HD vs SCA

[flwfg]

What, if any are the differences between SCA and HD secondary frequencies??? Is SCA even used anymore???

 

[nd2023]

There are more subcarrier radios than HD radios

 

[Darth_vader]

SCA operates at 67 or 92 KHz (sometimes both) whereas Ibiquity's baseband is farther out than that--I want to say it's around the 145-150 kHz range, but I'm probably way off.

SCA is still used these days, mostly for radio reading services and foreign programming, or the occasional telemetry or EAS data streams. Some people will tell you Muzak uses SCA as a transmission system--wrong; Muzak used SCA in the distant past, but they pretty much exclusively use satellites for that purpose these days. If you actually do manage to come across a market where they're still doing that, enjoy it while you can because it probably won't be around for much longer!

 

[jhardis]

What, if any are the differences between SCA and HD secondary frequencies??? Is SCA even used anymore???

SCA is still used a lot.

SCA and IBOC (HD Radio (tm)) are completely different. SCA is implemented by using ultrasonic frequencies on the same FM carrier as the regular audio. It's similar to how the stereo portion of FM is transmitted. The stereo frequencies are centered at 38 kHz, while SCA is usually centered at 67 kHz. (And in both cases, I mean audio frequencies, not radio frequencies.) The stereo and SCA signals are FM modulated around their center frequencies (38 kHz and 67 kHz respectively) -- FM on top of FM, as it were.

IBOC is not a modulation of the traditional FM carrier. You can think of it as completely separate carriers -- hundreds of them -- between 100 kHz and 200 kHz removed from the usual FM carrier, that is, in the two adjacent channels. (In practice, those 100's of carriers are formed by AM modulation of a single carrier at very high frequencies, but the time-domain and frequency-domain representations of the signal are equally valid.)

- Jonathan

 

[Kmagrill]

In addition to the very fine answers above, SCA is considered a subscription or non-public service. Non-commercial stations can have paid SCAs because they are not for the general public. SCA audio is frequency limited to 10kHz (or less), so SCA audio is not as good as regular FM. SCAs are also much more prone to noise than the main FM carrier, for a variety of technical reasons. For this reason, commercial SCAs were normally only found on higher powered stations.

 

[Darth_vader]

As has been covered in past threads, that "subscription" thing was lifted by the F¢¢ when SCA was deregulated in the late 1980s. Anything you may read about it still being as such on the F¢¢'s web page is about 24 years out of date.

Yes, there are probably still some services which demand that one give them money to listen to their transmissions (despite tunable MW/FM/SCA receivers being more-or-less "widely" publicly available) but for the most part, that's only because it was a requirement in the distant past.

 

[Kmagrill]

As has been covered in past threads, that "subscription" thing was lifted by the F¢¢ when SCA was deregulated in the late 1980s. Anything you may read about it still being as such on the F¢¢'s web page is about 24 years out of date.

Yes, there are probably still some services which demand that one give them money to listen to their transmissions (despite tunable MW/FM/SCA receivers being more-or-less "widely" publicly available) but for the most part, that's only because it was a requirement in the distant past.

Sorry, but the above is wrong and I got this directly from the chief of the FM branch. SCA is still not a public service.

Despite the flood of SCA radios from China being sold on eBay, SCA is not deregulated and is definately still considered a subscription/non-public service.

This very question was posed to the FCC in 2010 when a translator wanted to pick up an SCA and convert it to the main channel. Jim Bradshaw, himself, responded that this is illegal because SCA is not a public broadcast service.

 

[Darth_vader]

Nope, as has been covered in past threads, that "subscription" thing was lifted by the F¢¢ when SCA was deregulated in the late 1980s. Anything you may have been told about it still being as such by the F¢¢'s paper pushers is about 24 years out of date.

Yes, there are probably still some services which demand that one give them money to listen to their transmissions (despite tunable MW/FM/SCA receivers being more-or-less "widely" publicly available) but for the most part, that's only because it was a requirement in the distant past.

Just F.Y.I., the KBOO and KBVM translators in The Dalles and Hood River have been retransmitting their main channels' SCA audio for years. Same thing with KPBX and KFAE's translators retransmitting Evergreen Radio Reading Service on 67 kHz.

 

[Chuck]

This very question was posed to the FCC in 2010 when a translator wanted to pick up an SCA and convert it to the main channel. Jim Bradshaw, himself, responded that this is illegal because SCA is not a public broadcast service.

