Doug Lung /
07.22.2011 10:25 AM
FCC Sets Deadline for LPTV DTV Transition

The FCC has set a hard deadline of September 1, 2015 for the shutdown of all analog low power television facilities, although the Second Report and Order (FCC 11-110) does include rules allowing last minute extensions for stations needing additional time to complete the move to digital. Analog and digital LPTV stations operating above channel 51 must submit displacement applications by September and cease operations above 698 MHz by December 31, 2011.

Finding a new channel for DTV may be difficult, since in the most densely populated areas most UHF channels are already occupied by full service TV stations, other LPTV stations or land-mobile services. Analog LPTV stations that don't have a construction permit (CP) for DTV facilities may find it difficult to transition to digital on their existing channel due to the digital signal's larger desired-to-undesired (D/U) ratio for co-channel interference to an existing DTV station. Co-channel DTV to DTV interference protection requires a D/U of 15 dB compared to only 2 dB for analog to DTV interference where the DTV signal to noise ratio (SNR) is 25 dB or higher, although the D/U for analog LPTV increases to 25 dB where the SNR of the protected DTV signal is only 16 dB.

For some LPTV stations, the only available channel for DTV may be on VHF. At the current maximum ERP of 300 watts, it is very difficult for VHF LPTV stations to provide a reliable signal to indoor antennas. In the Second Report and Order, the FCC increases the ERP for VHF LPTV to 3,000 watts, the same ERP allowed for VHF analog LPTV. This should be good news for LPTV equipment makers as well, since current analog VHF LPTV stations transitioning to DTV on-channel will need to buy a new transmitter or at least additional amplifiers to match their analog peak power ERP.

To make it easier for LPTV stations to find a DTV channel, the FCC modified its minor change rule so that it covers a proposed transmitter site move of up to 30 miles (48 km). LPTV stations will also be able to use the emission mask used by full power TV stations. These two changes should help mitigate the problem of adjacent channel interference to other stations, either by moving to the same transmitter site as the adjacent channel station or using the full service mask to allow reduced D/U ratios. While researching on-channel DTV repeaters at NAB this year I found multiple filter manufacturers making reasonably priced low power DTV filters capable of meeting the FCC full service mask.

To accurately predict interference, actual vertical (elevation) antenna patterns must be used. The Second Report and Order allows LPTV applicants to use actual vertical (elevation) antenna patterns for calculating LPTV coverage and interference. This will benefit stations that employ a large amount of electrical and/or mechanical beam tilt at sites with a large height above average terrain (HAAT). Existing LPTV stations will be able to submit actual vertical patterns for their existing, allowing more accurate interference studies and, depending on the pattern, potentially greater interference protection. This assumes, of course, that the interference study uses the correct depression angle. The default FCC OET-69 software does not although it is now available as an option.

LPTV stations that delay filing applications for DTV or a DTV displacement channel may find few options as the September 1 deadline approaches. The FCC is also likely to freeze TV application filings, at least in major markets before it begins the proposed TV spectrum repacking.

