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06.19.2009 12:00AM
Fixing VHF DTV Reception Problems
Some VHF DTV stations have had significant problems with the DTV transition. Affected markets include Chicago, Philadelphia, and Washington D.C. While many of the news reports focused on ABC affiliates' difficulties in these markets, ABC wasn't the only network affected. NBC affiliate WHDH-TV in Boston had so many problems after moving to DTV Channel 7 that it applied for, and received, authority to move back to its original DTV Channel 42 until matters could be resolved. Fox affiliate WSVN, operating on Channel 7 in Miami, requested special temporary authority to increase power from its authorized 31 kW to 63 kW. CBS affiliate WJZ-TV Channel 13 in Baltimore, requested authority to increase power from 9.8 kW to 27.5 kW.

What is the solution to the VHF DTV reception problem?

Increased power helps. Many of the stations experiencing problems were operating at relatively low power. Circular polarization also helps. In Dallas, reception of WFAA improved after it moved from a pre-transition horizontally polarized antenna on Channel 9 at 18.5 kW to its post-transition Channel 8 with circular polarization at 45 kW.

Having the correct receiving antenna is also important. Most of the VHF DTV problems occurred in markets where there were no VHF DTV stations before June 12. Even rabbit ears are better than a bow-tie at VHF. Electrical interference is an issue. I had no problem receiving all the Los Angeles VHF DTV stations (channels 7, 9, 11, and 13) using a Winegard SS-3000 antenna with its preamplifier indoors, without line of sight to Mount Wilson. KCAL-TV, on Channel 9, took some hits until I moved the antenna to put a light fixture with compact fluorescent bulbs in a null. UHF reception was excellent. I took some photos of spectrum analyzer plots showing the VHF and UHF DTV spectrum before, during and after the DTV transition. Look for them in my next RF Technology column.

KYW NewsRadio reporter John Ostapkovich talked to RF expert Oded Bendov about VHF DTV reception problems. In his article Transmitter Expert Not Surprised by DTV Transition Woes, “The FCC has done very poor engineering and assigned Channel six and other channels in the VHF much lower power than they should have,” Bendov said. “For example, in the case of Channel six, they probably need as much as 15 times more power in the transmitter than they have now."

Bendov said that finding a UHF channel for channel 6 (WPVI-TV in Philadelphia) and “others in this pickle” might be the only solution.

While VHF DTV problems received a lot of attention in the press, I heard of cases where people in terrain-obstructed locations that were unable to receive UHF DTV were able to receive the VHF signals after stations returned to their VHF analog channel. VHF has its advantages—less power consumption, less attenuation from terrain and foliage, and the ability to use solid state transmitters, even at the maximum allowed effective radiated power—but it requires the viewer to use the appropriate indoor antenna or, in some cases, a large outdoor antenna.

Resolving VHF DTV reception problems will require action by stations and consumers. Stations will need to transmit the maximum power allowed and to request additional power if possible. Circular polarization provides a way to improve reception on UHF-only antennas by coupling into feed lines and phasing lines (in a bow-tie array). Consumers will need to use antennas that are large enough to effectively receive VHF signals and, if indoors, locate them to avoid interference from other electronic devices.