A fewl years ago, I asked this very question to Jim Bradshaw at the FCC. The answer was not only "No," but "Hell No." The FCC still considers SCA to be a private service.

 

[Kmagrill]

This very question was posed to the FCC in 2010 when a translator wanted to pick up an SCA and convert it to the main channel. Jim Bradshaw, himself, responded that this is illegal because SCA is not a public broadcast service.

A fewl years ago, I asked this very question to Jim Bradshaw at the FCC. The answer was not only "No," but "Hell No." The FCC still considers SCA to be a private service.

That's exactly right. No SCA should ever be on the main channel of a translator and the FCC is adamant about this. SCAs are private services. It is perfectly legal to retransmit an SCA as long as it remains an SCA, but it is still illegal to put an SCA on a main channel. Any translator that transmits an SCA on the main channel is setting themselves up for a big fine.

You don't have to take our word for this. Call the FCC's FM branch and speak to Bradshaw, Bickell or Gates. They'll tell you the same thing.

If you want to change the way translators are viewed at the FCC, file a petition for rulemaking to change the status of SCAs. I'm sure that there would be a lot of support, but be prepared for quite a lot of opposition, mostly from all of the broadcasters that are using SCAs. Many radio stations use SCAs for all sorts of raw audio backhauls and cueing. This is not something that they want to have the general public listening to and just one good reason why SCAs are still a private service.

 

[Darth_vader]

Nope, as has been covered in past threads, that "subscription" thing was lifted by the F¢¢ when SCA was deregulated in the late 1980s. Anything you may have been told about it still being as such by the F¢¢'s paper pushers is about 24 years out of date. Yes, there are probably still some services which demand that one give them money to listen to their transmissions, but for the most part, that's only because it was a requirement in the distant past.

If Dr. Elving were here/still alive, he'd be able to back me on this. Obviously I have no say in whether or not the F¢¢ want to remember and back their own actions. It's not surprising that the bureaucrats are trying to erase the past, since that's how things work in Wa$hington.

(I may as well give up now, since I'm getting nowhere with this crowd.)

 

[rbrucecarter5]

There is an aspect to this question that hasn't been explored --- perhaps they could dust off this tired old service and use it to solve the HD-2 dropout problem. Stations could carry their HD-2 formats on the SCA channel, then in event of a dropout the receiver could back to the SCA version of HD-2. Far better than dead silence on the HD-2 while waiting for lock to come back. I wonder how much of a receiver re-design would be required? Could it all be done in firmware?

 

[nd2023]

This very question was posed to the FCC in 2010 when a translator wanted to pick up an SCA and convert it to the main channel. Jim Bradshaw, himself, responded that this is illegal because SCA is not a public broadcast service.

A fewl years ago, I asked this very question to Jim Bradshaw at the FCC. The answer was not only "No," but "Hell No." The FCC still considers SCA to be a private service.

That's exactly right. No SCA should ever be on the main channel of a translator and the FCC is adamant about this. SCAs are private services. It is perfectly legal to retransmit an SCA as long as it remains an SCA, but it is still illegal to put an SCA on a main channel. Any translator that transmits an SCA on the main channel is setting themselves up for a big fine.

You don't have to take our word for this. Call the FCC's FM branch and speak to Bradshaw, Bickell or Gates. They'll tell you the same thing.

If you want to change the way translators are viewed at the FCC, file a petition for rulemaking to change the status of SCAs. I'm sure that there would be a lot of support, but be prepared for quite a lot of opposition, mostly from all of the broadcasters that are using SCAs. Many radio stations use SCAs for all sorts of raw audio backhauls and cueing. This is not something that they want to have the general public listening to and just one good reason why SCAs are still a private service.

I wish they had the same attitude about HD stations on translators. HD2 stations should be translated in HD, not analog.

It's also ironic that subcarrier radios were intended to be private, but broadcast in the clear by nature. HD is intended to be public, but it can be encrypted digitally.

 

[Chuck]

Actually, I wanted to use FMeXtra to feed a translator, but Bradshaw said, "It is an SCA service, not intended for public broadcast, so therefore you can't do it." On the other-hand, it is fine use a HD-2 signal for the same purpose. Go figure.

 

[fybush]

Actually, I wanted to use FMeXtra to feed a translator, but Bradshaw said, "It is an SCA service, not intended for public broadcast, so therefore you can't do it." On the other-hand, it is fine use a HD-2 signal for the same purpose. Go figure.

