JPS60138753A - Recording and reproducing method of digital signal - Google Patents

Abstract

PURPOSE:To attain compatibility between devices by recording a tracking pilot signal to a recording region of each track in lengthwise direction independently of a digital signal, reproducing surely a pilot signal and controlling correctly a rotary head. CONSTITUTION:When a head 1B scans over two tracks of 5A4, 5B5, pilot signals PA15, PB10 recorded on a central part area AT3 of the tracks are extracted by sampling pulses SP1, SP2, a tracking error signal to the head 1B is obtained through the comparison of the tracking signals corresponding respectively to both pilot signals and the tracking error signal to a head 1A is obtained similarly. The capstan has only to be controlled by a tracking control signal being a mean value of both tracking error signals. Thus, the tracking control of the rotary head is conducted by reproducing the tracking pilot signal surely so as to attain compatibility between device.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention converts, for example, a video signal or an audio signal into a PCM signal, and records this as one diagonal track on a recording medium by a rotating head in units of time. The present invention relates to a method for recording and reproducing digital signals suitable for use when reproducing .

BACKGROUND TECHNOLOGY AND PROBLEMS A helical scan type rotary helical rad device records video and audio signals on a magnetic tape once per unit time.
When a diagonal trunk of each book is formed and recorded and then reproduced, it has been considered to record and reproduce the video signal and audio signal by converting them into PCM. This is because PCM allows recording and reproduction with high surface quality.

In this case, tracking control to ensure that the rotating head correctly scans the recording track during playback is conventionally performed by sending a control signal recorded at one end of the tape by a fixed magnetic head to the fixed head. Generally, this is done by reproducing the information with a constant phase relationship between the reproduction control signal and the rotational phase of the rotary head.

However, this method requires a fixed magnetic head specifically for tracking control.

Providing such a fixed magnetic head is inconvenient when it is desired to downsize the recording/reproducing apparatus due to the mounting location and the like.

Therefore, the present applicant previously proposed a method of controlling the tracking of a rotary head for reproduction by using only the reproduction output of the rotary head for reproduction without using this fixed head.

In this method, PCM signals can be easily compressed and expanded on the time axis, so unlike analog signals, there is no need to record and reproduce signals in a temporally continuous manner.
This method was developed by focusing on the fact that it is possible to easily record this PCM signal and a separate signal by dividing the area into the tracks of a book.

In other words, when a PCM signal is compressed in the time axis and recorded by diagonally forming tracks on a recording medium using a plurality of rotating heads without forming a guard band, the PCM signal is recorded in the longitudinal direction of each track. Multiple tracking pilot signals are recorded independently as areas, and during playback,
A recording track is scanned by a rotary head whose scanning width is wider than the width of the track, and the tracking of the rotary head is controlled by the reproduction output of pilot signals from trunks on both sides of the trunk being scanned by the rotary head.

The reference signal for recording and reproducing this tracking pilot signal is a 30 fiz pulse signal (not indicating the rotational phase of the rotary head obtained in synchronization with the rotation of the rotary drive motor of the rotary head). PC) is used.

However, even during playback, if the PG double signal is used as a detection position reference when reproducing the tracking pilot signal, the PG double signal reference position may shift due to mechanical changes over time or temperature changes in the device, causing the PG double signal reference position to shift during playback. ζ appears as a kind of steady amount (offset) of tracking error.

For this reason, it becomes difficult to reproduce the tracking pilot signal at the same timing as during reproduction and recording, and to control the rotary head, and there is a problem in particular that compatibility between devices becomes incompatible.

In addition, since the sampling pulse for obtaining the reproduction output of the tracking pilot signal is formed over one rotation period of the head using the PC signal as a reference, the error increases when integrated, resulting in the effect of so-called jitter. As a result, the position of the sampling pulse may shift.

Furthermore, when considering tracking control in a rotary head type recording and reproducing apparatus, consideration must be given to not only normal reproduction (but also variable speed reproduction in which the tape speed is different from that during recording).

Purpose of the Invention In view of the above, the present invention provides a method for reliably reproducing a tracking pilot signal without being affected by mechanical aging, temperature changes, or jitter of the device, not only during normal reproduction but also during variable speed reproduction. The present invention provides a digital signal recording and reproducing method that can correctly control a rotating head and achieve compatibility between devices, and that can simplify the circuit configuration when performing reproduction by switching between multiple reproduction speeds. .

Summary of the Invention The present invention provides a method for compressing the time axis of a digital signal, forming a diagonal trunk on a recording medium using a plurality of rotary heads without forming a guard band, recording the signal, and reproducing the same. A plurality of tracking pilot signals are recorded in the longitudinal direction of each trunk as a recording area independently of the digital signal, and when the recording trunk is scanned by a rotating head whose scanning width is wider than the width of the trunk during double-speed playback. , during a first scanning period of the rotary head, a pulse signal is formed based on the regenerated output of the pilot signal located in the central portion of the trunk, and during the period of the pulse signal, the pilot signal located in the central portion of the upper track is activated. and in a second scanning period of the rotary head, a pulse signal is formed based on the reproduced output of the pilot signal near the scanning start position, and during the period of the pulse signal, the pulse signal is detected in the central part of the track during core scanning. The device is configured to detect a pilot signal and perform trunking control of the rotary head based on this detection output and the detection output during the first scanning period. It is possible to reliably reproduce the tracking pilot signal and perform tracking control of the ζ-rotating head without being equally affected by this, and it is possible to achieve compatibility between devices. Further, the circuit configuration when performing reproduction by switching between a plurality of reproduction speeds can be simplified.

EXAMPLE Hereinafter, an example of the present invention will be explained in detail based on FIGS. 1 to 7.

FIG. 1 shows the circuit configuration of this embodiment, and here,
Only the circuit configuration for recording a trunking pilot signal, which is directly related to this invention, and reproducing it by switching between normal playback and variable speed playback, for example, double speed, is shown. The circuit configuration is omitted.

