The January 15th issue of RF Update reported on Fox conducting ATSC site testing. The results of that study were published in last month’s issue of the IEEE Transactions on Broadcasting journal. According to the study, of the locations tested, the indoor reception rates were 85 percent. But, the study also found that use of two receive antennas in an antenna diversity scheme could greatly improve an ATSC’s receiver to successfully demod 8-VSB signals in multipath situations. Philips will use the data collected to design its next generation chipset.
Philips is not the only chipset vendor pushing the ATSC receive technology forward. Zenith has prototypes of its fifth generation chipset, and is already working on the technology that will produce a sixth.
The improvements made with each successive generation of the ATSC chipset illustrates how far the technology has come in a short period of time. In the case of Zenith, its first generation was a three-chipset for 8-VSB demod that had an equalization range of collected tap energies spanning 23ms. The second generation consisted of two chips with an extended equalization range of 44ms. The third generation used blind equalization with training, along with a predictive slice to know when to switch from the training mode. The fourth generation incorporated digital demod and improved indoor reception by being able to handle fast moving ghosts. The latest generation uses frequency domain equalization instead of time doman equalization, which improves multipath performance.