nasadude
join:2001-10-05
Rockville, MD
 ·Comcast
| FUD in fantasy land
NAB is complaining about failures of TEST units, not retail consumer electronics.
apparently, NAB is furiously spinning and sowing FUD about the early unit failures, WHEN REQUIREMENTS HAVE NOT EVEN BEEN FINALIZED yet. At this stage of the game, electronics companies and the FCC are simply trying to set requirements for the eventual consumer boxes, so it's good the FCC is allowing testing to go forward.
from the data gathered in these tests, consumer electronics manufacturers should be able to develop boxes that don't interfere. |
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cornelius785
join:2006-10-26
Worcester, MA
| the field of using white space is very new and has a long way to go to define standards and performance requirements, nevermind defining itself as a viable option or even selling devices. until standard are made and performance requirements are made, i don't see white space utilization leaving a pure research base any time soon. if it starts being commercialized too soon, i'm fearing it could be a entire mess that'll make hd-dvd vs blu-ray, betamax vs. vhs, early production of multiple versions of the still not ratified standard 802.11n devices, and probably others look like nothing. |
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RadioDoc
Sortofadog
Premium,ExMod 2000-03
join:2000-05-11
Chicago, IL
 ·AT&T Midwest
| reply to nasadude
said by nasadude  :from the data gathered in these tests, consumer electronics manufacturers should be able to develop boxes that don't interfere. What data would that be? That every prototype tested has failed to perform as designed and as the developer had defined?
Retail consumer electronics certainly would not performa any better if they can't even get their reference designs to work.
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Toolmaster of La Grange. |
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voipguy
join:2006-05-31
Forest Hills, NY
| reply to nasadude
The whole idea CAN'T work - I have to side with NAB on this.
Here is why:
Let's say I have a big antenna to receive a reasonably far-away TV station. My neighbor buys a white-space box. The little antenna in the white space box can't receive the station I'm watching, so it considers the channel available and transmits on it. My TV reception is blown away.
From what I have heard, that's the generally problem that was observed in the tests - the white space boxes did not detect weak but present broadcast signals. |
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RadioDoc
Sortofadog
Premium,ExMod 2000-03
join:2000-05-11
Chicago, IL
·AT&T Midwest
| Funny part is they've trotted out the usual "rural broadband" carrot as justification for these things (the tech equivalent of "do it for the children") and rural areas are precisely the places where most people are likely to be receiving OTA TV from distant transmitters. Which means rural areas are the places where these boxes would cause the most interference.
The whole half-baked idea needs to be put back in the oven.
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Toolmaster of La Grange. |
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PDXPLT
join:2003-12-04
Banks, OR
| reply to voipguy
said by voipguy :The whole idea CAN'T work - I have to side with NAB on this. Here is why: Let's say I have a big antenna to receive a reasonably far-away TV station. My neighbor buys a white-space box. The little antenna in the white space box can't receive the station I'm watching, so it considers the channel available and transmits on it. My TV reception is blown away. "Can't" work? That's not exactly an engineering analysis you've presented. Reads more like a touchy-feely, liberal-arts-major "assestment".
I could just as easily say: that "big antenna" is a high gain unit with a very narrow beamwidth, aimed right at the TV transmitter. The "litte antenna" on the "white space" unit is a near-isotropic unit, which directs only a small portion of its radiated power at the TV receiver's antenna, well off its center beam. Plus, a TV signal can be detected at a much lower signal level than that needed for adequate reception: this is even true with digital signals, thanks to the pilot signal which can be detected at very low levels by the white space device.
OK, that's equally touchy-feely words, that argue something other than the "can't work" scenario. The truth is somewhere in between, and is better expressed in terms of dB's, and SNR.
As for the White Space Coalition, what do they expect with hardware supplied by Microsoft.  |
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PDXPLT
join:2003-12-04
Banks, OR
| reply to RadioDoc
Well you have a couple of things wrong here:
** "distant" TV transmitters are not entitled to protection from interference under FCC rules. Outside the Grade B service contour of a TV transmitter, a TV station is subject to all sorts of interference - from other TV stations, from low-power "Class A" stations, from Low Power TV repeaters, etc. For the white space devices, they are only required to protect TV signals whose Grade B contour includes the location in question. As a practical matter, a rural resident is far away from their neighbors, and is unlikely ot be interfered with by low power white space devices used by their neighbors. In the tradition of other Part 15 issues, the rural resident can for themselves decide whether or not they wish to use white space portable devices, or try to receive distant TV signals.
** the rural broadband, save-the-children white space devices are so-called "fixed" devices. They're like what is being defined in the IEEE 802.22 group. They'll be installed and configured in a single location, by a professional installer, and set to an unused channel.
** the devices under discussion here are so-called "personal/portable" devices, for uses such as wireless LAN (not for broadband access). These are the ones that are the subject of these tests, and cause the concern. Although I'd point out that there are already ~200,000 unlicensed personal/portable devices out in the field that cause little problem: wireless microphones that are supposed to only be used by Part 74 license holders, but over 90% are used, illegally, by musicians, church groups, and others without a license. Users just manually set them to a locally-unused TV channel, which seems to work surprisingly well. |
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RadioDoc
Sortofadog
Premium,ExMod 2000-03
join:2000-05-11
Chicago, IL
·AT&T Midwest
| Sigh.
"Distant" as in inside the primary grade-B service area where an outside antenna is required for reception and not inside the grade-A service contour where it usually is not. These signals certainly are protected.
Bringing HSI to unserved/underserved rural areas is how the PR for this started. I'll predict right here that precious few of them will ever see one of these things.
Not sure where you got the rest of that. Whether a device is being used illegally or not, the legal, Part 74 licensed ones are entitled to protection from Part 15 devices. The "illegal" ones you try to use as justification for these "white space" devices are indeed set up manually. That infers a level of intelligence which these automatic "interference avoiding" devices will not have. Even assuming your ~200,000 wireless microphone count is remotely accurate, they are not all transmitting at the same time and are a drop in the bucket compared to the interference ten times that transmitting continuously would generate.
This is simply a bad idea no matter how you try to spin it.
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Toolmaster of La Grange. |
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