In the figure, (IA) and (IB) are rotating heads, (
2) is a magnetic tape as a recording medium. The rotating heads (IA) and (IB) are arranged around the periphery of the drum (3) at equal angular intervals, i.e. 180 degrees apart, as shown in FIG. On the other hand, the magnetic tape (2) is wound around the tape guide drum (3) over an angular range, for example 90 degrees, which is narrower than its 180 degree angular range. Then, the rotating heads (IA and IB) are rotated at a rate of 30 revolutions per second in the direction of arrow (4H), and the tape (2) is run at a predetermined speed in the direction shown by arrow (4T). Then, diagonal magnetic trunks (5A) and (5B) are formed on the magnetic tape (2) by the rotating heads (IA) and (IB) in a so-called overlapping state, as shown in FIG. be made to be done, i.e.
The head gap width (scanning width) W is made larger than the trunk width. In this case, the head (IA) and (IB
) The width directions of the gaps are different from each other with respect to the direction orthogonal to the scanning direction. In other words,
The so-called azimuth angles are made different.

There then occurs a period (which in this example is the period of the angular range bone of 90 degrees) in which the two rotating heads (IA)' (IB) do not abut against the tape (2) together, and this period is The apparatus can be simplified by adding redundant data during recording and performing correction processing during reproduction.

(6Δ) is an oscillator that generates a pilot signal P for tracking, and the pilot signal P is, for example, a frequency fo that has a relatively large value of azimuth loss, that is, a frequency at which azimuth loss is effective, for example, about several hundred kllz, and recorded at the target level.

Further, (6B) is an oscillator that generates a signal E for erasing the pilot signal, and the erasing signal E is later superimposed on the previously recorded tape while erasing the previously recorded information. This is used because when making a new recording, the recording track does not always match the previous recording trunk, so it is necessary to erase the previously recorded pilot signal, and the frequency f1 is the same as the pilot signal. It is set to a value that is practically distant from the frequency fo of , and that allows the pilot signal P to be erased. Further, the recording level is also set at a level that can practically erase the pilot signal P. (7^), (7B) are recording waveform generation circuits, and an edge detection circuit (17A) that detects an edge, for example, a rising edge, of a delayed signal related to pulse PC, which will be described later.
, (17B), the generation circuit (7A
) is based on the pilot signal from the oscillator (6Δ), 1
The generator circuit (7B) generates a pilot signal P having a predetermined time tp (tp is the recording time of each pilot signal) depending on how many pilot signals are inserted per trunk and in what arrangement. Based on the erasing signal from , an erasing signal E having a predetermined time -tp is generated at a predetermined interval T1 depending on how many erasing signals are inserted per trunk and in what arrangement. (8C) is an OR circuit that logically processes the outputs of the generation circuits (7A) and (7B). (9) is a rotating head (IA) and (IB)
) is a switch circuit for switching the switching signal 31 from the timing signal generating circuit Q(1) (Fig. 4A
) can be switched. This timing signal generation circuit aψ includes a rotating head (I) from a pulse generator (11).
A) A pulse PG of 3011z is supplied without indicating the rotational phase of the rotary head (1^) (IB) obtained in synchronization with the rotation of the rotational drive motor (12) of (IB). In addition, 39 from the timing signal generation circuit αω is applied to the pulse PG.
The pulse 11z is supplied to a phase servo circuit (13), and the rotational phase of the motor (12) is controlled by the servo output.

The pilot signal from the switch circuit (9) switched by the switching signal S1 from the timing signal generation circuit αψ is amplified by the amplifier (14A) or (14B) and then sent to the contact point of the switch circuit (15A) or (15B), respectively. It is supplied to the rotary head (1^) or IB) via the R side and recorded on the magnetic tape (2). Switch circuit (15^
) and (15B) are connected to the R side during recording, and are switched to the P side during playback.

In addition, the output signal S from the timing signal generation circuit QO)
2 (Figure 4C) is the delay time b! 1 (168), and after a delay corresponding to the distance between the rotating head (IA) (IB) and the pulse generator (11), etc., the input to the edge detection circuit (17A) is applied. Edge detection is performed as a reference for recording pilot signals. Note that the signal S3 (
The falling edge in FIG. 4D) is made to coincide with the time when the head first contacts the tape during one rotation period.

Also, (16B) , (16G) , (16D) , (
16E) and (16F) are the delay times T (time from the first pilot signal (or erasure signal) recorded on one track until the next pilot signal (or erasure signal) is recorded), T2 (time from the first pilot signal (or erasure signal) recorded on one trunk until the last pilot signal (or erasure signal) is recorded), T (time equivalent to half a rotation period of the head) ),
tp and --tp. Delay circuit (
16A) are sent to the delay circuits (16B) to (1
60) and the signal 34 from the delay circuit (16B).
(Fig. 4E) and signal Ss from the delay circuit (16C)
(Fig. 4F) are both supplied to the edge detection circuit (17A), and the signal Ss (Fig. 4G) from the delay circuit (160) is directly supplied to the edge detection circuit (1'7B) and delayed. The signal is delayed by time T1 in the circuit (16B) and becomes the signal S7 (M in FIG. 4) in the edge detection circuit (17B).
The signal is then delayed by the delay circuit (16C) by a time T2 to become the signal Ss (I in FIG. 4) and is supplied to the edge detection circuit (17^).

Then, the edge detection circuit (17A) detects the falling edges of the signals S3, S4 and S5, respectively, and outputs the signal Ss (J in FIG. 4).
is generated, thereby determining the reference for starting recording of the pilot signal in the period tB. Further, the edge detection circuit (17B) receives the signal Se.

A signal 310 (K in FIG. 4) is generated by detecting the falling edges of 87 and S8, respectively, and thereby the reference for starting recording of the erasing signal in period tA is determined.

Signals S9 and Sso from edge detection circuits (17A) and (17B) are applied to delay circuits (16B) and (16F), respectively.
), the signal 511 (L in FIG. 4) and the signal 512 (M in FIG. 4) are delayed by time tp and -tp, and these signals S
The durations of zt and S12 are the recording times of the biloft signal and the erasing signal in periods t8 and tA, respectively.

