Apparatus and method for corresponding frequency synchronization in on-channel repeater

• US 20090129450A1
• Filed: 05/12/2005
• Published: 05/21/2009
• Est. Priority Date: 05/12/2004
• 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, Heung-Mook, Eum, Ho-Min, Seo, Jae-Hyun, Kim, Seung-Won, Lee, Yong-Tae
• Granted Patent: US 7,773,665 B2
• Time in Patent Office: Days
• US Class Current: 375/214
• CPC Class Codes: H03J 7/04 where the frequency control is accomplished by varying the electrical characteristics of a non-mechanically adjustable element or where the nature of the frequency controlling element is not significant
• CPC Class Codes: H04B 7/15528 Control of operation parameters of a relay station to exploit the physical medium
• CPC Class Codes: H04H 20/02 Arrangements for relaying broadcast information
• CPC Class Codes: H04H 20/67 Common-wave systems, i.e. using separate transmitters operating on substantially the same frequency
• CPC Class Codes: H04H 20/72 of terrestrial networks
• CPC Class Codes: H04W 56/00 Synchronisation arrangements

Abstract

Provided is a frequency synchronizing apparatus and method that can synchronize frequencies between receiving signals and transmitting signals by extracting a carrier error and sampling timing error information in a synchronization process of the receiving signal from a main transmitter or another repeater and reflecting them in the transmitting signal in an on-channel repeater. The apparatus includes a carrier recovery means for compensating a carrier frequency error of a receiving signal; a timing recovery means for compensating a sampling timing error of the receiving signal; a carrier error reflecting means for reflecting the carrier frequency error extracted from the carrier recovery means to a transmitting signal; and a timing error reflecting means for reflecting the sampling timing error extracted from the timing recovery means to the transmitting signal. The present invention is used to form an on-channel repeating network in any transmission system including a digital television broadcasting system.

Claims

1. A frequency synchronizing apparatus for an on-channel repeater receiving signals on one channel and distributing the signals on the same channel, comprising:

a carrier recovery means for compensating a carrier frequency error of a receiving signal;

a timing recovery means for compensating a sampling timing error of the receiving signal;

a carrier error reflecting means for reflecting the carrier frequency error extracted from the carrier recovery means to a transmitting signal; and

a timing error reflecting means for reflecting the sampling timing error extracted from the timing recovery means to the transmitting signal.

2. The apparatus as recited in claim 1, wherein the carrier error reflecting means includes:

a numerically controlled oscillator for converting a carrier phase error extracted from the carrier recovery means into a frequency value;

a frequency inverter for inverting the sign of the converted frequency value; and

a frequency converter for shifting the carrier frequency of the transmitting signal as much as the sign-inverted frequency value.

3. The apparatus as recited in claim 2, wherein the carrier error reflecting means further includes:

a low pass filter for reducing phase jitter of the carrier phase error extracted from the carrier recovery means.

4. The apparatus as recited in claim 1, wherein the carrier error reflecting means includes:

a frequency inverter for inverting the sign of the carrier frequency error outputted from the numerically controlled oscillator of the carrier recovery means; and

a frequency converter for shifting the carrier frequency of the transmitting signal as much as the sign-inverted carrier frequency error.

5. The apparatus as recited in claim 1, wherein the timing error reflecting means includes:

a numerically controlled oscillator for converting the sampling timing phase error extracted from the timing recovery means into a sample rate;

an inverse converter for obtaining an inverse value of the converted sample rate; and

a resampler for resampling the transmitting signal according to the inverse value of the sample rate.

6. The apparatus as recited in claim 5, further including:

a low pass filter for reducing phase jitter of the sampling timing phase error extracted from the timing recovery means.

7. The apparatus as recited in claim 1, further comprising:

an inverse converter for obtaining an inverse value of the sample rate based on the sampling timing phase error outputted from the numerically controlled oscillator of the timing recovery means; and

a resampler for resampling the transmitting signal according to the inverse value of the sample rate.

8. A frequency synchronizing apparatus for an on-channel repeater receiving signals on one channel and distributing the signals on the same channel, comprising:

an analog-digital converting means for converting an analog receiving signal into a digital signal;

a carrier recovery means for compensating a carrier frequency error of the digital signal;

a timing recovery means for compensating a sampling timing error of the digital signal;

a carrier error reflecting means for reflecting the carrier frequency error extracted from the carrier recovery means to a transmitting signal;

a digital-analog converting means for converting the transmitting signal reflected with the carrier frequency error into an analog signal; and

a voltage controlled oscillator for reflecting the sampling timing error extracted from the timing recovery means to an oscillation signal and providing the oscillation signal to the analog-digital converting means and the digital-analog converting means.

