Demodulation apparatus and method for reducing time delay of on-channel repeater in terrestrial digital TV broadcasting system

Abstract

Provided is a demodulation apparatus capable of reducing time delay of an on-channel repeater in a terrestrial digital television (TV) broadcasting system and a demodulation method thereof. The demodulation method includes the steps of a) converting an analogue intermediate frequency (IF) signal into a digital IF signal; b) generating an in-phase (I) signal and a quadrature (Q) signal by converting the frequency of the digital IF signals and down-converting the frequencies of the pilot components of the I and Q signals so that the center frequencies of the I and Q signals could be shifted to 0; c) filtering the down-converted I and Q signals and maximizing signal-to-noise ratio; d) up-converting the filtered I and Q signals into baseband signals in which the center frequencies of the filtered I and Q signals are placed in baseband and shifting the frequency of the pilot components of the filtered I and Q signals to 0; and e) adding up the up-converted I and Q signals to restore the signals into baseband signals for broadcasting.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a digital television (TV) broadcasting service technology; and, more particularly, to a demodulation apparatus that can reduce time delay of an on-channel repeater (OCR) in a terrestrial digital TV broadcasting system and a method thereof. DESCRIPTION OF RELATED ART [0002] Generally, main transmitters and repeaters are positioned to provide broadcasting services based on the broadcasting coverage of each broadcasting station and the topological surroundings / natural features. [0003] The repeaters are installed in the area where broadcasting signals from a main transmitter are weakly received to solve the broadcasting signal reception problems in the regions which are out of the broadcasting service coverage and to expand the signal transmission area of the main transmitter. [0004] The repeaters that are used to provide the current terrestrial digital broadcasting services receive broadcasting signals from the main transmi...

AI Technical Summary

Benefits of technology

The present invention provides a demodulation apparatus and method for reducing time delay in a terrestrial digital TV broadcasting system. The apparatus includes an analog-to-digital conversion unit, a down-converting unit, a filtering unit, an up-converting unit, and an adding unit. The method involves converting an analog intermediate frequency signal into a digital signal, generating pilot components, filtering the signals to maximize signal-to-noise ratio, up-converting the filtered signals, and adding them back together to restore them to baseband signals for broadcasting. This invention allows for the use of on-channel repeaters with low time delay and excellent signal quality, which can expand the relay area and minimize the impact of system delay on receivers.

Problems solved by technology

This is very inefficient in the aspect of frequency usage, because the same frequency cannot be re-used in the neighboring area but it can be used in a far region where no interference between the same frequencies is generated.

However, as shown in FIG. 2, in case where broadcasting signals are relayed using the on-channel repeaters 22 to 25 through the same frequency band A, interference may be generated between the same channels and the time-delayed multi-path signals cannot be removed in the equalization unit of a receiver.

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