Phil Kurz /
Originally featured on BroadcastEngineering.com
LPTV broadcaster seeks Special Temporary Authority to transmit OFDM, OFDMA signals
Low-power television station operator WatchTV filed an amended application with the Federal Communications Commission on July 27 seeking Special Temporary Authority (STA) rather than an experimental license to put OFDM and OFDMA modulated signals on air in the Portland, OR, area.
According to the application, WatchTV is requesting the STA to gather field data on "real-life propagation considerations" involved with technologies that would allow broadcasters to transmit TV as well as other services, such as multichannel IP video services and wireless broadband service.
The application asks for authority to conduct test transmission of orthogonal frequency division multiplexing (OFDM) and orthogonal frequency division multiplexing access (OFDMA) signals from seven transmitter sites in the Portland area. Single-frequency networks may be operated on each channel as well as multifrequency networks to compare performance. WatchTV is requesting authority to conduct the test transmission from existing fixed sites already in use by the LPTV broadcaster for analog operation by licensed stations.
WatchTV president Greg Herman also heads SpectrumEvolution.org, an advocacy group seeking to win for broadcasters the right to choose the modulation scheme of their liking. Herman, who originally sought the experimental license, demonstrated in November 2010 to commission staff at agency headquarters in Washington, D.C., OFDM-modulated transmission to 12 Converged Multimedia Mobile Broadcasting (CMMB) receivers.
According to the amended application filing, WatchTV is seeking the STA to conduct its field trials with OFDM and OFDMA signals that are "well-known modulation schemes to the wireless industry," adding that "OFDMA is designed to accommodate two-way in-band services."
As part of its tests, WatchTV said it plans to test and evaluate methods to embed TV programming "in an alternative signal" that can be displayed on ATSC television receivers with "a very simple and inexpensive outboard or built-in adapter device."
The application also seeks permission to test up to 300 pico- or femto-cell boosters and mobile units with up to 2W ERP located within the 51dBu contour of the authorized main transmitter on the same channel.
On Oct. 19, 2010, WatchTV filed the application for an experimental license to conduct the OFDM/OFDMA tests, which was denied by the commission on Feb. 10, 2011. WatchTV filed a petition for reconsideration and will "any type of authorization" to allow its tests, "license or otherwise, independent of the prior pending proceeding," the application said.