JPH04339310A - Pilot signal recording and reproducing device - Google Patents

Abstract

PURPOSE:To simplify the device by generating a pilot signal for tracking as a part of a recording information signal at the time of modulation, and recording, reproducing the pilot signal modulated in digital. CONSTITUTION:For conversion into a recording code word, a 13-bit CDS recording code word is made to correspond to one input data word and by selecting any one of these words in a 4-input and 1-output selector circuit 23 according to a recording code word selection control signal Sc, the pilot signal is generated. Accordingly, by controlling the CDS of recording codes, a train of recording code words in which a DSV value at the end of the recording code word becomes zero in a cycle integer times a code conversion cycle, can be obtained. The converted 13-bit parallel codes are converted into serial data in a parallel/ serial conversion circuit 24 with a serial data transmission clock with a cycle equivalent to 1/13 of the code conversion cycle, and recorded on a magnetic tape 9 with a magnetic head 7.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention is applied to a device that divides a digital signal into a plurality of segments and records and reproduces it on a magnetic recording medium using a multi-channel rotary head, and generates and records a pilot signal for tracking error detection. The present invention relates to a pilot signal recording and reproducing device for reproducing.

0002

2. Description of the Related Art In recent years, magnetic recording and reproducing devices that digitize information signals and magnetically record and reproduce them have been increasingly attracting attention. In such devices, tracking control is extremely important to precisely control the running speed and position of the magnetic tape when reproducing recorded information, and to keep the magnetic head always running directly above the recording track. . Therefore, when recording information, a pilot signal for tracking error detection is recorded on the magnetic tape, and during playback, a signal is generated to detect and control tracking errors based on this pilot signal, and tracking control is performed. .

FIG. 11 shows, for example, Japanese Patent Application Laid-Open No. 59-6886.
2 is a block diagram showing the configuration of a pilot signal recording and reproducing device for tracking error detection and control used in a conventional magnetic recording and reproducing device disclosed in Publication No. 2. FIG. In the figure, (1) is a reference oscillator, (2) is a presettable counter, (3) is a flip-flop, (4) is a waveform shaping filter, and (5) is a sine wave output from the waveform shaping filter (4). (6) is a recording/reproduction changeover switch; (7) is a magnetic head for recording/reproducing; in this embodiment, 2. One set of these is attached to a rotating drum and constitutes a rotating head (8). (9) is a magnetic tape serving as a magnetic recording medium.

Furthermore, (10) is the track switching signal C1.
and a frequency division ratio control circuit (11) that controls the frequency division ratio of the presettable counter (2) by the recording/reproduction switching signal C2.
) is a low-pass filter to which the reproduced signal R is input, (12
) is a sine wave reference signal Ref and a low-pass filter (1
1) a balanced modulation circuit that mixes the reproduced pilot signal Pr output from 1); (13) is an amplifier; (14A), (1)
4B) is a band pass filter, (15A), (15B)
is an envelope detection circuit, and (16) is a differential amplifier that compares the outputs of the envelope detection circuits (15A) and (15B). FIG. 12 shows the relationship between a magnetic head (7) and a recording track (17) provided in contact with a magnetic tape (9), which is a magnetic recording medium.
7) with both ends covering parts of two tracks adjacent to the track currently being scanned (
17) It is designed to scan above.

Next, the operation will be explained. In FIG. 11, when recording an information signal on a magnetic tape (9) as a magnetic recording medium, a presettable counter (2
) to change the division ratio of this presettable counter (
After the output of 2) is further frequency-divided by a flip-flop (3), the waveform is shaped into a sine wave by a waveform shaping filter (4) to generate a pilot signal. Next, this pilot signal and the information signal A including video and audio information are added by an adding circuit (5), and then recorded on a magnetic tape (9) by a magnetic head (7) via a recording/reproduction changeover switch (6). .

In this way, the track switching signal C1 is switched every time the recording track (17) changes, and the frequency division ratio of the frequency division ratio control circuit (10) is changed. Four types of pilot signals with frequencies f1 to f4 can be recorded on the magnetic tape (9). At this time, since the pilot signal is extracted while reproducing the information signal A, the frequency of the pilot signal is set to a frequency that does not damage the information signal A. For example, a consumer 8mm video tape recorder (hereinafter referred to as
The frequency of the pilot signal of a commercial 8mm VTR is set around 100-odd kHz.

