SpectrumTalk has moved!

25th Anniversary of FCC Decision Enabling Wi-Fi and Bluetooth

25th Anniversary of FCC Decision Enabling Wi-Fi and Bluetooth
A series of posts describing how this all came about. (Click on picture above)

Monday, May 05, 2008


Wireless Microphones and
Docket 04-186:
Two Different Viewpoints

On May 1st, the Sports Technology Alliance, a trade group consisting of the major professional sports leagues and ESPN, submitted an ex parte filing to FCC on why the FCC should reject the TV whitespace proposals of Docket 04-186 because of the threat of harm to the production of live sports events or the possible resulting requirement that using beacons to protect legal wireless microphone use "would result in significant additional expense to acquire new equipment merely to enable existing equipment to continue to function." Presumably the "existing equipment" they mention is the analog FM FDMA equipment that is being replaced now in almost every other radio service by more efficient equipment.

To bolster their technical points, this group has hired Harbour Group, a Washington DC PR firm to explain the advantages of the status quo. Harbour's website explains their approach to advocacy:

“We have helped clients sharpen their messaging and delivery to provide support to their allies and put pressure on opponents, shaping the policy environment... Managing the public policy issues that can affect an organization’s success starts with identifying and prioritizing challenges. We conduct thoughtful research, target key constituencies, build successful alliances and mobilize supporters. Our collective backgrounds provide a powerful combination of expertise and experience that allow us to help shape policy development and deliver results.”

Oddly, Harbour has never mentioned why these multibillion dollar clients need continued cost free access to spectrum on demand anywhere in the US even if it denies the use of the spectrum to others and why they cling to using dated FM FDMA technology when even your neighborhood taxi is transitioning to more efficient technology.

SpectrumTalk welcomes Harbour Group to the fray and looks forward to the "pressure" they promise. However, the wireless microphone community might do better hiring technical advisers to see what their technical options really are rather than clinging to technical and regulatory approaches of the past.

Marcus Spectrum Solutions LLC
has filed with FCC today a response to the Sports Technology Alliance. Readers are encouraged to compare the two viewpoints and comment on them. While I nominally "moderate" comments on this blog to prevent spam, all comments received will be posted below except those that are clearly spam or contain words not fit for broadcasting. I suppose Harbour Group would not suggest that the other side be as open.

1 comment:

Henry Cohen said...

As in previous postings, I not only can offer no rebuttal to your filing, but find myself agreeing with it on whole. However, as in the past, I would like to address a couple of technical points you make.

From your FCC filing:
"The usual wireless microphone in the US uses frequency modulation (FM) technology and frequency division multiple access (FDMA), similar to the first generation of cellular radiotelephones in the early 1980s, except without the cellular architecture and high
frequency reuse used in the early cellular systems."

And

"The cellular industry has great experience in frequency reuse and temporary high density venues."

A couple of comments here. First, Part 74 BAS users already practice a form of frequency reuse: In different areas of a convention center; in different studios [on different floors] in a TV broadcast complex; among theaters on Broadway; in different areas of a city by ENG crews. This is very much the same type of frequency reuse compared to cellular infrastructure where channels in different sectors of the cell site are reused. In other words, utilizing geographic and antenna rejection isolation. Looking at a TDMA cellular structure where frequencies maybe reused in the same geographic sector means unacceptable latencies in the delivery of real-time audio (or video). Time division by its very nature can't be real time.

"For low capacity wireless microphone users (less than 10 microphones),
SpectraPulse™ ultra wideband (UWB) wireless microphone Part 15 technology technology is already available from Audio-Technica. (See http://www.audiotechnica.
com/cms/resource_library/literature/9398c060aadd718a/spectrapulse_brochure.p
df) While the present model has limited audio frequency range, there is no fundamental limit to extending it."

Actually there is, at least in the present. Besides cost to design and build a custom chipset, the increased bandwidth needed to extend the audio range means an increase in latency. Further, 6GHz propagation characteristics are highly problematic (again, at least in the present) for the way wireless mics, intercom, IFBs and IEMs are used. (If the 6GHz spectrum is so great, why don't the WSD proponents seek it?)

"In the UK market, Sony is already selling digital wireless microphones (see
http://www.sonybiz.net/res/attachment/file/95/1193315636495.pdf) that allows a 60% capacity increase."

But with 4mS of latency and 125KHz channel steps it's still not a viable solution in all applications, though it is a positive step in the right direction.

One last comment on the beacon topic. Whereas I have no doubt a simple stand alone beacon device or more than one, could be deployed in such a manner as to cover the necessary geographic area of a large event site, there are far too many unspecified details concerning the beacon for anyone to simply say "oh, okay. No problem." No one has offered any indication as to how the beacon will operate: Can the user simply plug in a TV channel number or numbers to broadcast as occupied or will the beacon only accept input based on how wireless units to be protected are programmed or on some arbitrary database; will a beacon be needed for each channel; will the beacon in fact be a stand alone device or will it have to be built in to the transmitter or receiver; will it simply be an inexpensive DTV pilot tone generator, or some very expensive and complex transmission that provides a definite pattern the sophisticated algorithm of an Adaptrum type unit will need to determine a legitimate signal? Conceptually, I welcome the beacon - The devil of course is in the details (or the wallets of lobbyists).