Broadcast Engineer at BellMedia, Computer history buff, compulsive deprecated, disparate hardware hoarder, R/C, robots, arduino, RF, and everything in between.
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Every Easter Egg Carved Into That Wall In Obi-Wan Kenobi

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Episode 5 of "Obi-Wan Kenobi" is a powerful one, and if you haven't watched it yet, I implore you to do so before you read further. There are spoilers ahead.

This week, Obi-Wan, Leia, and the gang end up on Jabiim, the safehouse planet for the Path, the road that secrets away Jedi and Force sensitive people out of the reach of the Empire. There is a whole lot happening in this episode, including me tearing up over a loss and last words, but that's not what I'm talking about today, mostly. As in many places where people stay temporarily while in desperate situations, they often carve their names or quotes or pictures into the walls. If you visit the Metropolitan Museum of Art in New York City and hit the Egyptian room with the Temple of Dendur, you can see carved graffiti from visitors to the site when it was still in Egypt. If you visit the Tower of London, there are carvings in the stone walls from prisoners, including possibly Anne Boleyn, the beheaded queen. We as humans feel the need to make our mark, and likely more so when our lives are in danger. 

Two episodes ago, we saw carvings in the safehouse that Tala took Leia and Obi-Wan to. Now, we see Obi-Wan reading more carvings in the wall on Jabiim. It's in Aurebesh, the language of Star Wars. Our own Bryan Young found a lot of stuff on there, and I did my level best with my printed Aurebesh alphabet to see some more of them. 

Quick note: I'm using the Jedi symbol in the center of the wall carvings as a point of reference.

'There Is No Death'

"There is no emotion, there is peace. There is no ignorance, there is knowledge. There is no passion, there is serenity. There is no chaos, there is harmony. There is no death, there is the Force."

This is the Jedi code, something the Jedi learn from the time they're taken away from their parents and families (way too young, which is a major issue with the Jedi). It's a lovely sentiment for the most part, despite it being a bit much for even a Force sensitive person to really commit to. Still, it's comforting. One of the things written on the wall on Jabiim is a line from that code, "There is no death." It's in the upper left corner. 

Likely the reason this is written out as the only line from the code is the death of so many Jedi during Order 66. All the lightsabers we see from fallen Jedi (especially the younglings) here and in the Fortress Inquisitorius from earlier episodes are heartbreaking, and likely the survivors are dealing with grief. Reminding oneself that there is no death, and only the Force is a powerful thing. Those who have left us are never really gone if we remember them. 

'May The Force Be With You'

My heart breaks for Tala and Ned-B, who sacrificed themselves to save the refugees with a thermal detonator. Her last words were, "May the Force be with you." Really didn't expect to be crying this early in the morning, folks. Anyway, another thing carved on that wall, right above the Jedi symbol is "May the Force be with you." 

It's a line we've heard since the very beginning of the "Star Wars" saga, a nod to the connection between all living beings, a connection that one can draw on if one is sensitive enough to do so, but something that feels very much like the deeper meanings of "aloha" or "namaste." It's an acknowledgement of the light that flows through us and lives within us. It's been used as a goodbye before when things are dire, from Holdo to Leia and back. RIP Tala and Ned-B, you wonderful silent droid.

Seriously, I did not expect to go this deep before I've finished my coffee.

'The Light Fades But Is Never Forgotten'

"The light fades but is never forgotten."

That one is under the Jedi symbol on the wall. It's not part of any saying I could find, but it does feel like something one says after a loss. Considering that this is "Star Wars" though, it could also mean the passing of a Force ghost who was advising a Jedi. They glow with light. I might be reaching here, but it was my first thought. 

Since I'm already getting heavy with this stuff, here's another thought. Not that I think the fictional carver would have meant this specifically, but the light has faded from Anakin, who has turned to the dark side of the Force, but as we know from "Return of the Jedi," Padme was right. There was still good in him. His son Luke does uncover it, right at the end. Anakin's light faded, but in the end, wasn't forgotten.

