Digital TV: Keeping Seniors Connected Campaign Antennas and Reception Issues

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Digital TV Keeping Seniors Connected Campaign
Antennas and Reception Issues

• Webinar
• Wednesday, June 10, 2009
• 200-300 PM EDT

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Digital TV Keeping Seniors Connected
CampaignWebinar Presenter

• Moderator
• Theresa N. Lambert, Director, Digital TV
  Keeping Seniors Connected Campaign, National
  Association of Area Agencies on Aging
• Presenter
• John Gabrysch, Electronics Engineer, Media
  Bureau, Engineering Division, Federal
  Communications Commission

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Federal Communications Commission
The Digital Television Transition Antennas and
DTV

• 1-888-CALL-FCC
• 1-888-TELL-FCC (tty)
• E-mail dtvinfo_at_fcc.gov

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Overview

• What is an antenna system?
• What can make someone need to upgrade an antenna
  system?
• How does someone know that they need to upgrade
  an antenna system?
• How does someone choose the correct upgrade?

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What is an antenna system?

• Every part of the chain from antenna to receiver
  can affect signal quality
• Antenna
• Rotor
• Baluns
• Cables
• Splitters
• Amplifiers, Attenuators
• Connectors

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What can make someone need to upgrade an antenna
system?

• A Change in Frequency
• A Change in Signal Level
• A Change in Direction

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DTV Frequencies

• Frequency where in the spectrum a signal is
  transmitted
• TV Frequency Bands
• Low-VHF
• High-VHF
• UHF

VHF Frequencies longer wavelength, which means
larger elements needed in antenna
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DTV Frequencies

• How do you know what frequency a station is?
• Analog World Frequency Displayed Channel
  Number
• 2-6 Low-VHF
• 7-13 High-VHF
• 14 UHF

VHF were usually the oldest stations, and
typically carry the major networks
UHF stations were the newer stations, LPTV,
Spanish Language, etc.
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DTV Frequencies

• How do you know what frequency a station is?
• Digital World Frequency NOT Displayed Channel
  Number
• Stations now have two different channel numbers
• Major Channel Number (Virtual)
• Usually same as their old analog channel.
• Displayed on the TV when that station is tuned.
• RF Channel Number
• The licensed frequency that station transmits on.
• Often different Pre- and Post-Transition

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Digital RF Channel Numbers

• Easiest to look up online
• http//www.dtv.gov/maps - enter location, then
  click on a callsign to display RF Channel
• http//www.dtv.gov/broadcastersupport.html -
  download the Full-Power Stations List, look
  under the Post DTV Chan column.
• General Trends

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DTV Signal Levels

• DTV signals were designed to cover the same area
  with less power
• Cliff effect if used to watching a snowy analog
  picture, may not get anything at all with DTV
• Some stations changed their coverage areas
• Can cause weaker signal because farther away or
  newly obstructed
• Can require antenna to be re-pointed at the new
  tower
• Gain/Loss maps (www.fcc.gov/dtv/markets) can
  illustrate these changes. Please note that
  loss might not be limited to red dots.
  Predictions assume directional rooftop antenna,
  30ft above ground.

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How do I know I need to upgrade my antenna
system?

• The current one doesnt work.
• Easiest prediction methods
• Good reception on analog channels 14
• Rabbit ears need a loop or a bow-tie

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How do I upgrade my antenna system?

• Start with the cheap, easy stuff
• Reposition current antenna. Use www.dtv.gov/maps
  to find direction to towers.
• Outdoor turn to point the little end at the
  towers
• Indoor move to side of house closest to towers,
  near a window, as high off the ground as
  possible. Use coax extension cable (only as much
  as needed to reach).
• Remove unnecessary splitters (a splitter halves
  the signal strength)
• Make sure connections are secure, not corroded.
  Make sure cables are in good condition.

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How do I upgrade my antenna system?

• Easy stuff didnt help, now what?
• Coaxial Cable is much better than flat two-wire
  cable, especially for long runs.
• Use www.dtv.gov/maps to find signal strength, RF
  channels, and directions to desired stations.
  Predictions assume directional rooftop antenna,
  30ft above ground.

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How do I upgrade my antenna system?
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Directional vs. Omnidirectional

• Omnidirectional antennas
• Dont have to be turned to get stations from
  multiple directions
• Not as good at receiving weak signals
• Vulnerable to multipath ghosting, echoes, etc.
• Directional antennas
• Better for receiving weak signals
• May have to be turned by hand or by rotor to get
  signals from different directions

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Analog vs. Digital Antennas

• Antennas work for both, as long as they cover the
  correct frequencies.
• HDTV Antenna is a marketing term
• Watch out some are UHF only (usually the small,
  cute ones). Some marked as combination VHF/UHF
  have poor VHF performance.
• Most new antennas designed for channels 7-51
• Most old antennas designed for 2-13 or 2-69

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Questions?