In addition, the signals S11 and S12 are each connected to a delay circuit (16F).
and (16B) and delayed by time -tp and tp, respectively, signals 513 (N in FIG. 4) and 514 (N in FIG. 4)
), and the durations of these signals S13 and 314 become the recording times of the erasure signal and pilot signal in periods tB and tA, respectively. Signals S11, S14 and S12
and 313 are passed through delay circuits (8A) and (8B), respectively, to become signals 515 (P in Fig. 4) and 516 (Q in Fig. 4), which are sent to recording waveform generation circuits (7^) and (7B), respectively. is supplied as a gate signal.

(18A) (18B) is the switch circuit (
15^) (15B) is an amplifier to which the playback output from the corresponding rotary head (1^) (IB) is supplied when it is switched to the contact P side, and these amplifiers (18^) (
Each output of 18B) is supplied to a switch circuit (19). The switch circuit (19) is a timing signal generation circuit Q
The head (I
The half-rotation period including the tape contact period of A) and the head (1
B) The half-rotation period including the tape contact period is alternately switched.

(20) is the passing center frequency f for extracting only the pilot signal P from the reproduction output from the switch circuit (19).
o narrowband bandpass filter, (21) is a peak hold circuit to hold the peak value of the output of filter (20) in order to improve response characteristics, (22) is a sample of the held peak value. (23) is a comparison circuit for comparing the respective outputs of the peak hold circuit (21) and the sampling and hold circuit (22), for example, a differential amplifier; (24) is a differential amplifier (23) ) is a sampling and holding circuit for sampling and holding the comparison error signal from these sampling and holding circuits (2
2) (24) essentially samples and holds the crosstalk of each pilot signal recorded at the end of the adjacent track adjacent to the track currently being scanned, as will be described later. work. The output of the sampling hold circuit (24) is taken out as a tracking control signal to an output terminal (25).

Further, in order to form sampling pulses etc. for the sampling and hold circuits (22) and (24), a waveform shaping circuit (26) is provided on the output side of the bandpass filter (20) to substantially detect the edges of the pilot signal. is provided, and its output signal is supplied to the delay circuit (27) to produce a signal 318 (FIG. 5J,
6G and 7G) are obtained. This delay circuit (2
The delay time tLlI in 7) is provided as a countermeasure against pilot signal drop-out, and may be longer than the pilot signal recording time tp, preferably tm.
=tp.

(28) and (29) are the signals S from the delay circuit (27)
A rising edge detection circuit and a falling edge detection circuit for detecting the rising edge and falling edge of
The rising and falling edges of the signal Sxs are detected at and tA, respectively. A switch circuit (30) is provided on the output side of the detection circuits (28) and (29), and is switched by a switching signal S1' from the timing signal generation circuit αψ. low level (period t
o) is connected to the contact a side and the rising detection circuit (28)
The output of the fall detection circuit (29) is connected to the side that contacts when the signal S1' is at a high level (period 8).

The output of the switch circuit (30) is connected to a plurality of gate circuits (3
31) to (335), and its gate signal is, for example, a window signal generation circuit (34) using a counter.
) Wind signal SW□~5W5 (Fig. 5 C-G)
is used. The window signal generation circuit (34) counts clocks from the clock terminal (42) in response to the output signal S2 from the timing signal generation circuit aΦ, and generates a signal of a predetermined width that can cover at least both ends of the signal S48. A wind signal is generated depending on the playback mode. That is, when the window signal generation circuit (34) receives a command signal for setting the normal playback mode from the mode setting circuit (32), it sequentially generates the window signals swi to Sv5, and also generates a command signal for setting the double speed playback mode. When received, the wind signal Sw2. Only Sν is generated.

Therefore, only the edge of the signal 5ill that has entered within the period of these window signals SWi to Sws is sent to each output side of the gate circuits (331) to (33s) as the output signal 51s (
K in FIG. 5, H in FIG. 6 and No. 71 old, passed through an OR circuit (35), and supplied as a substantial start pulse to one input side of a delay circuit (36) using a counter, for example. .

Also, multiple delay time setting circuits (3B), (39)
.

(40) and (41) are provided, and the setting circuit (3 days) operates from the time when the signal S1s is generated to when the pilot signal is substantially started to be sampled during the first half-rotation period of the head during normal playback, for example, within the period tB. delay time ta
The setting circuit (39) sets the signal S1 generated posttympanically within the first half-rotation period to during normal playback.
The next half-rotation period of the head from the time point 9 occurs, for example, the period t
The setting circuit (40) sets the delay time tb up to the actual sampling point of the first pilot signal performed within A setting circuit (41) sets a delay time tc from the time of generation of the °ζ signal Sts to when sampling of the pilot signal starts substantially within tA.
When playing at double speed, period 1. In addition to setting the delay time td from the time when the signal S1s is generated until the actual sampling of the pilot signal starts, at the time of double speed playback (
However, the delay time (j B + t c + t d ).

Each delay time set in the setting circuits (3B) to (41) in this way is determined by the window signal S from the window signal generation circuit (34) in the delay time setting selector (37).
It is selected by Wi to SWS and supplied to the other input side of the delay circuit (36). Therefore, the delay circuit (36), which is a counter, counts the clock from the clock terminal (42) for a set time using the signal Sss as a start pulse, and at the end of the count, a narrow signal 520 (fifth pulse) is sent to its output side. Figure L, Figure 6 I and Figure 7 I) are generated.

(43) is a pulse generation circuit using a counter, for example, which counts the clock from the clock terminal (42) using the signal 320 from the delay circuit (36) as a trigger pulse, and generates a pair of pulses at predetermined intervals during normal playback. Pi
(Fig. 5M), and during double speed reproduction, one of the pair of pulses Pi (Fig. 6J, Fig. 7J) is generated corresponding to each biloft signal to be detected. This pulse Pi is supplied to a peak hold circuit (21) and also to a sampling pulse generation circuit (44) using, for example, a D-type flip-flop circuit.

The sampling pulse generation circuit (44) generates a sampling pulse SP□ in response to the pulse Pi.

SF3 is connected to sampling hold circuits (22) and (24).
) occurs for.

