KR100215460B1 - Tracking error signal generating method and apparatus - Google Patents

Abstract

The present invention relates to an apparatus and method for generating a tracking error signal of a D-VCR (Digital-Video Cassette Recorder). The apparatus includes sampling means for sampling a reproduction signal read from a recording medium at a predetermined sampling frequency, discrete Fourier Transform (DFT) for discrete data successively outputted from the sampling means, 2 pilot signal, and a tracking error signal generating means for receiving a frequency component of the first and second pilot signals and generating a tracking error signal. The present invention can provide a system not only capable of accurately detecting a pilot signal of a single frequency component superimposed on a video signal but also having characteristics that are easy to manufacture an IC and are resistant to changes in temperature or surrounding environment.

Description

Apparatus and method for generating tracking error signal

The present invention relates to an apparatus and method for generating a tracking error signal of a DVCR. In general, the DVCR controls the driving of the head in accordance with an Automatic Track Following (ATF) scheme. 1 shows a pattern of a pilot signal recorded on a tape by the SD-DVCR format and a running state of the head. As shown, there are three types of pilot signals (pilot tones) used in the ATF scheme of the DVCR. The track f _{0 on which the} dual pilot signals f ₁ and f ₂ are not recorded is repeated in a period of two tracks and the first and second pilot signals f ₁ and f ₂ having different low frequencies are respectively recorded on four tracks Is recorded so as to overlap with the video signal of the corresponding track. When the head of the pilot signals (f _1, f ₂₎ is not recorded track to the left or right bias when driving a (f ₀₎ on this tape, since the frequency component of the pilot signal recorded in skewed tracks are more detected The current running state of the head can be known.

2 shows a configuration of an apparatus for generating a tracking error signal in a general DVCR. The video signal read out from the tape through the head is amplified by a playback amplifier (not shown) and then input to the buffer 21 shown in FIG. The buffer 21 applies the regenerated amplified input signal to the first low-pass filter 22 at the subsequent stage. The first low-pass filter 22 outputs a low-frequency band signal including the pilot signal. The preamplifier 23 receives the low frequency band signal and amplifies it to a predetermined size. The amplified signal is applied to the rear-end band-pass filters 24 and 26, and the first band-pass filter 24 having the pass band of the frequency f ₁ has the first pilot signal f ₁ superimposed on the image signal Component. Similarly, the second bandpass filter (26) detects a second component of the pilot signal (f ₂₎ which is superimposed on the video signal. The level detectors 25 and 27 connected to the output terminals of the band-pass filters 24 and 26 convert the first and second pilot signals f ₁ and f ₂ to DC voltage, . The automatic amplifier 28 receives the outputs of the level detectors 25 and 27, detects a level difference, and generates a tracking error signal indicating how much the current head is biased to the left or right. That is, the first when the frequency component of the pilot signal (f ₁₎ is more detection than the frequency component of the second pilot signal (f _2), the current head is shifted to the track which is recorded first pilot signal (f ₁₎ . In contrast the second case where the frequency component of the pilot signal (f ₂₎ More detected more frequency components of the first pilot signal (f ₁₎ is the head drive shifted to the track which is recorded in the second pilot signal (f ₂₎ . At this time, the level of the head is also known by the level character. The second low-pass filter 29 receives the tracking error signal and removes a noise component of a high-frequency component, and outputs the noise component to an unillustrated servo.

On the other hand, a technique for generating a tracking error signal is also disclosed in a patent publication No. 6-349157 filed by Matsushita, Japan. In this publication, a reproduction signal is first subjected to a balanced modulation through a band-pass filter having the widths of the first and second pilot signals (f ₁ , f ₂ ), and then the frequency components of the respective pilot signals are subjected to low- We suggest a method.

It is not easy to implement a band-pass filter for detecting a single frequency component of f ₁ and f _{2, so that} the above-described tracking error signal generating apparatus can not accurately detect the pilot signal from the video signal. In addition, since the tracking error signal is generated from a pilot signal that is detected incorrectly, there is a problem that accuracy can not be achieved even when performing tracking control. Therefore, in the present invention, it is necessary to more accurately detect the pilot signal superimposed on the video signal in the video signal.

