Antennas: Technology Revisited
The broadcast digital transition scheduled for June 12 may create some benefit for cable, which could see a boost in subscribers who figure this is a good time to make the switch to cable.
On the other hand, consumers are starting to realize they can get more “channels” from broadcast networks than ever before. DTV technology supports the transmission of high definition or a handful of standard definition streams within each 6 MHz channel slot. This creates a new competitive dynamic: Consumers who upgrade TV hardware – TV sets and antennas – rather than switching to or even continuing with cable, or direct broadcast satellite (DBS).
Antenna technology
Over the last five to 10 years, a lot of innovation has gone into antennas to make them more compact, powerful and intelligent. The latest innovation is called smart antenna, which is just starting to get integrated into a growing number of new products from DTV receivers to digital TV sets.
There are two types of smart antennas: switched beam and adaptive array. Switched beam antennas monitor available fixed beams and then select the optimum direction based on signal requirements (which station is being tuned). Adaptive array antennas operate in a similar way. However, rather than selecting among fixed beams, the adaptive array technology is able to steer the direction of the antenna while simultaneously rejecting interfering signals.
The FCC digital migration also gave broadcasters the choice to operate on VHF low band channels 2-6, in addition to VHF high band and UHF channels. Whether or not low band channels are used by broadcasters for DTV may seem like a nonissue, its impact on reducing the length of elements required on a traditional rooftop antenna could be significant. Eliminating channels 2-6 removes the need for the longest elements on traditional antennas and thus reduces the impact of strong winds and ice on the equipment.
As it happens, some 40 digital TV stations have been assigned channel allocations in the VHF low band; so whether a consumer can get away with a smaller antenna depends on the market, distance to the transmitter, and obstructions that may affect reception.
None of the traditional rooftop antennas offer the innovative smart antenna features. However, what they give up in leading edge technology, they make up in intelligently designed surface area that is optimized to receive as much signal at greater distances while rejecting interference. These antennas also offer reception options to residents who live up to 60 or more miles away from the broadcast transmitter.
Amps, costs
A consumer who wants to use a single antenna to supply signal to run multiple TV sets within the home may need to use amplification. Typically, a single good antenna supplies enough signal to run two devices, assuming adequate received signal strength.
There are three types of amplification: Pre-amplification, installed near the antenna; in-line amplification, installed prior to splitters; and distribution amplification, which reduces loss by amplifying across the split.
Upgrading an antenna system could cost between $200-$300 for the antenna and the professional installation–assuming someone with the appropriate skills is available. How many consumers opt for this investment is an open question, but given the economic climate, it would be prudent to expect that the appeal of this relatively low-tech and no recurring-fees approach to video will rise.
– Bruce Bahlmann
[Ed note: Corrections to original statements about channels 7-69, analog reclamation and "ghosting" posted 3/24; 11:48 a.m. Eastern]
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