The official final DTV Table Of Allotments/channel change thread - Page 4

Meanwhile, I've noticed another developing controversy involving a maritime communications company.

According to a document filed in early January, Maritime Communications/Land Mobile, LLC, is seeking relief from its duty to protect stations moving to channels 10 and 13 from its interference.

Under its current license, MC/LM must protect stations currently transmitting on those two channels. However, the company argues that it should not have to protect stations which the FCC plans to move to channel 10 and 13, if they weren't on those channels in analog mode.

"The Commission's long standing policy with respect to interference between TV stations and land mobile systems has been 'first-in-time, first-in-right,'" the company argued, noting that it has been operating automated marine telecommunications systems (AMTS) for nearly 20 years and won the disputed frequencies at an auction which closed in 2005.

Public station WEDU of Tampa is one of the stations which would be affected. It broadcasts analog on channel 3 (which it does not want to use for digital), currently has an out-of-core digital channel, and plans to move to channel 13 post-transition.

In its response, attorneys for WEDU wrote: "This is not a situation governed by some general proposition of 'first in-time, first-in-right', as suggested by MC/LM. Rather, there is a specific rule governing the relationship between AMTS stations and Channel 10 and 13 television stations, and it does not include the exclusion sought by MC/LM. Moreover, such an exclusion would not serve the public interest, and viewers of Station WEDU should not be subjected to adjacent-channel AMTS interference to its post-transition DTV broadcasts on Channel 13."

Also entering the fray was the Association for Maximum Service Television, which argued that AMTS coast stations have a "long established" secondary status to DTV.

"MC/LM, like the other AMTS licensees, knew when it applied for its license that the Commission had begun the transition to digital television, and it was well established that the Commission would make digital allotments on channels 10 and 13," attorneys for MSTV wrote. "Having applied for its license notwithstanding the ongoing transition, MC/LM cannot now ask the Commission to divest DTV stations of their right to interference protection. The Commission has already rejected such a policy, concluding that AMTS coast stations' authorizations are secondary to all analog and digital television broadcasts."

dline already answered where it came from, so I won't repeat him.

You most certainly may post it at the beginning of the thread, just mention that I gathered the data. =P

I'll see what I can do about power increase requests.

- Trip

Ah, good! I hope that one gets approved. I'm roughly equidistant from WMYT and WKTC (Columbia SC) both of which now have channel 39. I get fairly decent reception on WMYT-DT, but nothing at all on WKTC-DT because they're still at very low power. I've been wondering if those two would knock each other out at my location when WKTC-DT finally goes to full power.

Charlotte's WJZY currently has 46 for analog and 47 for digital. It looks like WJZY and WMYT share the same tower so having them on adjacent channels would work OK.

Not only work okay, they might even be able to use the same antenna. This would save them money as well.

- Trip

Also would like to add my thanks to the others to Trip for digging through all that+posting a summary of the most interesting goings on.

Since it looks like the comment period for "DTV proceeding" 7th FNPRM has been over since Feb 27 (it was extended from Jan 25) -- even though, some later comments were filed as well : it seems to me we probably should be seeing a R&O on it + a finalized table from FCC soon .... At least I hope we'll be seeing it soon ..



I finished reading through the 3rd DTV review last night, so have more comments+thoughts at this point than anyone probably wants to see or read

I'd generally probably like to wait until the R&O is out before commenting too much on it, but since you asked, it is fun to think about what's going to happen based on the NPRM as well ...


I'm not postive but regarding the "voluntary band clearing" comment you quoted, I wonder if they may be more reffering more about circumstances involving out-of-core stations ?

Given the numbers of OTA folks who need to make the switch to digital in a relatively short period of time, I'd think, in-core analog stations especially would probably have to produce a lot of evidence that virtually noone is watching those to be allowed to shut down before feb 17, 2009 ....

Other than perhaps regarding some out-of-core stations, Seems to me the possibility of allowing reductions in analog service area prior to analog shut off is more likely in more cases, rather than complete termination of it. Such as say, allowing moving the analog antenna to side mounted posistion on tower+digital to the top -- Judging by what I read in the NPRM, probably generally along the lines of allowing around 5% or less reduction in analog coverage area without the station having to go to much trouble to make their case to FCC for it ...


Yeah, me too .... That and several other things in that document "struck" me as well .... I'm thinking we might see a lot of comments submitted to FCC regarding that (3rd DTV review) proceeding... When the comment period begins, I'd think they should probably show up under a search for proceeding 07-91 at ECFS search page ....

I suppose what struck me the most after reading through the 3rd DTV review NPRM is that the gears seemed to have definitely changed now at the commission to looking at post-transistion DTV operation and stations being ready for it.

And, It seems to me from reading that, whereever possible they seem to want stations to have their post-transistion DTV facility per the current "proposed" new DTV table of allotments on the air on Feb 18, 2009. So as to, in many cases as possible serve their entire "service area" with DTV post transistion right off the bat ... It also looks like they are trying to look at as many options as possible for stations to bring that to fruitition ....

My eyes! They hurt me!

Yes, I just went back through almost 200 applications and dug up the power increase requests. These are in no particular order.