Youngling Crest?

Credit to DrunkWooky for finding this, because there is no way I would have figured out that carving, but to the right of the Jedi symbol is another one, that appears to be the crest of the Jedi younglings. It's a sort of circle right under what looks like the letters VAO, but in Aurebesh is "YOU" from the "May the Force be with you" line. 

It looks like a wing with a four-pointed star balanced on the second feather. This one is heartbreaking, not just because the killing of the younglings was the point Anakin couldn't come back from. It's brutal and awful, and especially poignant in both our current world and in episode 5. We learn in this episode that Reva pretended to be dead among the bodies of her slain friends to survive and it's so close to the news right now that I'm having a hard time typing this. 

Corwin Shelvay

In the big letters, to the left of the Jedi symbol, is the name Corwin Shelvay. This character was introduced in the RPG "Galaxy Guide 9: Fragments of the Rim" from 1993. Corwin was a human Jedi Knight during Palpatine's Jedi Purge. According to Wookieepedia, he was the apprentice of Darrin Arkanian, who died saving him from the Empire. He was tempted by the dark side as he wanted revenge. Later he joined the Rebel Alliance and joined the New Jedi Order.

This is from the Legends side of things, before the dark times, before the decision to make older Star Wars stories non-canon. (I'm mostly kidding, but not completely.) It's been very interesting to see which things from Legends that Disney has been allowing to seep into the current canon. We might not hear more about him, but who knows? Stranger things have happened. In his review, Bryan does mention another Legends character named Corran Horn listed in the credits, who was a member of Luke's Jedi Order, so he's on Jabiim as well. 

'Tiberus'

Diagonally to the left, under the Jedi symbol, to the right of Corwin Shelvay's name is what I believe says "Tiberus." The only one I could find is Tiberus Anderlock from "Star Wars Galaxies: Jump to Lightspeed," an extension pack from 2004 that added on to the MMORPG "Star Wars Galaxies: An Empire Divided." 

Tiberus Anderlock was a human Jedi pilot. We don't know a lot about him, but he was killed after the Battle of Yavin while he was piloting a Kihraxz assault fighter in the Dathomir system. If that sounds familiar to you, it's because of the Witches of Dathomir who were mentioned in "The Book of Boba Fett," which our own Danielle Ryan did an explainer about.

Tiberus was an NPC, but if he lived until the Battle of Yavin, it means he survived until "A New Hope." It's not much, but at least he made it that far. 

Ekria

Under the name "Shelvay" is something very tiny. It's hard to see and Drunk Wooky found this one as well. I did get my Aurebesh alphabet out to double check and I also translated Ekria. 

Ekria is a Barolian Jedi Padawan who later served in the Grand Army of the Republic during the Clone Wars, according to Wookiepedia. What's important about her, other than just being a Force user in her own right, is that she served under Jedi Master Aayla Secura, who was the first Jedi to fall in Order 66, or at least the first one we saw. Aalya was the padawan of Quinlan Vos, whose name we saw carved on a wall in an earlier episode. He was the one that Obi-Wan mentioned still being alive and who Tala said helps out with the Path from time to time. 

Roganda Ismaren

Under the Jedi symbol, sort of on the left side, there are two double letter symbols, and under that we have Roganda Ismaren. I could translate the first name, but had to look it up to get the second. According to Wookieepedia, she is a Jedi Initiate from Alderaan (sniff) who first appeared in the "Children of the Jedi" novel, but I haven't read that one. She survived Order 66 by being smuggled out with other younglings (which would make seeing her name here make sense), but was taken by Imperial fighters. She was -- give yourself a moment before you read this -- one of Palpatine's concubines. She fell to the dark side and had a son who killed her. 

I'm very squicked out by this one, just as I was when I learned that Palpatine had a kid. Nope. I don't want to think about that.