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1.
Posted by: Tom Butts
Sat, 07-18-2009 - 6:43PM Report Comment
During the transition period, I got decent reception on at least 20 digital channels on three TVs in my house. Since June 12, there are 3 that I get reliably on all of the TVs (and by "reliably" I don't even mean "flawlessly, 100% of the time"). I receive one VHF channel of the 4 in my market, and have inexplicably lost (either entirely, or severely degraded quality) most of the UHF channels as well. And I live in a major market city.
2.
Posted by: Tom Butts
Fri, 06-19-2009 - 2:17PM Report Comment
So what happens to the rural viewers who will lose the VHF signals if they switch to UHF? This seems like a lose-lose situation for everyone...
3.
Posted by: Tom Butts
Tue, 06-30-2009 - 2:44PM Report Comment
Peter Putman also has an article on this same subject. http://www.hdtvexpert.com/pages_c/TechTalk.html I'm in Poughkeepsie, NY and I actually have a large VHF antenna (25 year old Channel Master Crossfire deep fringe) that I'm sure would reach WRGB in Albany-Schenectady, NY. Unfortunately it is pointing in the wrong direction (at New York City). Why? Because I got more analog channels from NYC. However, after the transition, none of the NYC VHF DTV channels came in, so it would be better to aim it north toward Albany, NY. Poughkeepsie is a lousy location because I'm 70 miles from a major TV market (Albany or NYC). I'd tried to turn the VHF antenna to the north, but the mast is so rusted, it won't turn! Not even a pipe wrench and WD40 could loosen the mast from its eve mounting. Maybe it's time to take down the 25+ year old mast, antennas, and mounting hardware. I feel like taking a hacksaw and cut the mast off and let everything fall to the ground. Timber! It's so much easier to just call the cable company than to fiddle around with this junk on my roof. All my neighbors took down their antennas decades ago.
4.
Posted by: Tom Butts
Tue, 06-23-2009 - 5:01PM Report Comment
There are problems. I can't receive my local CW affiliate, and only sometimes receive my local PBS. Those two are transmitting in the UHF range (RF Channel 43 and RF Channel 34, respectively). However, I have been able to receive my local CBS, local FOX, local ABC, and local NBC affiliate (CBS, FOX, and the local NBC are transmitting in the VHF range--CBS affiliate on RF Channel 6, FOX on RF Channel 7 (Virtual Channel 23.1), and the local NBC on RF Channel 12 (Virtual Channel 13) . My local ABC is transmitting somewhere in the UHF range (RF Channel 26). Oddly I can sometimes receive a distant signal from Utica, NY in the UHF range (RF Channel 29, Virtual Channels 2.1, and 2.2). This contains the Utica, NY NBC affiliate on Virtual Channel 2.1 and the Central New York CW on Virtual Channel 2.2 From what I've read elsewhere, VHF signals are better for mountainous regions than UHF signals. From my experience it seems that UHF signals on RF Channels 30 and above are problematic in my area. Although this might be due to the distance I am from the transmitters.
5.
Posted by: Tom Butts
Sun, 06-21-2009 - 11:02PM Report Comment
I live in a rural area and have lost at least 4 stations. I don't care though as we found there is nothing on local stations worth watching. We haven't watched more than a few hours of local in 6 months. The 6 meg internet connection is much more important.
6.
Posted by: Tom Butts
Sun, 06-21-2009 - 7:08PM Report Comment
Does US DTV mean full employment for China? See: http://notionscapital.wordpress.com/2009/06/21/does-us-dtv-means-full-employment-for-china/
7.
Posted by: Tom Butts
Sun, 06-21-2009 - 1:35PM Report Comment
We need to know real life urban VHF field strength requirements. I was going to guess >75 dBu for our channel 5 situation. On the other hand, I'm getting VERY good reports of rural reception maybe 6 dB beyond the FCC F (50/90) 28 dBu contour. I'd like to know if real world scattering of multiple synchronized transmitters would really work in urban areas. Illuminating buildings from 3 or 4 sides should be a killer indoor antenna penetration technique. But can 8vsb receivers really deal with multiple signals? Interesting tech. question, eh? But its too late. Frustrated viewers that can afford and have access will opt for cable/DTH. And where is the $$$ for SFN?? Too bad. Way too late. Lucky me. I have both U and V signals. Sort of lucky. I guess. Financial constraints limited our station to use of the old analog VHF plant for 8vsb, at least for now, and we get to leave on air, as an LPTV, the UHF signal. 200 calls to our DTV hot line later, I can say having both VHF & UHF seems to be an excellent combo.
8.
Posted by: Tom Butts
Fri, 06-19-2009 - 5:37PM Report Comment
DTV reception is a real problem out near Alpha Centauri. See: http://notionscapital.wordpress.com/2009/06/19/digital-tv-transition-rough-on-space-aliens/
9.
Posted by: Tom Butts
Wed, 10-27-2010 - 10:41AM Report Comment
The VHF channels here pixillate since they went from their temporary UHF homes back to their original VHF allocations - they have way too little power to cut thru and keep a CONSISTANT decent signal. I can receive an NTSC VHF station (ch9) from CANADA with rabbit ears and have perfect audio and so-so video, but it doesn't even waver, yet my HDTV on CH11 pixillates. Low band VHF is a total waste and should be given to the AM/FM broadcasters.
10.
Posted by: Tom Butts
Wed, 10-20-2010 - 5:53PM Report Comment
The real problem with DTV is with the FCC ramming the inferior 8VSB modulation system down our throats. The European DVB-T system, which uses COFDM, works beautifully. We should either switch to COFDM or go back to analog. BTW, I live in mountainous northeastern Pennsylvania and my reception is very erratic.