Next, the operation of the circuit shown in FIG. 1 will be explained with reference to the signal waveforms shown in FIGS. 4 to 7.

First, during recording, in response to the pulse PC from the pulse generator (11) indicating the rotational phase of the rotary heads (IA) (IB), the fourth pulse from the timing signal generation circuit (101) is activated.
A signal S2 as shown in Figure C is generated, and this signal S2 is delayed by a predetermined time TR in a delay circuit (16), so that a signal S3 as shown in Figure 4 is outputted to its output side. This signal S3 can be applied directly or through a delay circuit (1) as described above.
6B), (16G) to the edge detection circuit (17A).
), its edge (falling edge) is detected, and in synchronization with this edge, a narrow signal S9 as shown in FIG. 4J is generated on the output side. The standard for starting recording of the biro I signal by the head (IB) is determined.

In addition, the signal S3 is supplied to the edge detection circuit (17B) via the delay circuit (16B) and further via the delay circuits (16B) and (16C), so that the output side thereof is shown in FIG. 4K. Such a narrow signal Sha is generated, and the reference for starting recording of the erasing signal by the head (IA) is determined by this signal SIO.

Then, by passing the signal Ss through the delay circuit (16B), the signal So is obtained, and the recording time of the pilot signal in the period tB is set, and further by passing this signal S1x through the delay circuit (16F), the signal SZ3 is obtained. is obtained, and the recording time of the erasing signal in the same period is set. Therefore, the fall of the signal S1t is also the reference for starting recording of the erasing signal by the head (IB). Further, the signal Sz2 is obtained by passing the signal SIO through a delay circuit (16r''), and the recording time of the erasing signal in period 8 is set.
Further, by passing this signal 312 through a delay circuit (16E), a signal S14 is obtained, and the recording time of the pilot signal in the same period is set. Therefore, the fall of the signal S12 is also the reference for starting recording of the pilot signal by the head (IB).

The signals Su and S14 obtained in this way are connected to an OR circuit (
8Δ) to form a signal S15 as shown in FIG. 4P, which is supplied to the recording waveform generation circuit (78). Also,
Signals 312 and 313 are added by an OR circuit (8B) to form a signal S□6 as shown in FIG. 4Q, which is supplied to a recording waveform generation circuit (7B).

The recording waveform generation circuit (78) uses the supplied signal S15 as a gate signal to substantially pass the pilot signal P from the oscillator (68) for a predetermined time tp every predetermined interval T1, thereby increasing its output. On the side, a signal SIO, which is an intermittent pilot signal as shown in FIG. 4K, is taken out.

Further, the recording waveform generation circuit (7B) receives the supplied signal 3.
16 as a gate signal, the erasing signal E from the oscillator (6B) is passed for a predetermined time -1p every predetermined interval T1.

The output signals from the waveform shaping generator circuits (7A) and (7B) are added by an OR circuit (18G), so that the output side has a signal including a pilot signal and a cancellation signal as shown in FIG. 4R. S17 is taken out.

On the other hand, the timing signal generating circuit α generates a switching signal S1 as shown in FIG. LA) It is synchronized with the rotation of (IB),
As shown in FIGS. 4A and 4B, the ζ head (18) comes into contact with the tape (2) during the half-rotation period tA of the head when the signal S1 is at a high level, and during the half-rotation period when the signal S1 is at a low level. Within the rotation period tB, Herad (IB) rotates the tape (
2). Then, the switch circuit (9) is switched by the switching signal S1 to the state shown in the figure in period 8, and to the state opposite to the state shown in the figure in period ts, thereby performing head switching.

Therefore, the signal S obtained at the output side of the OR circuit (18C)
17 indicates that when the switch circuit (9) is in a state opposite to that shown in the figure, the amplifier (14B) and the switch circuit (15
B) is supplied to the head (IB) through the R side, and period 1
．． At the beginning, middle and end of the contact period of the head (IB) in the tape (2), as shown in FIG.
5B) from the longitudinal center position to the geometric ratio 14uj2 (T1
Tracking signal recording areas ATi and AT2 provided at both ends of the track (5B) in the longitudinal direction, which are separated by a distance corresponding to Recorded during tp+-tp.

On the other hand, when the switch circuit (9) is in the state shown in the figure, the signal SIT is
A) is supplied to the head (18) through the R side for a period t.
At the beginning, middle and end of the period of contact of the head (18) in A with the tape (2), the trunk (5)
Equidistant f (T, equivalent) from the center position in the longitudinal direction of A)
Recording areas ATI and AT2 similar to those described above provided at both ends of the trunk (5A) in the longitudinal direction, which are separated by a distance of recorded for.

In addition, at times other than the time when these pilot signals and erasure signals are recorded, the audio PCM signal of one segment portion to be recorded as one track, although not shown, is
During the period tA, the head (1Δ) passes through the amplifier (148).
During the period ts, it is supplied to the head (IB) through the amplifier (14B), and each track (5A) (
5B) It is recorded in recording areas AP and AP2 other than the above-mentioned pilot signal recording area.

Next, reproduction of the signal recorded as described above will be explained.

Also during this reproduction, drum phase servo is applied to the motor (12) by the phase servo circuit (13) in the same manner as during recording.

First, during normal playback, the rotating head (IA)
The signals extracted from the tape (2) by (IB) and (IB) are sent to the contact P side of the switch circuit (15A) and the amplifier (
18^), the contact P side of the switch circuit (15B), and the amplifier (18B) to the switch circuit (19). This switch circuit (19) is activated by a switching signal st' of 3011z as shown in FIG. It is alternately switched between a period tA and a half-rotation period tB, which includes the tape contact period of the head (IB). Therefore, from this switch circuit (19), intermittent PCM of one segment as shown in FIG.
A signal sR is obtained, which is supplied to a reproducing processor (not shown), where it is converted into the original PCM signal, and further supplied to a decoder, where data for each block is detected using a block synchronization signal, and error correction and decoding are performed. Processing such as interleaving is performed, and the signal is converted back to an analog audio signal by a D/A converter and outputted to the output side.

I-racking control is done as follows.

