DVB, Sinclair to Demo COFDM in 6MHz Channel at NAB2000
Using DVB-T Hierarchical modulation, the HDTV and SDTV service will be transmitted using the facilities of Sinclair's KVWB-DT29 on Black Mountain, Nevada to various reception points, both static and mobile, in and around the Las Vegas Convention Center and Sands Expo.
A short 720p HDTV loop will be displayed at multiple fixed locations (Acrodyne Booth L9372 and DVB Booth L1150 amongst others). SDTV programming will be received in multiple locations (fully portable) on Nokia MediaScreen units
"These broadcasts underline the undeniable capability of the DVB-T standard," says Helmut Stein of Nokia, chairman of DVB Promotions. "Where there is a public demand for HDTV service, DVB standards deliver. At last year's NAB we scored a 'world's first' by demonstrating the robust nature of the DVB standards with mobile DTV reception. This year we are proud to be showing how DVB standards can be used to provide both HDTV and SDTV 6Mhz services in a single channel. DVB is an agnostic data pipe that allows packaging and transmission using interoperable standards in end-to-end solutions. The rapid deployment of digital television, new business models and the generation of new services to attract and satisfy the consumer is what DVB is all about".
Additional support came from Rohde & Schwarz (Modulation), STI (720P HDTV), Tandberg (TV Encoding and Decoding) Tektronix and Adherent (Additional Equipment).
What is Hierarchical Modulation?
In hierarchical modulation, two separate data streams are modulated onto a single DVB-T stream. One stream, called the "High Priority" (HP) stream is embedded within a "Low Priority" (LP) stream. Receivers with "good" reception conditions can receive both streams, while those with poorer reception conditions may only receive the "High Priority" stream.
Broadcasters can target two different types of DVB-T receivers with two completely different services. Typically, the LP stream is of higher bit rate, but lower robustness than the HP one. For example, a broadcaster could choose to deliver HDTV in the LP stream, while delivering an independent SDTV service in the HP stream.
Technical Details:
Uniform 64-QAM Hierarchical Modulation (Alpha=1). 8k, Guard Interval 1/32
HP: QPSK, ½ FEC = 4.909*.Mbits/s @ 204 Bytes per packet
LP: 16QAM, 2/3 FEC = 13.09*.Mbits/s @ 204 Bytes per packet
The Transport Stream Recordings are as follows:
Dvb_hd_204byte_13M09bps
Recorded at 13.09Mbits/s. 4.5 minutes of 720P60 HDTV material @ 11.093Mbits/s. 1 Dolby stereo audio channel @ 192kbits/s.
Dvb_sd_204byte_4M909bps
Recorded at 4.909Mbits/s. 12.5 minutes of DVB SDTV material. Recorded as PAL @ 2/3 res (720x480 i 25). 1 MPEG stereo audio channel @ 284kbits/s.
Edited by Tom Butts