There were a few others that I just couldn't translate, like what appears to be "Niami" to the lower right of the Jedi symbol, but I couldn't find that name anywhere. It's that first letter. I've tried every iteration, but no luck. Do let me know if you figure that one out! 

Read this next: The 20 Best Clone Wars Episodes Ranked

The post Every Easter Egg Carved Into That Wall In Obi-Wan Kenobi appeared first on /Film.

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tekvax
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The Origin of the Fresnel Lens

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If you are a Hackaday reader, you probably know what a Fresnel lens is. You find them in everything from overhead projectors to VR headsets. While it seems commonplace now, the Fresnel lens was an important invention for its day because it revolutionized maritime navigation and, according to a post over at IEEE Spectrum, that was the driving force behind its invention. In fact, the lens has been called “the invention that saved a million ships“.

The problem stems from issues in navigation. Navigating by the sun and the stars is fine, but not workable when you have heavy cloud cover, or other reasons you can’t see them. A lighthouse often marked an important point that you either wanted to navigate towards or, sometimes, away from.  Sure, today, we have GPS, but for a long time, a lighthouse was your best bet.

The problem is that in those days, a lighthouse was an oil lamp, a concave mirror, and an ordinary lens. This made the lighthouses difficult to spot. Napoleon started the Commission of Lighthouses as part of the Corps of Bridges and Roads. This is the Corps that employed optical genius, Agustin-Jean Fresnel. Although some lighthouses were already using lenses, they weren’t using the special Fresnel-style lenses. There had been speculation about building this type of lens, but Fresnel was apparently unaware of them when he proposed his lens for lighthouse use in 1819. His proposed lens was a bit different than earlier proposals, too.

The lens works like a series of prisms, the ones on the edges bending light more sharply and the center bending it hardly at all. Compared to a conventional lens, a Fresnel will be thinner and lighter or — conversely — for the same thickness and weight, the Fresnel can have better properties. However, the distortions make them less suitable for imaging where regular lenses still reign supreme. A thinner lens, of course, should let more light through, which is important when you are trying to shoot a beam a long distance. Fresnel’s lenses let through 98% of the lamp’s output, which could signal ships up to 32 km away.

By 1823, the lenses were appearing on lighthouses. By 1860, all lighthouses in the United States were using the improved optics. One of those things that you don’t really give a lot of thought to, but at one time it was major high tech. You have to wonder in 200 years what we are using today that will be relegated to the ordinary and commonplace.

You can see replica lighthouse lenses in the video below. If you make your own, though, be careful not to get a big head.

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How is Voyager Still Talking After All These Years?

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The tech news channels were recently abuzz with stories about strange signals coming back from Voyager 1. While the usual suspects jumped to the usual conclusions — aliens!! — in the absence of a firm explanation for the anomaly, some of us looked at this event as an opportunity to marvel at the fact that the two Voyager spacecraft, now in excess of 40 years old, are still in constant contact with those of us back on Earth, and this despite having covered around 20 billion kilometers in one of the most hostile environments imaginable.

Like many NASA programs, Voyager has far exceeded its original design goals, and is still reporting back useful science data to this day. But how is that even possible? What 1970s-era radio technology made it onto the twin space probes that allowed it to not only fulfill their primary mission of exploring the outer planets, but also let them go into an extended mission to interstellar space, and still remain in two-way contact? As it turns out, there’s nothing magical about Voyager’s radio — just solid engineering seasoned with a healthy dash of redundancy, and a fair bit of good luck over the years.

The Big Dish

For a program that in many ways defined the post-Apollo age of planetary exploration, Voyager was conceived surprisingly early. The complex mission profile had its origins in the “Planetary Grand Tour” concept of the mid-1960s, which was planned to take advantage of an alignment of the outer planets that would occur in the late 1970s. If launched at just the right time, a probe would be able to reach Jupiter, Saturn, Uranus, and Neptune using only gravitational assists after its initial powered boost, before being flung out on a course that would eventually take it out into interstellar space.