Calls-Final City-of-License Details

KUHT-8 Houston, TX 8.4 kW > 20 kW
WCTI-12 New Bern, NC 20.5 kW > "more"
KOMU-8 Columbia, MO 8.105 kW > 13 kW
KTWU-11 Topeka, KS 281m 26 kW > 302m 21.5 kW
KKCO-12 Grand Junction, CO 10.8 kW > 5.3 kW (not a typo)
KUID-12 Moscow, ID 129 kW > 78 kW
WHDH-7 Boston, MA 16.8 kW > 30 kW
WSVN-7 Miami, MI 14.3 kW > 145 kW
WSWP-10 Grandview, WV 2.5 kW > 20 kW
WMYT-46 Rock Hill, NC 200 kW (channel 39) > 336.4 kW (channel 46)
WGAL-8 Lancaster, PA 393m 13.4 kW > 415m 5.36 kW (not a typo)
WLFL-27 Raleigh, NC 568 kW > 910 kW
KMOT-10 Minot, ND 4.75 kW > 8 kW
KHAS-5 Hastings, NE 2.8 kW > 7 kW or 45 kW
KNOP-2 North Platte, NE 3.61 kW > 16 kW or more
WLAE-31 New Orleans, LA 66.7 kW > 200 kW
KXVO-15 Omaha, NE 530m 301 kW > 475m 486 kW
WPVI-6 Philadelphia, PA 2.548 kW > 4.8 kW
WTHR-13 Indianapolis, IN 6.75 kW > "the full amount" (13.5 kW?)
KOSA-7 Odessa, TX 7.53 kW > 160 kW (wowza)
KOAM-7 Pittsburg, KS 4.2 kW > 15.33 kW
KOED-11 Tulsa, OK 396m > 521m
WENH-11 Durham, NH 8.27 kW > 16 kW
WTVF-5 Nashville, TN 4.28 kW > 22 kW
WQED-13 Pittsburgh, PA 6.42 kW > 19.5 kW
WBPG-25 Gulf Shores, AL 67.5 kW DA > 1000 kW ND
WEDU-13 Tampa, FL 17.1 kW > 40 kW
WBOY-12 Clarksburg, WV 6.55 kW > "more"
WREX-13 Rockford, IL 5.07 kW > 12 kW
WGEM-10 Quincy, IL 5.56 kW > 12 kW
KFMB-8 San Diego, CA 5.42 kW > 11.1 kW
KCET-28 Los Angeles, CA 107 kW > 190 kW (dispute with KEYT-DT 27 Santa Barbara)
WGTV-8 Athens, GA 15.6 kW DA > 18 kW ND
WVAN-9 Savannah, GA 9.72 kW DA > 20 kW ND
WCIQ-7 Mount Cheaha, AL 19 kW DA > 21 kW ND
WAAY-32 Huntsville, AL 50 kW > 468 kW
KSWT-16 Yuma, AZ 196 kW > 510 kW
WCAX-22 Burlington, VT 435 kW > 443 kW or 550 kW depending on Canada issues

Also of note is that Bluestone Holdings, owner of WCTI listed above, is also upset about the low power of these stations, but provides no specific level of power they'd like:

WCYB-5 Bristol, VA 6.78 kW
KRCR-7 Redding, CA 11.6 kW
KECI-13 Missoula, MT 16.1 kW
KCFW-9 Kalispell, MT 3.2 kW
KTVM-6 Butte, MT 6.81 kW

A pair of petitioners including Northern California Public TV wants 32, 41, and/or 51 allocated to Weaverville, CA. They request two of the three, one for each applicant.

There was an objection to WNYA-51's request to be allocated to channel 13 and broadcast from west of Albany from WNYT-13/12.

WLLS-CA in Indiana, PA is fighting WPCW-DT, claiming the station should be forced to stay on channel 30 and from their current site near Johnstown. WPCW-DT wants to be on channel 49 licensed to Jeanette and broadcasting from the WPCB tower.

Whew.

- Trip

Some comments on this one ... Note -- Updated this entire post including better wording than my original post+providing more details :

After reading the comments on this one which were submitted to FCC -- At this point I think this one has to do with non-D/A I think WTHR expected given their filings during channel election process vs. D/A they say in their comments is specified in the new, proposed post-transistion DTV table. Note: I don't think I have the antenna pattern data available from proposed DTV table to look at, other than what dispatch/WHTR submitted to FCC in this engineering statement ...

I was about to say, without having more info, I also wonder if it could even be some sort of accidental error on FCC's part rather than what is described in these comments from dispatch regarding this matter.

However, I do notice there is also this letter stating they met with some FCCfolks and discussed this issue with them in a meeting on 5/1/07 -- there are also several attachments as noted with coverage maps+Polar plot the letter says was discussed at the meeting available at ECFS for this proceeding under a record for a 5/10/07 date .... I decided not to provide links to those as I don't think anything "stood out" to give us an idea of what they might have discussed or perhaps come to any resolution on in the meeting .....

As Trip said, "whew!" ...

I think it is cool this stuff is available to public, but some of it certianly is difficult to "interpet" properly ...

