HD Broadcast Deadline

[Bradtothebone]

Ok, I got my info, but what is considered low power? Is there a chart showing what wattage output corresponds to distance of reception? I realize factors such as terrain and will affect things.

Just keep in mind that most stations are going to be licensed at a "full-power level" that will approximately match the coverage of their analog signal. This "effective radiated power" number, or ERP, will vary all over the map depending on broadcast frequency, terrain, tower height, and probably some other reasons. A VHF station (channel 13 and below) will probably be 100 kW ERP or somewhat less at full power. A UHF station (most digitals are UHF) will probably be in the 500-1000 kW range at full power. YMMV, of course.

Brad

 

[SatinKzo]

Yeah, I realize that, but my CBS affiliate is 100kw analog and 6.9kw digital. But it's broadcasting in the VHF range, (Channel 3 analog and channel 2 digital). I get the analog just fine, but cannot get a steady lock on digital. I emailed them and inquired on their plans for full power. I am in the 38th DMA so at most only another month of no digital (well, hopefully!). The NBC affiliate near me is only 30kw digital right now, but they transmit from the same basic area (about 2 miles between the transmitters) as CBS and I get them just fine.

3 of my dtv channels are in the vhf range, making tuning in a bit more challenging and antenna placement is more particular for me for those compared to the 3 uhf signals that I can get with rabbit ears.

 

[Bradtothebone]

Yeah, I realize that, but my CBS affiliate is 100kw analog and 6.9kw digital. But it's broadcasting in the VHF range, (Channel 3 analog and channel 2 digital). I get the analog just fine, but cannot get a steady lock on digital. I emailed them and inquired on their plans for full power. I am in the 38th DMA so at most only another month of no digital (well, hopefully!). The NBC affiliate near me is only 30kw digital right now, but they transmit from the same basic area (about 2 miles between the transmitters) as CBS and I get them just fine.

3 of my dtv channels are in the vhf range, making tuning in a bit more challenging and antenna placement is more particular for me for those compared to the 3 uhf signals that I can get with rabbit ears.

OK, I went and looked at the FCC database for your "big four" networks. Here is what I found:

WWMT (CBS) Licensed at full power (6.9 kW) Service Map
WOOD (NBC) Licensed at full power (30 kW) Service Map
WZZM (ABC) Currently at 500 kW, will be 1000 kW Service Map
WXMI (FOX) Licensed at full power (725 kW) Service Map

If you're within the "circles" on the maps, you should, in theory get a signal. It doesn't always work that way, however, as you are well aware.

It appears (at least for now) that WWMT (channel 2) and WOOD (channel 7) have elected to stay on those VHF channels post-transition. They still could change in the third round of channel elections (2006?), but for now it looks like you have what you have with both of them. Hope this helps.

Brad

 

[SatinKzo]

You have it slightly wrong as we have 2 ABC's. WOTV is my ABC ( actually I think that is their tagline) WZZM is the other affiliate. WOTV has a much better picture where I am at being that they are based out of the Battle Creek area. They have the strongest signal by far (they are also owned by the same compnay that owns WOOD). The upn affiliate also is a member of that company so I get the DTV feed of UPN from two sources, but no HD UPN shows.

You showed me nothing I haven't already looked at, but I appreciate the effort. I actually got a response from WWMT saying they plan on full power by the deadline. So, basically that is all I wanted to hear. They said that they plan to stay on channel 2 indefinately. Either way I will finally have my CBS OTA HD and that will be all of them

 

[KKlare]

A VHF station (channel 13 and below) will probably be 100 kW ERP or somewhat less at full power. A UHF station (most digitals are UHF) will probably be in the 500-1000 kW range at full power.

I think the correct numbers dating back to the late 1950's are:
low VHF 2-6 54-88 MHz 100 kW (there is a small gap between 4 and 5)
high VHF 7-13 176-218 MHz 316 kW
UHF 14-up 430 and up MHz 1000 kW (numbers from memory FWIW)
(Upper UHF bound was 83, and is 69 now, waiting for all 70+ UHF to relocate to allow cell phones in the 700 MHz range.)

 

[SatinKzo]

well, I know UHF are going higher than 1000ikW now, but I don't know when that number was changed. There are UHF stations in my area (according to fcc page) at 5000kW.

 

[Bradtothebone]

I think the correct numbers dating back to the late 1950's are:
low VHF 2-6 54-88 MHz 100 kW (there is a small gap between 4 and 5)
high VHF 7-13 176-218 MHz 316 kW
UHF 14-up 430 and up MHz 1000 kW (numbers from memory FWIW)
(Upper UHF bound was 83, and is 69 now, waiting for all 70+ UHF to relocate to allow cell phones in the 700 MHz range.)

