[BC] Should We Now Wait on Digital-only TV?

[Thomas G. Osenkowsky]

Stop calling me Shirley! One thing that has not been fully
addressed here is the digital antenna. A recent NBC Nightly
News story claimed rabbit ears will NOT work with digital
TV. Why is this? One might say an RF signal, regardless of
modulation, is still propagated the same way as any other
signal of the same frequency(s). True enough. BUT....
digital is different as far as reception and conversion is
concerned.

An article in the August, 2008 edition of Sound & Video
Contractor magazine titled "HD Antennas" offers some
revelations about digital vs. legacy analog receive antennas.
Consumers may wish to receive HDTV off-air to avoid the
compression that satellite and cable providers employ to
squeeze more channels into a given system. The author,
Kent Martin, cites the experience of Richard Schneider.
"Schneider began by pulling apart a legacy antenna and
learning why older models were unable to deliver signals
with the quality he found in cable and satellite systems."
Schneider says "Basically, legacy antennas were simply
overwhelmed by all of the over-the-air transmissions that
are prevalent today, such as cellular phone towers and
FM-radio transmitters. Out-of-band transmitters were
wreaking havoc on the old legacy models."

Digital receive systems require attention to specifications
such as group delay in the bandpass and cleanliness of
the signal. Recall that in satellite dish alignment rejection of
adjacent bird signals is of greater importance than received
signal strength. I take exception to the claim that cellular towers
and FM-radio transmitters were "wreaking havoc" on legacy
antennas such as rabbit ears. Rabbit ears are connected to a
TV receiver. Towers and transmitters do not in themselves
wreak havoc on antennas. Emissions from these certainly can.
Some outdoor TV antennas (Winegard, for example) had an
element that could be trimmed to enable FM band reception.
Cellular telephone antennas are vertically polarized and TV
antennas are horizontally polarized, therefore cellular cannot
"wreak havoc" on vertical rabbit ears.

Many HD antennas are active....they have a built-in preamp and
filters, unlike their rabbit ear counterparts. In rabbit ears the
width of the elements can influence bandwidth as can the length.
We need to pay attention to factors in digital that we did not in
analog. Simply rotating the rabbit ears for best reception will not
work with digital. In digital, the signal is there or it is not. No ghosts,
no snow. For those who desire uncompressed digital, blacked out
sports, etc. we must bring forth antennas that are capable of 
receiving distant digital signals as well as being aesthetically pleasing.

Tom Osenkowsky, CPBE
who employed his own interpretation of the Theory of Relativity in the
composition of this post

>  RESPONSIBILITY in Washington ?
>  Shirley, you jest ?