Adjustable video frequency response filter for a set-top terminal

• US 20030018982A1
• Filed: 07/23/2001
• Published: 01/23/2003
• Est. Priority Date: 07/23/2001
• Status: Abandoned Application

• Current Assignee: General Instrument Corporation (CommScope Holding Company, Inc.)
• Original Assignee: General Instrument Corporation (CommScope Holding Company, Inc.)
• Inventors: Zeidler, David Eric, Muller, Mathias Anton, Petry, Joseph A.
• Application Number:
  US09/909,978
• Publication Number:
  US 20030018982A1
• Time in Patent Office: Days
• US Class Current: 725/151
• CPC Class Codes: H03H 17/06 Non-recursive filters
• CPC Class Codes: H04N 17/00 Diagnosis, testing or measuring for television systems or their details
• CPC Class Codes: H04N 17/02 for colour television signals
• CPC Class Codes: H04N 5/4446 IF amplifier circuits specially adapted for B&W TV RF amplifiers in general H03F3/189
• CPC Class Codes: H04N 5/455 Demodulation-circuits
• CPC Class Codes: H04N 7/173 with two-way working, e.g. subscriber sending a programme selection signal
• CPC Class Codes: H04N 9/455 Generation of colour burst signals; Insertion of colour burst signals in colour picture signals or separation of colour burst signals from colour picture signals H04N9/45 takes precedence
• CPC Class Codes: H04N 9/68 for controlling the amplitude of colour signals, e.g. automatic chroma control circuits H04N9/71, H04N9/73 take precedence; camera processing pipelines for controlling the colour saturation of colour signals H04N23/86

Abstract

A system and method for adjusting a video frequency response of a set-top terminal using a video frequency response filter. The video frequency response filter is included in a video processing subsystem. The video frequency response filter adjusts the video frequency response of the set-top terminal by using a set of filter coefficients determined by a microprocessor subsystem. The set of filter coefficients can be determined by various methods. One method is by measuring the frequency response degradation of the set-top terminal without the video frequency response filter installed in the set-top terminal. Another method is to measure the amplitude of a color burst signal included in the video input signal. Yet another method is to measure the amplitudes of a multi-burst signal included in the video input signal. The invention compensates for imperfections in the set-top circuit components and enables the set-top terminal to consistently meet the specification requirements for channel flatness without increasing the cost of the components.

Claims

1. A set-top terminal, comprising:

a tuner for receiving a video input signal;

a video demodulator/descrambler decoder for receiving the video input signal from the tuner; and

a video processing subsystem for receiving the video input signal from the video demodulator/descrambler, the video processing subsystem including a video frequency response filter for adjusting a frequency response of the set-top terminal.

2. The set-top terminal according to claim 1, further including a microprocessor subsystem operatively coupled to the video processing subsystem, the microprocessor subsystem determining a set of filter coefficients for the video frequency response filter.

3. The set-top terminal according to claim 2, wherein the set of filter coefficients comprises a set of Finite Impulse Response (FIR) filter coefficients.

4. The set-top terminal according to claim 3, wherein the FIR filter coefficients are determined by empirical measurements of a degradation of the frequency response of the set-top terminal prior to installation of the video frequency response filter.

5. The set-top terminal according to claim 3, wherein the FIR filter coefficients are determined by measuring an amplitude of a color burst signal included in the video input signal.

6. The set-top terminal according to claim 3, wherein the FIR filter coefficients are determined by measuring an amplitude of a multi-burst signal included in the video input signal.

7. The set-top terminal according to claim 6, further including a memory for temporarily storing at least a portion of the input video signal for measuring the amplitude of the multi-burst signal by the microprocessor subsystem.

8. A method for adjusting a frequency response of a set-top terminal, comprising the steps of:

receiving a video input signal using a tuner;

receiving the video input signal from the tuner using a video demodulator/descrambler decoder; and

receiving the video input signal from the video demodulator/descrambler using a video processing subsystem, the video processing subsystem adjusting a frequency response of the set-top terminal using a video frequency response filter.

9. The method according to claim 8, further including the step of determining a set of filter coefficients for the video frequency response filter using a microprocessor subsystem operatively coupled to the video processing subsystem.

10. The method according to claim 9, wherein the set of filter coefficients comprises a set of Finite Impulse Response (FIR) filter coefficients.

11. The method according to claim 10, wherein the FIR filter coefficients are determined by empirical measurements of a degradation of the frequency response of the set-top terminal prior to installation of the video frequency response filter.

12. The method according to claim 10, wherein the FIR filter coefficients are determined by measuring an amplitude of a color burst signal included in the video input signal.

13. The method according to claim 10, wherein the FIR filter coefficients are determined by measuring an amplitude of a multi-burst signal included in the video input signal.

14. The method according to claim 13, further including the step of temporarily storing at least a portion of the input video signal for measuring the amplitude of the multi-burst signal by the microprocessor subsystem.

16. The method according to claim 15, wherein the video frequency response filter uses a set of filter coefficients determined by a microprocessor subsystem operatively coupled to the video processing subsystem to adjust the frequency response of the set-top terminal.

17. The method according to claim 16, wherein the set of filter coefficients are determined by empirical measurements.

18. The method according to claim 16, wherein the filter coefficients are determined by measuring an amplitude of a color burst signal.

19. The method according to claim 16, wherein the filter coefficients are determined by measuring an amplitude of a multi-burst signal.

15. A method for adjusting a frequency response of a set-top terminal, comprising the steps of:

providing a video input signal to a set-top terminal, the set-top terminal including a video processing subsystem, a microprocessor subsystem, and a memory, the video processing subsystem including a video frequency response filter; and

adjusting a frequency response of the set-top terminal using the video frequency response filter.