----------------------------------------

You know, looking at those comments regarding WTHR and some of the other allotments as specified in the current proposed new DTV table -- In hindsight, if it would have been possible, I wonder if it would have been better, especially for stations moving to different channels, if they could have had more info, earlier in this process(such as during channel election) concerning such details as ERP and D/A patterns regarding what was going to "go" into the DTV table for their TCD's ...

I know in some situations, what the stations proposed in engineering statements and what the FCC would let stations do post transition were two different things. It seems the FCC used a much tighter standard in deciding post transition coverage than what has been historically used in the analog world and even in the early DTV transition. They never allowed waivers on it even for a .1 or .2 % difference in interference above what is currently in place. Because of that, stations that otherwise would have been able to use a channel non-DA under previous rules were either locked out entirely or had to propose restricted DAs to use a certain channel. I personally know of several stations that happened to, but I can't publicly comment on which ones at this time.

And of course the VHF-low ones are really getting squeezed, though it appears many don't know it yet because it's uncharted territory.

I was looking myself to see if there was anything from WHBF in the Quad Cities (licensed to Rock Island, IL) or WOI in West Des Moines (licensed to Ames) and saw nothing. If there are problems with WOI's 3.91 kW on Channel 5 or WHBF's 3.88 kW on Channel 4, we'll have to learn about them the hard way.

With fewer stations on these channels, there should be a little room for a boost.

I just realized that with the moves now of KJNP and WOAY, there are now only two stations in the US on channel 4.

WDKY Danville/Louisville, KY Fox (which tried to move off of channel 4 at one point in the past)
WHBF Rock Island/Quad Cities, IL/IA

I wonder if the FCC might try to move them somewhere else and reclaim channel 4 with such a small number of occupants?

- Trip

Well, there is no guarantee that the FCC will allow KJNP and WOAY to move to a different channel assignment. We need to keep in mind that these are requests and submissions and the FCC is not likely to grant all of them. But with no more than 2 to 4 full power stations on VHF 4, you are right, that will eventually lead to pressure to reclaim the frequency space. There are some low power stations opting for low VHF. Might we see a rush (of some sort) of low power stations, especially the religious stations, to the unused VHF channels? Many of them really don't care that much about actual OTA reception, but put up the low power station so they can get carried on the local cable systems.

There is a analog W06CJ low power station that started up very recently on VHF 6 in the Washington DC area in Arlington, VA. Spanish Language station. I don't get the station, but I am out of their small coverage area and don't have an antenna for low VHF (tempted to hook up a rabbit ear antenna in my attic length optimized for VHF 6 to see if it comes in at all). This is why I am wondering if we will see a bunch of low power stations pop up in low VHF once we are past the analog shutdown. Of course, they may be told to move to other channels if one of the low VHF channels was re-assigned, but possession does count for something in the political process.

5 kW isn't as small as you might think in digital for VHF-hi. Our channel 8 316 kW analog translates to 15 kW digital ch 8 pretty well. I have seen two studies that are very close in coverage for us post transition.

I'm hoping not too much, if any, of this white space is reassigned so that we have some room for growth.

Right now we get 16 channels from eight stations over-the-air even in little ol' Cedar Rapids, Iowa, and I'm glad we didn't choke off that growth by assuming that there would never be a need for a fourth or a fifth station in a market this size.

Naw, man, don't you know it's ALLWAYS the stations(or FCC's) fault ... Not enough power, regardless if the issues involved are really interference from various household appliances, terrain atteuation, attenuation by having antenna indoors, multipath, or perhaps even poor VHF band performance from some receivers/etc ..... The "signal meter" is showing low or "0" readings, so it MUST be not enough power ...

But seriously .... Yep. Same here AFAIK regarding a local DT on 10 currently running 16.3KW ERP. That's maximized win Non DA, they maximized a couple of years back a small fraction of a db from 13.7KW ERP, their post-transmstion allocation is 15.4KW ERP. They are one of the stations that was granted a "use it or lose it" waiver until feb 17,2009. But, that isn't a power issue, it's because of the analog transmit antenna(top mount), and digital antenna(side mount), with the DTV currently covering 98.4% of their analog's coverage area .... BTW, I don't know what they might be thinking about doing, but it seems to me in their case it makes more sense+would be more efficent(including for tower crews given all the other stuff they're going to have to do) if FCC simply allowed them to wait until AFTER analog shut off before moving the DTV antenna to top mount tower posistion ... that doesn't seem to be an "option" FCC said much if anything about in the 3rd DTV review NPRM, however ...

Anyway, 15KW ERP, of course would only be about 4.5db more signal than 5KW ERP .... sure, that's a 1.5x reduction in power, but I think that's really only a small piece of the pie when you consider it's typical that usually the majority, or at least a large portion of the population within coverage area can easily have 40~60db MORE signal than is needed for reception, including of course regarding 5KW or 15KW ERP VHF stations ...

From many comments I've read on this forum over the years, I have the feeling many people seem to have a quite incorrect general understanding of "power" .... Especially perhaps when it comes to directional antenna patterns or when they're used to seeing the bigger numbers for "peak" power numbers for analog vs. the "average" power as measured for digital ... Then, there's also the fact that we need less signal with digital for reception vs what is needed for decent analog reception ...

