[opendtv] White Space: SMPTE Tackles Threat

From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
To: <opendtv@xxxxxxxxxxxxx>
Date: Mon, 26 Jan 2009 11:42:42 -0500
http://www.tvtechnology.com/article/73388

White Space: SMPTE Tackles Threat
by James E. O'Neal, 01.23.2009

WASHINGTON

Even the recent uncertainty about a shifting date for the DTV cutover
(and all of the complications that would entail) hasn't completely
extinguished the spotlight on white space device (WSD) concerns.

That was in evidence at the Thursday evening (Jan. 22) meeting of the
Washington, D.C., SMPTE section. Officially the meeting topic was "DTV
Transition: White Spaces and Other Issues," but very little was said
about the transition itself. The focus was on WSDs, and four invited
speakers played to a packed house at NAB headquarters here.

James Snyder, who handles broadcaster frequency coordination in the D.C.
area, led off with some stats from the just completed presidential
inaugural event, a major spectrum-user event that had kept him and many
others very busy.

"Almost every spare television channel was used for mics and radios,
including all the 700 MHz channels," Snyder said. "From my perspective
as a freq coordinator in a major metropolitan area with large scale news
operations, the concept of white space is pretty much a fallacy. There's
always somebody operating there. There's no such thing as empty spectrum
in any of the top 100 markets because of protected contours of the
television stations."

Snyder stated that even the personal electronic devices in use today can
cause interference to legitimate spectrum users, stating that he
commonly sees cases of interference to wireless mics from cell phones.

"The proliferation of low-cost digital devices has increased the
potential for IF and baseband interference," he said, noting that he
observed a large number of "pings" along the inaugural parade route.

"These were not all from the DOD or other groups we can't mention," he
said.

With the anticipated proliferation of WSDs, Snyder envisioned an
environment in which not only off-air television reception would be
affected, but also newsgathering and other television broadcast
functions.

"What will happen when we have millions of these devices operating in
confined metropolitan areas?"

He admitted that he couldn't say the devices wouldn't work without
generating interference, but he remained skeptical.

"At this point I haven't seen anything that gives me a great deal of
comfort that they will work without affecting, very negatively, the
services that are already there, services that allow many of us in this
room to bring news to the general public."

"Given my perspective-having just gone through a major inaugural-I
believe that the potential for major interference is high, and
interference in general is pretty much guaranteed," Snyder said. "My
experience in the last several years as a frequency coordinator is that
if something can interfere it will interfere. No operator that uses
broadcast TV spectrum will be unaffected."

Snyder said that he was not convinced that the full scale deployment of
WSDs was carefully thought out by those involved in policy making.

"Real world decisions are being made by folks who haven't worked in this
environment and that concerns me," he said. "We need to make sure that
the decisions are realistic."

Alan Stillwell, deputy chief of the FCC's Office of Engineering and
Technology, said that some of the white space device concerns may be
overblown.

"The picture isn't quite as pessimistic as James is painting," Stillwell
said. "I think he's correct in that the amount of white space spectrum
in major markets in particular is going to be pretty limited. You have
TV there, you have wireless microphones, you have public safety
[radios]. On the other hand, there is white space out there and we
already have white space devices. These are called wireless microphones.
...I think that everybody in this room knows that people are using these
microphones illegally, and that is a practice that has developed over
many years."

Stillwell addressed several of the fears and misconceptions associated
with the use of WSDs and enumerated the protective measures that would
be built into the system governing WSD operation.

"What we saw was not a sufficient level of performance that we felt
could be relied upon to protect licensed services," Stillwell said. "So
we did not allow sensing-only devices."

He said that WSDs could be identified by the fact that they do not
operate continuously, and if a particular situation was problematic, an
enforcement action could be initiated to resolve the interference. He
also said that WSD allowable power levels would have to comply with
existing rules governing RF exposure to persons within their field of
operation.

Bruce Franca, vice president of policy and technology for the
Association for Maximum Service Television (MSTV), examined the FCC's
testing program leading to the adoption of the current policy on the
implementation of white space devices, addressing what the commission
got right and what it got wrong.

On the positive side, Franca acknowledged that the FCC was correct in
requiring geo-location and not basing WSD operation on sensing. Other
pluses were acknowledged for providing some "set-aside" for operation of
wireless mics, and in recognizing the need to protect cable headends,
low power television and translator operations.

One area of the white space plan that he criticized was the decision to
allow personal portable WSDs to operate at a 40 mW level on an adjacent
channel within a television station's service contour. Another was in
adopting a sensing level of -114 dBm and not defining how sensing levels
were to be measured.

Franca said that experience with digital television reception showed
that it took far less to knock out reception.

"There really is a big difference in analog and digital television
interference," he said. "In the analog world we've lived in,
interference can increase by about 8 dB before a viewer sees a change in
their picture. Actually interference can increase by 20 to 30 dB before
the picture becomes unusable. That's not the case with digital.

"Most digital sets go from a perfect picture and sound to no picture and
sound with one dB [of interference]. In fact [in testing] some of the
sets went from perfect pictures and sound to no picture and sound with a
tenth of a dB," he said. "We don't have the margin anymore."

Franca said that another area where the FCC had failed was in assuming
that consumer television antennas would provide sufficient rejection of
interfering signals to protect DTV reception. In some cases commonly
used antennas missed the mark by 16 to 26 dB.

Franca added that the decision to allow white space device operation was
based on policy and not science.

"Bill Gates called the shots," he said. "It's all about new technology
getting access to broadcast spectrum. And it's not just a U.S. issue;
it's a global threat."
 
 
----------------------------------------------------------------------
You can UNSUBSCRIBE from the OpenDTV list in two ways:

- Using the UNSUBSCRIBE command in your user configuration settings at 
FreeLists.org 

- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word 
unsubscribe in the subject line.
[opendtv] White Space: SMPTE Tackles Threat

Other related posts:
