JPS62246104A - Measuring instrument for recording and reproducing characteristic - Google Patents

Abstract

PURPOSE:To measure recording and reproducing characteristics with a high precision without the occurrence of disturbance, the generation of a spurious signal, neither unstableness of tracking servo by recording a pilot signal for tracking servo and a recording and reproducing characteristic measuring signal in positions independent of each other. CONSTITUTION:The signal from an electromagnetic conversion characteristic measuring signal generator 1 and a signal where the pilot signal and a bias signal are superposed are inputted to a switch 5; and when tracks are written by heads 71 and 72, the switch 5 is so switched that only the signal where the pilot signal and the bias signal are superposed is recorded on the first zone 152 and only the electromagnetic conversion characteristic measuring signal is recorded on the other zone 151. The reproduced signal from a head amplifier at the reproducing time is the signal, where the pilot signal and the bias signal are superposed, in case of the first zone 152 of each track and is the electromagnetic conversion characteristic measuring signal in case of the other zone 151. A switch 11 is switched to the side of a reproduced signal analyzer 12 when the reproduced signal is the electromagnetic conversion characteristic measuring signal, and the switch 11 is switched to the side of a low-pass filter 13 when the reproduced signal is the signal where the pilot signal and the bias signal are superposed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for measuring recording and reproducing characteristics in a recording and reproducing device.

(Prior art) Figure 3 shows, for example, an electromagnetic conversion characteristic measuring device for rVTR [automatic measurement of magnetic conversion characteristics'' announced at the 1984 Television Society National Conference, and is applied to VTRs that apply tracking servo using pilot signals. FIG. 3 is a block diagram showing a case where

Note that this electromagnetic conversion characteristic is one of the recording and reproducing characteristics.

FIG. 4 shows a track pattern on a magnetic tape recorded by the electromagnetic conversion characteristic measuring device. Note that the drum wrapping angle of the tape is 180°.

In FIG. 3, reference numeral 1 denotes a signal generator for measuring electromagnetic conversion characteristics.This may be, for example, an oscillator whose output level and frequency can be set arbitrarily, and some of which can be automatically controlled by a computer. 2 is a pilot signal generator for tracking servo, for example, when the measurement target is 8 mm VT.
In the case of R, four frequencies are recorded repeatedly on each track. 4.degree. is an adder that adds the output of the signal generator 1 for measuring electromagnetic conversion characteristics and the output of the pilot signal generator 2 at an appropriate level. 6 is a recording amplifier for recording the added signal; 71.
72 is channel l.

2 magnetic head, 8 is magnetic tape, 91.92
are head amplifiers that amplify signals induced in the magnetic heads 71 and 72, respectively; 10 is a head selector switch; 12
is a reproduced signal analysis device that analyzes the output of the head amplifiers 91 and 92. For example, it may be a device that combines a spectrum analyzer and a computer to graph output levels and the like. 13 is a low-pass filter that extracts a pilot signal from the output of the switch 10; 14 is a reproduction signal processing circuit that uses the pilot signal extracted by the low-pass filter 13 to apply tracking servo for reproduction. Further, in FIG. 4, 15° indicates one track on the tape.

Next, the operation will be explained. As shown in Fig. 3(a), the recording signal output from the signal generator 1 for measuring electromagnetic conversion characteristics and the pilot signal output from the pilot signal generator 2 are combined by an adder 4° to apply tracking servo during reproduction. The signals are added at a ratio that does not interfere with the recording signal and output to the recording amplifier 6. This output is converted into a current by the recording amplifier 6 and recorded on the magnetic tape 8 by the magnetic heads 71 and 72.

On the other hand, as shown in FIG. 3(b), the signals induced from the magnetic tape 8 to the magnetic heads 71 and 72 are each amplified by the head amplifiers 91 and 92, and the outputs of the two heads are selected by the switch 10 to produce the reproduction signal. The signal is sent to the analysis device 12, and electromagnetic conversion characteristics such as the t&current-reproduction voltage characteristics are obtained. Further, a pilot signal is extracted from the output of the switch 10 by a low-pass filter 13, and a reproduction pilot signal processing circuit 14 applies reproduction tracking servo using the pilot signal. An electromagnetic conversion characteristic measurement signal and a pilot signal are recorded in a superimposed manner on each of the 1-rack patterns shown in FIG. 4.

[Problem that the invention seeks to solve]

Conventional electromagnetic conversion characteristic measuring devices are configured as described above, and the pilot signal and the signal for measuring electromagnetic conversion characteristics are superimposed and recorded, so spurious signals are generated due to interference, and especially the pilot signal and! When the level difference between the spurious signal and the signal for measuring magnetic conversion characteristics (recorded with varying levels) is small, the spurious signal has a large amount of energy, resulting in a reproduction level different from that in the case of recording and reproduction at a single frequency. Also, C/N ratio 1 transmission vs. noise level)
Also in the case of spectrum measurement, spurious signals stand on top of the noise spectrum, making it difficult to see. Furthermore, the pilot signal is recorded with the electromagnetic conversion characteristic measurement signal as a bias, so if the level of the tm conversion characteristic measurement signal changes, the reproduction level of the pilot signal will also change, causing the tracking servo to become unstable. Become.

