MaroonGuru
join:2003-09-03
Oconomowoc, WI
| reply to qworster
Re: No..
said by qworster  :It can use an omnidirectional antenna and a VERY narrow bandwidth radio centered on the middle of the TV channels it's scanning. Since the UHF DTV channels are sequentially allotted and exactly 6 mHz apart, this kind of radio is EASY to build! Remember, all it has to do is SENSE a carrier signal-and a 250,000 watt - 1 megawatt signal from atop a tower 500 feet or higher at that! If a 25 year old Radio Shack scanner can do this-with low powered 2 way radio signals no less, then why can't a white space device? Also remember, both FM and TV channels (stations) are allotted by the FCC to broadcast to specific markets. TV stations are only afforded protection within clearly defined service contours. The fact that you might be able to pick them past these contours is irrelevant! Disclaimer: I am a broadcast engineer with over 30 years experience. I understand REAL WORLD interference, as opposed to LAWYERSPEAK interference, which is usually shown to the FCC and/or Congress by the NAB along with a sizable cash payment! First: Don't look at the "center" of the channel. ATSC broadcasts using 8VSB not COFDM, so the carrier is off-center. The device ought to look there. No more Audio carrier to hone in on anymore either.
Second: Although the broadcasters are licensed for coverage areas, and are afforded some measure of protection within them, it is in the public interest that reception is possible outside the defined contours. I for one enjoy receiving DTV stations from the two markets I straddle. It is entirely possible that one of these nifty white space devices could end up nearby and obliterate my reception of one or more channels.
If you are a broadcast engineer, you might recall the old maxim, that "Proximity beats Power." I recall a local low band VHF station got messed up pretty badly by a guy with an amplifier hooked to his VCR output and interfering with a sizeable chunk of nearby homes. This was in a town about 20 miles away and the affected viewers who were behind a hill. Something a white space device (WSD) could easily duplicate. FYI, I used to go through that town, and the residents have their antennas on tall roof mounted masts. So, a living room based WSD would not see the same signals as the TVs do.
I understand that the WSD could provide a multitude of benefits if used correctly, but I can see lots of possible problems. Probably the biggest from the collective brains of the internet. How long did it take between the introduction of 802.11b and people finding ways to increase the range and power. Remember, the FCC required special non-standard connectors in the beginning to avoid people boosting effective radiated power by changing antennas. The unhackable/secure iPhone didn't last long. Can we really expect us geeks to not find a way to get more out of a WSD? Even if you lock it as tight as say HD-DVD or BluRay?
And as a disclaimer, I am not only a broadcast engineer, I am also an attorney. A fun combo indeed. |
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qworster
join:2001-11-25
Los Angeles, CA
 ·DSL EXTREME
·Brand X Internet
 ·RoadRunner Cable
 ·Vonage
| reply to plk
Actually, there's a lot of white space even in the big cities. For example, almost a third if the UHF spectrum in Los Angeles will be white space. Similar space exists in every other city, including New York.
Some links:
»www.newamerica.net/files/whitesp···mary.pdf
»www.newamerica.net/files/WhiteSp···nder.pdf
»www.newamerica.net/publications/···dcasting
What's interesting about this study is it shows that smart radios can pick up signals well enough that the Defense Dept. has signed off on their use in the military 5.8 gHz band for sharing.
»www.latimes.com/news/opinion/la-···leftrail |
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plk
bo may sleep in loft
Premium
join:2002-04-20
Ogden, IA
| reply to qworster
I was thinking the same thing. However, I am no engineer and not that knowledgeable.
I was thinking..... Lots of channels are not in use in rural America. This is a waste of space. This system in some areas could see 20 mhz or more free for use, if not more.
Also, these devices could be "told" not to use a certain frequency by the tower supplying the signal to the CPE.
Lots and lots of ways to use this unused bandwidth in rural America where it's needed most. A dozen channels are not in use here in Iowa. Can you imagine rural Montana or rural northern Canada. ( I know )
It has alot more promise then BPL. I hope the Hams jump on this and help work out the solutions, so BPL will finally die.
This has promise!
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qworster
join:2001-11-25
Los Angeles, CA
·DSL EXTREME
·Brand X Internet
·RoadRunner Cable
·Vonage
4 edits | reply to MrMoody
It can use an omnidirectional antenna and a VERY narrow bandwidth radio centered on the middle of the TV channels it's scanning. Since the UHF DTV channels are sequentially allotted and exactly 6 mHz apart, this kind of radio is EASY to build! Remember, all it has to do is SENSE a carrier signal-and a 250,000 watt - 1 megawatt signal from atop a tower 500 feet or higher at that!
If a 25 year old Radio Shack scanner can do this-with low powered 2 way radio signals no less, then why can't a white space device?
Also remember, both FM and TV channels (stations) are allotted by the FCC to broadcast to specific markets. TV stations are only afforded protection within clearly defined service contours.
The fact that you might be able to pick them past these contours is irrelevant!
Disclaimer: I am a broadcast engineer with over 30 years experience. I understand REAL WORLD interference, as opposed to LAWYERSPEAK interference, which is usually shown to the FCC and/or Congress by the NAB along with a sizable cash payment! |
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MrMoody
Carbon Based Lifeform
join:2002-09-03
Smithfield, NC
·Embarq
·Skype
·magicjack.com
| No way
And I still say there's no way this thing can detect distant yet usable signals. It would have to be connected to a high-gain, directional outside antenna that rotates slowly through 360 degrees.
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"It is a future in which globalization really does work ... and everybody winds up getting to be part of the third world." - William Gibson |
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