Low band TV spectrum
This is a discussion on Low band TV spectrum within the DTV | HDTV Chat forums, part of the Over-the-Air (Antenna TV) category.
Low band TV spectrum
Since channels 2-6 due to propagation characteristics and higher noise levels are mostly unsuitable for DTV transmission, what's going to happen to them?
Is the gov't basically going to push more TV stations down there when it wants more UHF spectrum for broadband, or can it be used for broadband using advanced modulation techniques like S-CDMA?
(I started a new thread because the other one is mostly trashed.)
Well if the FCC takes away Ch 31 -51 some stations won't have any choice but to go to low-VHF. Now I will say my best station I receive out of Nashville is on Ch 5. My next 2 are on VHF 8 and 10. It's the UHF ones I have issues with. So for people like me out on the fringes VHF seems to be better. I can see Ch 5 and 6 being converted for FM radio. The FCC can probably earn more money from licensing those frequencies out for radio than they get form the 2 dozen or so TV stations that currently use it. And we all know the FCC is about the money.
This brings up another thought: how many stations that had plans to remove their top-mounted low-band antennas and replace them with UHF antennas are now 'hedging their bets' and are now waiting to see what the FCC decides? My local CBS and ABC stations have replaced their antennas, but the NBC affilliate (originally channel 5) has not, although they have had a construction permit to do so for many months.
Makes me wonder what WBBM-TV plans to do with their antennas for channels 2 & 3. They spent big bucks to add their digital antenna as well as replace the analog antenna on the John Hancock. Since most people complained that they couldn't receive WBBM-TV on RF 2 or 3 (more complaints with 3 than 2 since 2 was analog), they instead worked out a deal to acquire WTTW's old analog antenna to use for RF 12 on the Sears Tower. As it stands, both antennas on the John Hancock are sitting idle. Unless W25DW plans to use the old channel 2 antenna on the John Hancock, will CBS just leave the antennas there?
My local WHBF rf4 is apparently stuck with rf4 because of co-channel interference. Until they recently bumped up their power, people had trouble locking in from 28 miles away. In the metro area, WHBF simulcasts on RF47 at low power. I erected a roof antenna, but apartment dwellers & house renters do not have that option. Strange that before last year everyone could lock in rf 58 with YouTube antennas made from coat hangers.
Good point. However in the NYC market it may be a little too late as low power broadcasters are pretty much gobbling up the low band channels. I am not sure but I think the low VHF antennas from the ESB are going (or gone) already? I have to take a look and see.
Originally Posted by Jim In Seattle
ABC's WPVI 6 is one of them who has been pushed into the low band "ghetto" by the FCC. The upside is that channel 6 propagates well and even with the high VHF antenna pointed to philly I can get them. One day I will get around to putting an actual low band yagi towards WPVI.
One advantage of digital is that if the transmitters are co-located, you can run adjacent channels in some cases without interference to each other as long as each transmitters signal is kept tight and clean to FCC specs within its 6mHz channel . That will give some markets the ability to pack channels side by side if they even leave enough spectrum to do that as they say, and that was not easily done with analog, especially with channel 6 VHF. One of our transmitters is on 17, and a competitor just 300 yards up the road is on 18, and there have been no issues to date with interference with each others signals.
Originally Posted by n2rj
Our local PBS station is on channel 3 of all things (The worst digital assignment possible besides channel 2), and their signal is basically un-receivable during thunderstorms, when a car pass by my house with leaking spark plug wires, or when my AC unit fires up, or when a blender is turned on in the kitchen, or when my neighbor starts his lawn mower and on and on...and most all of the VHF channels will suffer the same fate with the low VHF's being the worst.
They are not digital friendly, and the FCC should have never allowed their usage for digital TV broadcasting. A lot of broadcasters shot themselves in the foot by choosing to go back to VHF, but a lot of testing was not performed at VHF frequencies, as the original plan was for all DTV to be broadcast all in the UHF band.
Originally Posted by FOX TV
Chicago is one market where they have RF 43, 44, & 45 & 50 & 51 all co-located on top of the Sears Tower. So far, no interference. WYIN in Indiana (licensed to Gary with their tower outside of Cedar Lake Indiana) on the otherhand has problems in certain parts of Gary. WHNW-LP on 18 is still transmitting an analog signal out of Downtown Gary, & it interferes with WYIN's signal from time to time. After I e-mailed WYIN about my problem, I learned I'm not the only onw who has problems with their signal. Even if WHNW-LP goes digital, their transmitter will still be approximately 20 miles north of WYIN's transmitter, and could still interfere with their signal.
During pre-transition digital, I was one of a few who had no trouble with getting WBBM-TV on RF 3. They were one of a few who did test digital on the VHF. WWMT Kalamazoo was another one who tested their digital on RF 2. I heard that the main reason there was heavy digital testing on UHF was because there were plenty of channels to test. VHF was well packed that it made it difficult to find channels to test for digital. New York was an all UHF pre-transitional market. Grand Rapids/Kalamazoo, Chicago, & Milwaukee were 3 markets I know of that did test their digital on the VHF. Milwaukee's WMVS tested on RF 8 and stayed on 8. Chicago's WBBM-TV tested on RF 3, but moved to 12, while WLS-TV didn't request another channel before June 12th, 2009, that they had to go back to 7 with little testing. Grand Rapids/Kalamazoo had WOOD-TV on RF 7 & stayed on 7, WWMT testing on RF 2, but went to RF 8 after WOOD-TV shutoff analog 8, WGVU tested on RF 11 & stayed on 11, WGVK (simulcast of WGVU) tested on RF 5 and stayed on 5 (and they increased their coverage too with that channel vs. their analog channel 52, which was out of core), & WZZM had the choice to stay on RF 39, but they chose to go back to 13.