The idea of visiting all the outer planets was too enticing to pass up, and with the success of the Pioneer missions to Jupiter serving as dress rehearsals, the Voyager program was designed. Like all NASA programs, Voyager had certain primary mission goals, a minimum set of planetary science experiments that project managers were reasonably sure they could accomplish. The Voyager spacecraft were designed to meet these core mission goals, but planners also hoped that the vehicles would survive past their final planetary encounters and provide valuable data as they crossed the void. And so the hardware, both in the spacecraft and on the ground, reflects that hope.

Voyager primary reflector being manufactured, circa 1975. The body of the dish is made from honeycomb aluminum and is covered with graphite-impregnated epoxy laminate skins. The surface precision of the finished dish is 250 μm. Source: NASA/JPL

The most prominent physical feature of both the ground stations of the Deep Space Network (DSN), which we’ve covered in-depth already, and the Voyager spacecraft themselves are their parabolic dish antennas. While the scale may differ — the DSN sports telescopes up to 70 meters across — the Voyager twins were each launched with the largest dish that could fit into the fairing of the Titan IIIE launch vehicle.

Voyager High-Gain Antenna (HGA) schematic. Note the Cassegrain optics, as well as the frequency-selective subreflector that’s transparent to S-band (2.3-GHz) but reflects X-band (8.4-GHz). Click to enlarge. Source: NASA/JPL

The primary reflector of the High Gain Antenna (HGA) on each Voyager spacecraft is a parabolic dish 3.7 meters in diameter. The dish is made from honeycomb aluminum that’s covered with a graphite-impregnated epoxy laminate skin. The surface of the reflector is finished to a high degree of smoothness, with a surface precision of 250 μm, which is needed for use in both the S-band (2.3 GHz), used for uplink and downlink, and X-band (8.4 GHz), which is downlink only.

Like their Earth-bound counterparts in the DSN, the Voyager antennas are a Cassegrain reflector design, which uses a Frequency Selective Subreflector (FSS) at the focus of the primary reflector. The subreflector focuses and corrects incoming X-band waves back down toward the center of the primary dish, where the X-band feed horn is located. This arrangement provides about 48 dBi of gain and a beamwidth of 0.5° on the X-band. The S-band arrangement is a little different, with the feed horn located inside the subreflector. The frequency-selective nature of the subreflector material allows S-band signals to pass right through it and illuminate the primary reflector directly. This gives about 36 dBi of gain in the S-band, with a beamwidth of 2.3°. There’s also a low-gain S-band antenna with a more-or-less cardioid radiation pattern located on the Earth-facing side of the subreflector assembly, but that was only used for the first 80 days of the mission.

Two Is One

Three of the ten bays on each Voyager’s bus are dedicated to the transmitters, receivers, amplifiers, and modulators of the Radio Frequency Subsystem, or RFS. As with all high-risk space missions, redundancy is the name of the game — almost every potential single point of failure in the RFS has some sort of backup, an engineering design decision that has proven mission-saving in more than one instance on both spacecraft over the last 40 years.

On the uplink side, each Voyager has two S-band double-conversion superhet receivers. In April of 1978, barely a year before its scheduled encounter with Jupiter, the primary S-band receiver on Voyager 2 was shut down by fault-protection algorithms on the spacecraft that failed to pick up any commands from Earth for an extended period. The backup receiver was switched on, but that was found to have a bad capacitor in the phase-locked loop circuit intended to adjust for Doppler-shift changes in frequency due primarily to the movement of the Earth. Mission controllers commanded the spacecraft to switch back to the primary receiver, but that failed again, leaving Voyager 2 without any way to be commanded from the ground.

