JPS59144013A - Error measuring device of multi-track recorder - Google Patents

Abstract

PURPOSE:To attain quick measurement of errors and at the same time to realize the miniaturization and low cost of an error measuring device, by giving the simultaneous reproduction and scan to plural tracks and processing en bloc the signals showing the presence or absence of errors every information signal through a microcomputer in the form of data signals. CONSTITUTION:A multi-track memory 2 containing heads 31-316 is provided together with error detecting circuits 41-416, ports 51-52, a CPU6, an internal memory 7, an external memory 8, a synchronizing signal detecting circuit 9, and a frame counter 10. The reproduced signals are supplied to the detecting circuits 4 from the heads and then demodulated. Then a signal showing the presence or absence of errors for every frame is produced by an error check signal. The ports 51 and 52 serve as interfaces of 8 bits to a microcomputer consisting of a CPU6 and an RAM7. In such a way, both miniaturization and low cost are attained for an error measuring device by means of a microcomputer. This ensures the quick measurement of errors regardless of the number of tracks.

Description

Detailed Description of the Invention The present invention provides a multi-track system that can determine the presence or absence of an error from a reproduced information signal and obtain data necessary for error analysis such as error distribution, error interval, and error size. The present invention relates to an error measuring device for a recording device.

Conventionally, information signals such as audio signals and video signals are
A so-called multi-track recording device is known in which a fixed head is used to distribute signals to multiple tracks for recording and reproduction.In particular, the PCM method, in which information signals are converted into tPcM (pulse code modulation) and recorded, is used for reproduction. In recent years, it has attracted a lot of attention because the S/N ratio of the transmitted information signal is very good.

FIG. 1 is a pattern diagram showing an example of tracks on a magnetic tape in a conventional PCM multi-track device for recording and reproducing a stereo audio signal tl, where 1 is a magnetic tape, w, . . . l WIRr w! L1-”・
, Wnr, wnR, Wp, WQ are tracks, S is a sync signal recording portion, and C is an error check signal recording portion.

In the figure, every other track WILIW! Ll
・・・・・・WnL has stereo audio signal P.
The left channel signal converted into a CM is recorded, and the same <
A right channel signal converted into PCM is recorded, and error correction code signals are also recorded on tracks wp and wQ, and as shown in the figure, the respective tracks w,...
, ,WIR,W,L, ......,WnL,W
A fixed head is provided corresponding to nR. but,
This signal distribution method is merely an example, and several other distribution methods are conceivable.

The PCM left and right channel signals are divided into fixed periods, and a synchronization signal and C
An error check signal such as an RCC code signal is inserted, and the left and right channel signals to which such a synchronization signal and error check signal are added are track W, L, W.
, a, . . . recorded in 2wnR. A synchronization signal is placed immediately before the divided period of the left and right channel signals, and an error check signal is placed immediately after that period, and the period from the synchronization signal to the error check signal is called a frame. There is. Also, truck wP,
wQ is divided into a synchronization signal and an error check signal, and a code (eg, P%Q code) signal for correcting or correcting an error is recorded for each frame.

So, track WIL + %H,...
, WARp Wp rwQ is a signal consisting of a series of frames, with a synchronization signal at the beginning of each frame and an error check signal at the end. Note that the error check signal is for checking code errors in the frame, that is, errors.

Figure 1 shows the tracks W, L, WlR, ---.
WnR, WP.

The recording period h of one frame of wQ is shown, and the synchronization signal is recorded in the synchronization signal recording part S, the error check signal is recorded in the error check signal recording part C, and the synchronization signal recording part Left and right channel signals and error correction code signals are recorded between the S1 and error check signal recording portions C.

Incidentally, dropouts generally occur in recording and reproducing apparatuses, and such dropouts have a large effect on reproduced information signals. 1st
In a PCM type recording apparatus as shown in the figure, even a slight dropout causes a code error in the left and right channel signals, which deteriorates the sound quality.

The causes of such dropouts include not only defects in the magnetic tape, but also defects in the structure and arrangement of the magnetic head, defects in the tape running system, and in particular defects in the recording device, such as defects in the rollers. There are some things. Such defects in the recording device cause damage to the magnetic tape such as peeling of the magnetic layer, causing undesired dropouts, and greatly impairing the reliability of the recording device.