It's understandable, though I suppose -- a number like 1000 just "seems" like a LOT more than say, a number like 500 .... Until you understand 500KW ERP is only a factor of 1x less power than 1000KW ERP, and ONLY about the same as the signal loss from 75FT of RG6 on UHF or a 2-way splitter ...

But, I've tried and tried and tried until I'm blue in the face, nevertheless, time and time again someone in my local threads will venture to FCC site and see "1000KW ERP" from one UHF DTV station, and "138KW ERP" for another, and will do something like tell someone having reception problems from 4 miles from the tower that they aren't receiving the 138 KW ERP station because they are at "low power" and it's "all sinclair's or so and so's fault"/etc/etc/etc(And no, i'm not exaggerating this exact thing has happened at least twice, now) ... Of course, in that particular circumstance, the station running 138KW ERP *IS* running at full power, just as they will be with the same facilities post-transistion .... Doesn't matter what I say, or point out regarding the 1000KW ERP station's directional antenna pattern when applicable+the receive location is in the null+getting less than 138KW squirted their way from that stations, or that there are some folks recieving the 138KW ERP station just fine with antenna in attic 60 miles away, 138 is just a 'significantly' smaller number than 1000, and that's what is important ... LOL ....

anyway, enough of that ... Personally, I was even pleasantly surprised regarding Low Power STA's some DTV stations in my area were running earlier on during transistion, at least when the transmit antenna was up nice+high. One was running 7.5KW ERP(with a 250W TPO via solid state transmitter) on UHF 34 32 miles distant+the reception here from 32 miles+down in a valley was just as perfect then as it is now with them running 400KW ERP ... In fact a couple of us(including me) reported detecting a signal from them, presumably just off their exciter shortly before they first came on the air ... That being said, can't say I saw many reports of successful reception when that station was operating with that STA from folks using indoor antennas, and DA and quite a null in antenna pattern towards a "signficant" portion of population in area(as little as .19 relative field value, or approx 270Watts ERP in that direction -- but not in my direction) probably didn't help with that either ... So sure - regarding indoor antenna reception in some cases, or issues involving terrain shielding or fringe reception, especially on higher frequencies some folks are allways going to beneifit from "more power" ...

But, overall, at this point I'm not sure I understand for DTV why much more than about 125~250KW ERP or so is necessary on UHF, or much more than 15~30 KW or so on VHF ....

Of course, the difference between say, 250KW ERP and 1000KW ERP isn't all that great (about 6db) on the receiving end, but I'd think it's another story entirely regarding all the extra power required to run the transmitters, especially when lower gain non-DA is used ....

sorry for the long rant/post on power, but it's nice to hear someone here occasionally tell it like it is .....

I don't know if anyone has found this or not, It is possibly every station's post transition channel and their ERP output the FCC is allowing them to have. I looked at it and found it interesting. This may be old news though, because it was released on Nov. 7, 2006. Anyways, the link to the list of stations is below. It is a text document. The ERP output is about the 8th column over from the state and city column. That's all I have at this moment.

http://www.fcc.gov/oet/dtv/appendixb...B_stations.lis


NashDigie signing off.

Yes, VHF-low and VHF-high is talking apples and oranges. The frequency range of channels 2-6 are 54-88 MHz and 7-13, 174-216 MHz and that brings in different propagation characteristics as well as how noise, man made and natural are distributed. Take into account as well interference from analog stations that will not be there post transition.

It is a known and verifiable fact that with the addition of digital stations in with the analog stations, interference of analog stations has increased to the point that some analog stations have reduced coverage area because of it. It also has been proven that digital stations that could be received easily early on in the transition are more difficult to receive now that most stations are on at full power, even though receiver rechnology has greatly improved over the last 10 years. And I am just talking about UHF stations in this example.

The problem with VHF low is the fact that natural and man made noise takes so much power to overcome. You see that now in analog. You do not have near the problems in VHF high and you can see that on analog as well. Propagation between the two bands differ greatly as well. Channels 2-6 are much more prone to tropo than 7-13 with channel 2 and 3 being the worst. The MUF will be at channel 2 or 3 and stay there for days on end in the spring and summer where channel 6 will only have tropo for hours at a time. Channel 7 will have tropo lasting for several hours but it is significantly reduced in intensity and takes a strong tropo opening to encounter the same level of interference channel 2/3 sees daily.

You also take that the FCC has shoe horned in stations to be sure the analog stations had digital channels. Just off the top of my head I can name two cases where analog/digital interference has made reception near or completely impossible for an analog station with just the addition of a digital station. And both examples are in the UHF range. It can happen anywhere. When you mix transmission modes, as has happened with analog and digital stations on the same channel, you will have interference issues that you would not normally have when you only have one mode of transmission. When analog shuts down, you will start to receive stations that you can't get now because of the analog interference. Let me guess, in your area you have a channel 9 analog right? Analog uses the upper sideband of the signal and digital uses the lower sideband of the signal also known as a N+1 digital assignment. The FCC made every effort to NOT issue N+1's analog/digital because of the overlap of the analog upper sideband signal on the digital lower sideband signal for that very reason. And that is just one of the issues with WBBM-TV/DT situation. They are cursed from many angles, VHF low just being one of them.