Now, for example, if the head (IB) scans a range of scanning width W including the trunk (5B2) as shown by the constant chain line in FIG. 3, the head (1B) will scan the tracks ( 5A2) (5A1)
As shown in FIG. 3, in the area ATL, the pilot signal PA2 of the trunk (5B2) and the pilot signal PB2 of the trunks (582) on both sides are scanned across the area.
and the pilot signal PB1 of the track (5Δ1), and in the area AT11, the pilot signal PA4 of the track (5B2), the pilot signal PB4 of the adjacent track (5A2) on both sides, and the pilot signal pBa of the track (58,) are reproduced. In the area AT2, the pilot signal P to 8 of the trunk (5B2), the pilot signal pee of the trunk (5A2) on both sides, and the pilot signal PB5 of the track (5^1) are reproduced.

At this time, the playback output of the head (IB) from the switch circuit (19) is supplied to a narrowband bandpass filter (20) with a passing center frequency fo, and as shown in FIG. Only the signal is extracted,
This is supplied to the peak hold circuit (21).

In addition, the output SF of the band pass filter (20) is waveform-shaped into a rectangular wave by the waveform shaping circuit (26) and then supplied to the delay circuit (27), so that its rear part is substantially delayed by a predetermined time tm. The signal S1e as shown in FIG.
is obtained. This signal Sis is transmitted to the detection circuit (28) and (
The rising edge and falling edge of the signal 31g are detected by the switch circuit (30), and during the period tB during scanning by the head (IB), the rising edge of the signal 31g detected by the detection circuit (28) is detected by the switch circuit (30). is supplied to the gate circuits (331) to (336) through the contact a side of the head (1).
During period tA during scanning in ^), the fall of the signal 3111 detected by the detection circuit (29) is detected by the switch circuit (30)
Gate circuit (331) to (33s) through the contact side of
supplied to

Further, the window signal generation circuit (34) outputs a signal S as shown in FIG. 5B from the timing signal generation circuit Ql.
2, window signals SWi to SWS as shown in FIG. 5C are sequentially generated and the gate circuit (331)
~(33s) as a gate signal, therefore, the window signal SW is supplied to the output side of these gate circuits.
Only the rising or falling edge of the signal 318 that entered during each period of i to SW5 is substantially taken out, and as a result, it is sent to the output side of the OR circuit (35) on the output side of the gate circuits (33z) to (33s). As shown in FIG. 5K, the narrow signal S1 coincides with the rising edge of the signal SZS during the period to, and coincides with the falling edge of the signal 3111 during the period tA.
s is obtained.

This signal sis is supplied to a delay circuit (36).

At this time, the selector (37) selects the delay time setting circuits (38) to (40) to set each delay time ta.

tb and tc are set for the delay circuit (36).

During the period IB, the delay circuit (36) sequentially generates the signal S20 delayed by the time ta from the signal S1s, as shown in the left part of the fifth diagram, and during the period IB, as shown in the center part of the fifth diagram. At the stage of transition from tB to period tA, period I
The first signal S during period tA delayed by time tb from the time when the last of the signals S19 generated during B is generated.2. .

During the period tA after the first signal 320 is generated, the signal 320 is generated as shown in the right part of the fifth diagram.
A signal 320 delayed by time tc from signal 19 is generated.

This signal 320 is supplied to a pulse generation circuit (43),
Now, as shown in FIG. 5M based on the signal 32 (l),
A pair of pulses Pi corresponding to each pilot signal to be detected is formed, and the sampling pulse generation circuit (4
4) and a peak hold circuit (21). Then, the sampling pulse generation circuit (44) generates sampling pulses SPt and SF3 as shown in FIG. 5 N and 0 based on the pair of pulses Pi,
The signals are supplied to sampling and hold circuits (22) and (24), respectively.

The pulse Pi thus obtained is supplied to the peak hold circuit (21), and the sampling pulses SP1 and SF3 formed based on this pulse Pi are supplied to the sampling and hold circuits (22) and (24), respectively. That will happen.

Therefore, while scanning the track (5B2) with the head (IB), as is clear from FIG.
The pulse Pli peaks the crosstalk of the pyro-node signal P B2+ P B4 and pea of the adjacent track (5A2) on the opposite side to the transport direction shown by the arrow (4T) (Fig. 3) in the peak hold circuit (21). The peak hold circuit (21) at this time enters a hold state.
The output of is supplied to the sampling bold circuit (22), where it is sampled by the sampling pulse sP1 generated at the falling edge of the first pulse Pit, and is sent to one side of the differential amplifier (23) as an advanced phase trunking signal. is supplied to the input end of

Further, the second pulse PL2 of the pulse Pi is the pilot signal PB1 of the adjacent trunk (5^1) on the tape transport direction side.
．． The crosstalk between PH1 and pes is held at its peak in the peak hold circuit (21).
The output of the peak bold circuit (21) at this time is supplied to the other input terminal of the differential amplifier (23) as a tracking signal with a delayed phase. Therefore, the differential amplifier (23
) are pilot signals PB2 and PBl, PH1 and pea,
The tracking signals corresponding to the crosstalk of pse and PH1 are sequentially compared.

The comparison error signal from the differential amplifier (23) is then supplied to the sampling hold circuit (24), where it is sampled by the sampling pulse SP2 generated at the falling edge of the second pulse PL2.

Therefore, from this sampling and hold circuit (24), the difference in power between the two persons to the differential amplifier (23) is obtained as a tracking control signal, and this is supplied from the output terminal (25) to the capstan motor (not shown) to record the tape. The amount of transfer is controlled, and the difference in the level of power applied by both people to the differential amplifier (23) is zero, that is, the head (IB) is connected to the track (
5B2), two tracks on both sides (5^
2) and (5Δ1) by the same amount. That is, the head (IB) is controlled to scan so that the center position of the gap in the width direction coincides with the center position of the track (5B2).

