Commission seeks comment on measurement of DTV signal strength
May 3, 2006 12:35 AM, RF Update e-newsletter
The FCC is looking at establishing measurement procedures for determining DTV signal strength at any given spot as a way to decide whether or not households are eligible to receive distant DTV network signals retransmitted by satellite.
On April 24, the commission issued a Notice of Proposed Rulemaking regarding the matter as required by the Satellite Home Viewer Extension and Reauthorization Act of 2004 (SHVERA). On Dec. 8, 2005, the FCC issued the SHVERA Report to Congress stating it needed to conduct a rulemaking proceeding to lay out procedures for measuring the field strength of DTV signals at individual locations and that it believed the procedures should be similar to those used to determine the field strength of analog signals.
Among the matters the commission is seeking comment on:
- Whether or not there are ways to minimize the cost of digital signal strength tests while ensuring the accuracy and reliability of the results;
- Whether measurements should be required to be taken using a calibrated gain antenna with a front-to-back ratio consistent with the DTV planning factors or with either a standard half-wave dipole antenna or a gain antenna with a known antenna factor for the channel(s) that are to be tested;
- A proposal to require digital signal measurement to be done by measuring the integrated average power over the signal’s entire 6MHz bandwidth and that the IF bandwidth of the measurement device not be greater than 6MHz.
- A proposal to require test instruments to be set up with a shielded transmission line between the test antenna and the field strength meter, that antenna impedance be matched to the transmission line at all measured frequencies, that the tester account for line loss and when an unbalanced line is used so must a suitable balun.
- A proposal that DTV measurements be made with a horizontally polarized antenna and a requirement that the antenna be oriented so its maximum gain faces the strongest signal coming from the transmitter being tested. If more than one station’s signal is being measured, the antenna must be oriented separately for each station.
- A proposal that testing antennas be elevated 20ft above the ground when measuring at one-story buildings and 30ft for buildings higher than one story.
- A proposal that tests should not be conducted in inclement weather.
- A proposal to require the same recording of DTV signal measurement strength as requirements for an analog signal.
- Whether it is possible to develop rules that address the lack of qualified, independent testers to perform the signal strength tests.
For more information, visit www.fcc.gov.
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