To condemn the whole idea of digital stations on VHF-high as a bad idea because you have trouble receiving a channel 10 35 miles away is not logical. There are many reasons for your poor reception. I can show 4 or 5 cases off the top of my head where VHF high digitals work very well and they are not running super power to do it.

It is also a fact that the Northeast and Midwest are beyond saturation of television signals, even digital. To be honest, I am surprised that many stations in the VHF low as well as high bands were allowed on in the Pittsburgh to Detroit corridor along the Great Lakes with Lake Effect tropo abounding. As many on AVS have attested to, living in one city and being able to pick up stations in the other cities in that area is the norm and they live with interference on a daily basis. If nothing else, the digital transition has forced stations to spread out spectrum wise and in the end, I think it will improve OTA in those congested areas.

My opinion is this was the first time the FCC has even seriously considered HOW to transition from a step-by-step point of view. When stations have brought this up in the past, they were ignored. Bottom line is when Feb 17 2009 comes around, the FCC wants to be FINISHED, COMPLETED, DONE WITH, NO MORE of the digital transtition. They are SO sick of it now.


In the beginning, it was all about the "number" of power. The bigger the number, the better the marketing. How many AM stations in the 50's and 60's and FM's in the 70's routinely touted their power output like that meant they were better because they generated a higher power bill? It all boils down to like signal strength in the digital world. The original digital allocations were based on comparible population, something the FCC is now transitioning to for all coverages, ie, how many people do you serve, not how much coverage area with no persons do you cover. Based on that it takes less power. But then the FCC let stations "maximize" meaning a station could go up in power as much as interference would allow up to the max for the band to fill in the small open spots you couldn't put a station in anyway and to level the playing field between the smaller stations and the bigger stations and that has pretty much done that. In my area, there was only one 5 MW UHF station and a bunch of 1 to 2 MW UHF stations along with 3 full power VHF low and high band stations. Digitally we have two 1 MW, (one VHF low and one VHF high analogs) one 814 kW, (VHF high analog) several 700+ kW, (all UHF analogs) and only two "low power" UHF's, one is 102 kW at 1700 ft and one at 194 kW at 900 ft (both UHF analogs). The 102 kW at 1700 ft has more coverage now than they do as a 1 MW at 500 ft analog.


Correct. See above.


Yep, again see above.


To people who just want to watch television, it is all so much techno babble and they don't care about it. If they can see a station that is 10 kW and can't see a station with 1 MW, the 1 MW station is stupid for not having enough power. D'OH!

Don't want to take anything "away" from your excellent posts, but do have a couple of comments regarding your comments about tropo ...


What you say regarding 2-6 and MUF sounds like a good description of what happens with E-skip, not tropo. However, it is extremely rare for E-skip MUF to rise much above FM band into higher VHF frequencies - It does happen. Very, very rarely however, including into Hi-VHF TV band.

Tropo, on the other hand generally effects UHF(and even higher frequencies) as much as VHF. In fact, with a "true" tropo duct as opposed to troposcatter(which is generally more common), there is a LUF (lowest usable frequency) involved .... The duct acts much like a open ended wave guide, with the LUF corresponding directly to wavelength involved and the width of the duct ... What I've sometimes seen happen with tropo ducting is, at first, you'll only see distant signals from a particular direction on the mid to upper UHF channels, then as things stablize+the duct grows "wider", you'll start seeing distant stations on lower frequencies, often down to hi-VHF TV band, but not allways down to low VHF.

That being said, I can see how the effects of "tropo", (using it not quite accurately IMO as a more extremely " general" term) can, in some or many cases can probably seem more "noticable" or frequent on lo-VHF - I think that's because small changes in "K factor" (mostly refraction) that are allways occuring(but not as much in drier winter months at least in this area) may be more more noticable to folks on Lo-VHF where the longer wavelenth lo-VHF signals can "bend" a little better around terrain or curvature of earth than is the case with signals on higher frequencies even if there is really not much "enhanced propagation" going on .... In my experience at least, nearby terrain issues usually have almost just as much(or more) of an effect regarding reception of signals propagated via "tropo" as they do for local signals, and in this sense, again, the lower the frequency/the longer the wavelength, the more the signal can "bend" around hills .....

Also, when there is a good tropo opening occuring that lasts more than just one night/morning, it often *IS* the case that in late-morning and afternoon hours, it can remain at least a bit more stable on VHF while becoming quite unstable on UHF, until the atmosphere "calms down" again in the even the UHF stations start becoming more stable again -- oftentimes(but not allways, depending upon what is going on with the inversion and the "weather"/etc), the "peak" of stability(and strongest/ most distant signals) will occur in the morning hours, just after the sun rises ....

