JP2001325759A - Reproducing device and reproducing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reproducing device and the reproducing method for performing satisfactory tracking control. SOLUTION: This reproducing device is provided with a reproduction means for reproducing such an information signal from a recording medium that a pilot signal having a specific frequency is superimposed, a pilot detection means for detecting the pilot signal component in the above reproduced information signal by using a filter taking a frequency around the above specific frequency as the center frequency, and a control means for controlling the tracking between the reproduction means and the recording medium in accordance with the output of the pilot detection means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reproducing apparatus and a reproducing method, and more particularly to a process for detecting a signal component of a predetermined frequency from a reproduced signal.

[0002]

2. Description of the Related Art As a device of this type, a digital VTR which records and reproduces image signals and audio signals as digital signals on a magnetic tape has been known.

In recent years, the DV format has been proposed by the HD Digital VCR Council as a format for consumer digital VTRs.

[0004] In the DV format, a pilot signal for tracking control during reproduction is superimposed using digital modulation processing using processing such as 24-25 conversion and interleaved NRZI of data to be recorded.

[0005] The pilot signal includes signals of frequencies f1 and f2. During recording, F0, F1, F0,
Tracks are formed in the order of F2, F0, and F1. here,
F1 is a track for recording data on which a pilot signal of frequency f1 is superimposed, and F2 is a track for recording data on which a pilot signal of frequency f2 is superimposed. Also, F
0 is a track for recording data on which neither pilot signal f1 nor f2 is superimposed.

At the time of reproduction, when the rotary head traces the track F0, the crosstalk amounts of the f1 and f2 pilot signals from both adjacent tracks are compared, and the crosstalk amounts of f1 and f2 are made equal. Tracking control is performed by controlling the transport operation of the tape so as to be as follows.

[0007]

As described above, in order to perform tracking control during reproduction, the frequency f
It is necessary to detect the pilot signal components 1 and f2.
For this purpose, a band-pass filter (BPF) is usually used.
Is used.

In a digital VTR, it has been considered that this BPF is constituted by a digital circuit in order to reduce the cost of the circuit and eliminate the need for adjustment.

As described above, in the DV format, a pilot signal having a relatively low frequency is superimposed using digital modulation processing, and the frequency of the superimposed pilot signal depends on the pattern of digital data to be recorded. May deviate from the original frequencies of f1 and f2.

For this reason, the BP having the center frequencies f1 and f2
If an attempt is made to detect a pilot signal component from data in which the frequency of the superimposed pilot signal is shifted by F, the detected output level will be low, and good tracking control will not be performed.

An object of the present invention is to solve the above-mentioned problems.

Another object of the present invention is to perform good tracking control.

Still another object of the present invention is to reduce the amount of pilot signal superimposed accurately even when the frequency of the pilot signal superimposed on reproduction data is slightly different from a predetermined frequency. It should be detectable.

[0014]

SUMMARY OF THE INVENTION In order to solve the above problems and achieve the above object, the present invention provides a reproducing means for reproducing an information signal on which a pilot signal of a predetermined frequency is superimposed from a recording medium; Pilot detection means for detecting the pilot signal component in the reproduction information signal using a filter having a center frequency near the predetermined frequency, and the reproduction means and the recording medium according to an output of the pilot detection means And control means for controlling tracking between them.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a reproduction system of a digital VTR to which the present invention is applied. The digital VTR in FIG. 1 is a VTR compatible with the DV format, which is a format of a consumer digital VTR proposed by the HD Digital VCR Council.

In FIG. 1, a rotary head 103 traces a number of tracks formed on a tape 101, reproduces a recorded signal, and outputs the signal to an amplifier 105. The amplifier 105 amplifies the reproduction signal to a predetermined level and outputs the signal to the equalizer 107. The equalizer 107 performs an integral equalization process for equalizing the deterioration of the reproduction signal waveform due to the magnetic recording / reproduction system, and outputs the result to the A / D converter 109. A / D converter 1
Reference numeral 09 denotes a sampled reproduction signal according to the clock output from the clock generation circuit 113, converts the sampled signal into multi-value digital data of n bits per sample (n is an integer of 2 or more), and reproduces the reproduction signal processing circuit 111. Circuit 113
And to the pilot detection circuit 115.