In addition, since tracking servo is applied using the crosstalk component of the pilot signal from the adjacent track, recording and playback must be performed using two heads, and the playback of the electromagnetic conversion characteristic signal is also affected by crosstalk. There was a problem.

This invention was made in order to solve the above-mentioned problems.The signal for electromagnetic conversion characteristic measurement and the pilot signal are not superimposed, so no spurious signals are generated, and the level fluctuation of the reproduced pilot signal is eliminated. An object of the present invention is to obtain a recording/reproducing characteristic measuring device that can perform stable tracking servo without any noise.

[Means for solving problems]

The recording/reproducing characteristic measuring device according to the present invention includes a reproducing tracker/7.
Instead of recording the pilot signal required to apply the king servo to the entire track, we record it only on a part of the time axis, apply the tracking servo during playback, and measure the recording and playback characteristics. It is composed of

(Operation) In the present invention, the pyro-node signal is recorded in a part of the track that is different from the part on the track where the recording and reproducing characteristics are measured, so that it does not interfere with the signal for measuring the recording and reproducing characteristics. Furthermore, since there is no level change in the reproduction pipe No. 813 due to a change in the recording level of the signal for measuring recording and reproduction characteristics, the reproduction tracking servo is applied stably and good recording and reproduction characteristics can be measured.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure shows a recording/reproducing characteristic measuring device according to an embodiment of the present invention, and in the figure, the same reference numerals as in FIG. 3 indicate the same parts. 3 is a carrier generator which is a high frequency bias source for recording a pilot signal, and 4 is an adder which adds the pilot signal output from pilot signal generator 2 and the bias signal generated by carrier wave generator 1113 in an appropriate ratio. 5 is a switch for switching between No. 13 output from the signal generator 1 for measuring electromagnetic conversion characteristics and a signal obtained by adding the pilot signal and bias signal; 11 is output from switch 10 in the opposite direction to switch 5; This is a switch that divides the reproduced signal into a signal for measuring electromagnetic conversion characteristics and a signal obtained by adding a pilot signal and a bias signal.

Further, in FIG. 2, 15.1 is a zone where the electromagnetic conversion characteristic measurement signal is recorded, and 15.2 is a zone where the added signal of the pilot signal and bias No. 1g is recorded.

Next, the operation will be explained. The switch 5 receives the signal output from the signal generator 1 for measuring electromagnetic conversion characteristics and a signal in which a pilot signal and a bias signal are superimposed, and the cough switch 7 is shown in FIG. like head 7
1.72 is the first 1/4 when writing one trunk
- 1/6 zone 152 (this level is enough for tracking servo) to record only the signal in which the pilot signal and bias signal are superimposed. The switch is made so that only the signal for electromagnetic conversion characteristic measurement is recorded in the zone 151. Also, the playback signal output from the head amplifier during playback is
The first 1/4 to 1/4 of one trunk as shown in the figure.
In zone 152 of No. 6, the pilot signal and bias signal are superimposed, and in the remaining zones 151 of 3/4 to 5/6, the signal is for electromagnetic conversion measurement (No. 8. Switch 1
1 switches to the side of the reproduced signal analyzer [12] when the reproduced signal is a signal for measuring electromagnetic conversion characteristics, and switches to the side of the low-pass filter L3 when it is a superimposed signal of a pilot signal and a bias signal.

FIG. 5 shows the operation timing of the device shown in FIG.
A) is a switching pulse of the switch IO, and when it is "H", channel 1 is selected, and when it is "L", channel 2 is selected. In the same figure, fbl is the switching pulse of switch 5 and switch 11,
The pilot signal and the bar measurement signal are selected at "H'". By the above switching operation, the electromagnetic conversion characteristic measurement signal is sent to the reproduced signal analyzer 12, and the superimposed pilot signal and bias signal 13 is sent to the low-pass filter 13, where the respective processes are performed.

Next, like an 8mm VTR, the tape is wound on a drum with two corners.
Let us consider a measuring device for the case of 16°. In 8mm VTR,
A portion corresponding to 36 degrees above 1806 is allocated for PCM audio. Tracking servo is applied in this PCM zone, and electromagnetic conversion characteristics can be measured in the remaining 180'.

Figure 6 shows its configuration. In the figure, 3° is a PCM audio signal processing circuit, 51.52 is a switch for switching between a video signal and a PCM audio signal, and 61.62 is a recording amplifier provided in a magnetic head 71.72, respectively.
02 is a head amplifier, 10f and 102 are head changeover switches.

