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OTA DTv

How to Get Free TV


Contents -- Viewing Devices | Planning Steps | Summary

Broadcast TV requires an indoor or outdoor antenna to receive signals, connected with a coax cable to a device (television etc.) for viewing. Indoor antenna's will work for broadcast tower ranges less than about 20 miles or so in most cases. Attic antenna's work better (longer ranges), and outside antenna's work the best.

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VIEWING DEVICES

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
PLANNING STEPS
1.) Find Broadcast Towers.
2.) Estimate Cable Loss.
3a.)
3b.)
Estimate Antenna Gain needed,
or existing antenna gain.
4.) Estimate Signal to TV's.
5.) Install an amplifier if needed.
Planning Steps

reception factors 1.) FIND BROADCAST TOWERS
Use the TV Tower Locator to find stations in your area. Note;

Also see signal Reception Factors.

2.) ESTIMATE CABLE LOSS
Cable loss depends on cable length(s) and the number of signal splitters / output ports. Connectors and adapters introduce a small loss.

Cable loss also varies with RF channel, the higher the channel the greater the loss. In most cases using the average of a frequency band (VHF-Lo, VHF-Hi, UHF) to calculate loss is close enough. Loss can also be calculated for a specific RF channel. The calculators below compute cable loss for RG-6 coax cables, the preferred cable for broadcast TV reception.

Also see TV Coax Cables, Splitters, and Connectors for more details.

3a.) ESTIMATE ANTENNA GAIN - new installations
Antenna gain needed can be roughly approximated from the smallest expected signal level, and cable loss.

Estimate Antenna Gain Needed
Band or Channel:
Broadcast Signal: dBm

Cable Length(s):
Signal Splitters: 2 Ports , 3 Ports
4 Ports , 8 Ports
Connectors:
Adapters: 300 / 75 ohm

SIGNAL POWER
AVAILABLE TO ANTENNA
Cable Loss
Splitter Loss
Connector loss
Adapter Loss
SIGNAL TO TV
Required: -65 dBm
GAIN
NEEDED

A negative gain indicates any antenna will work.
Gain is an estimate and should be padded 3 to 6 dB.

3b.) ESTIMATE ANTENNA GAIN - existing installations
Antenna gains average from around 3 dBi for indoor antennas, to 8 dBi for indoor/outdoor antennas, to 13 dBi for large outdoor antennas.

Antenna Type Gain (dBi)
Indoor Antenna 2 to 4
Attic / Outdoor Antenna 5 to 10
Large Outdoor Antenna 11 to 15

4.) ESTIMATE SIGNAL TO TELEVISION
Signal power delivered to the television equals broadcast signal available to the receive antenna plus antenna gain, minus cabling loss.

Broadcast Signal (dBm)
+ Antenna Gain (dBi)
- Cable Loss (dB)
= Signal to TV (dBm)

Estimate Signal to Television
Band or Channel:
Broadcast Signal: dBm

Antenna Gain:
Cable Length(s):
Signal Splitters: 2 Ports , 3 Ports
4 Ports , 8 Ports
Connectors:
Adapters: 300 / 75 ohm

BROADCAST
-SIGNAL
ANTENNA
-GAIN
Cable Loss
Splitters Loss
Connectors loss
Adapters Loss
TV SIGNAL

A good signal is from 8% to 50% (-60 to -35 dBm).
A strong signal is greater than 50% (-35 to -5 dBm).

5.) AMPLIFIERS
A preamplifier can be used to improve weak broadcast signals. A distribution or booster amplifier should be used to overcome cable loss.

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SUMMARY
ANTENNA POSITION
  • As high as possible.
  • Clear of clutter in tower directions.
  • Pointed in direction of broadcast towers.

ANTENNAS
  • Frequency Bands
    • Most broadcast are in the UHF band.
      In some cases a UHF antenna works for VHF signals.
    • Use a VHF / UHF antenna to get all bands.
  • Weak Signals
    • Use a high gain antenna.
    • Install an antenna pre-amp.
  • Distant and Spread Out headings;
    • Use 2 or 3 antennas.
    • Use an Omni antenna (360° coverage).
    • Rotor antenna (high gain and 360°).
CABLING
  • Coax
    • RG-6 coax cable (F-type connectors).
    • Cable runs as short as possible.
  • Connectors
    • Make sure all connectors are tight.
    • Check outside connectors for corrosion.
    • Outside connectors covered with a
      rubber weather boot or electrical tape.
    • Unused ports covered with a 75 ohm load.
  • Long cable runs, multiple Signal Splitters
    • Use a distribution / booster amp.

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