1 shows a pattern of a pilot signal recorded on a tape by the SD-DVCR format and a running state of the head,

FIG. 2 is a block diagram showing a tracking error signal generating apparatus of a general DVCR. FIG.

3 is a block diagram showing a tracking error signal generating apparatus according to the present invention.

DESCRIPTION OF THE REFERENCE NUMERALS

31: A / D converter 32, 33: Frequency detector

34: subtracter 35: D / A converter

An apparatus for detecting a pilot signal superimposed on a video signal of each track of a recording medium for tracking control, the apparatus comprising: Frequency detecting means for receiving the discrete data successively outputted from the sampling means and carrying out discrete Fourier transform (DFT) on the frequency components of the first and second pilot signals, respectively, 2 pilot signal, and generates a tracking error signal.

A method for generating a tracking error signal according to the present invention is a method for detecting a pilot signal superimposed on and recorded on a video signal of each track of a recording medium for tracking control, A frequency detecting step of detecting frequency components of first and second pilot signals by performing discrete Fourier transform (DFT) on discrete data output by the sampling step, And a tracking error signal generating step of calculating a difference value of frequency components of the first and second pilot signals detected in the frequency detecting step and generating a calculation result as a tracking error signal.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIG. 3 attached hereto.

3 shows a configuration of an apparatus for generating a tracking error signal according to the present invention. The tracking error signal generator of FIG. 3 is comprised of a device implementing discrete Fourier transform (DFT) as shown in the following equation.

_{One 2 One 2 One One One 2 One 2 One 2}

It is an object of the present invention to provide a tracking error signal generating apparatus for performing an Asynchronous Fourier Transform (DFT) on a video playback signal of a DVCR to accurately detect a recorded pilot signal superimposed on a video signal for tracking control, And to provide such a method.

Claims (9)

An apparatus for detecting a pilot signal superimposed on a video signal of each track of a recording medium for tracking control, the apparatus comprising: means for sampling a reproduction signal read from the recording medium at a predetermined sampling frequency; Frequency detecting means for receiving discrete data continuously output from the sampling means and performing discrete Fourier transform (DFT) on the discrete data to detect frequency components of the first and second pilot signals, respectively; And a tracking error signal generation unit receiving the frequency components of the first and second pilot signals and generating a tracking error signal. The method of claim 1, wherein the first and the second pilot signal is generated tracking error signal, characterized in that a pilot signal having a frequency of f ₁ and f ₂ of each SD format devices. 3. The apparatus of claim 1 or 2, wherein the frequency detecting means comprises: multipliers receiving the discrete data and generating signals having a quadrature phase with respect to each other; Sigma calculators for receiving and accumulating consecutive quadrature-phase discrete data; Squared value calculators for receiving and squaring the accumulated discrete data; An adder for adding the outputs of the squared value calculators; And a square root calculator for receiving an output of the adder and obtaining a square root. 4. The apparatus of claim 3, wherein the signals having a quadrature phase are a real component and an imaginary component of the discrete data. 2. The apparatus of claim 1, wherein the tracking error signal generating means comprises a subtracter for receiving and subtracting frequency components of the first and second pilot signals. A method for detecting a pilot signal superimposed on a video signal of each track of a recording medium for tracking control, the method comprising the steps of: sampling a reproduction signal read from the recording medium at a predetermined sampling frequency; A frequency detecting step of detecting frequency components of the first and second pilot signals by performing discrete Fourier transform (DFT) on the discrete data output by the sampling step; And a tracking error signal generation step of calculating a difference value of frequency components of the first and second pilot signals detected in the frequency detection step and generating a calculation result as a tracking error signal. The method of claim 6, wherein the first and the second pilot signal is generated tracking error signal, characterized in that a pilot signal having a frequency of f ₁ and f _2, respectively of the SD format. The method of claim 6 or 7, wherein the frequency detection step comprises: receiving the discrete data and generating signals having a quadrature phase with respect to each other; Accumulating the quadrature-phase discrete data; Squaring each of the accumulated discrete data; Adding the output of the squared discrete data; And obtaining a square root of the addition result. 9. The method of claim 8, wherein the signals having a quadrature phase are a real component and an imaginary component of the discrete data.