Next, the operation will be explained. On the recording side, a PCM audio signal processing circuit 3' superimposes the time-compressed PCM audio signal and the pilot signal and outputs a burst signal shown in FIG. 7 (C1). When the PCM audio signal is selected, the switch 52 selects the electromagnetic conversion characteristic measurement signal.

On the other hand, on the playback side, the switch 101 and the switch 102 select the head at the timing shown in FIG. The zero-separated signals that can be separated into a signal and a signal for measuring electromagnetic conversion characteristics are sent to a low-pass filter 13 and a reproduced signal analyzer 12, respectively.
Each process is performed.

Furthermore, when recording and reproducing are performed simultaneously using two heads, problems such as crosstalk between channels occur, making it impossible to obtain good 1a magnetic conversion characteristics. At times like this, for example,
If we investigate the electromagnetic conversion characteristics only for channel 1, we will find a burst shape as shown in Figure 5 (FC+) in the case of 180° winding, and as shown in Figure 6 (d) in the case of 216° winding. Signal electromagnetic conversion characteristics measuring device No. 2! h1
The electromagnetic conversion characteristics of a single head can be measured by generating an output from the generator l or by providing a switch to the output of the generator l. At this time, the pilot signal for tracking servo is recorded by two heads, and the recording pattern is as shown in FIG.

In the above embodiments, the bias signal and PCM audio signal were recorded by superimposing them on the pilot signal, but it is also possible to record only the pilot signal. However, in this case, the reproduction output is Since linear distortion occurs, the tracking servo becomes somewhat unstable.

Further, in the above embodiments, the case of a rotating head type magnetic recording/reproducing apparatus is shown, but it is of course applicable to a fixed head type. Furthermore, although the recording medium in the above embodiment was a tape, it may also be a disk.

Furthermore, it goes without saying that the present invention is applicable not only to magnetic recording and reproducing apparatuses but also to other recording and reproducing apparatuses such as optical recording and reproducing apparatuses and magneto-optical recording and reproducing apparatuses.

〔Effect of the invention〕

As described above, the recording/reproducing characteristics measuring device according to the present invention is configured to record the pilot signal for tracking servo and the signal for measuring recording/reproducing characteristics at different locations on the track. There is no interference between the pilot signal and the signal for measuring recording and reproducing characteristics, no spurious signals are generated, and the tracking servo does not become unstable, so that the recording and reproducing characteristics can be measured with high accuracy.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a recording/reproducing characteristic measuring device according to an embodiment of the present invention, FIG. 2 is a diagram showing a recording pattern on a magnetic tape according to an embodiment of the present invention, and FIG.
FIG. 4 is a block diagram showing the configuration of a conventional electromagnetic conversion characteristic measuring device, FIG. 4 is a diagram showing recording patterns on a magnetic tape by the conventional device, FIG. 5 is a timing diagram of an embodiment of the present invention, and FIG. Figure 7 is a block diagram showing the configuration of another embodiment of the invention, Figure 7 is a timing diagram showing another embodiment of the invention, and Figure 8 is a recording pattern on a magnetic tape according to another embodiment of the invention. FIG. In the figure, 1 is a signal generator for measuring electromagnetic conversion characteristics, 2 is a pilot signal generator, 3 is a carrier wave generator, 4 is an adder, 4' is an adder, 5 is a switch, 51° and 52 are switches, and 6 is a Recording amplifier, 61.62 Recording amplifier, 71.7
2 is a magnetic head, 8 is a magnetic tape, 91.92 is a head amplifier, IO is a switch, 101.102 is a switch,
11 is a switch, 12 is a reproduction signal analysis 'vL position, 13 is a low-pass filter, 14 is a reproduction pilot signal processing circuit, 1
5 is a recording track, 151 is an area in the recording track where an electromagnetic conversion characteristic measurement signal is recorded, and 152 is an area in the recording track where a pilot signal is recorded. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (3)

[Claims] (1) In a device for measuring the recording and reproducing characteristics of a recording and reproducing device that records and reproduces a recording signal and a pilot signal by superimposing them, and applies tracking servo based on the reproduced pilot signal, the recording and reproducing device It is characterized in that a pilot signal is recorded only in a part on the time axis of the track, and a signal for measuring recording characteristics is recorded in the remaining part, and tracking servo is performed by the reproduced pilot signal during reproduction. Recording and playback characteristics measuring device. (2) Claim 1, characterized in that the signal for measuring recording and reproducing characteristics is applied only to one head.
Recording and reproducing characteristics measuring device as described in 2. (3) The recording and reproducing device is an 8 mm VTR capable of PCM recording, and the 8 mm VTR records a pilot signal superimposed on a PCM audio signal, and also sends a signal for measuring the recording and reproducing characteristics in place of the video signal. 3. The recording and reproducing characteristic measuring device according to claim 1, wherein a signal for measuring electromagnetic conversion characteristics is recorded as a signal for measuring electromagnetic conversion characteristics, and a tracking servo is applied using a reproducing pilot signal.