I have stations within 100 Miles on every VHF-LO channel for example. (On 4+6 -- 3 stations for channel 4(one of those is DTV), 2 stations for channel 6 stations in different directions), and I almost see ALL of those ALL the time, but slight differences/changes in the propagation conditions mean the signals from the more distant ones is often(almost allways really) varying to some extent, without, I think, what I would call a "real" tropo opening involved ... also think these things may also be easier to see on VHF(lo-VHF especially perhaps) in some cases, because of issues such as less signal loss in the user's feedline on the lower frequencies vs the case for hi-VHF or UHF, possibly perhaps in some cases lower NF for some (analog anyway) VHF tuners, and possibly in some cases the better performance(or "greater capture area so to speak) on VHF from typical VHF/UHF combo antennas ...

I was using the word "tropo" in a VERY generic term. You can get so hung up in the syntax and miss the meaning that I wanted to avoid all of that difference with enhancement, tropo and E and F skip and how you tell the different. Too much for what we are talking about here.

At this point in the Sunspot cycle, we are dealing more with tropo than E layer anyway and will for a couple more years so I decided to not confuse things.

In my market channel 2 puts the strongest RF over me at 100 kw at 2000 ft at 20 miles, but I can see noise in the picture quite frequently where my 300 kW channel 8, 800 ft less in height and 5 miles farther in the same direction is noise free 99% of the time. We have a channel 3 digital 90 miles away on a 4000 ft mountain that is exactly 180 degrees opposite of channel 2 that Trip is VERY familiar with and I can tell it is there, but with the channel 2 first adjacent, I have never decoded it so I am not sure if the local impulse noise would effect it and how much.

Now I am not saying I want to see digital stations on VHF low (I don't) but there are so many things that have to be taken into account on reception, no matter what channel it is on and no channel is a pancea. They ALL have their issues in one way or another.

OK, I'll say it more "simply", but still accurately, but this time I won't go out of my way to try to be especially "nice" about it.

What I think you are mostly talking about is quite "normal" enhanced signal propagation. I would refer to it as troposcatter, but I agree tropo is fine and accurate enough. It happens all the time to some extent+to varying degrees, and especially is more of an issue regarding interference among stations in warmer months. Especially in the regions you mentioned, and for instance along gulf coast).

But, there is no MUF involved with it, at least not below 1GHZ or so. Usually and generally the distant non-local signals propagated in this manner are fairly weak and sometimes quite unstable. But not allways, as it sometimes can involve quite strong signals as well.

In reality, It effects UHF and higher frequencies just as much as VHF, but for reasons I've already mentioned(and probably more), it may be more "noticable" in some, or many circumstances on Lo-VHF, or even hi-VHF. The ways to improve this part of the "problem" are probably to have greater spacing between co-channel allotments/reduce power HAAT/etc, with of course even greater spacing necessary for low-VHF --- The latter certianly doesn't seem like it will be a problem for low-VHF DTV post transistion

And, as you say, the situation regarding this, in general should and I think *will* get better once the analogs are gone and we have only digitals using the spectrum, even though there is going to be less of it(ch 2-51 vs ch 2-69) .....


Solar/sunspot Cycle has nothing to do with sporadic-E("e-skip"), which is the E-layer propagation we often get in summer months on low-VHF TV band. E-skip is just as intense(sometimes more) during solar mininum as during Solar Max and periods in between. That's been known now for 60 years, but unfortuently it seems to be a myth that just won't go away. probably partly because I've heard if not currently, not too long ago it was even printed in engineering textbooks ....

In fact, we've had quite a bit of e-skip activity in my region over the past few weeks, and I believe we are currently near the minimum of sunspot cycle. Dx'er's in my region which don't have a strong local on 2 like I do have reported seeing it on an almost daily basis the past few weeks. One of them in fact reported an opening this morning with MUF up to channel 5, I missed it however as I was busy with other things ...

F-layer skip is a "solar max" thing, and MUF has never gotten much above 60MHZ or so AFAIK ....


I certianly agree with that 100% ...... That's exactly what I'm saying too ....

You probably already know this, but Keep in mind, if they are SE of you as you indicated in a previous post(rather than South as you say in above quote), you're also not getting 16KW ERP from them due to your location and their directional antenna pattern. One reason directional antenna patterns are sometimes necessary is to protect other stations from interference.

See the antenna pattern info listed at WWTO-DT FCC TV query here , presumably for the entry under their channel 10 "licensed" facilities.

To figure ERP sent in your direction from them, first find the azimuth bearing that corresponds to the direction of your house FROM their tower. In this case their pattern rotation shows 0 degrees, so we don't have to make any corrections for a pattern rotation from the figures that are shown. Then, under the info for their antenna pattern, find the relative field value which corresponds to that bearing. For instance, you said earlier that they were to your SE, so for below example, I will use a 180 degree "opposite" or, NW bearing from their antenna pattern info, where for 310 degree bearing it shows a .660 relative field value. Now, to calulate ERP squirted in that direction, we use the following formula :

Relative field value in your direction SQUARED x ERP that is equivilent to a 1.000 relative field value(16KW ERP in this case) = ERP being sent in your direction ...

So, in this case(assuming the antenna pattern for WWTO-DT in the real world actually matches what it says on FCC site) it's:

(.660x.660) x 16,000 watts = 6969.6 Watts ERP sent towards a 310 degree(true) bearing from their tower.

