'White Space' & DTV topic - Page 5

Desired/Undesired. I think. Check that with someone who's more certain.

- Trip

So people out in the sticks want broadband? OK. You and 10 others live miles away from any other life forms. So all of you go get the latest WS thingy. Oh, sorry-that 100mW dosen't get you even close to the nearest city. So google or whoever has to build a $100K site to get you
service. How much are they now going to charge you? $10, $20? Right!
If there was any profit in it, every inch of this country would have wireless broadband right now. The truth is they want to build their own data and PHONE network using "free" spectrum.
You will not have wide open access to the spectrum. The big guys will have most of it and everyone else a small slice. Software inside these things will make it so.
I bet when Mr. Martin loses his job after November, He will turn up with a cushy job at one of these places.

The telco's have run copper to nearly every home. They can run fiber, too. Then this will be a dead issue.

Note that the white space proponents even oppose TV stations improving reception!

http://www.avsforum.com/avs-vb/showthread.php?t=1082235

Thanks Falcon_77

(? Is it Scr or N)ew America Foundation didn't like LP digital companion channels, either, surprise, surprise ...


You got it Trip. The proposed D/U ratios in this case involves ratio between desired and undesired signals needed(according to FCC) to define "acceptable" service. In this case, the D/U ratio involves the ratio, or difference between the (D) Desired signal of licensed broadcast TV/DTV operations and (U) undesired WSD signal(anywhere in the WSD's service area).

See paragraph 30~32 of the 2004 WSD NPRM(link provided earlier in thread) for more details on their proposal/the table of D/U ratios ... Which as explained in the proposal are the same D/U ratios as FCC uses involving predicting/preventing interference among DTV broadcasters regarding submission of new applications/etc, EXCEPT(at the time) that they proposed to eliminate the first adjacent channel D/U requirements for the unlicensed devices ....Those rules (for broadcasters) are also stated in CFR 47, sec 73.623 currently available here :

http://www.hallikainen.com/FccRules/2008/73/623/

In addition, the 2004 NPRM proposed to not allow WSDs to operate within a stations protected service area.

So, for a UHF WSD to UHF, full service DTV station example, How I understand it is(Which may be wrong to some extent as how they explain it in the NPRM seems a bit difficult to interpet correctly) --- I understand the proposal to mean that at location right at the outside of a "line", the line being a stations predicted noise-limited service area contour (such as a UHF full service DTV station's 41dBu contour -- per 50.50 curves), for co-channel WSD operation there is(or was) a proposed a 23dB D/U ratio requirement.

Meaning, in the full service UHF DTV case, it "somehow" wouldn't be "allowed" for the WSD signal to be any stronger at that location right at the outside side of the 41dbU contour "line" than 23dB LESS than the (predicted) 41dBu field strength of the DTV signal .... This would of course still allow the possibility of 16dB SNR(+ a 7dB "margin") required for decoding DTV to be acheived at the "line" given use of OTA receive antenna setup which matches FCC planning factors for DTV - outdoors, 30ft AGL, 10dB gain, loss in 100FT RG6 of feedline/etc) ...

Of course, the "real world" use of OTA often doesn't match FCC "predicted service" contours and(not counting "DX"/enhanced signal propagation when it occurs) many are receiving reliable OTA TV/DTV signals just fine from beyond(sometimes well beyond) a station's interference-protected service area with receive antenna equipment which meets or exceeds FCC planning factors for reception ...

Imagine a scenerio where you're say, on a high hill in your area 30 Miles outside the service contour+using a CM4228 or XG91 and acheiving excellent reception, and a WSD operated by your neighbor in the same direction as the desired DTV signals "fires up" on the channels used by those stations .....

Also, as someone mentioned earlier, there is ATSC M/H -- and from what I've read, M/H streams can reportedly be decoded with as little as 4dB SNR. There is no reason I'm aware of why a fixed receiver using outdoor, hi-gain directional antenna couldn't be used with the M/H streams although M/H is intended for use with portable/handheld receivers ...

And there are the "differences" in FCC definitions of LP service contours making for "less" interference protected service area vs. full service contours, although in the absence of interference, of course the LP's can be received just as well at the SAME signal levels as full service stations (i.e. -- 74Dbu UHF analog LP "service"contour vs. 64dBu UHF full service analog "Grade B" contour) ...