Dropouts caused by a defect in the recording device and dropouts caused by a defect in the magnetic tape itself are very different in their occurrence distribution, and the distribution of dropouts varies depending on the type of defect in the recording device.
They differ in their location, interval, size, etc. Furthermore, in digital recording, pulses are demodulated from the reproduced signal, but for this purpose, it is usually necessary to have a sufficient amount of signal waveforms called eye patterns.

Generally, in high-density recording, a sufficient S/N ratio cannot be obtained, noise increases, and the aperture ratio of the eye pattern decreases.
This causes a stochastic error to occur. therefore,
It is important to detect errors from the reproduced information signal and to analyze the detected errors to know what causes such errors. This is because when designing a recording device, it is necessary to fully understand the circumstances in which such errors occur, and to design a frame structure and correction method that can sufficiently correct or correct data even if these errors occur. It can be done. Furthermore, when manufacturing a recording medium, by knowing the occurrence status of these errors, it is possible to clarify the cause of the error, come up with countermeasures, and manufacture a recording medium with fewer errors.

Therefore, error measurement is very important for quality control when manufacturing recording devices. Conventionally, as a method for measuring errors in a multi-track device with a track pattern as shown in L#Wln
r Was + ”' °°°r WnLt Wnu
r W p r A method is to perform error detection using an error check code for each WQ, obtain measurement data representing the position of the error occurrence from the frame number and track number where the error occurred, and perform error analysis using this measurement data. It was getting worse.

By the way, it is not known when an error will occur, and there is a need for an error measuring device that can quickly respond to such unpredictable errors and generate desired measurement data. Conventionally, such error measuring devices have been configured with mini-computers, and speeding up the operation of the measuring device has been achieved by using the interrupt function of the mini-computer to generate an interrupt with an error detection signal from each track. There is.

However, such a minicomputer error measuring device is very large in scale - and expensive. Furthermore, if the number of tracks is large and the frame length is small, measurement may become impossible due to operating time constraints.

An object of the present invention is to provide a multi-track recording device that eliminates the drawbacks of the prior art described above, can be constructed small and inexpensively using a microcomputer, and can perform measurable recording regardless of the number of tracks or frames. K provides an error measurement device.

In order to achieve this object, the present invention obtains a signal indicating the presence or absence of an error for each information signal obtained by simultaneously reproducing and scanning n (where n is an integer of 2 or more) tracks, and The signal is processed as n-bit data for each frame, and the frames are counted to generate data representing the number of frames, so that measurement data consisting of n-bit data at the time of error occurrence and data representing the number of frames can be obtained. It is characterized by the fact that it is

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram showing an embodiment of an error measuring device for a multi-track recording device according to the present invention, in which 2 is a multi-track recording capacity, 31 to 316 are heads, and 41 to 316 are heads.
4. . is the error detection circuit, 51,5! is a board, 6 is a central processing unit, 7 is an internal memory, 8 is an external memory, 9 is a synchronization signal detection circuit, and 10 is a frame counter.

In FIG. 2, a multi-track recording device (hereinafter simply referred to as a recording device) 2 performs recording and reproduction on a magnetic tape 1 having the track pattern shown in FIG. 1, and has 16 tracks. Therefore, the recording device 2 has 16 heads 31 to 3 .corresponding to each track. . is provided. The recording device 2 is a well-known device,
Further explanation will be omitted.

The error detection circuits '1141+..., 4, 6 are supplied with playback signals from the heads 31y3ffiy..., 3.6, respectively, perform demodulation processing on these playback signals, and perform error checking. A signal indicating the presence or absence of an error is generated for each frame. This signal is, for example, a binary signal of 61'' when an error is detected and +'' when no error is detected. These binary signals for each reproduced signal are transmitted to ports 58.5. is supplied and held. Boat 51+ 51 is a central processing unit (hereinafter referred to as
A microcomputer (called a CPU) 6 and an internal memory 7, which is a RAM (random access memory).
Each is an 8-bit interface to a microcomputer (hereinafter referred to as a microcomputer).

The synchronization signal detection circuit 9 is supplied with a reproduction signal from the head 3I, for example, processes the reproduction signal by demodulating it, detects a synchronization signal for each frame, and generates a frame halt. Further, the frame counter 10 is supplied with this frame pulse and counts up by 1 for each frame.