And therein lies the distinction (at least in the eyes of Bradshaw and his colleagues at the Commission): "subscription" is something of a red herring here. 1980s-era dereg or not, there's still a difference in the Media Bureau's eyes between "intended for public broadcast" and "not intended for public broadcast."

SCA is and has always been in the latter category. As a result, SCA operations are exempt from many of the rules that govern broadcast services. The FCC doesn't regulate SCA content, and there's no requirement for legal IDs or public service programming or EAS participation. Noncommercial stations can (and often did) sell SCA space to commercial services, albeit with the requirement after 1982 that they make one subcarrier available to a reading service at no more than a nominal charge.

As I understand it, FMeXtra ended up lumped in with analog SCA because of that 1980s-era deregulation. Until about 1983, the FCC required that stations request and receive Commission authorization for each SCA service they provided. Since dereg, stations don't have to be specifically licensed for SCA, and can do pretty much anything they want with the spectrum above +/- 53 kHz, so long as it remains within certain modulation limits and doesn't go beyond +/- 99 kHz from the carrier. When the FCC deregulated the technical specifics of SCA use in 1983, they may not have been anticipating the use of digital modulation - but FMeXtra otherwise fit within the rules and was thus allowed to be used in the same fashion as any other analog SCA service. In this case, that means all of the "not intended for public broadcast" rules (and privileges) applied to FMeXtra just as they did to analog SCA - and which is why neither analog SCA services nor FMeXtra can legally be rebroadcast on an analog translator, which is considered to be a public broadcast service.

HD was, of course, a different beast from the beginning. It was explicitly intended as a broadcast service (and couldn't have been otherwise initially, when there was only an HD-1 on FM). When HD-2/3/4 came along later, once they were authorized for non-experimental use, they were authorized as broadcast services and were subjected to all the same content requirements as HD-1. At least in theory, if not always in practice, HD-2/3/4 services must include legal IDs and EAS and could generate FCC fines for obscene content and for commercial content on a noncommercial license.

(The exception appears to be "conditional access" HD subchannels, which are exempt from those requirements but are also considered "not intended for public broadcast.")

I don't know if anyone has asked Jim Bradshaw yet whether a conditional access HD-x could be rebroadcast over an analog FM translator, but I strongly suspect the answer would be the same as for an analog SCA or FMeXtra service.

To the extent that the FCC itself can be deemed a reliable source for information about the FCC, all the relevant rulemakings and historical documents are collected here:

http://www.fcc.gov/encyclopedia/bro...rs-or-subsidiary-communications-authority-sca

If they're trying to erase the past, they're doing a spectacularly bad job of it.

For what it's worth, I knew Dr. Elving for more than a quarter of a century, corresponded with him frequently, hosted him at a WTFDA convention here in western New York, and even had the pleasure of visiting with him and his wife, Carol, at their Minnesota home and workshop. (Courtesy of Carol, the very last box of the very last FM Atlas edition is sitting about 15 feet away from me right now, and when the last of those have been sold here and by the NRC, which got the second-to-last-box, there are no more.)

Bruce was always very careful about the legality of the SCA-modified receivers he sold. As I understood it, he successfully skirted the FCC's prohibition on tunable SCA receivers by marketing his products as hobby kits. That allowed him to avoid the equipment-authorization requirement (47 CFR 2.803) that would otherwise have outlawed his units. It didn't hurt, either, that Bruce had made many friends at the Commission over many years of correspondence. As long as he kept his operation small and didn't widely advertise outside hobby circles, the FCC seemed to be happy to leave him alone. Had he marketed more aggressively or tried to manufacture or import compete receivers of his own design, things might have gone differently.

 

[Kmagrill]

Excellent clarification, Scott.

Actually, I wanted to use FMeXtra to feed a translator, but Bradshaw said, "It is an SCA service, not intended for public broadcast, so therefore you can't do it." On the other-hand, it is fine use a HD-2 signal for the same purpose. Go figure.

Well, if you or the FMeXtra folks were to petition for a rule change or maybe even an exception to the SCA rules to specifically allow tuneable receivers that could receive ONLY FMeXtra encoded SCAs, you might be able to get that through the FCC, provided that:

1. FMeXtra encodering is never sold as a product for private service and
2. any tunable FMeXtra receiver is incapable of receiving standard SCA.


There's an interesting exception that the FCC notes on their SCA information page that is very similar to this.

See:
http://www.fcc.gov/encyclopedia/bro...rs-or-subsidiary-communications-authority-sca


This still does not make FMeXtra a public service, however a petition for rulemaking might have a chance since normal SCA would be unaffected by the tunable digital receivers required to pick up FMeXtra. This would require expert writing skills, but a good argument could be made.