For these reasons(Will the geolocation "rules" be the same or similar to the proposals in the 2004 NPRM involving Stations Service contours, and D/U ratios?) it is going to be very interesting to see the WSD R&O and MO&O FCC adopted on Tuesday ...

I think what has been overlooked here is how much SNR (signal to noise ratio) you really have.
An average DTV transmitter has about 30dB SNR. A good receiver needs about 15dB to stay locked and give a good picture. This is the so-called cliff. Go lower and it's gone. This gives a 15dB window. This is ALWAYS true. It don't matter how far you are from the transmitter.
Add a preamp that has a 3 or 4dB noise figure and you are down to 11dB or so. This is the system noise and it never changes except as I'll explain soon.

Now, any noise that comes from outside the system can be overcome by having a stronger signal. Everybody on this thread understands this. Preamps fail here because they will amplify the signal and all the noise.

The problem comes when a signal is too strong. The preamp or front end is driven non-linear(overload) and generates it's own noise. This noise is either broadband or mixing products but the results are the same. As the signal reaches this point, the system noise goes sky-high and you are over the cliff--fast. On channel, forget it. I wiped out a DTV signal from a TX 18 miles away with a signal generator set at 0dB with a wire antenna in my basement. The 15 dB window goes fast. 0dB is about 1mW.

So, if your system overloads at, say, +30dB and you get a WS signal that reaches this point, it's over. You can be 4 or 40 miles from the DTV transmitter and the same thing will happen. Yes, as long as the signal is not on-channel, you can try to filter it.

The real point is everybody, no matter where they live, will have this problem. I guess the FCC forgot what CB was like in the 70's

PS: I once had a problem with a transmitter that caused the SNR to go down to 17dB. It still worked well out to the grade B contour.

You're driving me into disappointment. I'm beginning to think over-the-air television will be unwatchable by 2020, with homeowners only able to receive 3 or 4 immediately-local channels and that's it.

"Second Report and Order and Memorandum Opinion and Order in the matter of Unlicensed Operation in the TV Broadcast Bands" is now available at FCC site(I just found it via Edocs, Released Today)

Here's the link to the PDF version of the R&O and MO&O :

http://hraunfoss.fcc.gov/edocs_publi...C-08-260A1.pdf

Update: The CFR 47, Part 15 "Final Rules" for the WSD's are published in Appendix B, Page 98~112 of document at above link ....

Page 37 shows that rural OTA TV viewers are thoroughly screwed. Why even bother with spectrum sensing if the FCC isn't going to require devices to use it?

Still reading...

- Trip

Trip,

To be honest, I'm trying to think of any little chore to do rather than read the thing, as I'm dreading reading it given I already suspected there is a lot of bad news in there .....

I'm hoping on a "long-shot" OMB will find significant issues of some sort with it ....

Well, I ended up skimming most of it. Little else of interest outside of Paragraph 94 (Page 37).

- Trip

There's more ... I think #94 is mostly talking about the spectrum sensing ...

I also Pulled out a couple more things from the new rules+R&O on the WSD's which will also involve the geolocation/database, and I think should be of interest for OTA users(particularly Fringe area viewers) here, or those that help them with their reception ... if not, sorry for the length it has added to this post .....

First, some important notes regarding quotes farther below from new WSD rules and the R&O released today on the matter, Full text available at link provided to R&O in earlier post :

#1). First note what we've been calling "WSD's" (white space devices) have a new Abbreviation in FCC Lingo : TVBD (TV Band Devices) .... Specifically defined in the new rules as :

TVBD - Intentional radiators operating on Available Channels in the
broadcast television frequency bands at 54-60 MHz, 76-88 MHz, 174-216 MHz, 470-608 MHz and 614-698 MHz.

#2). I had to reformat the tables in the quote of 15.712 in order to post this portion of the rules ...

#3). Paragraphs/tables in (c)~(g) of 15.712 omitted for this quote - In summary :

(c) - Involves protection of Fixed Broadcast Auxiliary Service (BAS) Links ..

(d) - Involves protection of PLMRS/CMRS (land mobile) operations ...

(e) - Involves Protection of Offshore Rediotelephnoe Service ..

(f) - Involves protection of Low power auxiliary services, including wireless microphones ...

