Apparatus for recovering carrier

• US 20040067039A1
• Filed: 10/02/2003
• Published: 04/08/2004
• Est. Priority Date: 10/04/2002
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Jun, Jung Sig
• Granted Patent: US 7,251,295 B2
• Time in Patent Office: Days
• US Class Current: 386/1
• CPC Class Codes: H04L 2027/0028 at passband only
• CPC Class Codes: H04L 2027/0057 quadrature phase
• CPC Class Codes: H04L 2027/0067 Phase error detectors
• CPC Class Codes: H04L 2027/0087 Out-of-band signals, (e.g. pilots)
• CPC Class Codes: H04L 27/066 Carrier recovery circuits H04L27/2271 takes precedence
• CPC Class Codes: H04N 21/426 Internal components of the client ; Characteristics thereof H04N5/44 takes precedence
• CPC Class Codes: H04N 5/455 Demodulation-circuits

Abstract

An apparatus for recovering a carrier is disclosed, for recovering a carrier correctly even though ghost exists in a signal received in a television, which includes a signal converter outputting baseband I, Q signals by multiplying digitized passband I, Q signals by a complex carrier according to a phase error; first and second filters removing data components of the baseband I, Q signals; a divider dividing a signal outputted from the second filter by a signal outputted from the first filter; a multiplier multiplying a signal outputted from the divider by the baseband I signal delayed for a predetermined time period; and an oscillator generating a complex carrier according to a signal outputted from the multiplier.

Claims

1. An apparatus for recovering a carrier comprising:

a signal converter outputting baseband I, Q signals by multiplying digitized passband I, Q signals by a complex carrier according to a phase error;

first and second filters removing data components of the baseband I, Q signals;

a divider dividing a signal outputted from the second filter by a signal outputted from the first filter;

a multiplier multiplying a signal outputted from the divider by the baseband I signal delayed for a predetermined time period; and

an oscillator generating a complex carrier according to a signal outputted from the multiplier.

2. The apparatus of claim 1, wherein the divider divides a pilot component of the baseband Q signal by a pilot component of the baseband I signal.

3. The apparatus of claim 1, further comprising a gain multiplier multiplying the signal outputted from the divider by a gain according to the delayed baseband I signal.

4. The apparatus of claim 1, further comprising:

a delay delaying the signal outputted from the first filter for a predetermined time period; and

a sign extractor extracting a sign of the signal outputted from the delay, and providing the extracted sign to the multiplier.

5. A method for recovering a carrier comprising:

(a) converting digitized passband I, Q signals to baseband I, Q signals;

(b) removing data components from the baseband I, Q signals;

(c) dividing the baseband Q signal having the data component removed therefrom by the baseband I signal having the data component removed therefrom;

(d) delaying the baseband I signal having the data component removed therefrom for a predetermined time period, and multiplying the delayed baseband I signal by the division result; and

(e) generating a complex carrier according to the multiplication result.

6. The method of claim 5, further comprising a step of multiplying the division result by a constant gain according to the delayed baseband I signal, after delaying the baseband I signal.

7. An apparatus for recovering a carrier comprising:

a signal converter outputting baseband I, Q signals by multiplying digitized passband I, Q signals by a complex carrier according to a phase error;

first and second filters transmitting pilot components of the baseband I, Q signals;

a divider dividing the pilot component of the baseband Q signal by the pilot component of the baseband I signal;

a delay delaying the pilot component of the baseband I signal for a predetermined time period;

a gain multiplier multiplying a signal outputted from the divider by a constant gain according to a signal outputted from the delay;

a multiplier multiplying a signal outputted from the gain multiplier by the signal outputted from the delay; and

an oscillator generating a complex carrier according to a signal outputted from the multiplier.

8. The apparatus of claim 7, further comprising a sign extractor extracting a sign from the pilot component of the baseband I signal outputted from the delay, and providing the extracted sign to the multiplier.

9. A method for recovering a carrier comprising:

(a) outputting baseband I, Q signals by multiplying digitized passband I, Q signals by a complex carrier according to a phase error;

(b) filtering the baseband I, Q signals to transmit pilot components thereof;

(c) dividing the pilot component of the baseband Q signal by the pilot component of the baseband I signal;

(d) delaying the pilot component of the baseband I signal for a predetermined time period, and multiplying the division result by a constant gain according to the pilot component of the delayed baseband I signal; and

(e) generating a complex carrier according to the multiplication result.

10. The method of claim 9, further comprising:

extracting a sign from the pilot component of the delayed baseband I signal;

calculating a phase error by multiplying the multiplication result by the extracted sign; and

generating a complex carrier proportional to the phase error.