End Of An Era: NTSC Finally Goes Dark In America

A significant event in the history of technology happened yesterday, and it passed so quietly that we almost missed it. The last few remaining NTSC transmitters in the USA finally came off air, marking the end of over seven decades of continuous 525-line American analogue TV broadcasts. We’ve previously reported on the output of these channels, largely the so-called “FrankenFM” stations left over after the 2009 digital switchover whose sound carrier lay at the bottom of the FM dial as radio stations, and noted their impending demise. We’ve even reported on some of the intricacies of the NTSC system, but we’ve never taken a look at what will replace these last few FrankenFM stations.

If you are an American you may have heard of ATSC 3.0, perhaps by its marketing name of NextGen TV. Just like the DVB-T2 standard found in other parts of the world, it’s an upgrade to digital TV standards to allow for more recent video compression technologies and higher definition broadcasts. It has an interesting backwards compatibility feature absent in previous ATSC versions; there is the option of narrowing the digital bandwidth from 6 MHz to 5.5 MHz, and transmitting an analogue FM subcarrier where the old NTSC sound carrier on the same channel would have sat. Thus the FrankenFM stations have the option of upgrading to ATSC 3.0 and transmitting a digital channel package alongside their existing FM radio station. It’s reported that this switchover is happening, with one example given in the Twitter thread linked above.

The inexorable march of technology has thus given better quality TV alongside the retention of the FrankenFMs. We have to admit to being sorry to see the passing of analogue TV, it was an intricate and fascinating system that provided a testbed for plenty of experimentation back in the day. Perhaps as we see it slip over the horizon it’s worth pondering whether its digital replacement will also become an anachronism in an age of on-demand streaming TV, after all it shouldn’t have escaped most people’s attention that in 2021 the good TV content no longer comes to your screen via an antenna socket. Meanwhile we’ll keep our CRTs running, just in case we ever want to relive a 1980s night in with a VHS tape of Back To The Future.

Header image: Mysid, Public domain.

History Of Closed Captions: The Analog Era

Closed captioning on television and subtitles on DVD, Blu-ray, and streaming media are taken for granted today. But it wasn’t always so. In fact, it was quite a struggle for captioning to become commonplace. Back in the early 2000s, I unexpectedly found myself involved in a variety of closed captioning projects, both designing hardware and consulting with engineering teams at various consumer electronics manufacturers. I may have been the last engineer working with analog captioning as everyone else moved on to digital.

But before digging in, there is a lot of confusing and imprecise language floating around on this topic. Let’s establish some definitions. I often use the word captioning which encompasses both closed captions and subtitles:

Closed Captions: Transmitted in a non-visible manner as textual data. Usually they can be enabled or disabled by the user. In the NTSC system, it’s often referred to as Line 21, since it was transmitted on video line number 21 in the Vertical Blanking Interval (VBI).
Subtitles: Rendered in a graphical format and overlaid onto the video / film. Usually they cannot be turned off. Also called open or hard captions.

The text contained in captions generally falls into one of three categories. Pure dialogue (nothing more) is often the style of captioning you see in subtitles on a DVD or Blu-ray. Ordinary captioning includes the dialogue, but with the addition of occasional cues for music or a non-visible event (a doorbell ringing, for example). Finally, “Subtitles for the Deaf or Hard-of-hearing” (SDH) is a more verbose style that adds even more descriptive information about the program, including the speaker’s name, off-camera events, etc.

Roughly speaking, closed captions are targeting the deaf and hard of hearing audience. Subtitles are targeting an audience who can hear the program but want to view the dialogue for some reason, like understanding a foreign movie or learning a new language.

Continue reading “History Of Closed Captions: The Analog Era”

Time’s Almost Up For The FrankenFMs: The Impending Switchoff Of Analog TV

In a time when multi-channel digital TV is the norm it’s a surprise to find that a few low-power analog stations are still clinging on in some American cities. These are sometimes fill-in stations for weak signal areas, or more usually the so-called “FrankenFM” stations who transmit static images or digital patterns and derive income from their sound channel lying at the bottom end of the FM band to form unintended radio stations. Their days are numbered though, because the FCC is requiring that they be turned off by July 13th. There’s a way forward for the broadcasters to upgrade to low-power digital, but as you might expect they’re more interested in retaining the FrankenFM frequency from which they derive income.

The industry is represented by the LPTV coalition, who have requested permission to retain their FM frequency alongside their digital service. This has faced stiff opposition from other broadcasters, who see the very existence of the FrankenFM stations as a flagrant flouting of the rules that shouldn’t be rewarded. The FCC have yet to make a ruling, so there remains a slim chance that they may win a reprieve.

The sad tale of the few lingering analog TV stations in the USA is a last flickering ember of a once-huge industry that has been eclipsed without anyone but a few vintage technology geeks noticing, such has been the success of digital broadcasting. But analog TV is a fascinating and surprisingly intricate system whose passing however faint is worth marking.

Header: Tiia Monto, CC BY-SA 3.0.