Note that the external memory 8 is a large capacity memory such as a floppy disk device.

Next, the operation of this embodiment will be explained.

The recording device 2 includes, for example, heads 3□, 31 . ...
..., 31. The recording device 2 and the error measuring device are coupled by connecting an input terminal of the error measuring device to the external terminal connected to each of the external terminals.

Therefore, when the recording device 2 is set to playback mode, the head a11 a, ? . . . , 3 and 6 are respectively transmitted to error detection circuits 48, 4□, . . . , 4,
6. Error detection circuit 41 * 41 +
......, 4□, determines the presence or absence of an error in the supplied reproduced signal for each frame, and if an error is detected, it is 1'', and if no error is detected, it is '0'' 2 Generates a value signal. And error detection circuit 4+ r'a
t+..., the binary signal obtained at 48 is output from port 5. and error detection circuit 4Q + '10 m
The binary signal obtained at 416 is supplied to the boat 52. Beau)5. ．． 5. holds the supplied binary signal, and therefore each corresponds to a reproduced signal containing an error when all bits are 0 if no error is detected, i.e. the value is 0 if an error is detected. The bit is 1" and all other bits are 0'", that is, it holds 8-bit data whose value is not 0, and eventually the baud)
5. ．． 5□, 16-bit data will be held.

On the other hand, the reproduced signal from the head 31 is supplied to the synchronization signal detection circuit 9, and a frame pulse is formed every time a synchronization signal is detected. This frame pulse is the frame counter 10
is supplied to head 3, frame pulses are counted, and head 3
1y3R+・・・・・・-”tak passed fI/-
generates data representing the number of times.

CPU6 periodically baud according to the program)
51.5. Read the 16-bit data and judge whether the 16-bit data contains error information based on the presence or absence of the 1" bit, that is, whether the value is 0 or not. Then, data representing the number of frames is read from the frame counter 10, and these 16-bit data and the data representing the number of frames are stored as measurement data in the internal memory 7.If the data representing the number of frames is 16 bits, the internal In memory 7, four addresses are used for one measurement data, for example, 8 bits from boat 5., 8 bits from boat 5., upper 8 bits from frame counter 10, and 8 bits from frame counter 10. The data is written to each address in the order of the lower 8 bits.

Once the measurement data is written to the capacity of the internal memory 7, these measurement data can be transferred to the external memory 8 as needed.
and further error measurement continues.

Next, the operation of the microcomputer will be explained in more detail with reference to the flowchart shown in FIG.

When the error measurement operation starts, frame counter 1
0 and internal memory 7. Step 11.12
), reads the 8-bit data of boat 5□ and the 8-bit data of boat 5 (steps 13 and 14), and determines whether the values of each 8-bit data are zero (step 15). . If both of these values are zero, no error has been detected, so the process returns to step 13 and the steps 51, 5 . Read the data.

If at least one value of the read 8-bit data is not zero, the count number of the frame counter 10 is read (step 16), and it is determined whether this count number is the same as the previously read count number. (
Step 17). This step 17 consists of CPU 6 votes 5. ．． 5. The operation period of one cycle from reading 8-bit data from 8-bit data to storing measurement data in internal memory 7 is short, and 8-bit data in the same frame is transferred to ports 5□, 5. Since it is read repeatedly from
One piece of measurement data is obtained for each frame, and the 100 count of the frame counter is used to determine whether or not the measurement data is for the same frame.

If the count read from the frame counter 10 is equal to the count read previously, the measurement data is discarded as the previously obtained measurement data and the process returns to step 13.

However, if it is a new count number, this count number and the boat 5. ．． The 8-bit data, ie, the 16-bit data, taken from the 5t color H are transferred to the internal memory 7 and written as measurement data (step 18).

Next, it is determined whether the measured data has been written into the internal memory 7 to its full capacity (step 19).
, if the internal memory 7 is not full, the above operations are repeated.

When the internal memory 7 becomes full, all of the measurement data written in the internal memory 7 is transferred to the external memory 178 (step 20), a determination is made as to whether or not to continue the measurement (step 21), and the process returns to step 12. Either repeat the same operation or stop the error measurement operation.