So for the few markets where stations did test their digital on the VHF, I wonder how many used their existing VHF/UHF combo (or separate VHF & UHF antennas) to get their VHF stations. I used an antenna that I used for analog for digital, and was fortunate to get WBBM-TV on RF 3 with no problem. VHF now is so tight in & around Chicago that it would be difficult to get more VHF channels in Chicago. While W25DO has a CP to operate on RF 2, a station wanting full power operations could knock them off that channel at a later date. 3 is available as well. 4 is no longer available as 4 is a Class A digital, and protected. 5 is no longer available since WGVK Kalamazoo crosses over the lake, and if WWAZ ever gets their channel 5 on the air, that station, which is a Green Bay market station, will cover the Milwaukee market with their signal, along with the northern suburbs of Chicago. 6 might still be available, though it's currently being used by WLFM-LP as an FM station. 7 will still be available, but would stay at the current 4.75kw. 8 & 9 aren't available as 8 is being used in Grand Rapids/Kalamazoo & Milwaukee, & 9 would interfere with WWTO LaSalle (8 & 9 might only be available as low power stations). 11 is used by WGVU in Grand Rapids & by WLFI Lafayette Indiana, plus would interfere with WWTO (again, might be available as low power only). WBBM-TV is using 12. 13 was originally used by WOCK-CA, but they dropped this channel due to their sharp nulls toward Michigan & Rockford Illinois. Since they had to continue protecting WREX Rockford & WZZM Grand Rapids, 13 is not available for full power use, and is unattractive for low power use, due the sharp nulls. WOCK-CA used to not cover the west side of Chicago & portions of the south side too. As WOCK-CD, the coverage would have stayed the same if they remained on 13.
Co-locaton of transmitters only works if they are located at the same "Antenna Farm' as your example points out. There are some channel pairs that won't work due to harmonics, but this is a slight advantage if they actually re-pack channels to make room for the spectrum theft that is now being attempted by the broadband industry.
Originally Posted by dave73
There are other methods used such as the Distributed Transmission method where multiple low power transmitters on the same channel are used, but this technique has not been used in many markets as of now, and that method requires additional steps to protect the individual transmitters from interference from the others in the network.
This approach was not even possible in the days of analog, and some are predicting that this method may become popular if the spectrum is actually stolen away from the Full Power stations who currently use single High Power transmitters to cover their DMA.
We have a number of them using adjacent channels here, however not all are co-located. For example, WNJJ-LD is about 40 miles away from the ESB, they are on 41 whereas channel 40 is WXTV. WFME is on 29, WNBC is on 28, WTBY is on 27. They are all well packed here. I have to wonder how the FCC is going to reclaim anything. There is pretty much nothing to reclaim here.
Originally Posted by FOX TV
As for the VHF channels, mine tend to give trouble when there is lightning in the area.
In Chicago, the only reason most stations are located on the Sears Tower is because of height. The following stations that I know of are on the Sears Tower. All are digital except noted:
Originally Posted by FOX TV
WLS-TV on 7 (LP digital) & 44 (main channel)
WBBM-TV - 12 (also has a CP for a translator on 26, but hasn't been built yet)
WGN-TV - 19
WWME-CA - 23 (Analog)
WCIU - 27
WMAQ - 29
WFLD - 31
WEDE-CA - 34 (Analog) (has CP to flash cut to digital on 34 with same pattern)
WJYS - 36
WWME-LD - 39
WESV-LP - 40 (Analog) (has CP to flash cut to digital on 40 with same pattern)
WCPX - 43
WSNS - 45
WTTW - 47
WMEU-CA - 48 (Analog) (has a CP for LP digital on 32, but hasn't been built yet)
WXFT - 50
WPWR-TV - 51
On the John Hancock, here are the following stations, and only 2 of the stations are full power (WGBO-DT & WYCC), while the rest are low power.
WOCK-CD - 4
WLFM-LP - 6 (analog, & this station operates as an FM station on 87.7. Don't know what'll happen after their license is up for renewal)
WYCC - 21
WGBO-DT - 38
WOCH-CA - 41 (Analog) (has a CP for LP digital 49)
WCHU-LP - 61 (Analog) (has a CP for LP digital 33. They had one for 44, but WLS-TV took it away for full power use. An APP was put in for 7, but WLS-TV hasn't given up the license, and the owner of this station wants to get it running on digital since 61 is out of core. So they're waiting for 33 to get approved, and get it on the air)
There are 2 translators on the AON Building (formerly Amoco Building):
W25DW - 25 (Analog) (has a CP for LP digital 2, which actually would make better sense to use the abandoned facilities on the John Hancock rather than install new facilities on the AON Building).
W57DN - 57 (Analog) (Has CP for LP digital 30)
Why are people having problems with lighning on the VHF? On analog, I only had problems with lightning only on WBBM-TV 2 & WMAQ 5 in Chicago. WLS-TV 7, WGN-TV 9, & WTTW 11 on analog didn't give me problems when there was lighning. For digital, I didn't have any serious problems with WBBM-TV on 3 (minor and only if it was severe, or lightning didn't affect it for me). I have not once had any problems with lightning affecting WLS-TV on 7 or WBBM-TV on 12.
Originally Posted by n2rj
In Denver KWGN and KCNC are broadcast on channels 34 and 35 respectively, and KRMA and KTVD on 18 and 19 all from Look Out Mountain. I read that in the early days of analog UHF broadcasting a 6 channel separation was needed in UHF to prevent interference.
I could believe that, in the days before PLL synthesis most definitely.
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