The frequency f of the pilot signal in FIG.
Taking the case of 4-frequency pilot system of a consumer 8mm VTR as an example for 1 to f4, f1+fa=f2, f2+fb=f3...(1) f4
+fa=f3, f1+fb=f4... (2), when reproducing the recording signal recorded on the magnetic tape (9) by the magnetic head (7), the information signal A is mixed with The pilot signal Pr reproduced by is also taken out as crosstalk. The pilot signal from the above adjacent truck is
Since the frequency is sufficiently lower than that of the video signal, there is almost no azimuth loss even in azimuth recording, and the signal is reproduced as a large amount of crosstalk.

When the pilot signal Pr reproduced as described above and the reference signal Ref having a frequency equal to the frequency of the pilot signal written in the track being scanned are mixed in the balanced modulation circuit (12), A beat is generated between the pilot signal Pr and the reference signal Ref due to crosstalk from the track, and first and second beat signals Ba and Bb having frequencies fa and fb are obtained in equation (1). For example, when reproducing a track in which pilot signal f2 in FIG. 12 is recorded, pilot signals f1 and f3 are obtained as crosstalk, and these frequencies and the reference signal Re of frequency f2 are
When f is mixed by the balanced modulation circuit (12), the beat frequency is expressed by the absolute value of the difference in frequency between the two signals to be mixed, so from equations (1) and (2), |f2-f1|= fa...(3) |f2-f3|=fb...(4) It can be seen that the first and second beat signals Ba and Bb are obtained. And these beat signals Ba, B
b is amplified by an amplifier (13) and passed through a bandpass filter (14).
After extraction with A) and (14B), when the envelope detection circuit (15A) and (15B) detect the wave, the magnetic head (7
) is on-track on the track 17 indicated by f2 in FIG. 11, and if it shifts even slightly toward f1, the first
The second beat signal Ba increases, and when it shifts to the f2 side, the second beat signal Bb increases, so the differential amplifier (1
A tracking control signal Tc is taken out as the output of step 6).

[0009]

[Problem to be solved by the invention]

Conventional Problems Since the conventional magnetic recording/reproducing apparatus is constructed as described above, tracking control of extremely narrow tracks is required in order to perform high-density recording/reproducing. To do this, a means to detect track misalignment of the magnetic head (7) with high precision is required, and generally, track misalignment is detected by recording and reproducing a low frequency pilot signal as described above. There is.

[0010] However, when digital magnetic recording is adopted, even general recording/reproducing signals have an extremely wide power spectrum from components close to direct current to the highest recording frequency, so conventional analog FM record,
For example, it is difficult to multiplex pilot signals outside the carrier wave and its surrounding band, so-called gaps in frequency allocation, as is employed in consumer 8 mm VTRs.

Furthermore, even in digital recording, if the power level of the tracking pilot signal is sufficiently larger than the power level of the information signal in the surrounding band, the tracking pilot signal can be used during playback in the same way as in the apparatus shown in FIG. However, if the power level of the pilot signal is made too high relative to the recorded/playback signal, which is video and audio information, as described above, the waveform may become distorted when demodulated during playback. Distortion increases and the error rate of digital data increases.

In particular, when recording by adding the modulated digital data and the tracking pilot signal in an analog manner before the recording amplifier, there is no correlation between the digital data and the pilot signal. ,
The signals act as simple disturbance signals. In other words,
In the case of information recording devices such as digital audio recorders and digital video recorders that record and playback using digital signals, a characteristic of digital recording is that the frequency spectrum of the recording and playback signal contains many low-frequency components, so low-frequency tracking pilot signals are used. If the signal is added to the recording/reproduction signal and recorded, there is no correlation between the recording/reproduction signal and the pilot signal, so when demodulating the digitally recorded signal, waveform distortion occurs and the data error rate increases. Put it away. On the other hand, if the power level of the pilot signal is lowered in order to reduce waveform distortion, there are problems such as an inability to secure a sufficient pilot signal-to-noise ratio required for tracking control.

[0013] Furthermore, in a multi-channel multi-segment recording and reproducing type magnetic recording and reproducing apparatus, when trying to perform tracking control and segment detection using conventional pilot signals, a plurality of pilot signals must be generated simultaneously during recording, and when reproducing The frequency of each pilot signal must be set so that the number of beat frequencies between adjacent pilot signals equal to the number of segments is the same as the number of segments, which results in a problem that the scale of the apparatus becomes large. Therefore, there is a problem that the above problems must be solved.