(g) - Involves protection of Border areas near Canada and Mexico -- No Fixed or Personal/portable TVBD'(TV band devices - I.e. WSD's) will be allowed to operate within 32 km of the Canadian border, or within 40km of the Mexican border on UHF channels, or within 60 km of the Mexican border on VHF channels ...

(h) - Involves protection of Radio Astronomy Services, and prohibiting operation of fixed and personal/portable TVBD's on all channels within 2.4Km of specified table of locations (NRRO, Green Bank, VLA, Mauna Kei Observatory/etc/etc) ...



And, (in addition to Paragraph 94) follows is some more of interesting portion from some of the "discussion" relating to above portion of the rules(w/o footnotes), from the R&O text -- specifically Paragraphs #165~166 ... Note the "errors"(typographical/editing errors ?) I've noticed and bolded are there in the actual text of the R&O itself(the PDF version anyway), they aren't errors on my part in transferring the text to this post/etc ...


"while it is *possible* that a TVBD could be within the reception pattern of such antennas" ?????? ..... Not only is it POSSIBLE, it *WILL* happen in such circumstances when say, a neighbor with a WSD in same direction(or one of the "professionally installed" devices) as the transmitter uses a WSD which fires up on the relevant channel(s) involved ... It isn't going to matter to the folks it happens to that it may not happen in "most" cases ....

And, then there is this bit (more in the full text about this), regarding the additional protection given to Cable headends(and pickup sites for Translators) OUTSIDE of a stations predicted service area ...


So, It's OK if the OTA user/family/household beyond a stations predicted service area*(whom may not have cable service available, and even possibly in some cases may not have DBS service available due to blockage of LOS to the birds from terrain or trees) ---- folks who have gone to the effort and expense(not to mention paying sales TAXES on their equipment purchases) of installing tower/antennas/preamps to receive TV .... Folks who will be screwed per the actual "rules" which will actually allow for Harmful interference to effect their TV service if/when a nearby WSD fires up on a channel they're receiving TV stations, but a cableco headend is "protected", because they serve more people(for a fee for the service) than a single household with TV service ????

* - something in most cases they very well may only know the signal is "weak", not that they are specifically "outside" a stations predicted service contour .....

That's not quite the way I'm reading it -

Rural viewing (i.e within a station's normal area) is still safe -
However - DTV DXing (and other out-of-market viewing) maybe going bye-bye.

"Rural viewing" also often occurs Outside of a stations predicted coverage area, even IN some cases from INSIDE a stations's DMA ....


Many Stations predicted coverage area in some areas covers areas of multiple markets, therefore, no, this isn't a "in market/out of market" specific issue, it's an issue regarding Harmful interference for Fringe area viewers(not Dx'ing-*)located beyond stations predicted service contours, regardless of whether they are In-market or Out-of-market viewers ...

* - update/clarificaton: Of course, We're definetly screwed for Dx'ing, but keep in mind, Dx'ing is really about issues such as exploring enhanced signal propagation/weak signal reception, not about attempting to receive TV programming or distant "out-of-market" signals in a viable/reliable manner ...

Also, as noted/detailed in my last post, FCC is providing additional protection Outside of stations coverage area for distant/weak signal reception by distant cable Head-ends, but NOT for OTA Users ....

BTW, Even At some locations tested In FCC's own recent field tests - discussed previously/links posted previously (using recieve antenna - VU90XR which *did not* meet FCC planning factors for reception), Several stations were received (DTV signals decoded with consumer equipment used) from beyond stations service areas .....

Most of that is the spectrum the federal government took over during World War II and they're not that good about sharing.


Did I read that right, channels 3, 4, and 37 are excluded for use by TVBDs?

I looked at the Tyson's Corner report. I could clearly see either an NTSC or DTV station
on (roughly) every other channel (duh!!!!)....with a few cases where an NTSC and
an adjacent DTV station shared a common antenna.

Hence overall TV Band occupancy was about 50%....TWICE what SSC found.
Apparently their "occupancy threshhold" declares spectrum in between NTSC
video/chroma/audio carriers as "wasted"....until Post-Feb2009 repacking....

Adjacent channel protection will have to be provided, so overall occupancy available
for WSD was (maybe) a few percent.....

And their overall "occupancy" in Fig 2 is for nearly the entire DC-Light spectrum....

