JPH03119879A - Signal reproducing device - Google Patents

Abstract

PURPOSE:To always stably execute the correction of a reproducing property by providing a separating means to separate a reference signal from a reproducing signal and a correcting means to correct the reproducing property according to the separated reference signal and executing the above mentioned correction by using the plural reference signals. CONSTITUTION:A digital signal processor(DSP) 6 masks a lamp waveform, which is included in a video signal for each frame, with a synchronizing signal as a reference by a mask signal showing a fixed block in a figure (b). Sampling is executed plutal times in this masked period and data to be obtained by this sampling are stored onto a RAM in the DSP 6. A CPU 7 calculates correction value data to be written into a look-up table(LUT) 8 by using the respective sampling data stored in the RAM of the DSP 6 for each frame. Since the correction value data are calculated by averaging the plural data excepting for data considered as error, the extremely stable correction data can be obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a signal reproducing device, and more particularly to a signal reproducing device that reproduces an information signal multiplexed with a predetermined reference signal from a recording medium at predetermined intervals. .

[Prior Art] Conventionally, in a video signal magnetic recording and reproducing device such as a video cheap recorder, distortion may occur in the reproduced video signal due to variations in magnetic recording and reproducing characteristics.

Generally, to correct such distortion of a video signal, a level reference signal that serves as a level reference during playback is multiplexed onto the video signal on a magnetic recording medium during recording, and is recorded for each frame.
Correction that separates the level reference signal reproduced from the medium during playback, samples the separated level reference signal, calculates a correction value for a predetermined reference value for each frame of sampled data obtained, and indicates the correction value. A known method is to correct distortion of a video signal due to variations in recording and reproducing characteristics by correcting the reproducing characteristics using data.

[Problem 8 to be solved by the invention] However, in the above conventional example, correction data for correcting characteristics specific to a magnetic recording/reproducing device is created for each frame using data sampled for each frame. Therefore, if an error occurs in the level reference signal due to dropout, etc., and an error also occurs in the data obtained by sampling this signal, the effects of the error data will directly correct the characteristics of the magnetic recording and reproducing device. This will be reflected in the data for the purpose.

Therefore, the reproduced video signal of a frame in which an error has occurred in the level reference signal cannot be matched with the video signals of other frames, which may result in unsightly flickering on the reproduced screen.

Against this background, an object of the present invention is to provide a signal reproducing device that can stably correct the reproduction characteristics and obtain a distortion-free reproduced signal when a reproduction reference signal cannot be stably obtained. shall be.

[Means for Solving the Problems] For this purpose, in the signal reproducing device of the present invention, in a device that reproduces an information signal in which a predetermined reference signal is multiplexed from a recording medium at predetermined intervals, The apparatus includes a separating means for separating the reference signal from the reference signal, and a correcting means for correcting the reproduction characteristics according to the separated reference signal, and is configured to perform the correction using a plurality of the reference signals.

Further, in a preferred embodiment of the present invention, the correction means includes means for averaging a plurality of data obtained from a plurality of reference signals.

Furthermore, in another preferred embodiment of the present invention, the correction means is configured to perform correction by excluding data that is far different from the others among the plurality of data obtained from the plurality of reference signals.

[Function] By configuring as described above, even if the reproduction reference signal cannot be obtained stably, for example, if an error has occurred in the separated reference signal for some reason, the reproduction characteristics can be stably corrected. I can do it.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the configuration of a reproducing apparatus as an embodiment of the present invention. In the figure, 1 is a magnetic tape which is a recording medium, and 2 is a reproducing head for extracting signals recorded on the magnetic tape l. .

3 is an amplifier that amplifies the signal output from the playback head 2, 4 is an FM demodulator that demodulates the video signal from the amplifier, and 5 is an analog-to-digital (analog-to-digital) that converts the signal from the FM demodulator into digital. A/D) converter, 6
is a digital signal processor (hereinafter referred to as D
SP), 7 is a microprocessor (CP) that processes the sampling data of the ramp waveform from the DSP 6 and writes the obtained correction value into a look-up table (hereinafter referred to as LUT).
U), 8 is an LUT used to correct the video signal from the DSP as an address input, and 9 is an LUT.
This is a digital-to-analog (D/A) converter that converts the digital signal output from the device into an analog signal.