Luckily, the fault-protection routines switched the backup receiver back on after a week of no communication, but this left controllers in a jam. To continue the mission, they needed to find a way to use the wonky backup receiver to command the spacecraft. They came up with a complex scheme where DSN controllers take a guess at what the uplink frequency will be based on the predicted Doppler shift. The trouble is, thanks to the bad capacitor, the signal needs to be within 100 Hz of the lock frequency of the receiver, and that frequency changes with the temperature of the receiver, by about 400 Hz per degree. This means controllers need to perform tests twice a week to determine the current lock frequency, and also let the spacecraft stabilize thermally for three days after uplinking any commands that might change the temperature on the spacecraft.

Double Downlinks

An Apollo-era TWTA, similar to the S-band and X-band power amps used on Voyager. Source: Ken Shirriff

On the transmit side, both the X-band and S-band transmitters use separate exciters and amplifiers, and again, multiple of each for redundancy. Although downlink is primarily via the X-band transmitter, either of the two S-band exciters can be fed into either of two different power amplifiers. A Solid State Amplifier (SSA) provides a selectable power output of either 6 W or 15 W to the feedhorn, while a separate traveling-wave tube amplifier (TWTA) provides either 6.5 W or 19 W. The dual X-band exciters, which use the S-band exciters as their frequency reference, use one of two dedicated TWTAs, each of which can send either 12 W or 18W to the high-gain antenna.

The redundancy built into the downlink side of the radio system would play a role in saving the primary mission on both spacecraft. In October of 1987, Voyager 1 suffered a failure in one of the X-band TWTAs. A little more than a year later, Voyager 2 experienced the same issue. Both spacecraft were able to switch to the other TWTA, allowing Voyager 1 to send back the famous “Family Portrait” of the Solar system including the Pale Blue Dot picture of Earth, and for Voyager 2 to send data back from its flyby of Neptune in 1989.

Slower and Slower

The radio systems on the Voyager systems were primarily designed to support the planetary flybys, and so were optimized to stream as much science data as possible back to the DSN. The close approaches to each of the outer planets meant each spacecraft accelerated dramatically during the flybys, right at the moment of maximum data production from the ten science instruments onboard. To avoid bottlenecks, each Voyager included a Digital Tape Recorder (DTR), which was essentially a fancy 8-track tape deck, to buffer science data for later downlink.

Also, the increasing distance to each Voyager has drastically decreased the bandwidth available to downlink science data. When the spacecraft made their first flybys of Jupiter, data streamed at a relatively peppy 115,200 bits per second. Now, with the spacecraft each approaching a full light-day away, data drips in at only 160 bps. Uplinked commands are even slower, a mere 16 bps, and are blasted across space from the DSN’s 70-meter dish antennas using 18 kW of power. The uplink path loss over the current 23 billion kilometer distance to Voyager 1 exceeds 200 dB; on the downlink side, the DSN telescopes have to dig a signal that has faded to the attowatt (10-18 W) range.

That the radio systems of Voyager 1 and Voyager 2 worked at all while they were still in the main part of their planetary mission is a technical achievement worth celebrating. The fact that both spacecraft are still communicating, despite the challenges of four decades in space and multiple system failures, is nearly a miracle.

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tekvax
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GaryBIshop
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Wow! Such great technology.

A Secure Phone Fit For A Prime Minister

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The curtain of state secrecy which surrounds the type of government agency known primarily by initialisms is all-encompassing and long-lived, meaning that tech that is otherwise in the public domain remains top secret for many decades. Thus it’s fascinating when from time to time the skirts are lifted to reveal a glimpse of ankle, as has evidently been the case for a BBC piece dealing with the encrypted phones produced by GCHQ and used by Margaret Thatcher in the early 1980s. Sadly, it’s long on human interest and short on in-depth technology, but nevertheless from it can be deduced enough to work out how it most likely worked.

We’re told that it worked over a standard phone line and transmitted at 2.4 kilobytes per second, a digital data stream encoded using a paper tape key that was changed daily. If we were presented with this design spec to implement in a briefcase using 1980s components, we’d probably make an ADPCM (Adaptive Differential Pulse Code Modulation) system with an XOR encryption against the key, something we think would be well within the capabilities of early 1980s digital logic and microprocessors. We’re wondering whether the BBC have made a typo and that  should be kilobits rather than kilobytes to work on a standard phone line.