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Posted by: Anonymous
Sat, 05-26-2012 04:47 PM Report Comment
I'm a first timer at getting OTA HDTV. This has been an einerxmept in progress for the past 5 weeks. I have gone through four antennas (they are all here as I write this) before finding something that's satisfactory (rather than tolerable). I live around 25 miles from Manhattan, where the towers of most TV stations are located. I am also aware of the directional information from [. . . ], and have einerxmepted accordingly with its effects on reception. My apartment's windows all face north, while the signals all comes from southwest. I cannot get signals from where it comes from, and thus needed to get signals from deflections perhaps off nearby buildings and trees. It's a very poor circumstance for over-the-air reception, maybe just slightly better than being underground. Signals are weak, and are affected by weather. Stormy and windy days have shown effects at disrupting signal reception. With this said, and without going into much detail, let's talk about the antennas. Now all these antenna have been tested with the same equipment, setup, directional adjustments, location, etc. etc. and have been tested through good an foul weather, day and night, to observe differences. 1. Terk HDTVa Terk HDTVa Indoor Amplified High-Definition Antenna for Off-Air HDTV Reception- After reading some rave reviews and high ratings at [. . . ], log periodic types (looks like a fishbone) seems to be the way to go. I got the Terk HDTVa first, thinking that the amplification and VHF antenna should nail my reception problems at the start. However, after more than two weeks of fidgeting around ad nauseam (directions, locations, amplifications, different devices, etc. ), I only managed to pick up two ATSC channels' signals, and even those don't have strong enough signals to display anything. I thought maybe it's just my poor location, and that I should probably give up on the attempt. The included in-line amplifier dongle doesn't work at all. Powering it on makes no difference in signal strength readings, which hovered around 5-10%. It is well built, looks nice, good concepts, but it just didn't work. 2. Phlips PHDTV1 Philips PHDTV1 Digital HDTV-UHF Indoor Antenna- The venerated silver sensor which was previously sold under the Zenith brand also had great ratings and reviews. It's in fact nearly legendary. I decided, in desperation, to try it out, even if it doesn't have amplification. It seems all my local HD channels are in UHF anyway, so I won't miss the VHF dipoles. The unit has startlingly poorer build quality compared to the Terk. It has paint bubbles, hairs and dusts trappings in the paint, sharp edged cheap plastics and much thinner metal blades that's covered in oil and has some dings and bendings. I wasn't impressed with the quality, and didn't expect much from it as I set it up. To my surprise, it picked up 9 working channels (note: the terk got two channels' signals, but they didn't work) from the start, even if it's randomly placed. It's thrilling as it was the first time I saw OTA HDTV. After some adjustment and location einerxmepts, I was able to receive 19 channels. However, not all of these channels work well given the same direction. The directionally sensitive antenna needs to be adjusted as I switch channels. e. g. NBC and CBS seems to work well in one direction, while ABC has its own favorite direction, which works also with FOX. I tried as best as possible to find a compromise point where everything works. I couldn't. It just needs to be adjusted constantly. The transmission is often dogged by reception fluctuations. Signal quality tend to fluctuate quite a bit, especially affected by weather. That means the TV playback would get choppy at times, with its severity dependent on the direction I point the antenna at. I didn't think fluctuating signals was a characteristic until I tried the latter two antennas later. I also found that I had to constantly play with the directional positioning to get a stable signal from each of the stations. It works, and I was impressed, but then in retrospect it could only be best described as a tolerable HDTV experience as I struggled for a smooth signal delivery. 3. RCA ANT111 Basic Indoor Antenna- While shopping in stores, I saw this basic and classic RCA loop/dipole antenna for less than $[. . . ]. I couldn't resist the temptation to try it out, just for the heck of it. It is also a different type of antenna than the previous two. Again, I was surprised. This cheap antenna worked well, especially considering how it's only a fraction of the price of the two I'd tried. I ended up getting 17 channels, a few less than the PHDTV1, with the same location and setup. Some channels also don't work, even if signals were detected. The quality of the signals seems to be the key. So what's so special about it? It strangely had better signal delivery for the channels that worked. It's not as choppy, and quality level is very steady. It is also not as affected by directional positioning. I was for the first time able to view FOX, ABC, CBS, NBC without adjusting the antenna. However, the lack of directionality also makes it ambiguous when I lost the signal. It seems that there's no favorite direction for the channels, which also means I can't pull in stronger signals at my choosing. It is also quite susceptible to weather changes, particularly wind (which probably affected signals reflected by trees?)The signal strength also seems to be a little weaker, though the signal quality tend to be higher in general. That probably contributed to the smoother video delivery. It also tempted me to get a similar design that has amplification. 4. Philips MANT510 Philips High Performance Amplified Indoor Uhf/ Vhf/ Fm Antenna- This unit has a digital TV optimized, patent pending UHF panel array . I thought I'd try it out just for the slightly different antenna design, if not just for the adjustable amplification. Well, it works, and works quite well. The antenna doesn't work without power, and with amplification turned off it works a little less than unpowered PHDTV1 and ANT111. Yet with the amplification turned on, I get 24 channels, with strength up to 81% (compared to 3-10% unamplified, and quality consistently above 60 and usually in the 70-90%+. That generates the most reliable video delivery of all the ones tried. While thunderstorms still managed to distrupt signals, it's much less often and only momentarily. I also don't have to worry about hunting for signals as I just point it in one general direction and I get everything but three NJN channels (they are even further from here. . maybe a good 50 miles). I finally can just set the antenna and forget it. It lets me focus on the programming rather than antenna adjustment. While it needs to be powered, it gives me the confidence to finally enjoy HDTV, rather than tweaking and tolerating it. It's good enough that I can probably stop searching. I hope it'll be helpful to you who may be going through the same purchasing decision nausea as I have.

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