Your numbers (from the 50's) are correct for analog TV, except I think the maximum for UHF was increased to 5000 kW at some point. Digital requires less power for the same coverage, and the number I originally cited for VHF (</= 100 kW) was for high VHF. Sorry, I should have clarified that.

Brad

 

[Guderian]

Trasnmit power not going to change

I just checked and WFAA here in the DFW area is only broadcasting their DT channel at 18.6kW, while their analog channel is broadcasting at 316kW. Im assuming that 18.6kW isnt considered "full power", so hopefully the dropouts will stop soon.

I got this response today after contacting WFAA in Dallas about increasing the power to the digital channel.

Well, the simple answer is - Never. We are transmitting at our full licensed power as determined by the FCC. A lot of factors come into play in determining licensed power, but I will attempt to explain.

We transmit DTV on VHF channel 9 and all the other Dallas stations are on UHF channels (14-52). The laws of physics come into play here. VHF signals, because of frequency, travel farther than UHF signals. When we went on the air with the DTV channel back in 1998, we commissioned a study to see how well we replicated the current coverage area of WFAA Channel 8 and we discovered that we no only replicated it, we actually exceeded it a few miles.

The intermittent problems you are experiencing is because of local interference. The laws of physics come into play here, too. Also because of the frequencies involved, VHF signals are more prone to local electrostatic interference (car ignitions, power lines, etc) and inpulse noise (lightning, noisy switches, etc). Every time my dishwasher at home cycles, I get a glitch in WFAA-DT. I get the same thing whenever I turn on my ceiling fan or change it's speed. The only channels that get worse problems with electrostatic interference are VHF channels 2-6. They really get it bad because of the frequencies involved.

There are a few things you can do to improve your signal on Channel 9. First, make sure that the antenna you are using is a multiband antenna and that it is aimed properly. A lot of electronics stores try to sell customers an "HDTV Ready antenna." But because most of the DTV's in the Dallas market transmit on UHF channels, they think we all do and then sell customers a UHF-only antenna and that will not work on channel 9. Second, if you have an amplifier in line driving splitters and such, make sure it is a good one. Some of them pick up that local interference and amplify it, too. That just makes it worse. If you live in an area with lots of industry nearby, that can cause a lot of interference, too.

I hope this helps.

Don Guemmer
Chief Operator
WFAA-TV
dguemmer@wfaa.com

 

[StevenD]

Well, thats just crap! Good thing I dont watch WFAA very often.

 

[SatelliteGAL]

When I get my new antenna system I hope to get HD in Buffalo for CBS and UPN.

Well, I hope Buffalo CBS improves or you will be sorely disappointed. UPN is at such low power at the moment that I cant get it yet.

 

[Barry Erick]

Ok, I got my info, but what is considered low power? Is there a chart showing what wattage output corresponds to distance of reception? I realize factors such as terrain and will affect things.

There is NO chart showing power vrs coverage. VHF channels take less power by far than UHF. Equivalent coverage... For instance. Our main analog NBC affilate is 3.8 megawatts (Million) and for the same coverage, our VHF digital will be 30 kilowatts (Thousand). Right now we are low power at 2.7kw and cover the grade b area of our analog coverage.

Also, for VHF, power goes up for each channel for the same coverage.

There are other factors: Antennas. Most low power are using toss away antennas that are side mounted at a low spot on a tower. Our local Fox is one. They are side mounted 200 feet on a 900 foot tower. When full power, they will be side mounted at the top of a tower. Our low power antennas are at 500 feet on a 900 foot tower and will be wrapped around at the top in a month when we go high power.


BTW: At work we have a VHF only antenna for DTV monitoring. We can't pick up the full power UHF TV except for one and are 3 miles from the towers with a clear view. The antenna definately matters.

At home, blocked by trees and a mountain, I am 15 miles from the antennas and with my VHF/UHF antenna I get all VHF and UHF stations, less one, the fox which is at very low power and very low on the tower right now and is mostly just legally on and nothing else. It is not possible to get a viewable analog picture here, but digital is perfect, with ALL I get at least showing a 78 on my 811.

 

[SatinKzo]

Barry, I appreciate your information, but there must be a formula somewhere that can be used to estimate approximate coverage per wattage output at each broadcast frequency, otherwise we would not be able to produce some of the coverage maps that I see. I mean each frequency is going to have its own characateristics.

There is NO chart showing power vrs coverage. VHF channels take less power by far than UHF. Equivalent coverage... For instance. Our main analog NBC affilate is 3.8 megawatts (Million) and for the same coverage, our VHF digital will be 30 kilowatts (Thousand). Right now we are low power at 2.7kw and cover the grade b area of our analog coverage.

How do you know you cover grade b? Did you do a survey? How did they arrive at the number 2.7kW will cover the grade b area?