9. The apparatus as recited in claim 8, wherein the carrier error reflecting means includes:

a numerically controlled oscillator for converting the carrier phase error extracted from the carrier recovery means into a frequency value;

a frequency inverter for inverting the sign of the converted frequency value; and

a frequency converter for shifting a carrier frequency of the transmitting signal as much as the sign-inverted frequency value.

10. The apparatus as recited in claim 9, wherein the carrier error reflecting means further includes:

a low pass filter for reducing phase jitter of the carrier phase error extracted from the carrier recovery means.

11. The apparatus as recited in claim 8, wherein the carrier error reflecting means includes:

a frequency inverter for inverting the sign of the carrier frequency error outputted from the numerically controlled oscillator of the carrier recovery means; and

a frequency converter for shifting a carrier frequency of the transmitting signal as much as the sign-inverted carrier frequency error.

12. A frequency synchronizing method for an on-channel repeater receiving signals on one channel and distributing the signals on the same channel, comprising the steps of:

a) compensating a carrier frequency error of a receiving signal;

b) compensating a sampling timing error of the receiving signal;

c) reflecting the carrier frequency error extracted in the step (a) to a transmitting signal; and

d) reflecting the sampling timing error extracted in the step (b) to the transmitting signal.

13. The method as recited in claim 12, wherein the step c) includes the steps of:

c1) converting a carrier phase error extracted in the step a) into a frequency value;

c2) inverting the sign of the converted frequency value; and

c3) shifting the carrier frequency of the transmitting signal as much as the sign-inverted frequency value.

14. The method as recited in claim 13, wherein the step c) further includes the step of:

c4) reducing phase jitter of the carrier phase error extracted from the step a).

15. The method as recited in claim 12, wherein the step a) includes the step of:

a1) detecting a carrier phase error in the receiving signal and converting the carrier phase error into a frequency value, and

the step c) includes the steps of;

c2) inverting the sign of the frequency value; and

c3) shifting a carrier frequency of the transmitting signal as much as the sign-inverted frequency value.

16. The method as recited in claim 12, wherein the step d) includes the step of:

d1) converting the sampling timing phase error detected in the step b) into a sample rate;

d2) obtaining an inverse value of the sample rate; and

d3) resampling the transmitting signal according to the inverse value of the sample rate.

17. The method as recited in claim 16, wherein the step d) further includes the step of:

d4) reducing phase jitter of the sampling timing phase error detected in the step b).

18. The method as recited in claim 12, wherein the step b) includes the step of:

b1) detecting a sampling timing phase error in the receiving signal and converting the sampling timing phase error into a sample rate, and

the step d) includes the steps of;

d2) obtaining an inverse value of the sample rate; and

d3) resampling the transmitting signal according to the inverse value of the sample rate.

19. A frequency synchronizing method for an on-channel repeater receiving signals on one channel and distributing the signals on the same channel, comprising the steps of:

a) converting an analog receiving signal into a digital signal;

b) compensating a carrier frequency error of the digital signal;

c) compensating a sampling timing error of the digital signal;

d) reflecting the carrier frequency error extracted in the step b) to a transmitting signal; and

e) converting the transmitting signal reflected with the carrier frequency error into an analog signal,

wherein the sampling timing error detected in the step c) is equally used in the steps a) and e).

20. The method as recited in claim 19, wherein the step d) includes the steps of:

d1) converting the carrier phase error extracted in the step b) into a frequency value;

d2) inverting the sign of the converted frequency value; and

d3) shifting a carrier frequency of the transmitting signal as much as the sign-inverted frequency value.

21. The method as recited in claim 19, wherein the step d) further includes the step of:

d4) reducing phase jitter of the extracted carrier phase error.

22. The method as recited in claim 19, wherein the step b) includes the step of:

b1) detecting a carrier phase error in the receiving signal and converting the detected carrier phase error into a frequency value, and

the step d) includes the steps of;

d2) inverting the sign of the frequency value; and

d3) shifting a carrier frequency of the transmitting signal as much as the sign-inverted frequency value.