If you were at a 280 degree bearing from their tower(.430 relative field value) however, it would only be 2958 watts sent your way. That's close to their biggest null, which is .400 relative field value at 270 degrees(directly west of them), or 2560 Watts ERP sent towards the west ....

Or an easier(and more precise I'd think as it's not limited to 10degree increments as is the above, and assuming he is using the correct entry from FCC database for them) way to do this would be to punch in your address or lat/long coordinates using Andy S. Lee's "signal prediction("radar plot") tool at www.tvfool.com , the TX_KW Column in the table results will show the ERP sent in your direction ... (note, unfortunetly however that site appears to be down at present)

Decided I'd like to comment on this as well ...


There are no mountains here, and their transmitting antenna is about 1000' lower than that if you are referring to AGL or HAAT. And yet I have no problem, even during thunderstorms-* receiving local DT on 10 at 13.7KW ERP(what they were running the first 4 years I was watching them) to 16KW.3 ERP from 32 miles distant. I can even receive it just fine with rabbit ears, indoors.

* - In the 6 years I have been watching them, I have had 2 dropouts on that station(about 1 second of disruption), both occured in Spring 2002, and both were obviously caused by EXTREMELY nearby lighting strikes ... What I mean by extremely close is, in the middle of the day with all the windowblinds+drapes closed the flash from the lightning was bright INDOORS, meaning those lighting strikes occured VERY CLOSE to my antenna .... I've had the same thing happen regarding a weaker local DTV station on UHF 24 (yes, "impulse noise" spikes effect UHF+Hi-VHF as well, just nowhere near as much as low-VHF) ....

Their analog is on 9, BTW. I think that the facilities are co-located probably helps regarding the N+1 issue Foxeng mentioned ....

I also have a full power co-channel analog to them, but 78 miles distant to my ENE, the Local DT is South. this doesn't seem to cause any problem, even though if I aim antenna ENE, the analog signal is almost allways visable to some extent through strong digital "snow"(or hash if you want to call it that) coming in off side of antenna from the local DT on 10 ...

------------------

That's only one data point from One receiving location of course .... But, I'm sure FoxEng, the stations using VHF-HI (or that will be), and FCC are using a lot more than "one data point" .....

Sorry for all the posts, but I realize I left some probably important things out in earlier posts and want to be clear on a couple of things :

E-skip+Low VHF :

The reason I'm being such a "stick in the mud" concerning the details on this is precisely because frequent, "intense" and prolonged disruption of local reception on LOW-VHF from E-skip *is* one of the things that makes VHF-LO specifically less suitable for DTV (or analog for that matter) than is the case for Hi-VHF or UHF, where for all intents and purposes, this problem doesn't exist. Except perhaps on average(and this is very rough estimate) for several minutes per year on Hi-VHF, at least in some region of U.S. Compared to many, many hours per year on lo-VHF(you could probably usually measure it in many days or more most years and especially for ch 2). And that's NOT an average with other "years" for Lo-VHF.

Regarding interference via enhanced signal propagation, E-skip on Lo-VHF is something *in addition* to disruption of local reception from "tropo", which *also* effects hi-VHF and UHF just as much(more or less) .....

Signals propagated via E-skip are often(but not allways) VERY strong, often times just as strong as the strongest of local signals. An especially interesting characteristic of it is, ERP/power the station is running that is causing interference via E-skip can often have very little to do with this. It can be very disruptive to local reception, of course moreso the weaker the local signals, and/or when the signals propagated via E-skip are coming from same direction as local signals with use of directional recieve antenna. In a few words, what I've often seen on lo-VHF during intense E-skip activity, especially when MUF is at channel 6 or into FM band -- Is, well, a REAL big mess ....

Again, signals propagated via Tropo are usually weak. But not allways, they can be strong as well. And That is *not* saying there aren't certian situations where tropo is just as bad(or worse), even on say channel 2, perhaps especially in areas where lo-VHF is very "crowded"(such as North east) .... But the same thing can happen on any Hi-VHF or UHF channel as well with tropo, that's not the case with E-skip, it is, again, for all intents and purposes, "TV band wise", limited to lo-VHF "disruption" ...

I don't have time to look it up currently, but As I recall, in whatever FCC proceeding, NPRM, R&O or MO&O was involved regarding "discussion" and comments from interested parties on the issue of whether or not they were going to add 2-6 into the core channels for DTV (which they did of course) : I believe the comments submitted from Fox (not foxeng) on that issue were quite adament that they felt "e-skip" was one of the BIG reasons they did NOT favor the use of ch 2-6 for DTV .....

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As for Lo-VHF DTV :

To be clear regarding my opinon of it --- First, I must say I think I probably look at it as a much "finer line" than most broadcast engineers I've talked to about it, and most here seem to regarding whether or not the disadvantages outweigh the advantages. And in fact, unlike many here it seems, I was on the "other side" of that fine line until fairly recently ...

