JPH04321917A - Tracking controller - Google Patents

Abstract

PURPOSE:To exactly execute the tracking control without bein influenced by a short time noise. CONSTITUTION:By a sample and hold circuit 16, a level of a pilot signal of a track which is being reproduced at present is detected. By sample and hold circuits 14 and 15, reproducing level of a pilot signal f1 of the next track and the previous track is detected. As for outputs of the sample and hold circuits 14 to 16, its average value is operated by arithmetic circuits 22 to 24. Outputs of the arithmetic circuits 22 to 24 are added in an adder 20. With respect to a tracking error signal outputted from a substracter 19, an arithmetic circuit 21 controls the gain in accordance with a control signal inputted from the adder 20.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tracking control device for a rotary head type digital audio tape recorder (R-DAT) or the like.

0002

2. Description of the Related Art First, an overview of R-DAT will be explained. FIG. 3 shows the state of tracks recorded on the magnetic tape 1. As shown in the figure, the magnetic tape 1 has recording tracks 2 having a predetermined inclination angle (approximately 6 degrees) at different azimuths (A azimuth). B azimuth) is alternately recorded by two rotating heads (not shown). As shown in FIG. 4, this recording track 2 has a PCM audio recording area of 128 blocks in the center, and pilot signal recording areas of 5 blocks (ATF-1, ATF
-2), and 8 blocks of subcode recording area (S
UB-1, SUB-2) are formed.

FIG. 5 shows details of the pilot signal recording area.
Shown below. That is, in each recording track 2, the tracking pilot signal f1 is for two blocks, and the timing pilot signal f2 or f3 is for one block or zero.
．． Five blocks are recorded. This tracking pilot signal f1 and timing pilot signal f2,
f3 is a fixed frequency signal that is different from each other, and the tracking pilot signal f1 is recorded between three consecutive tracks so that they do not overlap each other when viewed from a direction orthogonal to the head scanning direction. Further, the timing pilot signal f2 or f3 is recorded at a corresponding position from the center to the rear end of the recording area of the tracking pilot signal f1 recorded in the following track. Note that f4 in the figure is a signal for erasing.

[0004] When reproducing a magnetic tape recorded in such a format, a rotary head having a width, for example, 1.5 times wider than the width of the recording track 2, is scanned over each track and recorded. Play the signal. Therefore, the reproduced signal of the tracking pilot signal f1 recorded on both adjacent tracks is also included as a crosstalk component, and the output level of the tracking pilot signal f1 from both adjacent tracks is equal. If the tape transport amount is controlled so as to achieve accurate tracking, accurate tracking can be achieved.

FIG. 6 shows a circuit that performs tracking control using the tracking pilot signal f1. A reproduction signal from the rotary head H is amplified by a reproduction amplifier 11 and then applied to a bandpass filter 12. This bandpass filter 12 uses a pilot signal f1
After the envelope component is detected by the envelope detection circuit 13, its output is given to the sample and hold circuits 14 to 16. On the other hand, the output of the reproducing amplifier 11 is given to the control circuit 17. This control circuit 17 detects the timing pilot signals f2 and f3 in the reproduced signal, outputs the sampling signal SH1 at the time of detection, and outputs the sampling signal SH2 after a time period of two blocks has elapsed from the time of detection. The sampling signal SH1 is sent to the sample hold circuit 14,
Further, the sampling signal SH2 is given to the sample and hold circuit 15.

[0006] Also, during tracing of the A track (track recorded by the A azimuth head), the ATF-2
After a time period of two blocks has elapsed since the output of the sampling signal SH2 in the area, and during tracing of the B track (track recorded by the head of B azimuth),
After a time period of two blocks has elapsed since the output of the sampling signal SH2 in the area of ATF-1, the sampling signal SH3 is output to the sample hold circuit 16 at the timing when the pilot signal f1 is present in the own track. Also, in the ATF area where this sampling signal SH3 is output, after a slight delay after outputting the sampling signal SH3, and in the ATF area where the sampling signal SH3 is not output, after a slight delay after outputting the sampling signal SH2. , outputs the sampling signal SH4 to the sample hold circuit 18.