Note that the determination of whether or not to continue the measurement in step 21 is to determine, for example, whether the end mark of the magnetic tape has been detected or the measurement stop button has been operated, and is not performed after step 20. , step 15 ryesJ
After the determination and step 17, 19, it is determined whether or not to continue the measurement.If ryesJ, return to step 13, if rnoJ, stop the measurement, and directly return from step 20 to step 12IC. You can also do this.

As described above, measurement data is obtained for the frame in which the error has occurred, and the 16-bit data of this measurement data represents the track number in which the dropout occurred, and is the count number from the frame counter 10. , that is, the data representing the number of frames is
Indicates the frame where the error occurred. Also, 16
The bit data can be considered to represent the position where the error occurs in the width direction of the magnetic tape, and the data representing the number of frames can be considered to represent the position where the error occurs in the longitudinal direction of the magnetic tape. Therefore, the measurement data is It also represents the location where the error occurred.

Therefore, using such measurement data, it is possible to analyze errors such as the distribution, size, shape, and spacing of errors on the magnetic tape, and it is possible to understand the cause of dropouts. You can know the performance.

Although the above embodiment describes a recording device with 16 tracks, the present invention is generally applicable to recording devices with 2 or more tracks. The present invention can be applied to a multi-track recording device for information signals of the above type, and furthermore, the present invention can be applied to a multi-track recording device other than the PCM method as long as it is capable of detecting dropouts for each unit period. I can do it. For example, in a multi-track recording device that records a video signal as an FM wave, it is possible to detect drop-out from changes in the envelope of the FM wave, so one horizontal period is defined as the above frame, and each frame is By determining the presence or absence of dropout, error measurement can be performed in the same manner as in the above embodiment.

In the above embodiment, the maximum count of the frame counter 1o is 216, and the time required to obtain this count is actually about 100 seconds, assuming that the number of frames per second is 500, and the time required to obtain this count is actually about 100 seconds. Since the playback time is generally longer than this time, the frame counter 10 becomes K if it is reset many times during the measurement period. Therefore, it is necessary to determine that this frame counter 10 has been reset, but generally a considerable error is detected while counting 216, indicating the number of frames in the series of measurement data obtained. It can be determined from the data that the frame counter 10 has been reset. Therefore, by adding 216 to the data representing the number of frames at each reset, the longitudinal position of the magnetic tape can be accurately determined.

As described above, according to the present invention, information signals obtained by simultaneously reproducing and scanning a plurality of tracks are used, and each signal representing the presence or absence of an error is combined into one data signal for each information signal. Since the data can be processed as follows, and data with different values are obtained depending on the track in which the error occurs, a microcomputer can be used as the processing means, resulting in miniaturization and cost reduction. In addition, it is possible to quickly measure errors regardless of the number of tracks, and it is possible to provide an error measuring device for a multi-track recording device with excellent functions except for the above-mentioned conventional drawbacks.

[Brief explanation of the drawing]

FIG. 1 is a pattern diagram showing an example of tracks on a magnetic tape in a multi-track recording device, FIG. 2 is a block diagram showing an example of an error measuring device for a multi-track recording device according to the present invention, and FIG. 3 is a flowchart showing an example of the operation of the central processing unit of FIG. l...Magnetic tape, 2...Multi-track recording device, 3, ~31σ...Head, 41~
416...Error detection circuit, 5. ,5.・・・
...Boat, 6...Central processing unit, 7...
...Internal memory, 8...External memory, 9.
...Frame detection circuit, 10...Frame counter.

Claims (1)

[Claims] Equipped with n (n minus an integer greater than or equal to 2) fixed heradora,
In an error measuring device for a multi-track recording device in which an information signal consisting of a series of frames is recorded on n tracks by the fixed head, the information signal simultaneously reproduced by the n fixed heads is supplied. means for determining the presence or absence of an error in each of the information signals for each frame; means for holding n signals obtained by the means and representing the presence or absence of an error; means for counting and generating data representing the number of frames; means for simultaneously reading the held n data as in-pit data; and determining whether or not there is an error; and a means for storing data representing the number of frames at the time of reading, and each of the stored data is used as measurement data to obtain measurement data that can be analyzed for errors. Error measuring device for track recording equipment.