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Over-the-Air Digital TV (OTA DTv)


Contents -- Digital vs Analog TV | Digital Channels | Watching DTv | Incidentals

TV Broadcast Tower One of the first steps to getting free DTv is to find transmitter towers in your area. Then with a little planning, and understanding best reception practices and signal factors, you can get the most stations possible. Antenna selection depends on frequency bands, coverage, and antenna gain needed. Signal loss from cabling depends on cable length(s), signal splitters and connections. Outside Antennas should be properly grounded for best reception and safety.

DIGITAL vs ANALOG BROADCAST

Over-the-Air (OTA) digital television (DTv) requires a stronger signal than analog TV. Additionally, most DTv broadcast are in the UHF frequency band instead of the VHF band. UHF signals are higher in frequency and do not pass through or around objects as well as VHF signals. Also, over-the-air transmission and cable losses are greater at UHF frequencies. Antennas that picked up analog TV signals will also pick up digital TV signals, if the signal is strong enough.

  • Digital TV Requires a Stronger Signal.
  • Most DTv Stations are in the UHF Frequency Band.
    • Elevated terrain (Masking) blocks UHF signals.
    • UHF does not bend around large structures as well.
    • UHF dose not go through walls, roofs or objects as well.
  • Analog antenna's will pick up digital TV signals.

A digital television's picture quality is either 100%, or nothing. There is not a gradual degradation of picture for weaker signals, it's a steep cutoff. In contrast analog pictures degrade gradually, weaker signals have more noise or snow in the picture.

Analog TV broadcast in the United States ended June 12th (Friday), 2009. Since the introduction of digital TV, the number of over-the-air network channels has dramatically increased.

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DIGITAL TV CHANNEL(s)

The old analog TV channels were the same as their broadcast Radio Frequency (RF) channel, one network per channel.

TV and RF channels

Digital TV can broadcast multiple channels in 1 RF channel, and uses 2 types of channels;

Analog TV Digital TV
TV = RF
Channel
TV Channel
-- displayed
.Sub-channels
1 to 7 or more.
RF Broadcast Channel

A stations's TV channel could be the same as it's RF channel, but in most cases they are different.

In 2009 most analog stations changed their RF channel (and most VHF stations moved to UHF) for the DTv transition, but were allowed to keep their old analog channel identification as their TV or Virtual channel. The 2017 spectrum reallocation has over 10% of stations changing their RF broadcast channel, but not their virtual TV channel.

Sub channels can be in high or standard definition resolution. Audio can be in monotone, stereo, or surround sound. Most sub channels have program guides, closed caption, language, and other options.

Cable and satellite operators often compress local channels before re-broadcasting. The compression reduces picture quality compared to over-the-air broadcast. Compressing signals opens up more bandwidth and allows providers to squeeze in more channels nobody watches.

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WATCHING DTv

Broadcast TV requires an indoor or outdoor antenna to receive signals, connected with coax cables to a device for viewing.

Digital Televisions (ATSC)
Most televisions manufactured since March of 2007 have a built-in Digital Tuner (ATSC standard) for viewing broadcast TV signals. Some televisions are video monitors only, and cannot receive OTA DTv signals without a separate tuner.

Computers, Tablets, & Smart Phones
Many electronic devices can receive TV broadcast using an external DTv Tuner. The coax cable from an inside or outside antenna plugs into the DTv tuner, the tuner connects, usually with an Ethernet cable or WiFi, to your computer or network router / switch. You may need to download a media/TV app for your devices. Some DTv tuners have multiple receivers for receiving multiple TV channels simultaneously.

Analog Televisions (NTSC)
Most TV's manufactured before March of 2007 require a Digital to Analog Converter Box, sometimes just called a Digital Converter, to receive OTA DTv. Most converters are also recorders. The coax cable from the antenna plugs into the converter box, the box is then connected with another coax cable to the televisions's Antenna Input. Some converters can also connect to the television with video, VGA, HDMI, or YPbPr cable sets for better picture and audio quality.

Digital TV Tuner
Digital to Analog Converters

SOME STATION'S CHANGING RF CHANNELS BETWEEN 2017-2020+
Some DTv stations will be changing RF channels over a 3+ year period, until about 2020 and probably longer. The FCC, at the direction of Congress in 2012, is re-allocating spectrum, forcing around 1000 TV stations to change RF Broadcast Channels. There are about 8000 TV stations in the U.S. and its' territories. See FCC Spectrum Auction Results, April 2017.

Stations Changing RF Channel
Stations Percent Change
145 1.8% Go off-the-air
13 0.2% Move to VHF-Hi
17 0.2% Move to VHF-Lo
1000(1) 12.5% Change UHF Channel
(1) -- approximate

When a TV Station Changes Broadcast (RF) Channels;

Incidentals
Over-the-Air Digital TV (OTA DTv)
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