The reproduction signal processing circuit 111 detects a binary digital signal from the reproduction digital data, performs a decoding process corresponding to the compression and encoding processes performed at the time of recording, and converts it into the original image and audio data. Output.

The clock generation circuit 113 has a PLL circuit, generates a clock phase-synchronized with the reproduced data from the A / D converter 109, and outputs the clock to the A / D converter 109 and the pilot detection circuit 115.

In this embodiment, as described above, the pilot signal for tracking control during reproduction is superimposed on the recorded signal by appropriately controlling the digital modulation processing during signal recording. The pilot detection circuit 115
Using the PG signal from the G generation circuit 117, the level of the pilot signal included in the reproduced data is detected and output to the microcomputer 119.

The microcomputer 119 includes a pilot detection circuit 11
5, a tracking error signal is detected based on the pilot signal level detection result from
A control signal for controlling the tracking between the head 103 and the track of the tape 101 is output to the control unit 21.

The tracking control circuit 121 includes the microcomputer 1
19 based on the control signal from the
3 is controlled, and the tracking operation between the tape 101 and the head 103 is controlled by controlling the transport operation of the tape 101.

Next, the pilot detection circuit 115 will be described.

In this embodiment, there are two frequencies F1 and F2 as the frequencies of the pilot signal.
In addition to tracks F1 and F2 for recording signals multiplexed with pilot signals of frequencies 1 and F2, tracks F0 for recording signals not multiplexed with pilot signals of any frequency are denoted by F1, F0, F2 and F0. Are formed in this order.

When the head traces the F0 track at the time of reproduction, the frequency F
By controlling the capstan motor so that the levels of the pilot signals 1 and F2 become equal, the tracks on the tape can be correctly traced by the head 103.

In the DV format, the frequency of F1 is 90 bits of 41.85 MHz which is the bit frequency of the recording data.
697 which is 1/465 KHz, and the frequency of F2 is 1/60 of the bit frequency 41.85 MHz.
5 KHz.

FIG. 2 is a block diagram showing a configuration of the pilot detection circuit 115.

In FIG. 2, n-bit reproduced data from the A / D converter 109 is supplied via a terminal 201 to multipliers 211a and 211a of an F1 detection circuit 203 and an F2 detection circuit 205.
13a and 211b and 213b.

An F1 detection circuit 203 functions as a BPF for detecting a signal level of a frequency F1-Δ slightly lower than the frequency F1 in the reproduced data. 205 is
Frequency F2-Δ slightly lower than frequency F2 in reproduced data
And has the same configuration as the F1 detection circuit 203. The reason why the F1 detection circuit 203 and the F2 detection circuit 205 detect signals having frequencies slightly lower than the pilot signal frequencies F1 and F2 will be described later.

In the F1 detection circuit 203, the multiplier 21
1a and 213a are supplied from pilot tone generating circuits 207a and 209a to the frequency F1-Δ
Sine wave and cosine wave are added. sin wave and cos
The waves mean sine waveforms that are 90 degrees out of phase with each other, and each of the pilot tone generation circuits 207a and 209a generates each signal regardless of the phase of the pilot signal recorded on the tape.

The multipliers 211a and 213a multiply the reproduced data by a sine wave and a cosine wave having a frequency F1-Δ, respectively, and output the multiplication results to the integrators 215a and 217a. The area signal from the integration area generation circuit 227 is output to the integrators 215a and 217a.
15a and 217a integrate the outputs of the multipliers 211a and 213a during the period indicated by the area signal.

The integration area generating circuit 227 includes the PG generator 1
An area signal indicating a period corresponding to the ITI area is generated in each track according to the PG signal indicating the rotation phase of the head 103 from the clock signal 17 and the clock from the clock generator 113.

FIG. 3 shows the relationship between the track format on the tape 101 and the integration area signal in this embodiment.

In the DV format, the ITI is located at the beginning of each track and is an area for recording data serving as a timing reference for the audio area. Also, I
Data to be recorded is predetermined in the TI area corresponding to each of the tracks F0, F1, and F2, and the level of each pilot signal to be recorded is higher than in other areas.

The multipliers 211a and 213a multiply the reproduced data by the sine component and the cos component of F1-Δ to obtain
It is possible to detect the correlation between the signal of the frequency F1-Δ superimposed on the reproduction data and the sine and cos components of the frequency F1-Δ output from the pilot tone generation circuits 207a and 209a. The output of 213a indicates the degree of correlation between the reproduced data and the frequency component of F1-Δ.