Purpose of the Invention The present invention has been made to solve the above problems, and it suppresses waveform distortion of a digital recording/reproduction signal caused by multiplexing a pilot signal with an information signal, and also enables recording of the pilot signal. To provide a pilot signal recording and reproducing device in which a tracking error detection signal obtained from each track obtained by the tracking error can have a large S/N ratio with a constant gain regardless of the channel, and can achieve higher recording and reproducing density by narrowing the track pitch. The purpose is to

[0015]

[Means for Solving the Problems] A device according to the present invention includes:
A pilot signal recording and reproducing device that generates and records and reproduces a pilot signal for tracking error detection, which is applied to a magnetic recording and reproducing device that divides a digital signal into multiple segments and records and reproduces it on a magnetic recording medium using a multi-channel rotary head. During recording, a data word with a word length of m bits expressed by a binary digital signal is converted into a recording code word with a word length of n bits (n is an odd number and n>m). At the time of encoding, there is provided means for associating four types of recording code words, in which the value of the sum of charges in the recording code word is -1, +1, -3, and +3, with one data word.

[0016] Furthermore, the above-mentioned recording code word selection control signal is generated from a drum PG signal for drum rotation phase control outputted from a sensor attached to a rotary drum constituting a rotary head and a count value of a recording encoding period. By selecting one of the four codewords and setting the accumulated charge value at the end of the recorded codeword to 0 at every predetermined period,
The apparatus is equipped with means for generating a pilot signal in which a plurality of frequencies appear repeatedly in sequence on every other recording track and whose envelopes are equal in size.

Furthermore, during reproduction, a tracking control signal is obtained from the difference in values obtained by envelope detection of the reproduced pilot signal, and it is determined which segment the track being scanned belongs to from the combination of frequencies of the reproduced pilot signal. have the means.

[0018]

[Operation] The pilot signal recording/reproducing apparatus according to the present invention uses recording code words with CDS (total charge sum) of -1, +1, -3, and +3 to encode, that is, modulate, an information signal. By sequentially switching the four types of recording codewords according to the recording codeword selection control signal for pilot signal generation, the power spectrum of digital data is located in a low frequency band where the power spectrum sharply attenuates, and is synchronized with the digital data. Pilot signals of a plurality of frequencies having varying DSV (cumulative charge) values and equal envelope sizes are generated so as to appear repeatedly in every other track. Therefore, since the pilot signal for tracking is generated as part of the recorded information when input data is modulated, waveform distortion during demodulation due to multiplexing of the pilot signal onto the information signal does not occur, resulting in a data error rate. deterioration can be improved. In addition, the gain of the tracking error detection signal obtained from the recording track is constant regardless of the channel, and the S/N ratio can be increased.
By narrowing the track pitch, it is possible to achieve higher density recording and reproduction.

In addition, it determines which segment the track being scanned is based on the frequency component of the reproduced pilot signal, and outputs a signal indicating on-track when a predetermined segment detection pattern is obtained during reproduction. Or it can be displayed.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a first embodiment of a pilot signal recording and reproducing apparatus according to the present invention. In the figure, (6) is a recording/reproduction changeover switch, and (7) is a magnetic head for recording/reproducing.
The set is attached to a rotating drum and constitutes a rotating head (8). (9) is a magnetic tape serving as a magnetic recording medium. Further, (11) is a low-pass filter that inputs the reproduced signal R, (13) is an amplifier, (14A), (14B
) is a bandpass filter, (15A) and (15B) are envelope detection circuits, and (16) is a differential amplifier that compares the outputs of the envelope detection circuits (15A) and (15B). The above configuration is similar to the conventional example shown in FIG. 11 except that it does not include the balanced modulation circuit (12), so the same or corresponding parts are described using the same reference numerals.

(21) is the input data word Dw of 256 ways in which parallel 8 bits are expressed as binary values of 0 and 1.
This is an encoder that converts the 13-bit parallel recording code word into a 13-bit parallel recording code word, and the value of CDS (charge sum) in the recording code word is -1.
, +1, -3, +3 to correspond to one input data word Dw. (22) is a recording code word selection control signal generation circuit that outputs a timing signal for selecting a predetermined recording code word from the value counted in the code conversion period and the drum PG signal, that is, a recording code word selection control signal Sc; 23) is a 4-input 1-output selector circuit that selects one of the four codewords according to the recording codeword selection control signal Sc output from the recording codeword selection control signal generation circuit (22); 24
) is a parallel-to-serial conversion circuit that converts the 13-bit parallel recording codeword into a serial codeword string transmitted at a serial data transmission frequency.

