A study on design of equalization DTxR for ATSC terrestrial DTV system

Abstract

Up to now, there have been many researches on the efficient use of the broadcast spectrum in advanced television systems committee (ATSC), and finally the single frequency network (SFN) is made possible. There are a few methods to implement a SFN, and one of them is the distributed translator (DTxR) network. But, the DTxR network requires special devices to synchronize multiple translators comprising a SFN, which inhibits broadcasters from investing on the networks.

To make implementing a DTxR network easy, this dissertation proposes a new design and implementation method for a new DTxR, termed as a baseband equalization DTxR (EDTxR), which does not require additional devices to synchronize the translators in the network. To satisfy this purpose, probable synchronization technologies among translators are studied.

For identical symbol outputs from all the translators, the equalization digital on-channel repeater (EDOCR) scheme, which omits the decoding and re-encoding of the channel codes, is adopted for EDTxR.

For frequency synchronization among translators, a method using a recovered clock from received signals is reviewed. By using the method, all the translators in a network can be synchronized in frequency on the average, but the receivers within the overlapped coverage area of two translators show about 4 dB performance degradation compared to a natural multipath condition. This phenomenon is mainly caused by the degraded phase noise of the recovered clock, and such phase noise degradation is confirmed through the theoretical analysis and the computer simulations on the phase noise characteristics of a timing recovery loop.

To reduce the receiver performance degradation, a new frequency synchronization method using its own crystal oscillator in each translator is proposed. In addition, a scheme to eliminate the effect of the frequency offset of the crystal oscillator on translator output frequency is proposed.

To verify the proposed EDTx...