The integrators 215a and 217a store integration results at the end of the ITI area in registers 219a and 219, respectively.
1a. The values of these two registers are output to the effective value calculation circuit 223a, and from the integration result of the sin component and the cos component, sqrt (x * x + y The effective value of the frequency component of F1-Δ superimposed on the reproduction data is obtained according to the calculation formula of * y), and is output to the register 225a.

The register 225a is connected to the bus 229 of the microcomputer 119.
The contents of 25a can be read out via bus 229.

The F1 detection circuit 203 has been described above.
As in the case of No. 3, the frequency component of F2-Δ in the reproduced data is detected and stored in the register 225b.

The microcomputer 119 includes registers 225a and 225
The value of 5b is read at a predetermined timing, and the level of the pilot signal from the F1 and F2 tracks is detected based on the value of each register to perform tracking control.

Here, the detection characteristics of the F1 detection circuit 203 are shown in FIG.

The horizontal axis is frequency, and the vertical axis is the detection level when the integration area ends.

As is apparent from FIG. 4, the detection level around 467 KHz is high, and the center frequency of the F1 detection circuit 203 functioning as a BPF is shifted to 467 KHz from the frequency F1 of 465 KHz. I understand.

FIG. 5 shows the detection characteristics of the F2 detection circuit 205.

As is clear from FIG. 5, the detection level near 700 KHz is high, and the F1 detection circuit 20
5, the center frequency of the F2 detection circuit 205 functioning as a BPF is 697.5 KH, which is the frequency F2.
It can be seen that it is 700 KHz, deviating from z.

As described above, after the integration of the sine component and the integration of the cosine component are completed, the F2 detection circuit 205
Although the S value is calculated to calculate the effective value, the integral value is
FIG. 6 shows a simulation result when the MS calculation is performed.

The horizontal axis is time, and the vertical axis is I of frequency F2.
R of integrator output when data in TI area is input
The MS values are shown.

The ITI areas are PRE, SSA, TIA,
It consists of four POST areas. PRE and POS
T is composed of the same pattern having a pure pilot signal component, while SSA is composed of a plurality of sync blocks called a start sync block indicating the current data position, and data such as TIA track pitch information is recorded. Therefore, PRE or P with a pure pilot signal component
It has a slightly different frequency spectrum from OST.

In FIG. 6, reference numeral 601 denotes the RMS value of the integral output when data in the ITI area having the normal F2 frequency is input. 603 is the RM of the integrated output when data having a frequency higher by about 3 KHz is input.
An S value is shown, and 605 indicates an RMS value of an integrated output when data having a frequency lower by about 3 KHz is input.

As described above, the data in the PRE and POST areas are not affected by the frequency fluctuation, but the data in the SSA or TIA
It can be seen that the area data has a pattern that is easily affected by the frequency fluctuation. Here, the F2 detection circuit 2
Although the description has been made with respect to F <b> 05, the F1 detection circuit 203 also has a similar tendency.

Therefore, in this embodiment, the pilot tone generating circuits 207a and 209b generate a signal having a frequency lower than the frequency F1 by Δ, and the pilot tone generating circuits 207b and 209b generate a signal having a frequency lower than the frequency F2 by Δ. Then, the center frequency of the BPF for detecting each pilot signal was set as the frequency of the pilot signal actually superimposed on the reproduced data.

Here, the frequencies F1 and F2 are respectively 1/90 and 1/6 of the recording frequency 41.85 MHz.
Since it is a simple integer ratio of 0, it is easy to generate a sine waveform. However, since F1-Δ and F2-Δ are not in a simple integer ratio, signals of frequencies F1-Δ and F2-Δ If it is to be generated directly, an enormous amount of data is required, and a large-capacity ROM may be required.

Therefore, in the present embodiment, the signals of the frequencies F2-Δ and F2 + Δ are generated with a simple configuration using a counter. FIG. 7 is a diagram showing the configuration of the F2-Δ sine wave generation circuit 207a.

When the bit frequency of the recording data is set to 41.85 MHz, the ROM 701 has a cycle of 0 to 59.
The sine wave data of the frequency F2 for the clock is stored. From the ROM 701, data of each of the 0th sample to the 59th sample is output.
03 is output to the corresponding terminal.

