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Discussion Starter · #1 ·
Has anyone been following the 'White Space' debates?

http://broadcastengineering.com/news/fcc_wireless_white_space/

I'm not sure what kinds of 'devices' will be transmitting but presume they will be related to data networks and video receivers.

So, where geographically can these devices operate without causing additional interference problems? Judging from the current difficulties related to spectrum management during the DTV transition, population centers are just not suitable.

Are the TV channel allocations going to be 'cast in stone' after Feb of 2009? Will concern about interfering with the devices hamper the allocation of channels to upstart TV stations wishing to operate where white space exists?

Will these be Part 15 devices. If so, the proposed built-in scanning must be effective because consumer users, who know nothing about radio interference, will assume the devices are appliances.

Certainly, in today's technological enviornment, spectrum cannot be wasted through under-utilization.

--- CHAS
 

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HIPAR said:
Has anyone been following the 'White Space' debates?

http://broadcastengineering.com/news/fcc_wireless_white_space/

Certainly, in today's technological enviornment, spectrum cannot be wasted through under-utilization.

--- CHAS
The frequencies are already in use. Hospitals use them for heart monitors. Do you know what happened at Baylor U. Medical Center when WFAA signed on their DTV transitter? WFAA-DT shut down until the hospital spent $200,000 on new equipment. Networks and broadcasters also use the frequencies legally for wireless mikes.

Many companies also sell wireless mikes and headsets that are on broadcast channels to theater groups, sports teams, and churches. It's not clear that such use is allowed under the current rules.

What is clear is that the current uses of the so called "white space" is threatenened by the new FCC proposal.

Recently the FCC has cracked down on illegal FM transmitters sold as part 15 devices. Both Sirius and XM Radio recalled products and redesigned their equipment due to wide bandwidth, excessive power, and operation below the FM band. Yet third party engineering companies had certified them as legal even though they weren't. Many FM transmitters for iPods have similar problems. The FCC was slow to address the issue.

The issue boils down to portability. If you find that a device works fine in your house, and you put it in your car, how will it know to turn off when your drive to another city? Can you bring it into a hotel room in another state without causing interference?

The FCC is asking if there are reasonable solutions to these problems. I believe that the FCC will approve such devices in spite of the interference that they will cause.

I hope that nobody dies.
 

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I just 'wooted' the XM Roadie XT -- it comes with two add-on chokes that I am
supposed to affix to the antenna wire and the 5v power cord. I am considering
leaving them off for asthetic reasons. What undesirable effects, if any, might be
expected without these external filters installed?

I wouldn't want it to adversly affect fellow exercisers down at my local hospital's
Cardiac Rehab Unit where I work out several times week! :eek2:
 

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Nick said:
I just 'wooted' the XM Roadie XT -- it comes with two add-on chokes that I am
supposed to affix to the antenna wire and the 5v power cord. I am considering
leaving them off for asthetic reasons. What undesirable effects, if any, might be
expected without these external filters installed?

I wouldn't want it to adversly affect fellow exercisers down at my local hospital's
Cardiac Rehab Unit where I work out several times week! :eek2:
Heart Monitors should not be in the FM band. If you have selected a clear channel with no stations above or below the frequency, the use of the device without the chokes shouldn't cause harm. If you drive to another city, select a clear channel in that area, or turn it off.
 

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Discussion Starter · #5 ·
Nick,

I think that placing choke on the antenna would defeat the purpose of an antenna.

Being curious, I searched for Tower Guy's cardiac monitor incident. It happened during the late 90's just as he reported. Consequently, the FCC created a new radio service for medical telemetry systems. But, I wouldn't be surprise if 'legacy' systems still operate in the TV band.

--- CHAS
 

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The "Heart Monitor Incident" has been blown a bit out of proportion. Even the Denver NIMBY's are using it for a scare tactic.

Any non-licensed device is subject to interference by licensed devices, and is used at the operator's own risk. And, since there are no records (since there are no licenses) on those devices, the licensed people don't know who to contact anyway.

When a DTV station (I think it was in Texas) came on the air, it happened to be on the same channel as some patient monitoring devices at a local hospital, and interfered with their reception. The FCC then decided it would be wise to have subsequent DTV stations send a registered letter to every known hospital in their area, before turning on their new transmitters.

"White Spaces" are a whole different matter. Due to physics, certain channels will interfere with certain others, unless they meet certain, strict criteria. Allowing "free reign" of unlicensed devices in the TV bands would mean you might have a several-watt transmitter operating from your neighbor's house, on a channel that invariably interferes with the station you are trying to watch. And, with DTV, you wouldn't even realize what was causing the problem.

"White Space" serves a purpose. Think of it like the spaces between adjacent buildings. Think of it like property setbacks. Think of it like "right-of-way"s. Think of what happened with Mrs. O'Leary's cow!
 
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