Japan’s Forgotten Analog HDTV Standard Was Well Ahead Of Its Time

When we talk about HDTV, we’re typically talking about any one of a number of standards from when television made the paradigm switch from analog to digital transmission. At the dawn of the new millenium, high-definition TV was a step-change for the medium, perhaps the biggest leap forward since color transmissions began in the middle of the 20th century.

However, a higher-resolution television format did indeed exist well before the TV world went digital. Over in Japan, television engineers had developed an analog HD format that promised quality far beyond regular old NTSC and PAL transmissions. All this, decades before flat screens and digital TV were ever seen in consumer households!

Resolution

Japan’s efforts to develop a better standard of analog television were pursued by the Science and Technical Research Laboratories of NHK, the national public broadcaster. Starting in the 1970s, research and development focused on how to deliver a higher-quality television signal, as well as how to best capture, store, and display it.
The higher resolution of Hi-Vision was seen to make viewing a larger, closer television more desirable. The figures chosen were based on an intended viewing distance that of three times the height of the screen. Credit: NHK Handbook
This work led to the development of a standard known as Hi-Vision, which aimed to greatly improve the resolution and quality of broadcast television. At 1125 lines, it offered over double the vertical resolution of the prevailing 60 Hz NTSC standard in Japan. The precise number was chosen for meeting minimum requirements for image quality for a viewer with good vision, while being a convenient integer ratio to NTSC’s 525 lines (15:7), and PAL’s 625 lines (9:5). Hi-Vision also introduced a shift to the 16:9 aspect ratio from the more traditional 4:3 used in conventional analog television. The new standard also brought with it improved audio, with four independent channels—left, center, right, and rear—in what was termed “3-1 mode.” This was not unlike the layout used by Dolby Surround systems of the mid-1980s, though the NHK spec suggests using multiple speakers behind the viewers to deliver the single rear sound channel.
Hi-Vision offered improved sound, encoded with PCM. Credit: NHK handbook
Hi-Vision referred most specifically to the video standard itself; the broadcast standard was called MUSE—standing for Multiple sub-Nyquist Sampling Encoding. This was a method for dealing with the high bandwidth requirements of higher-quality television. Where an NTSC TV broadcast might only need 4.2 MHz of bandwidth, the Hi-Vision standard needed 20-25 MHz of bandwidth. That wasn’t practical to fit in alongside terrestrial broadcasts of the time, and even for satellite delivery, it was considered too great. Thus, MUSE offered a way to compress the high-resolution signal down into a more manageable 8.1 MHz, with a combination of dot interlacing and advanced multiplexing techniques. The method used meant that ultimately four frames were needed to make up a full image. Special motion-sensitive encoding techniques were also used to limit the blurring impact of camera pans due to the use of the dot interlaced method. Meanwhile, the four-channel digital audio stream was squeezed into the vertical blanking period.

MUSE broadcasts began on an experimental basis in 1989. NHK would eventually begin using the standard regularly on its BShi satellite service, with a handful of other Japanese broadcasters eventually following suit. Broadcasts ran until 2007, when NHK finally shut down the service with digital TV by then well established.

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An NHK station sign-on animation used from 1991 to 1994.
A station ident from NHK’s Hi-Vision broadcasts from 1995 to 1997. Note the 16:9 aspect ratio—then very unusual for TV. Credit: NHK
The technology wasn’t just limited to higher-quality broadcasts, either. Recorded media capable of delivering higher-resolution content also permeated the Japanese market. W-VHS (Wide-VHS) hit the market in 1993 as a video cassette standard capable of recording Hi-Vision/MUSE broadcast material. The W moniker was initially chosen for its shorthand meaning in Japanese of “double”—since Hi-Vision used 1125 lines which was just over double the 525 lines in an NTSC broadcast.

Later, in 1994, Panasonic released its Hi-Vision LaserDisc player, with Pioneer and Sony eventually offering similar products. They similarly offered 1,125 lines (1,035 visible) of resolution in a native 16:9 aspect ratio. The discs were read using a narrower-wavelength laser than standard laser discs, which also offered improved read performance and reliability.