FIG. 2 shows the input data word Dw in the encoder (21) of the pilot signal recording and reproducing apparatus according to the present invention.
This shows an example of the correspondence between 1 and the recorded code word.
The maximum run length is 4 with 3 bits. In addition, each code word with 13 bits and maximum run length of 4 and CDS = ±1 is 1047.
There are 576 words and code words with CDS=±3, so
It is possible to accommodate all of the 256 8-bit input data words Dw. When magnetic recording is performed on a magnetic tape (9) as a magnetic recording medium, 256 types of input data words consisting of 8 bits often include consecutive 0s or 1s, and this part becomes a direct current. As it is, magnetic recording is difficult. Therefore, it is necessary to convert the input data word into a recording code word that has a larger number of bits than the input data word and whose maximum run length is not so large, that is, modulates it before recording. In this embodiment, an input data word is converted into a recording code word in an encoder (21) based on the conversion table shown in FIG. The word length of the recording code word is larger than the word length of the input data word and has an odd number of bits.

Next, the operation will be explained. Conversion to a recording codeword is performed using the CDS of the recording codeword for one input data word.
Four 13-bit code words with (total charge) values of -1, +1, -3, and +3 are made to correspond to each other, and any one of these is connected to a 4-input, 1-output selector circuit (
23), a pilot signal is generated by selecting according to the recording code word selection control signal Sc.

By controlling the CDS of the recording code as described above, a recording code word string can be obtained in which the DSV value at the end of the recording code word becomes 0 at a cycle that is an integral multiple of the code conversion cycle. The converted 13-bit parallel code is converted into serial data in a parallel-to-serial conversion circuit (24) using a serial data transmission clock having a period of 1/13 of the code conversion period,
The information is recorded on the magnetic tape (9) by a magnetic head (7) via a recording/reproduction changeover switch (6) and a recording amplifier (not shown).

FIG. 3 shows the input data word Dw of each channel in FIG. 1, the CDS value and D of the recording code word to be selected.
It is a figure showing the change of the value of SV. As shown in Figure 3, D
Recording code word selection control signal Sc when the change period of SV is set to be 28 times and 20 times the code conversion period, respectively.
The waveform of is recorded with the recording code 2 for each channel, respectively.
The DSV change pattern goes around in periods of 8 symbols and 20 symbols. Therefore, pilot signals having frequencies of 1/28th and 1/20th of the code conversion period are recorded on every other track on the magnetic tape (9).

Note that the power spectrum of a binary digital signal of 1 and 0 is determined by the probability of appearance of state transition. For example, in the case of an M-sequence random digital signal, its power spectrum is a nearly flat spectrum in the range from the DC component to the transmission clock frequency. In a code string that fluctuates symmetrically in positive and negative directions, a signal is obtained that does not have a DC component and has a spectrum that is strong at the DSV fluctuation frequency.

FIG. 4 shows the power spectrum of the output (recording signal) of the parallel-to-serial conversion circuit (24) under the condition that the DSV fluctuation period of the recording code is 28 times the code conversion period. A strong spectrum appears at a frequency that is 1/364 (=13×28) of the period, that is, the serial data transmission frequency fCH. Therefore, by recording such a signal on the magnetic tape (9), the low frequency pilot signal can be recorded in synchronization with the digital signal, as in the past.

FIG. 5 is a diagram showing the relationship between the recording track (17) on which the pilot signal is recorded in this way and the magnetic head (7), and the magnetic head (7) has two heads. It is formed by fixing two pairs of pilot signals facing away from each other in a fixed positional relationship, and f1 and f2 representing the frequency of the pilot signal are 1/28th and 20th of the code conversion period, respectively. 1, but the size of each envelope is equal.

