-to-Earth link across more than 550 million miles (900 million km) when Earth and Jupiter are at their point of greatest separation. The antenna must be radiation-hardened enough to survive an onslaught of ionizing particles from Jupiter, and it cannot be so heavy or so large that it would imperil the lander during takeoff and landing. One colleague, when we laid out the challenge in front of us, called it impossible. We built such an antenna anyway—and although it was designed for Europa, it is a revolutionary enough design that we’re already successfully implementing it in future missions for other destinations in the solar system
Traditionally, landers (and rovers) designed for Mars missions rely on relay orbiters with high data rates to get scientific data back to Earth in a timely manner. These orbiters, such as the Mars Reconnaissance Orbiter and Mars Odyssey, have large, parabolic antennas that use large amounts of power, on the order of 100 watts, to communicate with Earth. While the Perseverance and Curiosity rovers also have direct-to-Earth antennas, they are small, use less power (about 25 W), and are not very efficient. These antennas are mostly used for transmitting the rover’s status and other low-data updates. These existing direct-to-Earth antennas simply aren’t up to the task of communicating all the way from Europa.
So, to reiterate the challenge: The antenna cannot be large, because then the lander will be too heavy. It cannot be inefficient for the same reason, because requiring more power would necessitate bulky power systems instead. And it needs to survive exposure to a brutal amount of radiation from Jupiter. This last point requires that the antenna must be mostly, if not entirely, made out of metal, because metals are more resistant to ionizing radiation.

The antenna we ultimately developed depends on a key innovation: The antenna is made up of circularly polarized, aluminum-only unit cells—more on this in a moment—that can each send and receive on X-band frequencies (specifically, 7.145 to 7.19 gigahertz for the uplink and 8.4 to 8.45 GHz for the downlink). The entire antenna is an array of these unit cells, 32 on a side or 1,024 in total. The antenna is 32.5 by 32.5 inches (82.5 by 82.5 centimeters), allowing it to fit on top of a modestly sized lander, and it can achieve a downlink rate to Earth of 33 kilobits per second at 80 percent efficiency.
Mzg0ODg5Ng.jpeg

Each unit cell, as mentioned, is entirely made of aluminum. Earlier antenna arrays that similarly use smaller component cells include dielectric materials like ceramic or glass to act as insulators. Unfortunately, dielectric materials are also vulnerable to Jupiter’s ionizing radiation. The radiation builds up a charge on the materials over time, and precisely because they’re insulators there’s nowhere for that charge to go—until it’s ultimately released in a hardware-damaging electrostatic discharge. So we can’t use them.

As mentioned before, metals are more resilient to ionizing radiation. The problem is they’re not insulators, and so an antenna constructed entirely out of metal is still at risk of an electrostatic discharge damaging its components. We worked around this problem by designing each unit cell to be fed at a single point. The “feed” is the connection between an antenna and the radio’s transmitter and receiver. Typically, circularly polarized antennas require two perpendicular feeds to control the signal generation. But with a bit of careful engineering and the use of a type of automated optimization called a genetic algorithm, we developed a precisely shaped single feed that could get the job done.
 

ctg

Greatest Leader

Although the antenna isn’t done, it is already working and looks impressive. There’s a lot of wire, so this probably isn’t a condo-friendly solution. The name of the antenna derives from the three wires, one tuned for 3 MHz, one for 6 MHz, and the other for 9 MHz.

The mechanical construction is impressive, with springs and pulleys. The wire used is actually MIG welding wire which is cheap and durable. Supposedly, the antenna has already performed well with an average receiver, but we didn’t get to hear it ourselves. Maybe in the next video.
 
  • Tykkää
Reactions: M&R
Top