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Sample video from a MUSE Hi-Vision Laserdisc. Note the extreme level of detail visible in the makeup palettes and skin, and the motion trails in some of the lens flares.

The hope was that Hi-Vision would become an international standard for HDTV, supplanting the ugly mix of NTSC, PAL, and SECAM formats around the world. Unfortunately, that never came to pass. While Hi-Vision and MUSE did offer a better quality image, there simply wasn’t much content that was actually broadcast in the standard. Only a few channels in Japan were available, creating a limited incentive for households to upgrade their existing sets. Similarly, the amount of recorded media available was also limited. The bandwidth requirements were also too great; even with MUSE squishing the signals down, the 8.1MHz required was still considered too much for practical use in the US market. Meanwhile, being based on a 60 Hz standard meant the European industry was not interested.

Further worsening the situation was that by 1996, DVD technology had been released, offering better quality and all the associated benefits of a digital medium. Digital television technology was not far behind, and buildouts began in countries around the world by the late 1990s. These transmissions offered higher quality and the ability to deliver more channels with the same bandwidth, and would ultimately take over.

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Only a handful of Hi-Vision displays still exist in the world.

Hi-Vision and MUSE offered a huge step up in image quality, but their technical limitations and broadcast difficulties meant that they would never compete with the new digital technologies that were coming down the line. There was simply not enough time for the technology to find a foothold in the market before something better came along. Still, it’s quite something to look back on the content and hardware from the late 1980s and early 1990s that was able, in many ways, to measure up in quality to the digital flat screen TVs that wouldn’t arrive for another 15 years or so. Quite a technical feat indeed, even if it didn’t win the day!

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Countdown To Pi 1 Loss Of Support, Activated

The older Raspberry Pi boards have had a long life, serving faithfully since 2012. Frankly, their continued support is a rarity these days — it’s truly incredible that an up-to-date OS image can still be downloaded for them in 2025. All good things must eventually come to an end though, and perhaps one of the first signs of that moment for the BCM2385 could be evident in Phoronix’s report on Debian dropping support for MIPS64EL & ARMEL architectures. Both are now long in the tooth and other than ARMEL in the Pi, rarely encountered now, so were it not for the little board from Cambridge this might hardly be news. But what does it mean for the older Pi?

It’s first important to remind readers that there’s no need to panic just yet, as the support is going not for the mainstream Debian releases, but the unstable and experimental ones. The mainstream Debian support period for the current releases presumably including the Debian-based Raspberry Pi OS extends until 2030, which tallies well with Raspberry Pi’s own end-of-life date for their earlier boards. But it’s a salutary reminder that that the clock’s ticking, should (like some of us) you be running an older Pi. You’ve got about five years.

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Make Metal Rain with Thermal Spraying

For those of us hackers who have gone down a machining rabbit hole, we all know how annoying it can be to over-machine a part. Thermal spraying, while sounding sci-fi, is a method where you can just spray that metal back on your workpiece. If you don’t care about machining, how about a gun that shoots a shower of sparks just to coat your enemies in a layer of metal? Welcome to the world of thermal spraying, led by the one and only [Alec Steele].

There are three main techniques shown that can be used to coat using metal spools. The first, termed flame spraying, uses a propane flame and compressed air to blast fine drops of molten metal onto your surface. A fuel-heavy mixture allows the metal to remain unoxidized and protect any surface beneath. Perhaps one of the most fun to use is the arc method of thermal spray. Two wires feed together to short a high current circuit; all it takes from there is a little pressured air to create a shower of molten metal. This leaves the last method similar to the first, but uses a powder material rather than the wires used in flame spraying.

As with much crazy tech, the main uses of thermal spraying are somewhat mundane. Coating is applied to prevent oxidation, add material to be re-machined, or improve the mechanical resistance of a part. As expensive as this tech is, we would love to see someone attempt an open-source version to allow all of us at Hackaday to play with. Can’t call it too crazy when we have people making their own X-ray machines.

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