Next, when reproducing the recorded signal, the magnetic tape (
9) Information signal A recorded on the magnetic head (7)
The reproduced signal R that is reproduced at this time is the information signal A that includes a pilot signal. Since this pilot signal has a sufficiently lower frequency than the information signal A, it is hardly affected by the azimuth effect even in azimuth recording, and the two pilot signals from adjacent tracks on both sides are also extracted as crosstalk. Then, the information signal A is reproduced using the magnetic head (7) which does not record the pilot signal among the two pairs of magnetic heads (7), and the center frequencies are f1, f.
The two pilot signal components are extracted using two bandpass filters (14A) and (14B), and detected by envelope detection circuits (15A) and (15B), respectively, to obtain amplitude values. Next, the tracking control signal Tc can be obtained by obtaining an output proportional to the difference in amplitude between the two pilot signals using the differential amplifier (16). This tracking control signal Tc indicates that tracking is f1
If it deviates to the f2 side, a negative signal is output, and conversely, if it deviates to the f2 side, it is output as a positive signal.

FIG. 6 is a block diagram showing a pilot signal recording/reproducing circuit, a tracking error detection circuit, and a segment discrimination circuit according to a second embodiment of the present invention. In this embodiment, in order to divide one field of screen into three segments and record each segment on one track, pilot signals of three frequencies are sequentially and repeatedly generated in a circular order. There is. In FIG. 6, a recording/reproducing switch (6), a magnetic head (7) for recording and reproducing, a rotating head (8), a magnetic tape (9) serving as a magnetic recording medium, and a low-pass filter (11) for inputting the reproduction signal R. , the amplifier (13) is the first amplifier shown in FIG.
The structure is similar to that of the embodiment.

Furthermore, the output of the amplifier (13) is input to three band pass filters (14A), (14B), and (14C), respectively, and the outputs are input to envelope detection circuits (15A), (15B), and (15C) is input. Envelope detection circuit (15A) and (
15B), (15B) and (15C), (15C) and (1
The outputs of the differential amplifiers (16A) and (5A) are respectively
16B), (16C) and 2 input 1 output AND gate (2
5A), (25B), and (25C). The outputs of the differential amplifiers (16A), (16B), (16C) are 2-input 1-output AND gates (25A), (25B),
They are connected at one point via analog switch circuits (26A), (26B), and (26C) controlled by the output of (25C), and are output as a tracking control signal Tc. 2 input 1 output AND gate (25A), (25B)
, (25C) are the segment flags S
They become F1, SF2, and SF3.

(21) is the input data word Dw of 256 ways in which parallel 8 bits are expressed as binary values of 0 and 1.
This is an encoder that converts the code into a 13-bit parallel code word, and the value of CDS (sum of charge) in the code word is -1, +1,
-3, +3 code words are combined into one input data word Dw
It functions to correspond to the (22A) is a recorder that outputs a timing signal for selecting a predetermined recording codeword, that is, a recording codeword selection control signal Sc, from a value counted in the code conversion cycle, a drum PG signal, and a frame pulse that is a segment information signal. The code word selection control signal generation circuit (23) is the recording code word selection control signal generation circuit (23).
A 4-input 1-output selector circuit (24) selects one of the four codewords according to the recording codeword selection control signal Sc output from the recording codeword selection control signal Sc outputted from the 13-bit parallel codeword (22A). This is a parallel-to-serial conversion circuit that converts into a serial code word string that is transmitted at the transmission frequency. In the above description, the same reference numerals are used for the same or corresponding parts as in FIG. 1. Next, the operation will be explained. In recording on a magnetic tape (9) as a magnetic recording medium, a parallel input data word consisting of 8 bits is
Based on the conversion table shown in FIG. 2 by the encoder (21), C
The DS value is converted into four 13-bit code words -1, +1, -3, and +3, and any one of these is 4
The point that the input 1 output selector circuit (23) selects according to the recording code word selection control signal Sc is the same as in the first embodiment shown in FIG. Note that the pattern of the recording code word selection control signal Sc is a pattern determined by each pilot signal frequency, so this pattern may be generated using a sequential circuit with a gate circuit, or it may be written in advance in a read-only memory. It is also possible to read out the pattern that has been placed.