The same process is applied to other tracks. For example, when the head (18) scans the track (582), as shown on the right side of FIG. 5B3) and (5B2) pilot signal P
AT+PA! l+ P Ali and P8. +PA4
Since the crosstalk of +PAfl is obtained, this etc. is successively peak-bolded by the peak hold circuit (21) as described above, and the pilot is set by the sampling pulse S P 1 supplied from the sampling pulse generation circuit (44) to the sampling hold circuit (22). Signal PAT.

The crosstalk of P A11 is sampled to obtain a C tracking signal, and this is supplied to the next stage differential amplifier (23), as well as the pilot signal P A2+
The output from the peak hold circuit (21) corresponding to the crosstalk of PA4+PAQ is supplied, and thus the pilot signals FAT and PA2. PAII and PA4% P
By comparing the tracking signals corresponding to the crosstalk of AII and PAQ, and sampling the comparison error signal with the sampling pulse SP2 supplied to the sampling bold circuit (24),
A tracking control signal can be obtained for.

Also, in the same way, move the track (583) to the head (IB).
When scanning, as shown in FIG.
Since the crosstalk of +PBθ is obtained, the crosstalk of the biloft signals PB71 PBIII PBll is sampled with the sampling pulse SP1, and the crosstalk of the pilot signals PBT, PH2, PH8, PR4~pei1, and PBG is sampled by the differential amplifier (23). By comparing the corresponding tracking signals and finally sampling the comparison error signal with the sampling pulse SP2, a trunking control signal for the head (IB) can be obtained.

Next, during double speed reproduction, the rotary head scans the position shown by the broken line in FIG. 3 so that the center of the gap width passes through it. In other words, two adjacent recording trunks (5
Δ) One of (5B), for example, track (5B), is scanned in the first half of the tape contact period of each rotary head (LA) (IB), and the other, for example, track (5A), is scanned in the second half.

In this scanning manner, the rotary head (18) and
The signals extracted from the tape (2) by B) are sent to the contact P side of the switch circuit (15A) and the amplifier (18A), respectively.
), the contact P side of the switch circuit (15B, ), and the amplifier (18B) to the switch circuit (19). This switch circuit (19) is activated by a switching signal 81' of 30 tlz as shown in FIG. It is alternately switched between a period tA and a half-rotation period tB, which includes the tape contact period of the head (IB). Therefore, from this switch circuit (19), an intermittent PCM signal SR of l segments as shown in FIG. The data is then sent to a decoder, where the data for each block is detected using a block synchronization signal, and processing such as correction and de-interleaving is performed.The data is returned to an analog audio signal by a D/A converter and sent to the output side. be derived.

Tracking control is performed as follows.

Now, for example, if the head (IB) is to scan in the direction shown by the broken line across two tracks (5A2) (5BB) in FIG. In the trunk (5B
3) Pilot signal PA? and trunk (5B2)
The pilot signal PA2 of the truck (582) and the pilot signal PR2 of the truck (582) are reproduced.
The pilot signal PB4 of ^2) is regenerated, and the area A T
2, the pilot signal PA of the truck (5B3)
□1. Pilot signal PB11 of truck (5Δ3)
and the pilot signal PBII of the track (5A2). At this time, the reproduced output of the head (IB) from the switch circuit (19) is supplied to a narrowband bandpass filter (20) with a passing center frequency fO, and as shown in FIG. 6F, the output Sp is the pilot Only the signal is taken out and supplied to the peak bold circuit (21).

Further, the output SF of the bandpass filter (20) is shaped into a rectangular wave by the waveform shaping circuit (26) as described above, and then supplied to the delay circuit (27), so that the rear part thereof is substantially shaped into a rectangular waveform by the predetermined time tm. A signal 31g as shown in FIG. 6G is obtained, which is delayed by . This signal 31s is transmitted to the detection circuit (28
) and 29), and during period tB during scanning by the head (IB), the rising edge of the signal S1e detected by the detection circuit (28) is supplied to the switch circuit (30).
), and during period tA during scanning with the head (IA), the signal SIJ detected by the detection circuit (29)
The rising edge is supplied to the gate circuits (33□) to (335) through the contacts of the switch circuit (30).

Further, during double speed playback, the window signal generation circuit (34) generates window signals Sw2 and SW4 as shown in FIG. 332) and (33
4) as a gate signal, therefore, the output side of the gate circuits (332) and (334) only receives the rising signal Sza that is input during the periods of the window signals SW2 and SW+. As a result, as shown in FIG. Signal 5i in period tA
A narrow signal 31s corresponding to each falling edge of ll is obtained.

This signal 31s is supplied to a delay circuit (36).

Also, at this time, the delay time setting circuits (40) and (41) are selected in the selector (37), and the delay times tc and t
d is set for the delay circuit (36).

The delay circuit (36) operates during period 1. As shown in the left part of FIG. 6I, a signal 320 is generated which is delayed by a time td from the signal Srs, and during period tA, as shown in the right part of FIG. 6I, a signal 320 is delayed by a time tc from the signal Srs. A delayed signal 320 is generated.

This signal S20 is supplied to the pulse generation circuit (43),
Based on the signal S20, a pair of pulses P1 corresponding to each pilot signal to be detected is formed as shown in FIG.
) and a peak hold circuit (21). Then, the sampling pulse ordering circuit (44) generates sampling pulses SPi and SF3 as shown in FIG. 6 K and L based on the pair of pulses Pi.
The signals are supplied to sampling and hold circuits (22) and (24), respectively. Note that the interval between the pair of pulses Pi in this case is a wide interval equivalent to 2 tp, unlike the normal reproduction mode.

Therefore, the head (IB) tracks (5^2) and (5B
During scanning in the direction shown by the broken line in FIG. 3 across the two tracks of 3), as is clear from FIG.
The crosstalk of the pilot signal PA9 of the trunk (5B3) on the opposite side to the transfer direction shown in FIG. 3) is peak held in the peak hold circuit (21),
The output of the peak hold circuit (21) at this time is supplied to the sampling hold circuit (22), where it is sampled by the sampling pulse SP1 generated at the falling edge of the first pulse PL1 of the pulse Pi, and the output of the leading phase is It is supplied as a tracking signal to one input terminal of the differential amplifier (23).