The deciding factor for me at this point is that I suspect, even if stations were allowed to run the highest amount of power they could reasonably implement given the size+tower loading requirements of "high power" lo-VHF transmit antennas .... and, even in the *best* of circumstances, such as say, rural viewers using outdoor directional antennas suitable for lo-VHF reception and at a "suitable height" :

Unless something could be done about it to improve the situation in a desireable "enough" fashion(such as without reducing data payload rate significantly/etc -which at least at this point I doubt) --- I expect "impulse noise" spikes from lightning to be strong enough "spikes" and frequent, and disruptive enough even in strong signal areas and under the best of circumstances that it should be a no-go for DTV -- because of the severity of this problem on lo-VHF, and because of the very nature of how DTV "works" vs. analog ...

Analog channel 50/digital channel 51 in Chicago has the same problem just not as bad.

Let's see if I can do this without getting too technical on the "hows" of this.

Both the analog and digital signals are AM or Amplitude Modulation. The same AM as on your AM radio. AM has a carrier and within this carrier are 2 independent sidebands, one above center carrier and one below center carrier, called Double Sideband when they contain the same information as with television signals.

In analog, the lower sideband is filtered out before transmission and the carrier is reduced producing a signal that looks like this with f(MHz) being center frequency and the lower band edge being f-1.25 MHz below f(MHz) and the upper being f+4.75 giving the full 6 MHz bandwidth for both visual and aural carriers:



Digital also uses a 6 MHz wide signal but uses the lower sideband and filters out the upper sideband and it looks something like this:



where the pilot carrier (the peak on the left side of the signal) is .31 MHz from the lower edge of the signal and the center carrier is shifted to the upper side of the signal. Since this is a "square wave" you do not see the actual carrier sitting higher up the spectrum as you see the visual carrier in the analog signal. Everything is referenced off the pilot signal in digital unlike analog where the visual carrier is the reference. The digital signal has more "average band power" than analog (you can plainly see that between the two pictures) and therefore doesn't require the same levels to maintain the same coverage. The peak power for analog and the average power for digital. That is where it comes from. That is how you can have 15 kW digital equal 300 kW analog. It takes the same size transmitter to produce either signal, depending on which mode you use. A 30 kw analog transmitter (used for 300 kW) is the same EXACT transmitter used to produce a 4 kW digital signal that produces that 15 kw digital. The only difference is the modulation scheme used. The rest of the box is EXACT. To put it another way, a 30 kW analog transmitter can only produce 4 kW of digital power because the demand on it is 5 times greater than analog and looking at the pictures of the different spectrum, I think you can plainly see the duty cycle difference of the modes.





One station is on my channel to the south of us and they are definitely NOT on a mountain (VERY flat land where they are). They were shoe horned in between us and an analog channel 9 so they are directional to stay out of a both us on channel 8 and the channel 9 that is halfway between them and us and they get very reliable service in their market. It is so good, they decided to NOT go back to their analog UHF channel, which was a viable choice for them. The other station I personally know about is an O & O on channel 12 in Tampa (and no mountains there! ) that does pretty well from what we hear (I haven't been there to check it out for myself) and we all talk a lot between ourselves frequently.

Sorry, yep ... Then of course, as your calculatiing shows, you're pretty much getting the "full" 16KW ERP Meaning, 15,054 watts being only a small Fraction of a db less than 16KW ....


Nope.


Yep. Here's another "easier" way you can do it -- FCC provides an online calulator for this here. You'll notice it produces the same result as the equation I detailed :

http://www.fcc.gov/mb/audio/bickel/f...#RELATIVEFIELD



It would matter a lot more if the relative field value was lower, say .500 .....

.500x16,ooo watts = 8000 watts (wrong)

(.500x.500) x 16,000 watts = 4000 watts (correct)

Each 1/2 'ing of power is -3db, or 50% reduction in power from what you started with(in this case relative field value of 1.000 or 16KW ERP) . Db "scale" is logarythmic, however, so within the coverage area(other than on the "fringes"), 3db is only a small piece of the entire "pie" ....

When you consider that you can easily have 20db "extra"(can be less than that, though, but also can be more - I think -20db is a good conservative rule of thumb to use to estimate attenuation of having antenna indoors) attenuation added by having the antenna UNDER the roof(indoors) rather than above the roof, -3db doesn't really seem all that signficant, does it?



short non-technical answer -- Because of what the relative field values are and how they "work" ....

Follows is explanation as detailed in OET bullitin #69 - Note, that's in PDF format --- sorry, that bullitin in its entirety isn't really "specific" to this discussion(although you might find some if it interesting), but it was the best thing I found with the specific info we want via a quick search ....



That seems like a LOT of hinderance !

BTW, I'm not sure I understand from your post where the cable leakage is coming from, but hopefully you or your cableco can do something about that while your waiting for analog shut off ....

Update, oh ... I also don't know what you mean by "noise" coming from direction of chicago ... I don't know, but I expect the source of it is probably a lot closer than that ... I know if I stick antenna in attic here, it picks up all sorts of "electrical noise" and RFI on VHF(VHF lo especially) off my home's electrical wiring and various household applicances, as well as some "sparkly stuff" off a nearby ethernet switch+cat 5 cable sitting in the attic ....

with antenna Outdoors, the situation regarding this is much, much better, although on one weaker, distant channel 3 analog , with antenna aimed right at utility lines+a transformer/service "drop" to a neighbors house, I get a bit of "power line noise" issue .....