By controlling the CDS value of the recording code in the manner described above, a recording code word string can be obtained in which the DSV value at the end of the recording code word becomes 0 at a cycle that is an integral multiple of the code conversion cycle. The converted 13-bit parallel code is converted to serial data using a clock with a cycle that is 1/13 of the code conversion cycle, and is sent to the recording/reproduction changeover switch (6) and the recording amplifier (
(not shown) on the magnetic tape (9) by the magnetic head (7). As shown in FIG. 7, the waveforms of the recording code word selection control signal Sc when the DSV change period is set to be 28 times, 20 times, and 12 times the code conversion period are respectively recorded for each channel. The DSV change pattern goes around in periods of 28 symbols, 20 symbols, and 12 symbols. Therefore, pilot signals having frequencies of 1/28, 1/20, and 1/12 of the code conversion period are recorded on every other track on the magnetic tape (9).

Similar to the first embodiment, in the second embodiment, the DSV uses a code string that fluctuates symmetrically in positive and negative directions within a fixed period and a finite range, so it does not have a DC component, and
A signal having a strong spectrum at the DSV fluctuation frequency is obtained. Furthermore, by recording such a signal on the magnetic tape (9), a low frequency pilot signal can be recorded in synchronization with the digital signal, as in the conventional case.

FIG. 8 is a diagram showing the relationship between the recording track (17) on which the pilot signal is recorded in this manner and the magnetic head (7). The configuration of the magnetic head (7) is the same as that of the first embodiment, and f1, f2, and f3 representing the frequencies of the pilot signal are 1/28th, 1/20th, and 12th of the code conversion period, respectively. 1, and the size of each envelope is equal.

Next, when reproducing the recorded signal, the magnetic tape (
9) Information signal A recorded on the magnetic head (7)
The reproduced signal R that is reproduced at this time is the information signal A that includes a pilot signal. Since this pilot signal has a sufficiently lower frequency than the information signal A, even in azimuth recording, two pilot signals from adjacent tracks on both sides are also extracted as crosstalk without being affected by the azimuth effect. Then, the information signal A is reproduced using the magnetic head (7) that does not record the pilot signal among the two pairs of magnetic heads, and the information signal A is filtered through bandpass filters whose center frequencies are f1, f2, and f3. (14A), (14B), (
14C), the three pilot signal components are extracted and detected by envelope detection circuits (15A), (15B), and (15C), respectively, to obtain amplitude values. Then, the differential amplifiers (16A), (16B), and (16C)
Outputs proportional to the difference in amplitude between the two pilot signals recorded on tracks on both sides of the track being scanned are obtained, and the analog switch circuits (26A), (26B) and (26C) are ON/OFF
By switching, the tracking control signal Tc can be obtained. Analog switch circuit (26A), (26B)
The ON/OFF control signals of (26C) and 2-input 1-output AND gates (25A), (25B) and (25C)
The combination of regenerated pilot signals can be detected by

[0037] The magnetic head (7) has a frequency f1, for example.
and f2 is scanning the track being played, then
The output SF1 of the 2-input 1-output AND gate (25A) is "
H", the analog switch circuit (26A) closes and the output of the differential amplifier (16A) is output as the tracking control signal Tc. At this time, the tracking becomes f
If the tracking control signal Tc shifts to the 1 side, a negative signal is output as the tracking control signal Tc, and conversely, if the shift shifts to the f2 side, a positive signal is output as the tracking control signal Tc. In addition, the above analog switch circuit (26A), (
26B) and (26C) are segment flag signals SF1, SF2, and S, respectively.
Since it is F3, when the tracks of frequencies f1 and f2 are being played, the segment flag output SF1 is "H".
becomes. Similarly, when frequencies f2 and f3 are being reproduced, the segment flag output SF2 is "H", and when frequencies f3 and f1 are being reproduced, the segment flag S
F3 becomes "H" and outputs the corresponding tracking control signal Tc and segment flags SF1 to SF3. Therefore, in a recording/reproducing apparatus that records one field of screen divided into three segments, it is possible to determine which segment the track being reproduced belongs to based on the frequency component of the pilot signal Pr.

FIG. 9 shows each segment flag output SF1 of the pilot signal recording and reproducing apparatus in the second embodiment.
FIG. 3 is a block diagram of an example of a segment pattern inspection circuit (30) connected after SF2 and SF3. Here, as in the second embodiment, one field of screen is divided into three segments, and in order to record each segment on one track, pilot signals of three frequencies are sequentially and repeatedly generated in a circular order. explain.

