JPS6352301A - Crosstalk quantity measuring circuit - Google Patents

Abstract

PURPOSE:To accurately measure the quantity of crosstalk from successively connecting tracks with a simple constitution by recording a measuring signal even on the track as the measurement object by a crosstalk quantity measuring circuit. CONSTITUTION:At the time of recording, a first reference measuring signal REF is recorded on measurement object tracks TA1, and a second reference measuring signal DUM is recorded on auxiliary tracks TB2, TA3, TB4, TA5, and TB6 which are so connected that they are partially overwritten on the leading edge part of the track TA1 successively. At the time of reproducing, the first reference measuring signal REF is reproduced from the measurement object track TA1 and auxiliary tracks TB2-TB6 to measure the quantity of crosstalk between the measurement object track TA1 and each of auxiliary tracks TB2-TB6. Since the second reference measuring signal DUM is recorded on auxiliary tracks TB2-TB6 in this manner, the quantity of crosstalk is accurately measured in consideration of the influence of overwritten parts on the same condition as recording and reproducing of an actual device.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a crosstalk amount measuring circuit, and is suitable for application to, for example, an information recording/reproducing apparatus such as a helical scan type VTR.

B. Summary of the Invention The present invention provides a crosstalk amount measuring circuit that accurately measures the amount of crosstalk from successively connected tracks with a simple configuration by recording a measurement signal also on the track to be measured. obtain.

C. Conventional technology For example, in a helical scan type VTR, the recording and reproducing performance of a magnetic tape is determined by measuring the amount of crosstalk between recording tracks that are sequentially formed in a diagonal direction with respect to the magnetic tape. This has been confirmed.

As a conventional method for measuring the amount of crosstalk, as shown in FIG.
(this is called no-signal recording), and a quantitative measurement signal of a predetermined signal level is superimposed on the bias signal on a track TN adjacent to the track TM to be measured, and the track TM to be measured is recorded. A method is used in which a reproduction signal obtained from a scanning reproduction head P is obtained as a detection signal representing the amount of wolf talk from an adjacent track TN.

D Problems to be Solved by the Invention However, in practice, when performing guard panless recording, when forming recording tracks so as to be connected in sequence, the following A method of forming recording tracks in an overlapping manner has been adopted, and in such a case, if the amount of crosstalk is detected using the conventional method, the following problems arise.

That is, as shown in FIG. 6(B), the overwritten portion SP where the measurement target track TM overwrites the adjacent track TN is essentially only an overwritten bias signal, so it is in a completely no-signal recording state. Therefore, the signal on the adjacent track TN remains. At this time, the signal obtained by scanning the measurement target track TM with the reproducing head P includes not only the amount of wolf talk from the adjacent track TN but also the signal of the overwritten portion SP.

However, since it is not possible to remove only the signal obtained from the overwritten portion SP, there is a problem in that it is not possible to accurately measure the amount of spider talk from the adjacent track TN.

The present invention has been made in consideration of the above points, and by recording a measurement signal also on the measurement target track TM, the amount of crosstalk can be accurately measured under measurement conditions that are almost the same as actual recording and playback operating conditions. This paper attempts to propose a crosstalk measurement circuit that can measure the amount of crosstalk.

E Means for Solving the Problem In order to solve the problem, in the present invention, in a crosstalk amount measuring circuit that measures the amount of crosstalk between tracks TAI to TB6 successively connected on the recording medium MT, a measurement method is provided. The first reference measurement signal REF is recorded on the target track TA1, and the second reference measurement signal DUM is recorded on the auxiliary tracks TB2 to TB6 connected to the measurement target track TAI, and the first reference measurement signal DUM reproduced from the measurement target track TA1 is recorded. auxiliary track T82 to TBS based on the signal level of the reference measurement signal REF of
The amount of crosstalk between B2 to TBS and the measurement target track TAI is measured.

During F action recording, after the first reference measurement signal REF is recorded on the measurement target track TAI, the auxiliary tracks TB2, T are connected so as to partially sequentially overwrite the preceding side edge of the first reference measurement signal REF.
A second IU measurement signal DUM is recorded in A3, TB4, TA5, and TBG.

Therefore, at the time of reproduction, if the first reference measurement signal REF is reproduced from the measurement target track TAI and the auxiliary tracks TB2 to TB6, the measurement target track TAI and each auxiliary track TB
The amount of goji stalk can be measured between 2 and 2 TBS.

Therefore, by recording the second reference measurement signal DIJM on the auxiliary tracks TB2 to TB6, the influence of the overwritten portion can be included under measurement conditions that are almost the same as the recording and playback conditions in the actual device. Therefore, the amount of crosstalk can be measured accurately.

Embodiment G An embodiment in which the present invention is applied to a two-head double azimuth recording VTR will be described in detail with reference to the drawings below.