At least the sensitivity was in the ball park of a DTV receiver with Preamp and
moderate gain antenna.

=====================================
Military/Civilian Aviation/SAT UHF band (225-400 MHz) would probably measure
as being much busier using an antenna with significant OVERHEAD coverage.

Although light aircraft typically use lower VHF freqs, there are 1000's of Military/Civilian
aircraft IN THE AIR AT ALL TIMES using 225-400 MHz to talk to airports, plane-plane, etc.
There's a total of 20,000+ airports in U.S., each using multiple VHF & UHF freqs....
And each aircraft has LOS propagation for a radius of several hundred miles,
meaning each one affects a much greater "DMA" than television....
PS: The aeronautical community complains about shortage of VHF and UHF freqs....

If you've ever listened into the air controller channel when flying commercial,
you'll also understand that there is a very low, long term DUTY CYCLE when a
freq is shared among a large number of human beings....which is apparently
being "averaged out" in the spectrum "occupancy" report...

GIGO....

This is exactly what I'm talking about. I live 79 miles from my local stations, and they boom in here, but I'm outside of the "protected contour" of more than half of them. I'm in the Roanoke DMA and the signals are strong, but they'll receive no protection. If someone wants to start a WSD on channel 18, it's bye-bye CBS-HD.

The Roanoke stations actually carry out 95 miles due to their location on Poor Mountain, but the contour only goes out about 75 miles because the FCC uses the 2000' HAAT to calculate the contour instead of noting that Poor Mountain actually has a 3000' height advantage.

The FCC treats the protected contour as though it's a hard limit on coverage, when it's very much not true. Many stations can be received outside their protected contours reliably. I think the contours assume that terrain is completely or almost completely flat, and that's almost never the case.

- Trip

It could also result in much more dire consequences if their communications are interfered with than our watching of CSI is interrupted.

With only fixed devices being able to use channels 2, and 5-20 and 2 channels between 21-51 being reserved for wireless microphones in 13 major metros not to mention the exclusion of TVBD use in border areas it sounds like the personal portable devices will be worthless in some urban areas.

In addition to the apparent lack of available spectrum in many areas for WSD operation per the rules ... I wonder what happens if say, someone purchases a personal/portable WSD and uses it somewhere in Mid-america, and then moves to say, the Detroit area, to a (work or home) location within 32km of the Canadian border where the WSD operation won't be allowed on *any* channel ??? Assuming the WSD as required actually "stops functioning" when it is moved to this new location, Will the manufactuer of the device provide the consumer a full refund

To be honest, I personally think there are so many things wrong with this R&O and the rules adopted, as well as, fundamentally, the decision to allow WSD's in the Broadcast bands that I don't even know where to start ...

In summary, I think it's a mess, and I wouldn't be surprised if we don't soon see some modifications to the rules as currently adopted, although I doubt any such modifications will actually make this mess "better" .. ... if I were to sum up a response to it into one word, the one word that comes to mind at present is :

NUTS!

Here are a few additional general thoughts, though :

With the apparently limited resources FCC has(it seems they already have more than enough to deal with), I Really can't imagine how FCC is going to be able to properly implement and enforce many of the rules they've adopted ...

Also, given what has occured in the past with various unlicesned services (CB'er's running 2KW or not more/etc - how many of those guys "got caught"?), I would be very surprised if we don't see hacked, and/or grey market/non-compliant WSD's relatively soon .... Then there's the Geolocation database and concerns about potential accuracy and maintenance issues ...

Also there is the question of how harmful interference is going to be detected and identified ... I suspect in many cases, the only folks who are going to potentially know harmful interference to their (protected by the rules/within service area) OTA reception is being created *ARE* individual OTA users --- I say "potentially", because in the vast majority of cases, OTA DTV users are not going to have the equipment necessary to diagnose and identify the cause of interference .... Suspect in most cases, they will have *no idea* what is causing their poor reception or dropouts ... could be WSD's, could be Multipath/etc/etc ....


Yep. And as you noted in your most recent post, 2 additional channels will be excluded for wireless microphone use (1 somewhere between 21~36, one somewhere between 38~51) in areas near 13 of the Metro areas using Land Mobile. And, as you also noted, all channels are excluded for use by TVBD's within certian distances of Mexican and Canadian Borders(the area involved - within 32km of Canadian border would include much of the Detroit area for example), and within 2.4km of certain sites used for Radio Astronomy ....