FIG. 2(a) shows a reference signal in a video signal reproduced by the apparatus of this embodiment. The illustrated reference signal is included as a signal of 1942 minutes per frame of the video signal. In this embodiment, the ramp wave portion (shown as R portion in the figure) of this reference signal is sampled at each position, and the reproduction characteristics are corrected using this sampling data. Incidentally, an example of sampling points is shown in FIG. 2(a).

The operation of each part will be explained below with reference to FIG.

First, a video signal recorded on a magnetic tape 1 is taken out by a reproduction head 2 and amplified by an amplifier 3. The amplified video signal is FM demodulated by an FM demodulator 4 and converted into a digital signal by an A/D converter 5. The digitized video signal is then supplied to the DSP 6, where it undergoes predetermined processing. In addition, the DSP 6 masks a certain section of the ramp waveform included in each frame in the video signal using the mask signal shown in FIG. 2(b) based on the synchronization signal, and performs sampling multiple times within this masked period. , the data obtained by this sampling is stored on RAM (Random Access Memory) in the DSPB. Then, the CPU 7 calculates correction value data to be written into the LUP 8 using each sampling data stored in the RAM in the DSP 6 every frame.

This calculation will be explained in detail below with reference to FIGS. 3, 4, and 5. FIG. 3 is a flowchart showing the correction value calculation operation of the CPU 7, FIG. 4 is a diagram for explaining sampling data of a ramp waveform, and FIGS.
), (C), and (D) are CPU7. It is a figure which shows the data table in LUT8.

In this embodiment, it is assumed that the ramp waveform to be sampled has already been subjected to peak AGC or DSP 6, and level non-linearity is corrected in LUT 8. As shown in Figure 4, the sunblink point of the ramp waveform is 1.
There are no samples up to n, and each sample data D, , is DS
The table A of the RAM in P6 is as shown in FIG. 5(A).
D, (1) to Da (no). In addition, D, , (0) has 0°Da (no + 1
) stores 255. In addition, the data from each sample point 1 to no corresponding to the ramp waveform that does not require correction is used as reference data s(i) to S(n,), and the table (C) of the RAM in the DSP 6 shown in FIG. 5(c) is used. Store it in advance.

Of course S (o) is o + s (r+n+i) is 2
55.

Table B in FIG. 5(B) is a table in which corrected sampling data (average data in this embodiment) is stored as Db(1) to Db(no) corresponding to sample points l to no. FIG. 5(D) is a table of LUT8 with each address A.

~A255 contains the calculated data DL(0)~DL2
55) or l number. Furthermore, the address A n of LUT8,
A zss data D t, (o) ~ D L (25
5) are respectively 0.255.

The process will be explained below according to the flowchart shown in FIG.

First, a predetermined value n1 is set to the frame count value C2 by the number δ, and table B is initialized (S2). and,
The above-mentioned numerical value n is used as the sample count value C1 corresponding to the sampling point.

t number of times (S3). Next, sample data D is added to variable A.
, (C1) by the number of rows (S4), and it is determined whether the absolute value of the difference between this sample data and the corresponding reference data s (CI) is less than a predetermined value (S5).

This determination is made by determining how far the obtained sample data is from the reference data, and if the sample data is significantly different from the reference data, it is determined that the sample data is incorrect, and the data in step S6 is Db(C
1,) is not used in the calculation, and the process moves to step S7.

In step S6, first x (ci) is
Let A be the number t. This X (CI) is data indicating the total sum of sample data at the sample point corresponding to the sample count value (ci), and the total number of data is counted as Y (CI). Therefore, at this sample point The average value of sample data is average data DB (cl)
It is calculated as X (CI)/Y (C1).

In step S7, the sample count value CI is decremented, and the processes from steps 84 to S7 are repeated until ci=o, and the process for all sample points ends (S8). Next, the frame count value is decremented (S9), and the processing from steps 84 to S9 is performed at 02:00.
This is repeated over nr frames until Db(1) to Db(ntl) are set to the average value of the sample values of each ramp waveform of n2 frames,
Furthermore, sample data that is considered to be incorrect is excluded from the calculation of this average value.

Next, this average data D b(1) to Db(nD
) to correct the correction data DL(1) to DL of LUT8.
(254) is calculated. First, DL(0) is O, DL(2
55) to 255, and another sample count value C3 to 1
The (Sll) operation is started by counting .