Sample and hold circuits 14 to 16 sample and hold the output of envelope detection circuit 13 according to sampling signals SH1 to SH3, respectively, and output them as signals a to c, respectively. The subtracter 19 subtracts the signal a from the signal b and outputs the result as a signal d. Adder 20 adds signals a, b, and c and outputs the result as signal e. The arithmetic circuit 21 generates a gain g that is inversely proportional to the signal e, multiplies the signal d by this gain, and outputs the resultant signal as a signal h. The sample and hold circuit 18 samples and holds the signal h according to the sampling signal SH4 and outputs it.

Now, the truck shown in FIG. 5 (own truck)
If the rotary head H is tracing over A2, since the width of the rotary head H is wider than the track width, the recorded signal on track A2 will be traced along with the adjacent tracks B1 and B.
The second recorded signal will also be reproduced. When the rotary head H starts tracing the recording area of the timing pilot signal f2, the control circuit 17 outputs the sampling signal SH1 at that point. At this time, since the tracking pilot signal f1 of the adjacent track (next track) B2 is being reproduced as a crosstalk component, the sample and hold circuit 14 samples and holds the level of the tracking pilot signal f1 of the adjacent track B2. .

Then, at the timing when the rotating head H starts reproducing the tracking pilot signal f1 of the adjacent track (previous track) B1 as a crosstalk component, the control circuit 17 outputs the sampling signal SH2, and the sample hold circuit 15 The level of the tracking pilot signal f1 of track B1 is sampled and held. At this point, the output of the subtracter 19 is the level difference between the tracking pilot signals f1 of both adjacent tracks B1 and B2, and has a value corresponding to the track deviation of the rotary head H.

[0010] Also, a pilot signal f1 is applied to the track A2.
At the timing when the sampling signal SH3 exists
is generated, the sample-and-hold circuit 16 samples and holds the level of the pilot signal f1 of its own track.

On the other hand, the output of the adder 20 is
, B1, and B2, the level of the pilot signal f1 is unaffected by track deviation. In the arithmetic circuit 21, a gain inversely proportional to the output of the adder 20 is added to a subtracter 19.
By multiplying by the output of , a tracking error signal is generated that is not affected by the level of the pilot signal f1 during recording or the retention force of the pilot signal f1 on the tape. Good tracking can be obtained by sample-holding this using the sampling signal SH4 and feeding back the value to the capstan drive system (not shown).

0012

[Problems to be Solved by the Invention] However, since the tracking control device having such a gain adjustment function is intended to compensate for variations in recording equipment and tapes, it is difficult to adjust the generation period of the sampling signals SH1 to SH4. In comparison, although it is sufficient to respond to long-term fluctuations, conventional devices have a problem in that the gain fluctuates even due to short-term noise.

The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to provide a device that is stable against short-term fluctuations such as noise.

[0014]

[Means for Solving the Problems] The tracking control device of the present invention is a tracking control device having an automatic gain adjustment function, and includes a first detection means for detecting the pilot signal level of the next track, and a first detection means for detecting the pilot signal level of the previous track. A second detection means for detecting the pilot signal level, a third detection means for detecting the pilot signal level of the own truck, and a detection method according to the amount of tracking deviation using the detection results of the first and second detection means. means for calculating a deviation signal; means for averaging the detection results of the first to third detection means according to preset calculation formulas; and means for controlling the gain of the deviation signal in accordance with the averaged output. It is characterized by having the following.

[0015]

[Operation] In the tracking control device with the above configuration,
Since the gain of the tracking error signal is controlled in accordance with the average value of the pilot signal of each track, the influence of short-term noise can be suppressed.

[0016]

[Embodiment] FIG. 1 shows the configuration of an embodiment of the tracking control device of the present invention. Parts corresponding to those in FIG. may be omitted as appropriate.

Arithmetic circuits 22 to 24 each have the same configuration, receive output signals a to c of sample and hold circuits 14 to 16, perform predetermined calculations (described later), and convert signal a to
' to c' are output. Adder 20 adds signals a' to c' and outputs the result as signal e'. The arithmetic circuit 21 generates a gain g' that is inversely proportional to the signal e', multiplies the signal d by this gain, and outputs the resultant signal as a signal h'. The sample and hold circuit 18 samples and holds the signal h' according to the sampling signal SH4 and outputs it.

