Commission puts the kibosh on hybrid digital/analog transmission system that would have allowed Channel 6 licensees to provide additional audio-only service.

Video-less TV, an idea embraced by a number of Channel 6 LPTV stations, has suffered a set-back. In August the FCC rejected a proposal by two Channel 6 LPTV licensees to use a digital transmission system that would have permitted them to transmit – in addition to their digital TV service – a separate audio signal receivable by analog FM radio receivers.

Spectrum-wise, TV Channel 6 sits immediately below the FM radio band. In pre-DTV NTSC analog technology, the video and audio components of the TV signal were separately generated (sometimes even through separate transmitters), with the audio located near the top of the band and using FM modulation. That meant that the audio of an analog Channel 6 station could be heard easily on most FM radios (which can normally tune down to 87.7 MHz). 

Analog Channel 6 TV stations, both full and low power, reportedly enjoyed a boost in their audience size thanks to drivers tuning in on their car radios and joggers listening on their arm band radios. In fact, some Channel 6 LPTV operators found the FM radio audience so attractive that they programmed primarily to that audience, paying little attention to video. How little? We suspect that some didn’t even have working video transmitters. (Cautionary note: It’s not at all clear that audio-only transmission –  or even audio with only a dribble of a video signal – complied with FCC requirements.) The Channel 6 audio business prospered in a few major markets, with a few stations reaching reportable Arbitron ratings levels.

The audio-only TV business has foundered in recent times, presumably because it was based on analog technology and could not co-exist with digital video. (That’s because: (a) under the ATSC digital standard, the analog signal is no longer separate from the video; and (b) digital TV audio can’t be received on FM radios – not even digital “HD” FM radios.) With virtually all full-power TV stations converted to DTV operation since 2009, and with a fast-approaching end-date for analog LPTV broadcasting, future prospects for video-less Channel 6 operations are not good.   LPTV licensees recognize that it’s difficult, if not impossible, to make a viable business plan when you ‘re likely to hit a brick wall in only three years.

But where there’s a will, there’s often a way.

Transmitter manufacturer Axcera came up with something they call Bandwidth Enhancement Technology (BET), which combines a digital TV signal with an analog audio signal. A Channel 6 station operating with a BET transmitter can broadcast a DTV signal (combined audio and video) using most of its 6 MHz bandwidth, but still insert an analog audio signal in a little slice at the top of the band. Digital TV sets can receive full TV service, while analog radios can receive a separate audio service. Audio programming service can even be transmitted two ways at the same time – on the TV dot 2 stream (Channel 6.2) in digital format and on the BET stream in analog.

This innovative approach sounded like a winner to Venture Technologies Group (VTG), which proposed to install BET at two of its stations. After all, didn’t the FCC tout digital TV as a way to introduce both more services and new services to the public? And doesn’t the ancillary services rule (that would be Section 73.624(c)) encourage TV stations to “offer services of any nature, consistent with the public interest, convenience, and necessity, on an ancillary or supplementary basis.” VTG saw its proposed use of BET as a win-win, increasing service to the public while providing a much-needed additional revenue source for LPTV stations struggling to survive without carriage rights on cable or satellite.

Sorry, the FCC responded, no deal.

 According to the Commission, it has yet to adopt technical standards for the “hybrid” operation of a BET transmitter. The FCC claims that its rule (i.e., Section 74.795(b)(1), which in turn references Section 73.682(d)) require that digital LPTV stations comply with ATSC standards, and ATSC standards require the use of 8VSB transmission throughout the entire 6 MHz bandwidth of a TV channel. Since the BET system uses part of that bandwidth to transmit an analog signal, it doesn’t comply with the ATSC standard and thus can’t be licensed, as the FCC sees it.

On top of that, the FCC was skeptical of VTG’s claim that no interference would be caused to any other station. The Commission’s skepticism arose because there is no established desired-to-undesired (D/U) signal ratio for hybrid-into-DTV operation – without that ratio, how can interference (or lack thereof) be determined? The FCC also noted that the probability of interference to co-channel DTV operations is higher than VTG let on, because VTG’s proposal would not decrease digital power to offset the analog audio power and so could increase the total power of its Channel 6 operations by as much as 33%. 