In the figure, (31) is a parallel latch circuit with an input/output bit length of 3 bits, which receives segment flag outputs SF1, SF2, and SF3 as inputs, and its three outputs are connected to three exclusive OR gates, respectively. It is connected to one input terminal of the circuits (32A), (32B), and (32C). The outputs of the exclusive OR gate circuits (32A), (32B), and (32C) are input to a 3-input 1-output OR gate circuit (33), which is configured to output an on-track signal Ot. Next, the circuit operation of the segment pattern inspection circuit (30) shown in FIG. 9 will be explained. The operations of generating the tracking control signal Tc and discriminating segments are the same as those of the second embodiment, so their explanation will be omitted. When normal tracking control is performed in the pilot signal recording/reproducing circuit in the previous stage, the output pattern of each segment flag SF1, SF2, and SF3 shifts by one segment each time the track is scanned, as shown in FIG. go. Focusing on this point, the current segment flags SF1, SF2, and SF3
Exclusive OR is performed to determine that the output pattern of 1 and the pattern obtained by shifting the output pattern of the segment flag at the time of one track before, which is held at the timing based on the drum PG signal by the parallel latch circuit (31), by one segment, respectively match. Inspection is performed using gate circuits (32A), (32B) and (32C). Then, only when all of the test results match, the outputs of the exclusive OR gate circuits (32A), (32B), and (32C) become "L", and the 3-input 1-output OR gate circuit (33)
The output becomes "L", and an on-track signal Ot indicating that the segment pattern is changing normally is generated.

[0040] In each of the above embodiments, a case has been described in which 8-bit input data is converted into a 13-bit recording code, but the present invention is not limited to the above-mentioned number of bits, and can be applied to data and codes with other bit numbers. But that's fine.

Further, in each of the embodiments described above, the recording code word is set to make one cycle in a period of 28 symbols, 20 symbols, and 12 symbols, but the cycle in which the DSV makes one cycle may be set to other combinations.

Furthermore, in the second embodiment, one field of screen is divided into three segments, the segment information signal is used as a frame pulse, and three frequencies of pilot signals are generated in cyclic order. The present invention is not limited to the case where one field is used as a unit, but can be applied to all cases where one block of information is divided into a plurality of segments and one track is assigned to each segment for recording and reproduction. If it is necessary to generate k types of pilot signal frequencies (k≧3) by dividing into k segments, then in the recording system, k types of recording code word selection control are required to generate k types of pilot signal frequencies. All you have to do is write the signal pattern into a read-only memory, and the reproduction system uses k bandpass filters, an envelope detection circuit, a differential amplifier, a 2-input 1-output AND gate, and an analog switch circuit to eliminate tracking errors. A detection circuit may also be configured.

In addition, in the second embodiment, the number of segment flag outputs is equal to the number of segments, but if a binary encoder circuit is provided after the 2-input 1-output AND gate circuit, the number of bits of the segment flag output can be increased. can be less than the number of segments. Note that the number of segments p(p
≦2) and the number of segment flag outputs q.
There is a relationship: g2 p-1 < qlog2 p.

FIG. 9 shows a segment pattern inspection circuit when one screen is divided into three segments. A segment pattern test circuit may be configured using the circuit, p exclusive OR circuits, and p input 1 output OR circuit.

Furthermore, in FIG. 9, the parallel latch circuit (31)
Although the number of stages of the parallel latch circuit (31) has been described as one stage, the number of stages of the parallel latch circuit (31) may be two or more stages.Generally, r stages (r≧2) of parallel latch circuits are provided, and It is also possible to hold the output patterns of the segment flags up to the present time and check whether the patterns shifted by a predetermined number of segments match each other by using an r-input exclusive OR gate circuit.

[0046]

[Effects of the Invention] As explained above, the pilot signal recording and reproducing device according to the present invention generates a pilot signal for tracking as part of a recording information signal during modulation, and records and reproduces the digitally modulated pilot signal. This makes it possible to suppress waveform distortion when demodulating the information signal. Further, the gain of the tracking error detection signal generated based on the pilot signal reproduced from each track is constant regardless of the channel, and
A large S/N ratio can be obtained, and the track pitch can be narrowed to achieve high density recording and reproduction. Furthermore, there is no need for an adder circuit for adding the modulated information signal and the information signal to the pilot signal, resulting in an excellent effect that the device can be simplified and manufactured at low cost.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a pilot signal generation device for generating a tracking error and a tracking error detection circuit showing a first embodiment of the present invention.