Further, the second pulse P[2 of the pulse Pi is in a state where the crosstalk of the pilot signal PB4 of the track (5A2) on the tape phase shift direction side is peak-bolded in the peak hold circuit (21), and the peak hold circuit at this time The output of (21) is supplied to the other input terminal of the differential amplifier (23) as a tracking signal with a delayed phase. Therefore, the differential amplifier (23) compares the tracking signals corresponding to the crosstalk of the pilot signals PAfl and PH1, respectively.

The comparison error signal from the differential amplifier (23) is then supplied to the sampling hold circuit (24), where it is sampled by the sampling pulse SP2 generated at the falling edge of the second pulse P12.

Therefore, from this sampling hold circuit (24), the difference in the power applied to the differential amplifier (23) is obtained as a tracking error signal, which is supplied to the capstan motor (not shown) from the output terminal (25).

In addition, for example, the two trunks of trucks (5A3) and (5B4) can be moved with the head (1) in the direction shown by the broken line in FIG.
^) scans, in the area ATL shown in the figure, the pilot PAa of the track (5B4) and the pilot signal PA? of the track (583) are scanned. and truck (5A
3), and in area AT8, the pilot signal PAlo of track (5B4) is reproduced.
, the pilot signal PAII of the truck (5B3) and the pilot signal PB11 of the truck (5A3), and in the area AT2, the pilot signal PA12 . The pilot signal PB12 of the track (5A4) and the pilot signal PRt□ of the track (5A3) are reproduced.

Therefore, the head (1^), trunk (5A3) and (5
While scanning the direction shown by the broken line in FIG. 3 across the two trunks of B4), as is clear from FIG.
Truck (5B4) on the opposite side to the transport direction shown in (Figure 3)
The peak hold circuit (21) holds the crosstalk of 10 to the pilot signal P of It is sampled by a sampling pulse SP1 generated at the falling edge of the first pulse P, and is supplied to one input terminal of the differential amplifier (23) as a tracking signal with an advanced phase.

Further, the second pulse PI2 of the pulse Pi enters a state in which the crosstalk of the pilot signal PB9 on the track (563) on the tape phase shift direction side is peak held in the peak hold circuit (21), and at this time, the peak hold circuit (21) ) is supplied to the other input terminal of the differential amplifier (23) as a tracking signal with a delayed phase.

Therefore, the differential amplifier (23) receives the pilot signal P^10
The tracking signals corresponding to the crosstalk of Pss and Pss are compared.

The comparison error signal from the differential amplifier (23) is then supplied to the sampling and hold circuit (24), where it is sampled by the sampling pulse SP2 generated every time the second pulse PL2 rises.

Therefore, from this sampling hold circuit (24), the difference between the two power inputs to the differential amplifier (23) is obtained as a tracking error signal, and this is sent to the output terminal (25).
Although not shown, it is supplied to the capstan motor.

In this example, the periods tB and t7+ as described above.

The tracking error signals obtained at the output terminal (25) are the same in level but have opposite polarities. Therefore, the actual tracking control signal supplied to the capstan motor is The tracking error signal is averaged using, for example, a low-pass filter (not shown), and this is then supplied to the capstan motor. However, depending on the performance of the capstan motor, the fluctuations in the tracking error signal may be absorbed and averaged using its inertia without using the above-described low-pass filter.

By controlling the capstan motor using the tracking control signal averaged in this way and controlling the amount of phase shift of the tape, the head (IB) moves from track (5 to 2).
(583), or head (l^) or track (5A
When scanning over two tracks, 3) and 5B4, the rotary head is controlled so as to draw a scanning locus as shown by the broken line.

Similarly, the head (IB) is connected to the track (5A4
) and (5Bs), 15 and PBl are applied to the pilot signal P recorded in the central part (area ATs) of these tracks.

Also, the head (18) is connected to the track (5^6) and (5
86) (not shown), the pilot P711s (not shown) and PB recorded in the central part (area A T3 ) of them are scanned.
16 is extracted with sampling pulses SPi and SF3, respectively, to obtain pilot signals PA16 and PB1.

A trunking error signal for the head (IB) is obtained by comparing the tracking signals corresponding to the crosstalk of 2 and 2, respectively, and a trunking error signal for the head (IA) is obtained by comparing the tracking signals corresponding to the crosstalk of B16 and PB15, respectively.
Then, as described above, the capstan motor can be controlled using a tracking control signal obtained by averaging both of these tracking error signals.

FIG. 7 shows another embodiment in the double speed playback mode. As mentioned above, in the example of FIG. 6, tracking error signals for the corresponding heads (IB) and (1Δ) are obtained for each period tB and tA, respectively. In contrast, in this embodiment, one tracking error signal is obtained only during the rainy period of periods tB and tA, that is, one rotation period of the head.

Therefore, in this embodiment, for example, in the period te, the pilot signal that first appears in the central area of the track being scanned by the first pulse Pi1 of the pulse Pi from the pulse generating circuit (43), that is, the head (IB) is 5A2
) and (5B3), the peak hold circuit (21) holds the crosstalk of the pilot signal PA9 of the track (5B3) at its peak, as shown in FIG. 7F and J. Pulse generation circuit (
The second pulse PL2 of the pulse Pi from 43) causes the last birch word to appear in the central region of the track being scanned, i.e. the head (1^) is connected to the trunk (5A3) and (
584), the pilot signal p of the track (5^3) is
The sa crosstalk is held at its peak.

Therefore, in this mode, the pulse generating circuit (43) generates only the I-th pulse ptt of the pulse Pi during one scanning period of the head, e.g. period to, and the second pulse Ptt of the pulse Pi during the other scanning period of the head, e.g. period tΔ. Pulse PL2 of
only to be generated.

Note that the timing of generating the first pulse Pi1 in the period tB is the same as in the example of FIG. 6, and therefore the delay time t
There is no need to change the setting of d, but the second
Although the timing of generating the pulse P12 is the same as in the example in FIG. 6, it is necessary to generate this pulse PL2 in coincidence with the signal S20 delayed by a predetermined time from the signal Sss, so the delay time in the example in FIG. Unlike tc, the delay time in this case is ta + tc + td as shown in FIG. 7T. Therefore, in this mode, the selector (37) selects the delay circuit (38) in addition to the delay circuits (40) and (41), and the delay times tc+td and ta are set to the delay circuit (38).
6).

