What kind of antenna or antennas do you need for the best DTV reception?
There are many answers. IPTV Chief Engineer Bill Hayes and Gary Sgrignoli, a professional consulting engineer, gives some satifyingly specific answers.
Q. Why can’t I get your station to come in? – and -- Why does the signal break up or go to ‘no signal?
A. Bad reception is the main cause of no signal or signal break up. You need to consider everything from what kind of antenna to buy, where to place it in your home, and even what kind of wiring to use. Here are the six basic questions we use to help identify problems.
1. Are you using rabbit ears?
The sticks part of the rabbit ears will not work well, or at all, right now, since digital transmitters are on UHF (14-69) channels. The analog transmitters are still taking up the old VHF channels (2-13) until analog shut off so the digitals have had to use channels in the UHF region so as not to interfere with analog transmissions. [This will depend on the area where the viewer resides, of course. Analog stations may already be in the UHF region].
2. Is there a Loop in between the rabbit ears?
If the rabbit ears have the loop (circle, square, etc) between the sticks, that loop will be the part you need to adjust to receive the signal. The broad side of the loop needs to be pointed in the direction of the transmitter(s) to be fully effective. Small adjustments may be necessary. If you still do not receive a signal or it is ‘pixelating’ (breaking up), you may have to either move the antenna higher or to a different location or consider using an antenna on the roof or in the attic (see below).
3. Do you have an outdoor antenna, or one in the attic?
This will be better for reception, but needs the following questions asked.
4. How old is the antenna?
If more than 10-15 years or you can’t remember, you may need to consider getting a newer VHF/UHF antenna. Also check to see if it is at least pointed in the right direction.
5. What kind of down lead (wire) is used: flat brown, or round black?
If it is the flat brown twin lead, they must really consider changing to coaxial cable since twin lead ages with exposure to weather and does not have the bandwidth to receive the signals.
If it is the round black coaxial cable it has to be the RG-6 type and not the RG-59 type. Usually, this is printed or stamped on the coax covering. ‘CATV CABLE’ on the covering is also a no-no.
RG-6 cable (usually with ends attached) is available from several places that supply consumer television antennas (Menards, Radio Shack, Best Buy, etc.) It is not very expensive (for example, approx. $20.00 for a 50ft roll with ends.)
6. How far from the transmitters are you?
No hard and fast rule on this, but if you were having snow in your analog signal or are more than 40-50 miles in relatively flat terrain, you should consider getting a preamplifier for their antenna. The best one would be the one that is at the antenna and is powered through the coax from a power supply in the house at the other end.
Any amplification or increase in antenna height is better.
Places like www.antennaweb.org and www.winegarddirect.com , can help to answer some of you questions. Winegard has a toll free number (866) 454-7566 where there are people who can make suggestions to the viewer as to a suitable antenna for their location.
Q: What specific techniques can I use to determine if my current television antenna is acceptable for digital reception or whether a new antenna is required?
A: In general, if your current antenna (outdoor or indoor) provides good or excellent reception quality, that antenna should be acceptable for DTV reception. This presumes that the current antenna covers the same television bands (low-VHF, high-VHF, UHF) that are being used by the digital stations.
To help in this determination, you can easily identify on your current analog television set:
· weak signals by seeing a snowy picture
· impulse noise from motorized devices in the home (e.g., vacuum cleaners, popcorn poppers, etc.) by seeing white speckles on the screen
· “ghosted” signals by seeing multiple images shifted horizontally on the screen
· interference from other analog signals by seeing diagonal stripes on the screen. Observing these analog transmission artifacts on an analog television set can provide some insight into potential digital reception on similar channels.
Q: Is there such a thing as a “digital” antenna or an “HDTV” antenna?
A: No. While the box in which the antenna is sold may contain the words “DTV Antenna” or “HDTV Antenna,” the analog and digital television signals share the same frequency bands (low-VHF, high-VHF, and UHF) and therefore can be picked up (i.e., received) with the same antenna.
Q: How can I determine what channels I will receive?
A: DTV uses a virtual channel numbering system that links the digital channel to the TV station’s legacy analog channel. This provides two advantages:
· a station gets to keep its branding (e.g., Action 7 News, Sports Center 5, etc.) even though a different actual RF channel is used for digital
· it is more convenient for you to make the change to digital.
DTV receivers make the connection between the analog and digital channels when it scans the entire television spectrum looking for digital signals, and then stores this relationship in its electronic memory much the same way that the phone company stores a call forwarding telephone number in its electronic memory.
Q: What general types of antennas are best to use for DTV reception?
A: Just as for analog television reception, a good outdoor antenna is the best option, an attic antenna (if there is not a metal roof) is the next best option, and the last option that should be considered is an indoor antenna.
Not all antennas on the market are designed to cover all three television bands. Some are VHF only (CH 2 – CH 13) while others are UHF only (CH 14 – CH 69). Some individually cover the upper VHF band (CH 7 – CH 13) and the UHF band (CH 14 – CH 69). Yet others cover all three television bands (CH 2 – CH 69), and are referred to as all-band or “combo” antennas.
After the transition to all-digital transmission ends, the same antenna that currently provides acceptable analog reception may also provide acceptable DTV reception in the same television band. However, this is not guaranteed.
Q: What should I consider when purchasing a new antenna for DTV reception?
A: If you know that there will be no VHF (2-13) DTV signals after February 17, 2009, then a smaller UHF-only (14-69) antenna may be the most desirable. However, if it is determined that there will be high-VHF (7-13) in addition to UHF digital channels, then a high-VHF/UHF combo antenna would be best, which is still smaller than a complete VHF/UHF (2-69) combo antenna.
It is very important to know what actual television channels will be used for digital transmission after February 17, 2009 in order to make an informed decision on antenna selection. For information on what digital television channels will be used locally after full-power analog television is turned off on February 17, 2009, go to: www.antennaweb.org.