On-channel repeating apparatus and method for terrestrial digital television broadcasting service

• US 20040237117A1
• Filed: 12/30/2003
• Published: 11/25/2004
• Est. Priority Date: 05/20/2003
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: Park, Sung-Ik, Lee, Soo-In, Kim, Seung-Won, Lee, Yong-Tae
• Granted Patent: US 7,809,048 B2
• Time in Patent Office: Days
• US Class Current: 725/131
• CPC Class Codes: H04H 20/06 among broadcast stations
• CPC Class Codes: H04N 21/426 Internal components of the client ; Characteristics thereof H04N5/44 takes precedence
• CPC Class Codes: H04N 21/6112 involving terrestrial transmission, e.g. DVB-T
• CPC Class Codes: H04N 5/211 Ghost signal cancellation H04N23/81 takes precedence
• CPC Class Codes: H04N 5/40 Modulation circuits
• CPC Class Codes: H04N 5/455 Demodulation-circuits

Abstract

A repeater and method for an ATSC terrestrial digital TV broadcasting service. The on-channel repeater includes: a receiving unit for receiving a Radio Frequency (RF) broadcast signal from a main transmitter; a frequency downlink converting unit for converting the received RF broadcast signal into an intermediate frequency (IF) signal; a demodulating unit for converting the converted IF signal into a baseband signal; an equalizing unit for removing noise and multi-path signals generated from the converted baseband signal; a modulating unit for converting the baseband signal into an IF signal; a frequency uplink converting unit for converting the IF signal into a RF broadcast signal; a high power amplifying unit for amplifying and repeating the converted RF broadcast signal; a transmitting unit for transmitting the RF broadcast signal outputted from the high power amplifying unit; and a signal synchronizing unit for generating the first reference frequency, and generating the second reference frequency based on the first reference frequency such that the transmission/reception signal are frequency-and-phase synchronized.

Claims

1. An on-channel repeating apparatus for an Advanced Television System Committee (ATSC) terrestrial digital TV broadcasting service, in which a terrestrial digital television broadcast signal is repeated over an on-channel, the on-channel repeater comprising:

a receiving unit for receiving a Radio Frequency (RF) broadcast signal from a main transmitter;

a frequency downlink converting unit for converting the received RF broadcast signal into an intermediate frequency (IF) signal based on a first reference frequency;

a demodulating unit for converting the converted IF signal into a baseband signal;

an equalizing unit for removing a predetermined signal generated between the main transmitter and the on-channel repeater from the converted baseband signal;

a modulating unit for converting the baseband signal outputted from the equalizing unit, into an IF signal;

a frequency uplink converting unit for converting the IF signal into a RF broadcast signal based on a second reference frequency;

a high power amplifying unit for amplifying and repeating the converted RF broadcast signal;

a transmitting unit for transmitting the RF broadcast signal outputted from the high power amplifying unit; and

a signal synchronizing unit for generating the first reference frequency to provide the generated first reference frequency for the IF downlink converting unit to the demodulating unit which shifts the IF signal to the baseband signal, and generating the second reference frequency based on the first reference frequency to provide the generated second reference frequency for the RF uplink converting unit such that the transmission/reception signal are frequency-and-phase synchronized.

2. The on-channel repeater as recited in claim 1, wherein the receiving unit includes:

a reception antenna for receiving the RF broadcast signal from the main transmitter; and

a RF receiving unit for receiving the RF broadcast signal from the reception antenna.

3. The on-channel repeater as recited in claim 1, wherein the predetermined signal of the equalizing unit includes:

a noise signal and a multi-path signal generated due to a transmission channel between the main transmitter and the on-channel repeater; and

a feedback signal generated due to low isolation of transmission/reception antennas.

4. The on-channel repeater as recited in claim 3, wherein the equalizing unit includes:

an input-to-equalizer signal storing unit for storing the signal input from the demodulating unit therein;

a filtering unit for performing channel equalization by repetitively filtering the signal input from the demodulating unit;

a modified viterbi decoding unit for detecting a symbol representing decision data from the output signal transmitted through the filtering unit by using a modified viterbi decoding algorithm with a Trace Back Depth TBD being one and a complexity being reduced to output the detected symbol at a decision directed mode;

a statistical data computing unit for computing and outputting necessary statistical error data at a blind mode;

a switching unit for selecting an output signal in one of the decision directed mode and the blind mode;

an error signal calculating unit for comparing the output signal representing decision data or statistical error data in the decision directed mode or the bind mode selected by the switching unit with an output signal as decision feedback equalization data of the filtering unit to calculate the error signal;

a FFF tap coefficient renewing unit for renewing a tap coefficient applied to a feedback filter unit (FFF) by using an output signal of the input-to-equalizer signal storing unit and the calculated error signal; and

a FBF tap coefficient renewing unit for renewing a tap coefficient applied to the feedback filtering unit (FBF) by using the output signal of the modified viterbi decoding unit and the calculated error signal.

5. The on-channel repeater as recited in claim 4, wherein the equalizing unit use a viterbi decoder, a modified viterbi decoder, a Soft Output Viterbi Algorithm SOVA decoder and a simple slicer as a symbol detector.

6. The on-channel repeater as recited in claim 5, wherein the equalizing unit uses a training sequence as an output signal thereof at a data duration including the training sequence, and uses an output signal of the symbol detector as an output signal of the on-channel repeater at a data duration excluding training sequence.

7. An on-channel repeating method of an on-channel repeater, the on-channel repeating method comprising the steps of:

a) receiving a Radio Frequency (RF) broadcast signal from a main transmitter to convert the received RF broadcast signal into an intermediate frequency (IF) signal based on a first reference frequency;

b) converting the downlink-converted IF signal into a baseband signal, and removing a certain predetermined signal generated between a main transmitter and the on-channel repeater, from the converted baseband signal;

c) at the time of transmission, converting the baseband signal without the predetermined signal into an IF signal, and then converting the converted IF signal into a RF broadcast signal based on the second reference frequency based on the first reference frequency so as to perform a frequency and phase synchronization with the received broadcast signal; and

d) amplifying and transmitting the uplink-converted RF broadcast signal.

8. The on-channel repeating method as recited in claim 7, wherein the predetermined signal includes:

a noise signal and a multi-path signal generated due to a transmission channel between the main transmitter and the on-channel repeater; and

a feedback signal generated due to low isolation of transmission/reception antennas.

9. The on-channel repeating method as recited in claim 7, wherein in the step b), one of a viterbi decoder, a modified viterbi decoder, a SOVA (Soft Output Viterbi Algorithm) decoder and a simple slicer is used as a symbol detector.

10. The on-channel repeating method as recited in claim 9, wherein in the step b), a training sequence is used as an output signal of the equalizing unit at a duration including the training sequence, and an output signal of the symbol detector is used as an output signal of an equalizing unit at a duration excluding the training sequence.

11. The on-channel repeating method as recited in claim 7, wherein the RF broadcast signal of the fourth step is a signal having the same frequency and phase as those of the received RF broadcast signal.