The counter 705 includes a clock generation circuit 113
And resets itself when it counts up to 59. The switch 703 is switched according to the value of the counter 705, selects an output corresponding to the count value from the outputs of the ROM 701, and outputs the selected output.

The counter 707 counts the clock from the clock generation circuit 113 from 0 to 239, and when the count value becomes 239, the counter 705
Output a hold signal and reset itself. The counter 705 counts from 0 to 59 and resets itself when counting to 59.
Output a hold signal, the output is held for one clock period. That is, the counter 705 is
When 3 cycles are switched and a signal of frequency F2 is generated for 4 cycles, one clock is held. As a result, the frequency of the data output from the terminal 709 is about 694.6 KHz, and the frequency of about 2.9 KHz can be reduced as compared with the frequency F2.

Similarly, by holding the frequency F1 for one clock period every 240 clocks, the frequency of the pilot tone to be output can be reduced by about 1.9 KHz. Although the ROM 701 is used in FIG. 7, it is also possible to combine the gates with an HDL (hardware description language) logic synthesis tool.

Next, the tracking control operation by the microcomputer 119 will be described.

FIG. 8 is a flowchart showing the tracking control processing by the microcomputer 119. FIG. 9 shows a state of a track formed on the tape 101.

When the reproduction process starts, the next track to be reproduced is determined (S801). If the next track is the F0 track, the current track is the F1 or F2 track, and the off-track amount cannot be detected. Therefore, the process ends.

When the next track is F1, that is, the track currently being traced is 901 or 909 in FIG.
In the case of (1), the detection outputs of the pilot signal components of the frequencies F1 and F2 output from the pilot detection circuit 115 as described above are compared (S802).

Here, if the values of the pilot signal components of F1 and F2 are the same, it is determined that the tracking state is good, and the process is terminated. When the value of F1 is large,
For example, when the track 909 is currently being traced, it indicates that the trace position of the head is offset toward the track 911, so that the voltage applied to the capstan motor is reduced and the transport speed of the tape 101 is reduced ( S804). On the other hand, when the value of F2 is large, it indicates that the value is offset to the track 907 side.
The voltage applied to the capstan motor 123 is increased to increase the transport speed of the tape 101 (S805).

When the next track is F2, that is, when the track currently being traced is 905 in FIG. 9, the pilot signal components of frequencies F1 and F2 output from pilot detection circuit 115 as described above are used. The detected outputs are compared (S803).

Here, when the values of the pilot signal components of F1 and F2 are the same, it is determined that the tracking state is good, and the process is terminated. When the value of F1 is large,
For example, if the track 905 is currently being traced, this indicates that the trace position of the head is offset toward the track 903, so that the voltage applied to the capstan motor is increased and the transport speed of the tape 101 is increased ( S805). On the other hand, when the value of F2 is large, it indicates that the value is offset to the track 907 side.
The voltage applied to the capstan motor 123 is reduced, and the transport speed of the tape 101 is reduced (S804).

As described above, according to the present embodiment, when the tracking control is performed by detecting the pilot signal component from the reproduced data, the BPF for detecting the pilot signal component is used.
Is set to a frequency slightly shifted from the frequency of the original pilot signal, a pilot signal component that would actually be obtained from the reproduced data can be detected satisfactorily.

Therefore, accurate tracking control can be performed.

In this embodiment, the F1 detection circuit 20
3, the F2 detection circuit 205 detects a pilot signal component having a frequency lower than F1 and F2 by about 2 KHz and 3 KHz, respectively. In addition, the center frequency of the BPF is set to a different frequency, It is also possible to detect components.

In this case, the counter 70 shown in FIG.
7 and the timing and period of time held by the counter 705 are changed as appropriate so that the pilot tone generation circuits 207a, 209a and 207b, 20
It is possible to change the fraction of the signal output from 9b.

Further, in the present embodiment, the result of multiplication of the reproduced data and the signals of the frequencies F1-Δ and F2-Δ in the ITI area is integrated. However, the integration results of other periods may be used. As described above, since the ITI area is an area on which the pilot signal is more strongly superimposed, the multiplication result is integrated in the ITI area in this embodiment.

In the above embodiment, the case where the present invention is applied to a digital VTR has been described.
Other than this, the present invention is applicable to a device that reproduces a clock phase-synchronized with the reproduced data, and has the same effect.

