A different approach to digital radio

[Chuck]

In the most recent Radio World engineering edition, there is an article that suggests using existing HDTV transmitters to distribute digital radio to the masses. Sorry, I don't have a link. The magazine just arrived by snail mail a day or so ago.

It's an interesting idea. There is spare bandwidth available in a digital TV channel. The transmitters are already up and running. Adding audio streams would not be very difficult to do. Nobody said these transmitters have to be used exclusively for additional TV channels. In fact the FCC refused to make any digital TV standard, so it is a fairly open book at this point. So why not audio on TV channels?

A TV station could conceivably run their primary HDTV feed, maybe a secondary video channel, and still have plenty of room for numerous audio streams. The coverage would be quite good, or at least very predictable, since it is easy enough to figure out where the TV station is receivable. Most importantly, it wouldn't cause any interference to existing analog or digital broadcasting.

Now here is the part that some large broadcasters would not like: It would level the playing field for all the stations who signed on to use this transmission service. The current 100 watt college station would go just as far as the present day 100 KW flame-throwers who were distributed digitally through these existing TV transmitters.

TV stations should love it though. It would give them additional revenue streams with very little additional effort or cost on their part.

Yes, I know that there are currently no radios on the store shelves to receive this, but worrying about that is a bit premature. This is just another example of the potential ways to convert to digital radio without leaving a bigger mess than the one you were trying to clean up. I’ll bet there will be more good ideas coming down the pipe. Stay tuned. It is going to be an interesting ride. 8)

 

[dbdigital]

In the most recent Radio World engineering edition, there is an article that suggests using existing HDTV transmitters to distribute digital radio to the masses. Sorry, I don't have a link. The magazine just arrived by snail mail a day or so ago.

It's an interesting idea. There is spare bandwidth available in a digital TV channel. The transmitters are already up and running. Adding audio streams would not be very difficult to do. Nobody said these transmitters have to be used exclusively for additional TV channels. In fact the FCC refused to make any digital TV standard, so it is a fairly open book at this point. So why not audio on TV channels?

A TV station could conceivably run their primary HDTV feed, maybe a secondary video channel, and still have plenty of room for numerous audio streams. The coverage would be quite good, or at least very predictable, since it is easy enough to figure out where the TV station is receivable. Most importantly, it wouldn't cause any interference to existing analog or digital broadcasting.

Now here is the part that some large broadcasters would not like: It would level the playing field for all the stations who signed on to use this transmission service. The current 100 watt college station would go just as far as the present day 100 KW flame-throwers who were distributed digitally through these existing TV transmitters.

TV stations should love it though. It would give them additional revenue streams with very little additional effort or cost on their part.

Yes, I know that there are currently no radios on the store shelves to receive this, but worrying about that is a bit premature. This is just another example of the potential ways to convert to digital radio without leaving a bigger mess than the one you were trying to clean up. I’ll bet there will be more good ideas coming down the pipe. Stay tuned. It is going to be an interesting ride. 8)

Interesting idea. Some time ago at a trade show I attended (not NAB) I talked to a television engineer about the transition from analog to VSB-8. He said that what had TV broadcasters salivating was not HDTV but the ability to stream two or three SDTV channels within the same bandwidth. They believe that this will help them compete with cable, much as FM stations feel that HD Radio will help them compete with satellite.

But why not radio as well? Instead of three channels of standard def TV, a broadcaster could have two TV and several audio-only channels. As mentioned, the HDTV signal is more robust than HD Radio and can be received and stay locked-in at greater distances.

db

 

[MotoMuzak]

Huh. That idea's interesting.

Kind of like a "Digital SAP (or TAP, FAP.........) channel" of sorts, at least in concept, right?

 

[Chuck]

Huh. That idea's interesting.

Kind of like a "Digital SAP (or TAP, FAP.........) channel" of sorts, at least in concept, right?

It's remarkably simple. I wish I'd thought of it. According to the author of the article, who occasionally posts on a radio engineering/history newsgroup, a TV station should be able to run a primary HDTV feed and up to 19 stereo 64 KBS audio channels. If the choice was to run mono, or even just at a lower streaming rate, even more channels could be used.

I know that some will scoff at 64 KBs as being substandard, but using the right codecs, it can sound very good. Certainly, it is a lot better than the NRSC version of AM, and probably as good as most FM stations. Most people would deem it as acceptable. It is also likely that compression technology will improve over the years, so things could get even better.

Given that just about every major market has 10 or more TV stations, it could make a lot of audio (radio) channels available. In fact, I don't believe it would even require an FCC license to be the provider of content for one of these "radio" streams. The TV station is already licensed. What is broadcast on it comes under the area of programming. Content providers are not regulated (directly) by the FCC. In fact, this idea could open up broadcasting outlets to any organization that had the money to lease the bandwidth. That is a very interesting proposition.

This is way too simple for it to ever fly.....

 

[clichemoth]

I could see this happening. TV stations have all this bandwidth and not much to use it for. The idea of putting scrambled cable channels on them didn't work where it was tried (is USDTV still even in business?), so why not rent some of it out for radio or start some feeds of their own and sell some ads? 64 KB/s would sound just fine to anyone who isn't a hardcore audiophile with a high-end system (Of course, if they could fit 19 feeds at 64, they could go to 128 and still have room for 9.

Of course, the big advantage of this would be that, unlike HD radio, an HDTV receiver can be made portable, maybe not as small as an iPod, but something the size of a PSP or Discman is definitely possible.

 

[desert_er]

Very interesting concept... Maybe the TV broadcasters could "skip the middleman" and air their own audio programming...
I thought there was some issue with VSB-8 not being robust enough to be receiveable on "moving" (i.e. portable) devices... note that even with the analog shutoff looming, we've yet to see any handheld ATSC televisions. Japan has a separate DVB standard for portable devices, I believe to address the previous issue.
As a side note, all the technology would be there to listen to the evening news or the tonight show on your car radio.
What this really goes to show is how efficiently a band can be used when it isn't "hybridized"... Imagine if the TV broadcasters had to encode their digital signal into an SAP channel Eureka's got it right, but the canadians just got stuck with a band that has crummy propagation for broadcast. It'd be great if digital radio reclaimed the 46-50MHz "cordless phone" band.