In FIG. 1, reference numeral 1 generally indicates a recording/reproducing circuit of a VTR, which performs normal image recording and reproduction when a mode selector switch 2 is switched to the switching input terminal a side.

That is, the input video signal V D I N inputted from the recording signal generator (not shown) of the VTR is FM-modulated in the FM modulation circuit 3 through the switching input terminal a to the output terminal C in the mode switching switch 2, and is then subjected to recording amplification. Recording signal S□ via circuit 4. A pair of recording/reproducing heads RPA and RP with mutually different azimuth angles are mounted on the rotating drum 5 as
B and recorded on the magnetic tape MT. Also,
Pickup signal 5 of the recording/reproducing heads RPA and RPB
The PCI is demodulated by the FM demodulation circuit 7 via the reproduction amplifier circuit 6 and the switching input terminal C1 switching output terminal a of the mode switching switch 2, and is sent to the reproduction section (not shown) of the VTR as an output video signal VDouv. Output.

On the other hand, when the mode selector switch 2 is switched to the switching input terminal side, the VTR enters the crosstalk measurement mode.

That is, in the synchronization signal separation circuit 8, the input video signal V
A synchronizing signal S3'/NC is taken out from DIN and supplied to the timing pulse generation circuit 9. As shown in FIG. 2, the timing pulse generation circuit 9 receives a synchronizing signal 5sy.
In synchronization with Nc, a timing pulse signal Sa is generated that rises only during one vertical interval 1■ out of six vertical intervals (that is, 6■ periods).

Here, the timing pulse signal STP rises to 1
As shown in FIG. 3, the track TAI to be measured is assigned to the period Tl of (2), and the following are read sequentially <period T2 of IV.
, T3, T4, T5, and T6 are connected with five auxiliary tracks TB2, TA3, TB4, TA5, and TB6. The track assignment during this period T1 to T6 is repeated sequentially thereafter. The timing pulse signal STP generated in the timing pulse generation circuit 9 is input to the FM modulation circuit 3 via the switching input terminal b and the switching output terminal C of the mode switching switch 2.

The FM modulation circuit 3 generates a first measurement reference signal REF at a predetermined frequency f1, for example, 5.1 (MHz) during a period in which the timing pulse signal srr is rising, that is, during a first period T1. On the other hand, the period in which the timing pulse signal syr is falling, that is, the second to
6, a second measurement reference signal DUM having a frequency f2 different from that of the first measurement reference signal REF, for example, 5.0 (MHz), is generated.

Measurement reference signal REF generated in FM modulation circuit 3
Alternatively, DUM receives the recording signal S1. through the recording amplifier circuit 4 in the recording mode. The information is recorded on the magnetic tape MT by the recording/reproducing heads RPA and RPB.

Thus, as shown in FIG. 3, after the first measurement reference signal REF of frequency f1 is recorded on the measurement target track TAI by the recording/reproducing head RPA, the recording/reproducing head R
Auxiliary track TB2 connected using PB and RPA,
A second measurement reference signal DUM is recorded on TA3, TB4, TA5, and TB6 so as to partially overwrite the leading edge of the trailing track. Among the recording tracks formed on the magnetic tape MT, the first measurement reference signal REF recorded in the measurement target track TA1 is in the reproduction mode.
The pickup signal SPL+ obtained at this time is scanned by the recording and reproducing heads RPA and RPB and is sent to the reproducing amplifier circuit 6.
Furthermore, the switching input terminal C1 of the mode selection switch 2
The signal is input to the crosstalk amount measuring section 10 via the switching output terminal.

As shown in FIG. 4, the wolfberry talk amount measurement unit 10 uses a first measurement base l! 1! Bandpass filter 1 for signal REF
1 and input it to the oscilloscope 12 as the crosstalk amount detection signal S and A.

Thus, the crosstalk amount detection signal SCT is displayed on the oscilloscope 12 as a waveform whose level changes sequentially as shown in FIG. 5 during the first to sixth periods T1 to T6.

In FIG. 5, the signal level S1 of the crosstalk amount detection signal SCT during the first period T1 is on the left side of FIG.
In other words, it represents the signal level of the first measurement reference signal REF recorded on the measurement target track TAI (on the trailing side).

On the other hand, the signal level S2 of the crosstalk amount detection signal Set in the second period T2 indicates the amount of crosstalk from the measurement reference signal REF recorded on the left measurement target track TAI in the adjacent auxiliary track TB2. represent.

Further, the crosstalk amount detection signal S in the third period T3
The signal level S of CT is the same as that of the adjacent auxiliary track TA.
3 represents the amount of crosstalk from the measurement reference signal REF recorded in the left measurement target track TAI.

