Editor's note by Steve Taranovich : We are bringing you a lost article from The Connecting Edge site written by Bill Schweber, that used to be run by Martin Rowe. The reason I want this on Planet Analog is twofold: one is that Bill Schweber's blogs are most informative, educational, entertaining and great tech pieces, and two is that Bill Schweber refers to this particular article in a new Analog Angle blog here on Planet Analog. Enjoy!
I have always had a few battery-powered AM/FM radios around, but I also had a special radio that had a third band for TV sound (VHF only, channels 2-13).
The ostensible reason I had it was that it would be good in case of some emergency, so I could follow the news and updates even if AC power (and my TV) were out. The other reason was that it was a handy way to keep an ear on shows when watching a TV set was impractical or would look bad to others or when I didn't want to be distracted by the picture. Let's be honest. Many TV shows — whether alleged comedies, drama, news, or talking heads — are primarily audio events.
The switchover to digital TV a few years back made my radio's TV sound band useless. Frankly, it was no big deal, because I wasn't using it much anyway. It was one of those purchases that seemed like a good idea at the time. Recently, though, I happened to come across an online discussion where someone wondered if digital TV-band sound radios were even available. I thought that was a good question from a technical standpoint.
I did some searching on the web and came up empty. There were a few posts about radios that supposedly carried AM/FM/digital TV sound, but there were no specs and no pricing, so maybe they didn't exist. Certainly, none of the top-tier radio vendors had one.
One commenter said that, if you really need or want a TV-only radio, you should just get a digital TV converter box (about $50) and hook up its audio output jacks to a speaker. Ironically, you would first have to connect the converter box to a TV to configure it to your local channels and set some other parameters. That seems kind of weird. Also, I don't know if the audio output from the box can drive a speaker, since it is intended as a line-out connection to an amplifier.
The whole thing seems like a lot of work, and it's certainly not something the average person would be willing to do. Plus, in the end, you'd still need an AC line for the converter, so you haven't solved the portable/emergency power aspect of the problem.
Losing this kind of radio isn't a big deal. I guess you could buy a small, battery-powered digital TV for around $75 and just cover the screen. Unfortunately, the batteries are good for only a few hours of operation, because these things draw a lot of current. Furthermore, there are various web streaming possibilities — some legal and some perhaps not so legal.
But the lack of a TV sound-only radio band made me wonder: Why not? I have several possible explanations. First, there's probably little demand for it. Second, given the complexity and topology of the digital TV tuner and TV decoder, the audio-only option is probably as complex as the complete video/audio one, so the savings would be minimal. Third, the AM/FM/TV sound radio would be an expensive beast. The AM/FM circuitry is quite different from the TV circuitry. You'd have to have one signal chain for AM/FM (albeit with some differences) and one for the TV sound tuning and decoder. I don't think software-defined radio is an option for the consumer market here.
In a world where adding functionality to the point of extremes is fairly common, are there any discontinued or obsolete products or functions that you miss? Why do you think they are gone?