The Last Few Analogue TV Stations In North America

Analogue TV is something that most of us consider to have been consigned to the history books about a decade ago depending on where in the world we are, as stations made the transition to much more power and frequency efficient digital multiplexes. However some of them still cling on for North American viewers, and [Antenna Man] took a trip to Upstate New York in search of some of them before their final switch-off date later this year.

What he reveals can be seen in the video below the break, an odd world of a few relatively low-power analogue TV stations still serving tiny audiences, as well as stations that only exist because their sound carrier can be picked up at the bottom of the FM dial. These stations transmit patterns or static photographs, with their income derived from the sound channel’s position as an FM radio station. While his journey is an entertaining glimpse into snowy-picture nostalgia it does also touch on some other aspects of the aftermath of analogue TV boradcasting. The so-called “FrankenFM” stations sound much quieter, we’re guessing because of the lower sound carrier deviation of the CCIR System M TV spec compared to regular FM radio. And we’re told that there are more stations remaining in Canada, so get out there if you still want to see an analogue picture before they’re gone forever. Where this is being written the switch to DVB was completed in 2013, and it’s still a source of regret that we didn’t stay up to see the final closedown.

Does your country still have an analogue TV service? Tell us in the comments.

Continue reading “The Last Few Analogue TV Stations In North America”

Grey Gear: French TV Encryption, 1980s Style

Who among us didn’t spend some portion of their youth trying in vain to watch a scrambled premium cable TV channel or two? It’s a wonder we didn’t blow out our cones and rods watching those weird colors and wavy lines dance across the screen like a fever dream.

In the early days of national premium television in America, anyone who’d forked over the cash and erected a six-foot satellite dish in the backyard could tune in channels like HBO, Showtime, and the first 24-hour news network, CNN. Fed up with freeloaders, these channels banded together to encrypt their transmissions and force people to buy expensive de-scrambling boxes. On top of that, subscribers had to pay a monthly pittance to keep the de-scrambler working. Continue reading “Grey Gear: French TV Encryption, 1980s Style”

Run Your Favorite 8-bit Games On An ESP32

Here at Hackaday HQ we’re no strangers to vintage game emulation. New versions of old consoles and arcade cabinets frequently make excellent fodder for clever hacks to cram as much functionality as possible into tiny modern microcontrollers. We’ve covered [rossumur]’s hacks before, but the ESP_8-bit is a milestone in comprehensive capability. This time, he’s topped himself.

There isn’t much the ESP 8-bit won’t do. It can emulate three popular consoles, complete with ROM selection menus (with menu bloops). Don’t worry about building a controller, just connect any old (HID compliant) Bluetooth Classic keyboard or WiiMote you have at hand. Or if that doesn’t do it, a selection of IR devices ranging from joysticks from the Atari Flashback 4 to Apple TV remotes are compatible. Connect analog audio and composite video and the device is ready to go.

The system provides this impressive capability with an absolute minimum of components. Often a schematic is too complex to fit into a short post, but we’ll reproduce this one here to give you a sense for what we’re talking about. Come back when you’ve refreshed your Art of Electronics and have a complete understanding of the hardware at work. We never cease to be amazed at the amount of capability available in modern “hobbyist” components. With such a short BOM this thing can be put together by anyone with an ESP-32-anything.

There’s one more hack worth noting; the clever way [rossumur] gets full color NTSC composite video from a very busy microcontroller. They note that NTSC can be finicky and requires an extremely stable high speed reference clock as a foundation. [rossumur] discovered that the ESP-32 includes a PLL designed for audio work (the “APLL”) which conveniently supports fractional components, allowing it to be trimmed to within an inch of the desired frequency. The full description is included in the GitHub page for the project and includes detailed background of various efforts to get color NTSC video (including the names of a couple hackers you might recognize from these pages).

Continue reading “Run Your Favorite 8-bit Games On An ESP32”

This Commodore 16 Is An NTSC One… No, Wait, It’s A PAL One!

We’re used to our computers being powerful enough in both peripheral and processing terms to be almost infinitely configurable under the control of software, but there was a time when that was not the case. The 8-bit generation of home computers were working towards the limits of their capability just to place an image on a TV screen, and every component would have been set up to do just the job it was intended for. Thus when different countries had different TV standards such as the mostly-European PAL and the mostly-American NTSC, there would have been different models of the same machine for each market. The Commodore 16 was just such a machine, and [Adrian Black] has modified his NTSC model with a custom ROM, an Arduino and an Si5351 clock generator to be switchable between the two.

The differences between a PAL and NTSC C16 are two-fold. The clock for the video chip is of a different frequency, and the ROM contents differ too. [Adrian]’s machine therefore has a larger ROM containing both versions which are switchable via one of the upper address lines. A couple of tracks cut in the crystal oscillator circuit allow him to inject a new clock from the Si5351 module, and and Arduino controls everything. The appropriate ROM and clock are selected via a very simple interface, the reset button is captured and while a short press still resets the computer a long one switches the mode.

Despite having its principal engineer, [Bil Herd] as a colleague here at Hackaday, it’s sad that we don’t see as many Commodore 16s as we should. A recent feature showed a 64k C16, but didn’t make it into a C64.

Continue reading “This Commodore 16 Is An NTSC One… No, Wait, It’s A PAL One!”