And all that stuff about favoring innovation and ancillary services? That doesn’t matter to the Commission when you run the risk of interference. Application dismissed!

We checked out the FCC’s reasoning. As far as conforming to all ATSC standards goes, that requirement appears in Section 73.682(d). We think the FCC’s reasoning is a bit stretched, though, because Section 73.682(d) comes into play here only through Section 74.795(b)(1), and that section requires only that digital LPTV systems be “satisfactorily viewed” on consumer digital TV receivers that operate based on Section 73.682(d).  In other words, while Section 73.682(d) is indeed mentioned in Section 74.795, that mention does not require the LPTV transmission system to comply with all aspects of Section 73.682(d). The whole point of the BET technology is to preserve satisfactory DTV viewing. The compression of the digital TV signal to carve off a sliver for analog audio is not supposed to impact TV reception on consumer digital receivers. If Axcera is right about that, then where is there any violation of Section 74.795(b)(1)?

Don’t take our word for this: the FCC itself has expressly stated that digital LPTV stations do NOT have to comply with all aspects of Sec. 73.682(d).  In the Report and Order adopting digital rules for LPTV stations, the FCC said:

LPTV and TV translator stations are not required to comply with either Section 73.682(a) or (d). [That appears at Paragraph 163.]


Digital companion channels to Class A stations will be licensed on a secondary, LPTV basis and at this juncture operation of companion channels will not be subject to the requirements of Section 73.682(d) of the rules. [This one’s at Paragraph 165.]

(By contrast, the Commission also observed, also at Paragraph 165, that “Class A TV stations that choose to convert to digital on their existing analog channel will be licensed on a primary, Class A basis and their converted digital facilities will be subject to the requirements of Section 73.682(d).”)

So it seems that, while digital Class A stations must comply with all aspects of with Section 73.682(d), LPTV stations only have to be receivable on consumer receivers.

What about the argument that there are no standards for measuring interference from hybrid stations? There the FCC is on stronger ground. There has never been a rulemaking on hybrid standards, so hybrid operation is not mentioned in the interference rules. 

But what might happen in real life? The BET technology was designed to be compatible with digital TV operation. We talked to one of the leading industry engineers who helped develop the technology. We learned that, while there is little possibility of any damage to the host hybrid station itself (i.e., the analog audio won’t interfere with the digital TV signal of the same station), it is not as clear that there won’t be any increase in interference to other Channel 6 stations. To avoid co-channel interference, more distance between Channel 6 stations might be required than would be the case without the analog carrier.

In our view, the FCC ought to give hybrid DTV technology like the BET system a closer look. That’s particularly so given the FCC’s relentless quest for more efficient use of all spectrum everywhere. The hybrid here is a “two-fer” – one TV station can provide two kinds of service. Why stifle that kind of creativity, innovation, and efficiency? 

And, if the technology does work, it would not necessarily be limited to LPTV. At least one full-power station in Schenectady, New York found that its audience enjoyed listening to the audio from TV newscasts and talk shows that they could pick up in cars and while “puttering around the garage.” That station pulled the plug on the service, however, because the licensee “didn’t want to risk annoying” the FCC. Since 73.682(d) plainly applies to full-service stations, approval of hybrid gear for such stations would require some adjustment on that end – but if the result is an increase in innovation and service, why not?

We hope that proponents of BET will conduct the necessary tests to show how much analog audio power is possible without adversely affecting any other station. Convincing the Commission that hybrid technology does not pose a serious threat of interference could open the door for that innovative technology. And that, in turn, could allow LPTV stations that have experimented successfully with some kind of audio-only service to continue to develop both that service and digital video programming, unthreatened by the impending end of analog LPTV. Moreover, enabling hybrid operation could provide analog Channel 6 LPTV stations an incentive to convert to digital operation sooner rather than later and to bring to the public the increased quality and quantity of services available with digital TV technology.