FIG. 2 shows the configuration of one embodiment of the arithmetic circuit 22 (and the same applies to 23 and 24). The adder 31 is an adder 31
The input a(b, c) to the multiplier 32 is added to the output m of the multiplier 32, and a signal k is output. The sample and hold circuit 33 samples and holds the signal k according to the sampling signal SH1 (SH2, SH3). The multiplier 32 receives the output of the sample and hold circuit 33, multiplies it by a multiplier of (α-1)/α, and outputs a signal m. Here, α is a constant such that α>1. The multiplier 34 receives the signal k, multiplies it by a coefficient 1/α, and outputs the result as a signal a'(b', c').

Next, its operation will be explained. The control circuit 17 generates sampling signals SH1 to SH4,
The sample and hold circuits 14 to 16 each receive the pilot signal f1 of the next track, the previous track, or the own track.
It is the same as the conventional example up to the point where the subtracter 19 samples and holds the level of , and generates the level difference d between the pilot signal f1 of the front track (for example, B1) and the rear track (for example, B2).

The operation of the arithmetic circuit 22 shown in FIG. 2 will now be explained. To simplify the description, we set (α−1)/α=β. First, assume that the output of the sample and hold circuit 33 is 0. Here, as the input signal a to the adder 31, x
Assuming that a value of 0 has arrived, the output of the adder 31 is x0. If this is sampled and held by the sample and hold circuit 33 using the sampling signal SH1, then the multiplier 32
The output signal m becomes βx0. Next, when the value x1 comes as the signal a, the output of the adder 31 becomes (x1+βx0). When this is sampled and held by the sample hold circuit 33 according to the sampling signal SH1, the output of the multiplier 32 becomes (βx1+β2x0).

Next, when x3 comes as an input and the same operation is repeated, the output of the adder 31 is

[Math 1] The output of the multiplier 34 (arithmetic circuit 22) is

[Number 2
] becomes.

Now, if x0=x1=...=x, and k→∞, the output of the arithmetic circuit 22 is

[Formula 3] Therefore, the output of the arithmetic circuit 22 can be regarded as the average value of the inputs (this average value is gradually improved).

The arithmetic circuits 23 and 24 operate in the same manner.

In this way, the arithmetic circuits 22, 23, 2
The signals a', b', and c' outputted from 4 are input to the adder 20, and after being added, the signals a', b', and c' outputted from the arithmetic circuit 21 are outputted as the signal e'.
is output to. The arithmetic circuit 21 multiplies the signal d input from the subtracter 19 by a gain g' that is inversely proportional to the signal e' input from the adder 20, and outputs the result to the sample and hold circuit 18 as a signal h'. Sample hold circuit 18
is a signal h' inputted from the arithmetic circuit 21 to the control circuit 1.
Sample and hold is performed at the timing of the sampling signal SH4 supplied from 7, and the held value is supplied to a capstan drive system (not shown). In this way, tracking control is performed so that the rotary head H correctly tracks the track.

[0025]

As described above, according to the tracking control device of the present invention, since the gain of the tracking error signal is controlled in accordance with the average value of the pilot signal of each track, the influence of short-term noise can be reduced. It becomes possible to suppress this.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of a tracking control device of the present invention.

FIG. 2 is a block diagram showing the configuration of one embodiment of arithmetic circuits 22, 23, and 24 in FIG. 1.

FIG. 3 is a diagram illustrating the relationship between a magnetic tape and tracks.

FIG. 4 is a diagram showing a track format in R-DAT.

FIG. 5 is an enlarged view of the format of FIG. 4;

FIG. 6 is a block diagram showing the configuration of an example of a conventional tracking control device.

[Explanation of symbols]

13 Envelope detection circuit 14, 15, 16 Sample hold circuit 17 Control circuit 18 Sample hold circuit 19 Subtracter 20 Adder 21 Arithmetic circuit 22, 23, 24 Arithmetic circuit 31 Adder 32 Multiplier 33 Sample hold circuit 34 Multiplier

Claims (1)

[Claims] 1. A tracking control device having an automatic gain adjustment function, comprising: a first detection means for detecting a pilot signal level of a next track; and a second detection means for detecting a pilot signal level of a previous track. , third detection means for detecting the pilot signal level of the own truck;
means for calculating a deviation signal according to the amount of tracking deviation using the detection results by the first and second detection means; and a calculation formula set in advance for each of the detection results by the first to third detection means. A tracking control device comprising means for performing an averaging operation according to the average operation, and means for controlling the gain of the deviation signal according to the average operation output.