How to get free HDTV
Five Steps to Free HDTV By J.D. Adams
Television broadcasters have completed the digital transition and now offer high quality video, audio, and integrated services.
All of the major network channels are still available for free along with local and alternative programming, retro movies, music videos,
and Public Broadcasting. To receive digital TV signals, you only need a digital tuner on your TV set or a digital converter box, and an inexpensive antenna.
1) The process of getting free broadcast digital television begins with some research into its availability at your location.
Several factors will affect your reception such as the distance from the transmitter, geography, and the presence of any obstructions
such as trees or buildings. Running one of the online DTV signal locators will give you a good idea of the signal in your area.
2) Next, you’ll want to select an antenna type based on your DTV signal level. There’s a lot of hype concerning DTV antennas and reception. Specific information on antenna
performance is often hard to find or misleading. Antennas are rated by their signal Gain parameter, which is a measure of how much the antenna can gather
and focus the incoming energy into a narrow beam.
Signal power is measured in decibels (dB), which is a logarithmic scale that allows gains and losses to be added directly. A power Gain of 3 dB is twice the power.
A dBi is a dB referenced to an isotropic source; that’s a theoretical spherical wave front emanating from a point source. A dBd is a dB referenced to a dipole, which
have a predictable Gain of 2.15 dB over an isotropic point source.
As a point of reference, a DTV antenna having a Gain of 15 dBi or greater can receive DTV signals 60 miles away from the transmitter over rugged topography.
Whether an antenna works at a distance of 150 miles for UHF (as is often advertized) depends to a great extent on the transmitter broadcast power, the flatness
of the intervening terrain and the weather conditions at the time.
If you live within ten miles of a DTV transmitter, your signal level is strong and a single element indoor antenna such as a loop or dipole
will probably suffice. Generally speaking, the major DTV transmitters will be at high elevations in or near the largest cities of your region, with a
scattering of local transmitters that broadcast at lower power. These local stations are often gems of pertinent information and culture.
Local obstructions can always come into play regardless of the overall signal strength, so prepare to be flexible and creative about locating your DTV antenna. Trees can severely
weaken DTV signal strength for UHF; however during the winter signal can be good while the leaves are down. If you live within twenty miles of a DTV transmitter, reception is
usually not a problem. A dual-element indoor antenna should bring in all available channels.
The conventional wisdom is that height is everything in locating your antenna but
beams of strong signal exist at lower elevations if you know where to look. You can “witch” the incoming DTV signal by putting a 10 or 20 ft. section of 75 Ohm coaxial cable on
your digital tuner antenna input and connecting a portable antenna to it. Look toward your closest DTV transmitter and find a convenient window that faces in that direction.
Try moving your portable antenna around near the window and usually there’s a place where the signal is stronger. The DTV signal sometimes appears with useable strength in
unexpected places with intervening walls or structures. You never know where DTV signal will turn up unless you look around.
At thirty miles distance from the transmitter, you may need to upgrade to a quad-element antenna or a “Super-Antenna”, seen below. At forty miles distance more extreme
solutions may be necessary, such as mounting a reflector 5 inches behind your antenna to double the received power or using a rooftop antenna installation. 20 ft. sections of 1 1/2 “ pipe
are available for making a mast that runs from the ground past the roofline, and is fastened at the edge of the roof so that guy wires are not needed. 15 ft. sections of pipe are more manageable
for when the antenna is taken down for maintenance.
At fifty miles we enter the fringe zone where you’ll need at least 15 dBi of antenna Gain and possibly a VHF/UHF amplifier, especially if you want to distribute that signal to
several rooms in your house. An amplifier with a good noise figure of around 2 dB will insure that your reception won’t be degraded by unnecessary electrical noise in your DTV signal.
You’ll want to test your location without an amplifier first and use an antenna with high Gain because that Gain is relatively noise-free.
Also popular are 4 element or 8 element antenna arrays that have significant signal-gathering power if an unobstructed view of the sky is available. Bowtie style antenna arrays are
reasonably broadband, but these antennas are quite large and the Gain can be disappointing unless you have a uniform “wall of signal” to capture with the array. The Yagi-Uda style
DTV antennas have the long booms on them, studded with multiple director elements. Yagi-Uda antennas also have high Gain with some limitation on bandwidth. The trade-off with
these antennas is that they are tuned to the upper portion of the UHF DTV band and the Gain drops off at the lower frequencies. Parabolic antennas are another
possible solution where high Gain is required.
The antenna should be matched to the size and shape of the beam of DTV signal that exists at your location. That means that different types of antennas will
respond differently, and that a huge array may not be the best answer. A more focused reception pattern is often the best answer for most situations. Efficient antennas types
combine good impedance matching with high Gain and moderate beamwidth for reception that is both stable and forgiving of errors in aiming the antenna toward the DTV transmitter.
My DTV antenna eBooks will allow anybody to construct their own DTV antennas with sufficient Gain to perform under fringe conditions. Deep fringe reception
usually requires large antenna arrays, long Yagis with 18 dBi or over of Gain, or an array using two UHF-17 DTV antennas that achieves 19 dBi of Gain.