That's how I understand it as well, as is specified in Appendix B, CFR 47, Section 15.107, 15.709 and Paragraph 105 of the text regarding explanation of the 4 W EIRP Max for Fixed devices and taking antenna gain into account ....


Follows is what it says in appendix B, for 15.712(d), regarding protection of LM (PLMRS/CMRS) operations and regarding co and adjacent(N +/- 1) channel TVBD operations -- In other words, this seems to say 1st adjacent channel WSD's aren't allowed within 131km of the LM operations of the metro areas listed in CFR 47, Sec 90.303(a), and within 51km of LM operations outside of those metro areas not specified in sec. 90.303(a) -- well, actually, specifically they are specified in 90.303(b) .... :



CFR 47, Sec 90.303 is available here (currently - note the link for the "current" rule will change to having a "2009" in it in 2009/etc ...) :

http://www.hallikainen.com/FccRules/2008/90/303/

LA is shown as one of those 13 metro areas, using 470–476, 482–488, 506–512 (MHZ), or channels 14,16 and 20 ...

So, it would seem WSDs would not be allowed on channel 21 within 131km of the "Urbanized area geographic center" shown in 90.303(a+b) for LA area ...



Also, Do be sure to note, as I posted earlier as detailed from the rules(sec 15.712 (a)(1) and R&O -- LP stations will be protected from interference from WSD's using the same threshold for service as used for full service TV stations, which or course involves a larger(in some cases significantly larger depending upon the stations faciltiies/etc) area than LP stations service (noise-limited) contours ...

For example, while a analog UHF LP stations noise-limited service contour is defined in FCC rules as being 74dBu contour, vs 64dBu contour for UHF full service analog stations .... For the WSD's, the LP's will be protected/WSD's won't be allowed to operate within their 64dBu contour, just like Full service stations ....

Also, note the required allowed seperation distances between (in this case for UHF) the 64dBu contour and a WSD for co or adjacent channel operation, with WSD outside of the stations coverage area is the same for LP analog or full service (see table in 15.712 (2) in appendix B or as I posted earlier) ....

Whose database will be used, and how will it be updated?

Antennaweb?
TVFool?
Google?
etc...

Funny that Dell would build WSD into their computers (with spectrum sensing and/or GPS location, I hope) but would scream bloody murder if they were required to put a DTV receiver in their computers.

I hereby predict that the very first hack for WSDs will be one that allows the user to operate on whatever channel they want regardless of what is programmed into the database.

Are the clowns at FCC really this so stupid as to think that this silly database idea is going to prevent interference.

Goodbye Philadelphia.
Goodbye Baltimore.

I will soon not be able to watch these cities thanks to this incredibly idiotic rule. I'll be stuck with just my Lancaster PA locals which are rather deficient.
Could a whitespace-equipped device be used to detect interference?

Another thought is how can the FCC ever approve the signal sensing only TVBDs (no matter how rigorous the certification) and still protect the border areas and radio astronomy sites? For that matter without geo-location (that any attempt to hack or disable will result in complete disablement of the device) how can they prevent illegal exportation into foreign countries?

Basically, the new WSD rules say the commision will designate "one or more entities" to administer a "TVbands Database" ,for 5 year terms ...

Section 15.714 says :


As for what is to be in the database, it will involve information which is specified in the rules that is and is not "recorded in Official commission database" ....

How they plan to implement it is seems difficult to summarize and describe properly, and would be WAY too long to quote here .... It is laid out in sections of The R&O's appendix B, which contains the text of the actual "Final Rules" from this proceeding for the WSD's --- the part 15 rule modifications, which will I believe will become actual Rules in Code of Federal Regulations after/if OMB approves them and they are published in Federal register) of the R&O ...

Specifically, the Database rules are in Section 15.713~15.715 which begins on page 107~111 of the Report and Order ... Note, in addition to (PDF) link provided earlier, and digging it up via Edocs, currently you can also acccess this R&O in Word doc or PDF format from links by the R&O under the 11/14/08 date here (At some point, this will eventually "scroll off" the first page/but will still be available in the "more headlines" section of FCC site) :

http://www.fcc.gov/