Understanding TV Signals
As in analog TV signals, digital TV signals are broadcast in two main frequency ranges: VHF and UHF. The VHF channels range is 2-13, while the UHF range is 14-83. Over 90% of DTV stations are broadcasting in the UHF frequency band until February 17, 2009. This can be a little confusing because the FCC requires digital stations to embed a reference code to their analog channel so viewers don’t have to memorize a new set of channels. For example WGEM is currently broadcasting on the UHF band on channel 54, but actually what you see on your TV is 10.1, 10.2 and 10.3. KHQA is on channel 29 and you see their channel as 7.1 and 7.2.
Analog vs Digital reception
The digital signal is quite different from the analog signal. With analog you could adjust the antenna and normally receive some type of signal, maybe the signal was noisy or you would have ghosting. Not so in digital. You must maintain a constant signal to maintain the quality of the picture. Many say either you have it or you don’t. If you notice freezing or pixilation that is a good indication you might have a weak or interrupted signal.
Over-the-air digital reception provides the best picture quality and it’s FREE
Most cable and satellite companies offer plenty of channels to choose from. By doing so they must use data compression or other techniques which compromise picture quality, resulting in a "soft" image, distracting video artifacts (distortion), or both. Off-air antenna reception is the best way to enjoy digital TV and High Definition TV at the full resolution the TV stations intended.
UHF or VHF – February 17, 2009
Digital Television broadcasting stations operate on two bands VHF and UHF. After 2-17-08 many stations may change from the UHF band to the VHF band, why?
The FCC set down a mandate telling stations they were required to broadcast digital and analog signals simultaneously, forcing many stations operating their digital signal in the UHF band while maintaining their analog signal on the VHF band.. Once the analog signal is turned off, many stations will locate back to their VHF home. You need to know what is happening with the stations in your area before you make an investment in an antenna for digital TV.
In the Quincy Television market there are four digital television stations broadcasting a total of 9 digital signals. Digital TV allows multicasting or the ability for broadcasters to provide multiple digital TV signals. In order to receive these signals you must have a converter box or digital TV with ATSC tuner and the proper antenna.
NOW-UHF DIGITAL STATIONS
WGEM-NBC 10.1, WGEM-CW 10.2, CGEM-FOX, 10.3
KHQA-CBS 7.1, KHQA-ABC 7.2
WQEC-PBS 27.1, WQEC-PBS-HD 27.1, WQEC-PBS 3, 27.3
WTJR-16.1
AFTER 2-17-09 –DIGITAL UHF STATIONS
WQEC-PBS 27.1, WQEC-PBS-HD 27.1, WQEC-PBS 3, 27.3
WTJR-16.1
AFTER 2-17-09 –DIGITAL VHF STATIONS
WGEM-NBC 10.1, WGEM-CW 10.2, CGEM-FOX, 10.3
KHQA-CBS 7.1, KHQA-ABC 7.2
What type of antenna should you use?
1. Determine the distance from the broadcast towers. If you are less than 10-15 miles you may be able to use a set of rabbit ears. Make sure this type of antenna is capable of receiving UHF and VHF signals. These will cost from $14.00 to $30.00 depending on the features. NOTE: This is an indoor antenna and you may have some reception problems due to movement in your home which can interrupt the signal. Remember digital TV needs a constant or steady signal in order to produce a clean picture unlike analog.
2. If you are having indoor reception issues an outdoor antenna might be the answer. Newer antenna designs allow for placement outside the window or under the eve of your house. All you will need to do is choose the proper antenna for this placement.
3. If you live more than 20 miles from the broadcast towers you may want to consider a roof antenna. Consult with a professional before you choose the antenna for your location. Don’t trust the word of the teenager working the part time shift at your local store. In general the larger the antenna surface, the stronger the signal it will provide. The relative strength of the signal an antenna can deliver to your TV or converter box is known as the gain and is measured in decibels (db). The higher the db rating, the greater he gain.
4. If you have an older antenna it’s possible it may produce enough signal to satisfy your digital TV or converter box. Normally the biggest problem with older antennas is the coax leading to the antenna. You should use RG6 antenna cable for the best performance. Weather can also have an effect on older antennas by breaking-off elements or corroding connectors causing a weak signal. If your older outdoor antenna works for you great but be prepared to replace the coax or the antenna itself.
5. You may be able to use an antenna in your attic. The effectiveness of an antenna in the attic is decreased by up to 50% so keep this in mind.
6. Amplified antennas can improve your antenna performance or cause real problems. An electronic device is placed in the coax line between your TV and antenna. It amplifies the effect of the antenna and can improve the signal to your receiver. There is a potential drawback of an amplified signal. It can actually make a strong signal worse. You would not want to use an amplified antenna if you live near the transmission tower. This will cause too much signal into your receiver and result in a bad or inconsistent signal.
Posted under DTV Reception - Antennas
This post was written by New Media QNI on May 6, 2008
9 Comments