Pre-amplifiers are another solution to the weak signal problem. Amplification can be ineffective at improving reception if the amplifier has a high Noise Figure or the amplifier is installed
after a long run of cable from the antenna. Noise Figure is a measure of the electrical noise that is added to the signal. Pre-amplifiers with a NF of 2 dB or less are preferred but more expensive.
Those with a NF of 4 to 5 dB are acceptable if installed fairly close to the antenna, within 20 ft. Amplifiers with a NF much higher than 5 dB will have a questionable degree of
improvement to reception.
Ideally, the amplifier is installed as close to the antenna as possible, often on the antenna mast in a weatherproof case. In this installation, the DC to power
the amp is supplied through the coaxial cable, and then filtered out before passing the amplified signal to a digital tuner. Another approach that is usually sufficient is to have the
amplifier inside the house with the cable run to the antenna as short as possible, preferably 20 ft. or less. The system NF seen at the DTV digital tuner is the sum of the
cable loss (in dB) between the antenna and the amplifier and the NF of the amplifier itself, hence the mast-mounted pre-amplifier is considered optimal for good reception.VHF can tolerate
a longer run of coax before the pre-amplifier because the lower frequencies have less loss per ft. than UHF. A good pre-amplifier is the
Channel Master Titan 2 (CM-7777).
The legacy roof-mounted television antennas still work fine for receiving the VHF channels 2 through 12 for DTV. With a device called a combiner, you can
add the VHF TV signal to a UHF signal from an inexpensive indoor antenna and have an economical system for receiving all the available DTV channels. These are
known as “low-loss” combiners (technically they are diplexers) and are usually only available from better electronics stores or online,
such as at: Antenna Direct and Pico Macom
The commonly available 2-way splitter can be used as a combiner but there is no VHF/UHF filtering and the through loss is 3.5 dB. That’s not considered
low loss and there are many of these splitters being marketed with that claim.
Another solution to having separate VHF and UHF antennas is use a coaxial cable A/B switch instead of a
combiner to select either signal path for input to the digital tuner.
If your DTV channels originate from different points on the compass, an antenna rotator is sometimes used to aim the antenna remotely. Another solution to divergent
transmitter sites is multiple antennas, with the signals added together with a combiner or a splitter used as a combiner. Two or more antennas can be mounted on the
same mast and pointed in different directions, with three ft. of spacing between antennas. It’s also possible to have separate VHF and UHF amplifiers
with their signals added using a combiner.
3) RG-6 coaxial 75 Ohm cable is preferred for long runs, being of lower loss than the RG-59 cable. Use it to connect the antenna or pre-amp output to
the antenna input of your digital TV set or converter box. If you are using a converter box, remember to set your TV channel to 2, 3 or 4,
whichever your converter box output channel is set to, or select the Audio/Video inputs from the converter box.
4) So you have your available DTV channels located in your area, you’ve selected an appropriate antenna for your signal strength, and you’ve even
aimed your antenna toward the best DTV transmitters. You have fresh batteries in your digital TV or converter box remote control, and you’re ready to
enjoy some HDTV. Next, you might need to set your TV to “Off Air”’ to receive these digital TV signals.
5) One more very important step needs to be done – scanning for channels. All the available DTV channels need to be memorized by either your
digital TV tuner or converter box. A typical sequence is to press “Menu” first, then “Setup”, “Autotuning”, “OK”. Subsequent scans can use “EZ Add”,
if available, to add new channels to existing memorized channels, or you may have to re-autoscan. Scanning may take a few minutes, and then you’re
ready for free digital television.
Some background information on broadcast television
The DTV (an abbreviation of digital television) transition in the United States is the switchover from the legacy analog television to exclusively digital
broadcasting of free over-the-air television programming. NTSC (National Television System Committee) is the system used in most of the Americas until around 2010.
It was adopted in 1941, became popular after WW2, and was revised in 1953 to accommodate color television. PAL and SECAM were analog color encoding systems used in other countries.
In response to technological change Congress passed the Telecommunications Act of 1996 that was signed into law by Bill Clinton. Of the seven titles of the act,
Title II, "Broadcast Services", outlines the granting and licensing of broadcast spectrum by the government, including a provision to issue licenses to current
television stations to commence digital television broadcasting. The original transition date was December 31, 2006.
The transition went into effect on Friday, June 12, 2009, and by August 31, 2011 in Canada and most other NTSC markets for full-power TV stations, ending
regular programming on their analog signals after 70 years. The new Television system is known as ATSC, for Advanced Television Systems Committee.
An ATSC tuner or HDTV receiver is a type of digital television tuner that allows reception of DTV television channels transmitted by television stations
in North America, parts of Central America and South Korea that use ATSC standards. These tuners may be integrated into a television set, VCR, or set-top
box that provides audio/video output connectors. Since March 1, 2007, all new television devices that receive signals over-the-air, including portable
televisions, personal computer video capture card tuners and DVD recorders have been required to include ATSC tuners.
Channels 52 to 69 were auctioned off and reallocated during the transition. The FCC is considering grabbing even more bandwidth from broadcast
television in the future. The most credible polling numbers indicate a fifth of American households watch broadcast television exclusively,
against stiff competition from Internet-based services. The digital transition has made free broadcast television a better value than ever
during these demanding economic times.