Regarding the recent fuss over 8VSB vs. COFDM:
sbgi.net
The following is some background on the "fuss" snipped from an InStat report dated 10/18/99:
Sinclair Broadcast Group Petitions FCC To Abandon 8-VSB
A few weeks ago, we published an article in the Information Alert stating that engineers at Motorola and Sarnoff Labs had introduced a new generation of digital TV emodulator devices that would "fix" 8-VSB and save digital television. In a report released October 1, the FCC recommended no changes to the US DTV standard. Evidently, not everyone agreed with the above.
Last week, the Sinclair Broadcast Group officially petitioned the Federal Communications Commission to abandon the ATSC 8-VSB modulation standard that previously had been chosen as the standard for US digital terrestrial broadcasts.
While this step had been expected, we were quite surprised to see 12 other Station Group Owners agree to sign on in support of Sinclair's petition. The co-petitioners own about 250 US TV stations. Interestingly, none of the co-petitioners owns a lot of local TV stations that are affiliated with the four major US networks, so they are not under the gun to have their local TV stations on-the-air with a digital terrestrial signal until sometime in 2002. Their participation in Sinclair's petition might be motivated by the desire to delay their target date for converting to Digital TV. This would save them some money.
Jamie Kellner, president of The WB TV network, has stated that his station group - Acme Broadcasting - will not sign the petition, but he will send a letter to the FCC offering to help pay for side-by-side comparison tests between the "latest and greatest" versions of 8-VSB products, side-by-side against similar COFDM receivers.
It appears that a coalition of broadcast station owners is in agreement with Sinclair that 8-VSB doesn't work. 8-VSB stands for Eight Vestigial Side Bands. The current US analog TV standard uses a single Vestigial Side Band.
Sinclair has recommended that US broadcasters be permitted to adopt the European COFDM standard, which is specified by the Digital Video Broadcast, or DVB, standards group. COFDM stands for Coded Orthogonal Frequency Domain Multiplexing.
Sinclair engineers have performed tests of early model digital TV receivers in Philadelphia, using a combination of outdoor and indoor antennas. Their results were extremely negative, showing that on most occasions and under most circumstances, 8-VSB did not work.
Later on, Sinclair engineers performed a much more public test and demonstration, using six locations in the Baltimore, Maryland, area. These tests used "rabbit ears" and "bow tie" antennas in local private residences. Two receivers were set up and used: one 8-VSB and one COFDM. The 8-VSB receiver never successfully locked onto the signal, while the COFDM receiver never lost the signal.
The Consumer Electronics Manufacturing Association has, by far, the most at stake, because a failure of digital TV in the US means the failure of High Definition TV sets. But the Computer Industry, terrestrial broadcasters, television equipment suppliers and the semiconductor industry will all see important new markets delayed if the Sinclair petition gains momentum. |