Here, the reason why the signal level S2 of the wolf talk amount detection signal Set in the second period T2 is smaller than the signal level S in the third period T3 is because the auxiliary track TB2 is This is because scanning is performed by the recording/reproducing head RPB having an azimuth angle different from that of the measurement reference signal REF recorded on the recording/reproducing head RPB, resulting in an azimuth loss (FIG. 5).

Wolf stalk amount detection signal SCT in the fourth period T4
The signal level S4 of the adjacent auxiliary track TB4 is
This crosstalk amount represents the amount of crosstalk from the measurement reference signal REF recorded on the left and right track to be measured TAI. , the signal level is low enough for practical use due to azimuth loss.

In addition, the signal level of the crosstalk amount detection signal SCT in the fifth and sixth periods T5 and T6 is free from the influence of the trailing left track to be measured TAI (Fig. 3), and the signal level of the crosstalk amount detection signal SCT in the fifth and sixth periods T5 and T6 is It is determined by the amount of crosstalk from the measurement target track TAI.

That is, the signal level S of the crosstalk amount detection signal Sea in the fifth period T5 is the amount of crosstalk from the measurement reference signal REF recorded on the right measurement target track TAI in the adjacent auxiliary track TA5. represent.

Further, the crosstalk amount detection signal S in the sixth period T6
The signal level S of CT is the same as that of the adjacent auxiliary track TBS.
represents the amount of crosstalk from the measurement reference signal REF recorded in the measurement target track TAL on the right side. From this waveform of the oscilloscope 12, the measurer can determine the amount of crosstalk from the auxiliary track connected to the track to be measured TAI in the following manner.

That is, the amount of crosstalk CT, □ from the preceding adjacent track TB2 can be determined by )I. Similarly, the amount of crosstalk from the preceding adjacent track TA3 is CT? A3, crosstalk amount CTT14 from preceding adjacent adjacent track TB4
can be determined by Sa 1 , respectively.

Also, the amount of crosstalk CT from the adjacent adjacent track TA5 that follows with respect to the preceding track TAI to be measured on the right side.
TAS, the crosstalk iEI CT t s h from the trailing adjacent track TB6 can be determined by each.

According to the above configuration, each of the measurement target track TAI and the auxiliary tracks TB2 to TBS connected thereto has a first
and second measurement reference signals REF and DUM, the adjacent tracks TAI and TB2, TB2 and Ta3, Ta3 and TB4, TB4 and Ta2, Ta
Overwritten part SP between 2 and TB6, TBS and Ta1
The amount of crosstalk including the influence of (FIG. 6) can be accurately measured under the same measurement conditions as the actual recording and reproducing conditions.

In the above embodiment, the recording/reproducing heads RPA and RPB were used as means for recording and reproducing the first and second measurement reference signals REF and DUM, but instead of this, a recording-only head and a reproduction-only head were used. The same effect as described above can also be obtained by using .

Further, in the above description, two recording/reproducing heads RPA and RPB facing each other at 180° are used, but instead of this, a single head recording force type may be used.

Furthermore, in the above-described embodiment, the timing pulse generating circuit 9 outputs the timing pulse Stp every 6 vertical intervals, but the synchronization is not limited to this and can be changed in various ways.

Furthermore, in the above-mentioned embodiment, a crosstalk amount measuring circuit and an oscilloscope 12 were used.
For example, other configurations such as a spectrum analyzer may be used.

Further, in the above description, an embodiment has been described in which the present invention is applied to a VTR with a two-head double azimuth recording method, but the present invention is not limited to this. The present invention can be applied to a wide variety of devices.

Effects of the Invention H As described above, according to the present invention, a crosstalk amount measuring circuit that can accurately measure the amount of crosstalk from successively connected tracks can be easily realized with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the crosstalk amount measuring circuit according to the present invention, and FIG.
Figure 3 is a route map showing the signal recording pattern on the recording medium, Figure 4 is a block diagram showing the detailed configuration of the crosstalk amount measurement section, and Figure 5 is the crosstalk i horizontal diagram. FIG. 6 is a route map showing the waveforms of signals S and A, and is a route map for explaining the conventional method of measuring the amount of crosstalk. 1... Recording/reproduction circuit, 3... FM modulation circuit, 8... Synchronization signal separation circuit, 9...
- Timing pulse ordering circuit, 10...Crosstalk amount measuring section, REF...Reference frequency signal.

Claims (1)

[Claims] In a crosstalk amount measuring circuit that measures the amount of crosstalk between tracks successively connected on a recording medium, a first reference measurement signal is recorded on a track to be measured, and a first reference measurement signal is recorded on the track to be measured. A second reference measurement signal is recorded on connected auxiliary tracks, and the signal level of the first reference measurement signal reproduced from the measurement target track, and the signal of the first reference measurement signal reproduced from each of the auxiliary tracks. A crosstalk amount measuring circuit, characterized in that the amount of crosstalk between the auxiliary track and the track to be measured is measured based on the level.