FIG. 2 is a chart showing an example of the correspondence between input data words and digitally modulated recording code words in the encoder of the pilot signal generation device according to the present invention.

FIG. 3 Input data in the first embodiment of this invention,
It is a figure which shows an example of the fluctuation|variation of the recording code word CDS value and DSV value selected in the recording signal.

FIG. 4 is a diagram showing the power spectrum of a recording signal generated from four types of recording code words in an embodiment of the present invention.

FIG. 5 is a diagram showing the relationship between recording tracks and magnetic heads in the first embodiment of the invention.

FIG. 6 is a block diagram of a tracking error generating circuit, a tracking error detection circuit, and a segment discrimination circuit, showing a second embodiment of the present invention.

FIG. 7 Input data in a second embodiment of the invention,
FIG. 6 is a diagram showing an example of variations in the CDS value and DSV value of a recording signal word selected in the recording signal.

FIG. 8 is a diagram showing the relationship between a recording track and a magnetic head in a second embodiment of the invention.

9 is a block diagram of a segment pattern inspection circuit used in a subsequent stage of the second embodiment of the invention shown in FIG. 6; FIG.

10 is a diagram showing changes in the segment flag output pattern obtained each time a track is operated during playback in the segment pattern inspection circuit shown in FIG. 9; FIG.

FIG. 11 is a block diagram of a pilot signal recording/reproducing device for tracking control and a tracking error detection circuit employed in a conventional magnetic recording/reproducing device.

FIG. 12 is a diagram showing the relationship between recording tracks recorded by a conventional magnetic recording/reproducing device and a magnetic head.

[Explanation of symbols]

(1) Reference oscillator (2) Presettable counter (3) Flip-flop (4) Waveform shaping filter (5) Adder circuit (6) Recording/reproduction selector switch (7) Magnetic head (8) Rotating head (9) Magnetic tape ( 10) Frequency division ratio control circuit (11) Low-pass filter (12) Balanced modulation circuit (13) Amplifier (14A), (14B), (14C) Band-pass filter (15A), (15b), (15C) Envelope detection circuit (16), (16A), (16B), (16C) Differential amplifier (17) Recording track (21) Encoder (22) Recording code word selection control signal generation circuit (23)
4-input 1-output selector circuit (24) Parallel-serial conversion circuit (25A), (25B), (25C) 2-input 1-output AND gate (26A), (26B), (26C) Analog switch circuit (30) Segment pattern inspection Circuit (31)
Parallel latch circuit (32A), (32B), (32C) Exclusive OR gate circuit (33) 3-input 1-output OR gate circuit Ref Sine wave reference signal A Information signal C1 Track switching signal C2 Recording/playback switching signal R Playback signal Pr Pilot signal Tc Tracking control signal Dw Input data word Sc Recording code word selection control signal Ot On-track signal

Claims (3)

[Claims] 1. A pilot that generates and records/reproduces a pilot signal for tracking error detection, which is applied to a magnetic recording/reproducing device that divides a digital signal into a plurality of segments and records/reproduces it on a magnetic recording medium using a rotary head of multiple channels. In a signal recording/reproducing device, when recording, a data word with a word length of m bits represented by a binary digital signal is recorded with a word length of n bits (n is an odd number and n>m).
means for associating four types of recording code words with charge sum values in the recording code word of -1, +1, -3, and +3 to one data word when performing recording encoding to convert the recording code word into a recording code word; , the four codes are selected according to a drum PG signal for drum rotation phase control output from a sensor attached to a rotating drum constituting a rotating head, and a recording code word selection control signal generated from a count value of the recording encoding cycle. By selecting one of the words and setting the accumulated charge value at the end of the recorded code word to 0 at every predetermined period, multiple frequencies appear repeatedly in every other recording track, and each envelope 1. A pilot signal recording and reproducing apparatus comprising: means for generating pilot signals having the same magnitude. [Claim 2] During reproduction, a tracking control signal is obtained from the difference in values obtained by envelope detection of the reproduced pilot signal, and it is determined which segment the track being scanned belongs to from the combination of frequencies of the reproduced pilot signal. The pilot signal recording and reproducing apparatus according to claim 1, further comprising means. 3. The present invention is characterized by comprising means for determining which segment is the track being scanned during playback and at the same time outputting or displaying a signal representing on-track when a predetermined segment detection pattern is obtained. A pilot signal recording and reproducing device according to claim 2.