First, data DL[Db(
Set the reference data S (C:l) as C3)) (
S12). This means that the input level to LUT8 is D b (
C3) corresponds to setting the output to S (C:l); for example, in the case of C3=1, when D b (t) is input, the output is 5(1). And this data DL
[Db(C3)] and the already obtained D L[Db(
C:3-1)], address A, b(C3-1
) to Aob(C3) D L[Db(C3-
January~D Ltob(C3)] is determined by the linear approximation method (Sll). Then, the sample count value C3 is incremented (S14), and the operations of steps S12 to S14 are repeated for each sample point, and when the sample count value C3 becomes (no◆l), the process ends (S15).

By configuring as described above, the correction data is obtained by taking the average of multiple data excluding data that seems to be incorrect, so extremely stable correction data can be obtained, and stable reproduction characteristics can be corrected accordingly. can be done.

FIG. 6 is a flowchart showing another calculation operation of the CPU 7 in FIG. The calculation operation according to this flowchart will be explained below. First, initialize table B (521), set l'lo to sample count value CI (522), set sample data D to variable A, (cl)
is set (S23). Next, steps S24, S2
In step 5, it is determined whether the sample data set in this variable A is incorrect, and this determination operation is performed in the third step.
This is different from the flowchart shown in the figure. That is, the predicted value Z of the current sample data is obtained by adding the difference between the sample data D, 1 (C1+1) of the adjacent sample point and the reference data S (CI+1) to the reference data S (CI) of the current sample point. (S24) It is determined whether the difference between this predicted value Z and the current sample data A is within a predetermined value α (
S25) If a relatively large correction is required, the sample data may have a value that is different from the reference data, but it is unlikely that sample data that is different from the reference data will be mistaken for incorrect data. It can be said that this method is also effective when performing relatively large corrections.

In step S27, DbD:1) is set to [Db(CI)+
A]/2 is set. As a result, the data D used for correction
b(CI) is data weighted in order from the current sample data, such as % for the current sample data, % for the sample data for the previous frame, and % for the sample data for the frame before the previous frame. Similarly, stable correction data can be obtained using this data. Steps 829 to S33 for calculating correction data to be written to LUT8 are explained in the third step.
Since it is the same as Sll to S]5 in the flowchart of the figure, the explanation will be omitted.

Steps 322 to S33 according to the flowchart in FIG.
The calculation will be repeated until an instruction to end the calculation is issued (S34), for example, until the end of the playback operation.

Incidentally, in the above embodiment, the reproduction characteristics were corrected using the ramp waveform part in the reference signal, but the present invention can be similarly applied when using the step waveform part shown in part 8 in FIG. can.

[Effects of the Invention] As explained above, according to the signal reproducing device of the present invention, it is possible to extremely stably correct the reproduction characteristics according to the reference signal.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic configuration of a reproducing device as an embodiment of the present invention, FIG. 2 is a waveform diagram showing a reference signal and its mask signal reproduced by the reproducing device of FIG. 1, and FIG. A flowchart explaining an example of the operation of the CPU in FIG. 1, FIG. 4 is a diagram showing the sample link point and sample data of the ramp waveform in the reference signal in FIG. 2, and FIG. 5 is a diagram showing the DSP in FIG. FIG. 6 is a flowchart illustrating another example of the operation of the CPU in FIG. 1. In the figure, 1 is a magnetic tape, 2 is a playback head, 3 is an amplifier, 4
is an FM demodulator, 5 is an A/D converter, 6 is a digital signal processor (DSP), and 7 is a microprocessor (C
PU), 8 is a lookup table (LUT), 9 is D
/A converter.

Claims (3)

[Claims] (1) A device for reproducing an information signal multiplexed with a predetermined reference signal from a recording medium at predetermined intervals, including a separating means for separating the reference signal from the reproduced signal, and a reproducing characteristic according to the separated reference signal. A signal reproducing device comprising: a correction means for performing correction, and performing the correction using a plurality of the reference signals. (2) The signal reproducing device according to claim (1), wherein the correction means includes means for averaging a plurality of data obtained from the plurality of reference signals. (3) In claim (1), the correction means includes, among a plurality of data obtained from the plurality of reference signals,
A signal reproducing device characterized in that the correction is performed by excluding data that is far different from other data.