 

[fybush]

I see where you're going with that, and I suspect you'd be right...but for two things. First, you'd probably have to have the support of the FMeXtra folks themselves, and weren't they bought out by Ibiquity a few years back and essentially taken off the market? And second, even an exemption from the tunable-receiver rules for digital-only FMeXtra receivers still wouldn't get Chuck what he was seeking, which was the ability to use an FMeXtra subchannel to feed a translator. As you note, allowing tuneable FMeXtra receivers still wouldn't make it a public service, and it has to be a public service in order to be relayed (legally) as the main channel of a translator. (A translator can carry SCA services on its own SCA, of course, though the coverage is highly unlikely to be satisfactory.)

Which raises a question to which I don't know the answer: early on, wasn't FMeXtra selling those "Aruba" receivers to the public for $500 or so a pop? In theory, that would have required FCC approval. I know the guy I need to ask about that if I see him at NAB in a couple of months...

 

[Chuck]

The FMeXtra folks suggested that I petition the FCC to make it a "Public Service." I think that was their job, but since they got a buy-out from Ibiquity, they weren't very interested. I really didn't feel like going to battle for someone else. That is sad because their system actually worked and was reasonably priced.

For me, it was cheaper and easier to buy a local AM station and have the translators assigned to it. Some AM stations are quite reasonably priced, much less than Ibiquity licensing and equipment would cost for my existing FM. All in all, I think it worked out OK for me. I have a great deal of respect for AM radio, and saving one from the scrap heap feels pretty good. Ask me in a couple of years if this was a good investment.

 

[Kmagrill]

I see where you're going with that, and I suspect you'd be right...but for two things. First, you'd probably have to have the support of the FMeXtra folks themselves, and weren't they bought out by Ibiquity a few years back and essentially taken off the market? And second, even an exemption from the tunable-receiver rules for digital-only FMeXtra receivers still wouldn't get Chuck what he was seeking, which was the ability to use an FMeXtra subchannel to feed a translator. As you note, allowing tuneable FMeXtra receivers still wouldn't make it a public service, and it has to be a public service in order to be relayed (legally) as the main channel of a translator. (A translator can carry SCA services on its own SCA, of course, though the coverage is highly unlikely to be satisfactory.)

Which raises a question to which I don't know the answer: early on, wasn't FMeXtra selling those "Aruba" receivers to the public for $500 or so a pop? In theory, that would have required FCC approval. I know the guy I need to ask about that if I see him at NAB in a couple of months...

Right, so in order to carry on a translator's main channel, a PRM would have to be filed seeking to classify a specialized digital system, like FMeXtra, as a non-private service. As for the Aruba receivers, I think we can surmise the answer. Although the receivers are tuneable, they cannot receive standard SCA, so they fall into the same exception as the FCC noted on their information page. Further, it could be argued that the subscription fee was paid in the purchase price of the radio itself. As long as the tuner cannot receive any SCA other than FMeXtra, this should be firm legal ground.

As far as I know, FMeXtra is now owned by a company called vucast, but I think they're only using the technology for datacasting. I think FMeXtra, per se, is a dead duck, possibly as the result of a deal with ibiquity to remove competition for HD.

 

[fybush]

The FMeXtra folks suggested that I petition the FCC to make it a "Public Service." I think that was their job, but since they got a buy-out from Ibiquity, they weren't very interested. I really didn't feel like going to battle for someone else. That is sad because their system actually worked and was reasonably priced.

I saw it in action up near me at a small station cluster in the Finger Lakes that was using it on one of their class A FMs to get STL to two more distant AMs. Worked great, sounded good, and was still in use there last I checked.

The trouble, I think, with petitioning the FCC to make FMeXtra a public broadcast service is that you can't really easily have it both ways. Make it public and you're now obligated to maintain program logs and EAS and do legal IDs...and then what happens when ASCAP and BMI and SESAC come around for their money, too? Kind of defeats a lot of what they were originally marketing FMeXtra to do, doesn't it?

One other consideration that hasn't been mentioned here yet is that it's very much in the interest of reading services to have SCA and FMeXtra be considered "non-public" services. By restricting availability of their audio to the blind or vision-impaired, many reading services are able to get blanket licensing to use copyrighted material at low or no cost. And no, I don't know how stations like WRBH in New Orleans and WYPL in Memphis, which do radio reading over open FM, handle the copyright issue.