A year and a half ago I wrote in Display Daily about a talk Bob Ross at CBS gave to SMPTE on the coming shutdown of analog broadcasting. Last night I was at another SMPTE meeting where he compared his February 2008 predictions to what actually happened during the shutdown.

Matt Brennesholtz
Insight Media Analyst

One key prediction he made in 2008 did not come true. He said the shutdown would not be delayed and cited the Federal Law that ensured it would happen on time. He also said then, in practical terms, since various companies had paid billions of dollars for the spectrum that would be freed up by the shutdown, the shutdown could not be delayed or there would be some very unhappy, very powerful companies. As every reader of DD knows, Federal law can be changed by Congress and this one was: The shutdown was delayed from February to June 12th. Ross commented that the powerful companies didn’t seem that unhappy about it either, at least not in their public statements.

One thing Ross feared in 2008 was the local stations would not be ready for the shutdown in terms of transmitters and tower work. There are only so many teams qualified to work on 1000-foot or taller transmitting towers and they (understandably) don’t like to work in the winter. He said his fears hadn’t come to pass and as far as he could tell all the local stations were ready for the changeover, at least in terms of tower work. This status is something Ross, Senior Vice-President of East Coast Operations for CBS, should know, especially for CBS affiliates.

Predictably, there were problems and not all of them were in consumers homes. For example, CBS had been sending its affiliates its digital feed for about a year, in parallel to its analog feed. On June 12th, the analog feed was cut off, not so coincidentally coinciding with the shut down of analog broadcasting. The problem was with the audio in the digital feed: no one at the affiliates had ever listened to it, presumably because it was delayed 3 seconds relative to the analog audio. When it came time to switch to the digital feed, apparently the audio quality was poor to unusable. I don’t understand all the technical details, but apparently the digital and analog audio use the same nominal bandwidth but the digital audio in fact uses the full bandwidth and the analog only part of it. Filters in the system that could pass the full analog bandwidth cut off some of the digital signal.

There were some problems in consumers homes, of course, that resulted in hundreds of calls to call centers. According to Ross, about 75% of these calls were relatively easy to handle over the telephone with instructions like "readjust your rabbit ears," "rescan your tuner" or my favorite, "Take the converter box out of the cardboard box and follow the instructions in the box to install it."

The other 25% of the calls were more difficult to handle and some required an engineer from the local station to go to the consumers home with a RF spectrum analyzer to find out what the problem was. It turned out many of them were related to the signal to noise ratio in the signal from the antenna. This problem was, in part, created by the Federal requirement that digital HDTV broadcast at about 10% - 20% of the power of the analog channel it replaced, dramatically reducing the signal to all receivers. Apparently there is a 15dB signal to noise ratio built into the ATSC spec and when the signal goes down but the noise does not, you can loose all reception. With an analog system, you are more likely to just see a noisy image. The noise came from a surprising variety of sources, including a wireless phone power supply, a halogen lamp power supply and a 52" plasma set from a major but unnamed manufacturer.

Ross, as a broadcaster, considers the proposed "White Space" spectrum use as a major potential source of noise in signals. He said "White space is going to kill us!"

There were a number of questions from the audience, two of which I will touch upon.

Q: Why did they lower the power?
A: One of the reasons the power was reduced at all stations has already been mentioned: some of the spectrum used by analog broadcasting, UHF channels 52 - 69, was sold for other purposes. This meant that more channels needed to squeeze into a smaller spectrum and allowing full power broadcasting would cause interference between stations, especially at the fringes of each channel coverage. Reducing the power did not hurt these fringe areas very much, since they tend to have high, outdoor antennas. On the other hand, in an urban area where indoor antennas are more common and the signal loses 20dB just to get into an ordinary wooden house, the loss was in many cases unacceptable.

Q: What about 1080p 60Hz broadcast?
A: 1080p/60 is not included in the current HDTV specification. CBS recently ran a test using a 1.5GBit uncompressed 1080i feed from the US Tennis open and ran it into a consumer HDTV. Ross said the image was essentially perfect and the TV set deinterlacer was so good they couldn’t see any deinterlacing artifacts. He then went on to say that 3D-TV and 1080p/60 both require about the same amount of additional bandwidth. If 1080i broadcasts don’t create any problems to the trained eyes at CBS, why use this extra bandwidth on 1080p?

Incidentally, this SMPTE meeting was held in Studio 45, which until last Friday was the source of the soap opera "Guiding Light." The show had been on the air since 1937, first on the radio and later on TV. When I asked a CBS person (not Ross) why it was killed, he said succinctly "No Ratings."