[0070]

As described above, according to the present invention,
A pilot signal component can be accurately detected from the reproduced information signal.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a VTR to which the present invention is applied.

FIG. 2 is a diagram illustrating a configuration of a pilot detection circuit of FIG. 1;

FIG. 3 is a diagram showing a state of each track on the tape of FIG. 1;

FIG. 4 is a diagram illustrating characteristics of the circuit of FIG. 2;

FIG. 5 is a diagram illustrating characteristics of the circuit of FIG. 2;

FIG. 6 is a diagram for explaining the operation of the circuit of FIG. 2;

FIG. 7 is a diagram showing a configuration of a pilot tone generating circuit of the circuit of FIG. 2;

FIG. 8 is a flowchart illustrating a tracking control operation by the microcomputer of FIG. 1;

FIG. 9 is a diagram showing a state of a track formed on the tape of FIG. 1;

Claims (11)

[Claims] 1. A reproducing means for reproducing, from a recording medium, an information signal on which a pilot signal of a predetermined frequency is superimposed, and a filter having a center frequency near a frequency of the predetermined frequency as the center of the reproduced information signal. A reproducing apparatus comprising: pilot detecting means for detecting a pilot signal component; and control means for controlling tracking between the reproducing means and the recording medium according to an output of the pilot detecting means. 2. The reproducing apparatus according to claim 1, wherein said pilot detecting means detects said pilot signal component in an information signal reproduced from a predetermined portion of said recording medium. 3. The pilot signal includes a first pilot signal having a first predetermined frequency and a second pilot signal having a second predetermined frequency different from the first predetermined frequency. 2. The reproducing apparatus according to claim 1, wherein the first pilot signal component and the second pilot signal component are detected. 4. The control means compares the detection result of the first pilot signal component with the detection result of the second pilot signal component, and according to the comparison result, the control means and the recording medium 4. The reproducing apparatus according to claim 3, wherein tracking control is performed. 5. A reproducing means for reproducing an information signal on which a pilot signal of a predetermined frequency is superimposed by tracing a number of tracks formed on a tape-shaped recording medium with a rotary head, and a frequency near the predetermined frequency. Reference signal generation means for generating a reference signal having: a pilot detection means for detecting a pilot signal component in the reproduction information signal using a multiplication result obtained by multiplying the reference signal and the reproduction information signal; and the pilot detection And a tracking control means for controlling tracking between said tape-shaped recording medium and said rotary head in accordance with an output of said means. 6. The pilot detecting means has a multiplying means for multiplying the reference signal and the reproduction information signal, and an integrating means for integrating an output of the multiplying means, and the tracking control means is provided by the integrating control means. The reproducing apparatus according to claim 5, wherein the tracking is controlled using an output. 7. A clock generating means for generating a clock phase-synchronized with the reproduced information signal, wherein the reference signal generating means stores each sample value of the signal of the predetermined frequency, and counts the clock. 6. The reproducing apparatus according to claim 5, further comprising: a counter; and selecting means for selecting and outputting each sample value stored in the storage means according to the value of the counter. 8. The reproducing apparatus according to claim 7, wherein said signal generating means generates said reference signal by holding a count value of said counter at a constant cycle. 9. The pilot detection means detects different first and second frequency components in the reproduced information signal, and the reference signal generation means controls a counting operation of the counter to thereby control the first and second frequency components. 8. The reproducing apparatus according to claim 7, wherein a signal having a frequency of 2 is generated, and the reproduction information signal is multiplied by the signals having the first and second frequencies. 10. The reproducing means reproduces an information signal conforming to the DV format proposed by the HD Digital VCR Council, and the reference signal generating means reproduces the first reference signal of the pilot signal which is 2 KHz lower than the F1 frequency. 6. The reproducing apparatus according to claim 5, wherein a second reference signal 3 KHz lower than the F2 frequency is generated. 11. A method for reproducing, from a recording medium, an information signal on which a pilot signal of a predetermined frequency is superimposed by a reproducing unit, wherein the reproduction information is obtained by using a filter having a frequency near a predetermined frequency as a center frequency. A reproducing method for detecting the pilot signal component in a signal and controlling tracking between the reproducing means and the recording medium according to a detection result of the pilot signal component.