No doubt there are people in the comments who could tell us if they were willing to break the Official Secrets Act, but we’d suggest they don’t risk their liberty by doing so. It’s worth noting though, that GCHQ have been known to show off some of their past glories, as in this 2019 exhibition at London’s Science Museum.

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Inside an eBay Marking Laser

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When it comes to trolling eBay for cool stuff, some people have all the luck. Whereas all we ever seem to come across is counterfeit chips and obviously broken gear listed as, “good condition, powers on”, [Les Wright] actually managed to get more than he bargained for with one of his recent eBay purchases.

In his video teardown and tour of an industrial marking laser, [Les] suggests that he was really just in it for the optics — which is not a surprise, given his interest in optics in general and lasers in particular. The 20-W CO2 laser once etched barcodes and the like into products on assembly lines, but with a 2009 date code of its own, it was a safe bet that it was pitched due to a burned-out laser tube. But there were still high-quality IR optics and a precision X-Y galvanometer assembly to be harvested, so [Les] pressed on.

The laser itself ended up being built around a Synrad RF-stimulated CO2 tube. By a happy accident, [Les] found that the laser actually still works, at least most of the time. There appears to be an intermittent problem with the RF driver, but the laser works long enough to release the magic smoke from anything combustible that gets in its way. The galvos work too — [Les] was able to drive them with a Teensy and a couple of open-source libraries.

Galvos, lenses worth more than $800, and a working laser tube — not a bad haul. We’ll be following along to see what [Les] makes of this booty.

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Boot Mainline Linux On Apple A7, A8 and A8X devices

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iPhone 6 with Linux boot log on its screen

[Konrad Dybcio] tells about his journey booting Linux on A7/8/8X processors, playing around with an old iPhone 5 he’s got in a drawer. It’s been a two-year “revisit every now and then” journey, motivationally fueled by the things like Linux on M1 Macs announcement. In the end, what we have here is a way to boot mainline Linux on a few less-than-modern but still very usable iPhones, and a fun story about getting there.

[Konrad]’s work is based on the Sandcastle project research, but he couldn’t quite figure out how to make their code work, and had to make sense of it as he went. At some point, he got stuck on enabling the MMU, which was the main roadblock for a while. Joined by another developer intrigued by Apple hardware, they were hacking away at it, developing tools and neat tricks on their way, but to no avail. With the framebuffer accessible and no other decent debugging methods in sight, he tells about a code snippet they wrote that printed register values as valid barcodes

Then, looking deeper into the known-working code, he realized that there was a single line difference in how they loaded the Linux image. Fixing that, they got the MMU to enable! From here, the Linux hacking part ensued, and still continues, with other people pulling their old iDevices out of their respective drawers and joining in on the fun. Integration work is ongoing, with basic peripherals being brought up. Some of the peripherals, we might not see working anytime soon, but from here, it should be way easier to develop drivers and conquer these devices one-by-one.

This development should work for iPhone 5S, 6 and 6 Plus, iPod touch 6th gen, as well as iPad Air 1/2 and iPad Mini 2/3/4. Would you like to boot Linux on one of these devices in your possession? [Konrad] shares instructions on how to get your device from zero to a Linux bootlog on the screen; assistance is available but Linux experience is desired! If you do decide to play around with your own old iDevice, you should spend a minute or two helping him along the way – he is collecting ADT files from different iDevices, and instructions for providing one are super simple!

We haven’t seen Linux on an iPhone in a while – most such hacks come from 2008 or so, dying down a bit afterwards with only a few cool things like PostmarketOS on the iPhone 7 appearing here and there. However, we hope that this brings our smartphones a bit closer to our personal computers when it comes to usefulness.

We thank [Matthew Carlson] for sharing this with us!

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