180 likes | 275 Views
Digital TV: Keeping Seniors Connected Campaign Antennas and Reception Issues. Webinar Wednesday, June 10, 2009 2:00-3:00 PM EDT. Digital TV: Keeping Seniors Connected Campaign Webinar Presenter. Moderator:
E N D
Digital TV: Keeping Seniors Connected CampaignAntennas and Reception Issues Webinar Wednesday, June 10, 2009 2:00-3:00 PM EDT
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
Federal Communications Commission The Digital Television Transition: Antennas and DTV 1-888-CALL-FCC 1-888-TELL-FCC (tty) E-mail: dtvinfo@fcc.gov
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?
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
What can make someone need to upgrade an antenna system? • A Change in Frequency • A Change in Signal Level • A Change in Direction
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
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.
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
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
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.
How do I know I need to upgrade my antenna system? • The current one doesn’t work. • Easiest prediction methods: • Good reception on analog channels 14+ • Rabbit ears need a loop or a bow-tie
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.
How do I upgrade my antenna system? • Easy stuff didn’t 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.
Directional vs. Omnidirectional • Omnidirectional antennas • Don’t 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
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