11.
Posted by: Tom Butts
Wed, 06-01-2011 - 6:55PM Report Comment
Here in central NH we used to get the 3 largets networks from Boston, about 75 Miles south. With DTV we get one channel just 20 Miles south in Manchester. We used to get two networks in Maine, now only one. But we do get Public TV from both NH and VT now, too many public channels and very little objective programming. The antenna is Winegards second larget antenna at about 30 Feet. Looking at TV maps, even if I raise my antenna to 90 Feet, we'd only pick up one more channel- another public TV offering. What can we do?
12.
Posted by: Tom Butts
Sun, 08-01-2010 - 8:33AM Report Comment
I have to agree with the poster above. I live 21 miles from Roanoke Va and have never had consistant reception. Even with 4 or 5 bars, signals will pixilate, out completely, and the sync is not accurate at times.. I see the same with stations in the Greensboro/Winston Salem market. In addition, I use a high gain panel antenna, and all stations have UHF authorizations. It's also amazing how the signal strength can vary from day to day. When it works, the quality is very good, but still the addage applies "garbage in, garbage out". I'd take back analog any day!
13.
Posted by: Tom Butts
Fri, 01-22-2010 - 5:03AM Report Comment
Find television transmitters with these web sites. dtv.gov , tvfool.com
14.
Posted by: Tom Butts
Tue, 10-20-2009 - 9:27AM Report Comment
In Florida, there is a station in West Palm Beach broading on Channel 27 and in Orlando, just 170 miles away also broading on Channel 27. When a weather system comes through, reception is impossible.
15.
Posted by: Tom Butts
Sat, 09-19-2009 - 4:06AM Report Comment
Just because a station calls itself "Fox4", for example, does not mean that it is actually transmitting on channel 4. We in the Dallas/Fort Worth area of Texas have a station that calls itself channel 52 but transmits on channel 9. Only two stations transmit on the channel that they claim that they are on. Thanks to the FCC for "virtual channels" so it is a little harder to determine the problem for the layman.
16.
Posted by: Tom Butts
Fri, 09-18-2009 - 10:21PM Report Comment
IS there anything I can do to or someone I can complain to where it might make a difference? Somtiems I get channels and sometimes I don't . I've bought 3 different antenna's and none of them work great. I live in the city so I wouldn't think that reception would be that bad. I'd get cable except I now think it's a plot to make us pay for cable in order to watch tv.
17.
Posted by: Tom Butts
Thu, 09-17-2009 - 8:03PM Report Comment
Everyone i know in my area cannot get hardly any stations. I used to get 12 now i only get sometimes 3. I have 4 tv's that got all 12 channels and i can only get 1 tv to get sometimes 3 channels. This hog wash about your antenna is just that.The government bragged about how good it would be and knows that half the people in the USA cannot get any channels after the so called big switch. All these people spent money on the converter boxes and new antennas and cannot get any channels. I have herd anything about the government trying so solve this. Not one thing. It is not just a few people but the majority of people who have no TV to watch.
18.
Posted by: Tom Butts
Fri, 09-25-2009 - 10:22AM Report Comment
There are many players in the reception problem scenario that need to share the blame for all of the reception issues that we are now seeing. The FCC, NTIA (National Telecommunications and Information Administration), the CEA (Consumer Electronics Association), as well as the NAB (National Association of Broaders) all need to admit that the DTV transition did not go as well as hoped, and that they all contributed to the confusion that the consumers are now dealing with. Just like every big project they tackle, this one had many blunders that led to all of the issues we are now dealing with. The converter box coupon program was one of the leading promoters of mis-information that has caused lots of the confusion we are now seeing among consumers. The FCC website has always stated that in order to receive broad TV signals reliably, you need a properly selected antenna installed at least 30 feet above the surrounding terrain. Can someone please explain why "Rabbit Ears" were always promoted in the DTV answers commercials that we were deluged with for almost 2 years, even when the reception issues were well known very early in the game? Even those who were not going to use converter boxes were led to believe that "Rabbit Ears" would provide adequate reception, even when all of the DTV testing was done with antennas mounted 30 feet in the air. The main enemies of DTV reception seem to be VHF power levels, improper antenna selection, the belief that indoor antennas work well in every situation, Multi-path or ghosting, and antenna amplifiers that are of poor quality and were designed mainly for analog signal reception. It has damaged the reputation of TV broading in general, when digital TV broading is actually a good concept that works quite well with the proper equipment, but it was promoted incorrectly and it will be quite some time before all of the misconceptions are dispelled.
19.
Posted by: Tom Butts
Mon, 08-03-2009 - 4:19PM Report Comment
HDTV SUCKS,BRING BACK ANALOG!THIS IS JUST A PLOT BY THE CABLE AND SATELITE COMPANIES TO SELL THEIR PRODUCT!
20.
Posted by: Tom Butts
Mon, 08-24-2009 - 9:10PM Report Comment
Question for anybody, including the FCC....please educate me, why are we still using VHF ?? Why isn't all DTV on UHF ???? My experience with VHF both on analog and digital is less than good..heavy interference on analog and just plain hard to get on digital...




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