For example, where I work we deal with large volumes of paper. Paper is mostly water even when "dry" so it absorbs pretty much everything over 900mhz and 13.56 mhz will penetrate water easily, but only short range, even with a 10 watt transmitter. However for wireless networking and our internal cell paging system, we use 900-7.65 ghz. One set of frequencies for info and data another for handling the backhaul between them all that will not interfere with the data portions. For our site though it is only 27 acres and a site survey was possible.
I can't believe they did site surveys for every single tower in the US. They must have come up with some formula somewhere that I just cannot seem to find. THe closest stuff I can find is pretty much like this:
http://www.broadcastpapers.com/tvtran/BBCDTTCoverage%20-%20print.htm

Please don't take any of this as being angry or antagonistic. I am simply looking for some info that must exist somewhere and am just curious if any has any info to help me find it.

 

[R-U-Q-R-U]

May I add the Zenith Silver sensor, although it looks like a toy, is a rocking Digital antenna !

I'll second that

 

[Barry Erick]

Barry, I appreciate your information, but there must be a formula somewhere that can be used to estimate approximate coverage per wattage output at each broadcast frequency, otherwise we would not be able to produce some of the coverage maps that I see. I mean each frequency is going to have its own characateristics.

How do you know you cover grade b? Did you do a survey? How did they arrive at the number 2.7kW will cover the grade b area?


For example, where I work we deal with large volumes of paper. Paper is mostly water even when "dry" so it absorbs pretty much everything over 900mhz and 13.56 mhz will penetrate water easily, but only short range, even with a 10 watt transmitter. However for wireless networking and our internal cell paging system, we use 900-7.65 ghz. One set of frequencies for info and data another for handling the backhaul between them all that will not interfere with the data portions. For our site though it is only 27 acres and a site survey was possible.
I can't believe they did site surveys for every single tower in the US. They must have come up with some formula somewhere that I just cannot seem to find. THe closest stuff I can find is pretty much like this:
http://www.broadcastpapers.com/tvtran/BBCDTTCoverage%20-%20print.htm

Please don't take any of this as being angry or antagonistic. I am simply looking for some info that must exist somewhere and am just curious if any has any info to help me find it.

There is a formula, but nothing you can put in there without alot of tech knowledge. It is the Longley-Rice predicted chart. It is what each station had to use to match the same thing the FCC used in laying out the channels over several years.

 

[Barry Erick]

Also, we did NOT arrive at 2.7 ke covering the area. For startup, the FCC only requires you cover the city of license. We did that, and measurements after that showed the coverage.

For full power, the Langley-Rice scale was used, and the top stations have to be full power by July 1, this year, or risk loosing the coverage.

 

[Barry Erick]

I'll second that

And I'll vote with a raised hand on that!

 

[SatinKzo]

That is exactly what I was looking for thanks, I used the formula and it is telling me that only 3 more kW and I should have the coverage I need from my CBS affiliate. Which shoud be a moot point come deadline day as they said they will be increasing well more than 3kW. Of course a upgraded anteanna would help with db loss, but from what I am seeing and hearing, I am good to go as I get all the rest just fine, just needed some info for the CBS problem.

I found a couple sites with apps to use that formula. They even mapped a satellite image of my area with terrain effects somewhat taken into account.
I am so close to locking the signal, I figure i didn't need much and during the right conditions, I can lock, but not aquire PSIP info.
Reminds me of the days in my parents house where on a overcast night, we could pick up CBC OTA, but not on sunny days.
All I needed was some info on where to look. Much easier when you have the name.

 

[James Long]

In most cases, "full authorized power" is supposed to replicate the analog coverage area for the station, or be very close to it.

The initial power levels granted for most stations wasn't enough to match the coverage their analog stations. There were a lot of amendments made to both power levels and channel placement by stations that could afford the engineering studies and fees.

"Full authorized power" is a moving target.

JL

 

[Barry Erick]

The initial power levels granted for most stations wasn't enough to match the coverage their analog stations. There were a lot of amendments made to both power levels and channel placement by stations that could afford the engineering studies and fees.

"Full authorized power" is a moving target.

JL

Yes, but most stations did not even go to the initial granted power level.. just enough to make them legal. Our current max granted, for instance, is way more than the initial granted max level and most of the gain will be with the antenna and not actual transmitter power, so it is an initial investment and not an operating expense.

 

[James Long]

ERP is a balance of the gains and losses involved in the transmission system. One can lower the transmitter power output by having a higher gain antenna or lower loss feedline. There are some physical limits to deal with, but it is an equation. Make the antenna too heavy and one has to replace the tower (or kick off all the renters if the existing tower cannot handle the weight). All part of the math.

JL