As mentioned above, for example, when the bed (IB) scans across two tracks (5Δ2) and (583), the crosstalk of the pilot signal PAIL in the area AT3 is caused by the pulse generation circuit (43 pulses Pf). 1st
The peak hold circuit (2
1), and the output of the peak hold circuit (21) at this time is the sampling pulse sp1 (Fig. 7K) from the sampling pulse generation circuit (44).
) is sampled by the sample hold circuit (22) and supplied to one input terminal of the differential amplifier (23).

Also, the head (IA) has two tracks (5A3) and (
5B4), the crosstalk of the pilot signal pea in the area AT3 peaks at the second pulse P12 (FIG. 7J) of the pulse Pi of the pulse generation circuit (43). (21)
The output of the peak hold circuit (21) at this time is supplied to the other input terminal of the differential amplifier (23).

Then, the comparison error signal (tracking error signal) from the differential amplifier (23) at this time is sent to the sampling pulse generation circuit (4) in the sampling hold circuit (24).
4) is sampled by the sampling pulse SP2 (FIG. 7L), and is led out to the output terminal (25) as a tracking control signal.

This derived control signal is supplied to the capstan motor to control the tape transport amount, and the differential amplifier (23)
The difference in the level of the two people's strength is zero, that is, the head (IB) is connected to the track (5A2) and (5B3), and the head (IA
) scans over two tracks (5^3) and (5B4), the rotary head is controlled so as to draw a scanning locus as shown by the broken line in FIG.

In addition, in the above-mentioned embodiment, the frequency fo of the pilot signal
In this case, a frequency at which azimuth loss is effective is used, but a frequency at which azimuth loss is not effective, that is, a frequency at which azimuth loss is relatively small may also be used.

As described above, in this embodiment, during reproduction, at least the period tB
, the beginning of the reproduced output of the pilot signal recorded in the central area of the trunk, and the end of the reproduced output of the pilot signal recorded in the first area of the trunk as a reference point in the period tA, and the pilot of each central area. Since the sampling pulse is self-generated by detecting the signal, that is, the self-clock as the sampling pulse is generated substantially from the trunk pattern, there is no adverse effect such as an offset when the pulse PG is used as a reference.

In addition, each head generates a sampling pulse as described above to detect the tracking position during each scanning period of each head, in other words, each head generates a self-clock as a sampling pulse each time substantially on the track pattern.
Since the tracking position of each track is detected, the influence of jitter is also eliminated.

Furthermore, in each reproduction mode, the detection position of the pilot signal can be changed by substantially changing the delay time from the input/output, so that most of the circuit configurations can be made common.

In the above-described embodiment, the variable speed playback is not limited to double speed, but can be similarly applied as long as the playback speed is an integral multiple.

In addition, the above-mentioned embodiment is a special rotary head device that records and plays back by winding the tape over an angular range narrower than the head angular interval, but as in the conventional example, the tape is wound over an angular range that is the same as the head angular interval. Of course, the present invention can also be applied to the case where a rotating head device for winding is used.

Effects of the Invention As described above, according to the present invention, when a recording trunk is scanned by a rotary head, pulse signals for extracting pilot signals are formed from pilot signals recorded in at least the central portion of the trunk. , when played by a tracking control signal based on its rain detection output,
In particular, since the dragging control of the rotary head is performed during double-speed playback, even if there is mechanical aging, temperature change, or jitter in the device, it will not be affected by any of these factors, and the playback will be the same as when recording. Even if the devices are different, tracking control during playback can be performed with good viscosity, and compatibility between devices can be achieved. In addition, when the playback speed changes, it is only necessary to selectively change the delay setting time and change the pilot signal detection position, so it is possible to use a common circuit in a playback system that can substantially switch between different playback speeds. can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing an example of the rotary head device used in FIG. 1,
3 is a diagram showing an outline of the recording track pattern of the present invention, FIG. 4 is a signal waveform diagram for explaining the recording operation in FIG. 1, and FIG. 5 is a diagram for explaining the normal reproduction operation in FIG. 1. 6 is a rounded signal waveform diagram for explaining the double speed playback operation in FIG. 1, and FIG. 7 is a rounded signal waveform diagram for explaining another example of the double speed playback operation in FIG. 1. FIG. (IA) (IB) is a rotating magnetic head, (2) is a magnetic tape, (6A) is a pilot signal oscillator, (6B) is an erasing signal oscillator, (7A) and (7B) are recording waveform generation circuits, (16A) - (16B) , (27) , (
36) is a delay circuit, (17A), (17B) are edge detection circuits, (20) is a band pass filter, (21)
) Hahik hold circuit, (22) and (24) are sampling and hold circuits, (23) is differential amplifier, (2
6) is a waveform shaping circuit, (28) is a rising edge detection circuit, (
29) is a falling detection circuit, (31) is a mode setting circuit, (331) to (336) are gate circuits, (34) is a window signal generation circuit, (37) is a delay time setting selector,
(38) to (41) are delay time setting circuits, and (43) is a pulse generation circuit.

Claims (1)

[Claims] In a method of compressing the time axis of a digital signal, forming diagonal tracks on a recording medium using a plurality of rotary heads without forming a guard band, and reproducing the same, the A digital signal is a recording area in which a plurality of tracking pilot signals are recorded independently, and when the recording trunk is scanned by a rotary head whose scanning width is wider than the width of the track during double-speed playback, the first During the scanning period, a pulse signal is formed based on the reproduced output of the pilot signal located at the center portion of the track, and during the period of the pulse signal, the biloft signal located at the center portion of the upper track is detected. In a second scanning period, a pulse signal is formed based on the reproduced output of the high lot signal near the scanning start position, and during the period of the pulse signal, the pilot signal in the center part of the track being scanned is detected; A method for recording and reproducing digital signals, characterized in that tracking control of the rotary head is performed based on the detection output and the detection output during the first scanning period.