JP2646550B2 - Digital recorder - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a digital recorder used for recording acoustic signals and the like.

[Summary of the Invention]

The present invention relates to a digital recorder, in which a line for feeding back the output of an encoder used for digital recording and reproduction to the input of a decoder is provided, a test signal is supplied to the input of the encoder, and the period of the test signal is determined by the total processing time of the encoder / decoder. The function of the encoder / decoder or the like is diagnosed by comparing the inspection signal with the output of the decoder.

[Conventional technology]

Digital recording of acoustic signals and the like has been put to practical use. According to such a digital recorder, even if signal processing such as dubbing is performed, there is very little risk of signal deterioration, so that good signal editing and the like can be performed.

In such digital recorders, encoder decoders and the like used for digital recording and
Complex processing incorporating U etc. is performed. Therefore, if such a processing function has a defect, normal recording and reproduction cannot be performed. In particular, if there is a defect in the encoder function, the recording itself may be completely invalidated. Therefore, for example, in a device for an expert, it is required to provide a diagnostic mechanism for detecting a malfunction of a function before recording or the like.

In such a case, a conventional method is to supply predetermined digital data, for example, to the input of an encoder decoder, compare the output data obtained by processing the data with prediction data obtained separately by calculation or the like, and when these data do not match. Detecting a malfunction is performed. However, in this method, there is a limit to the types of data that can be inspected in a short time, and it takes an extremely long time to inspect all data.

Alternatively, a line for supplying the input of the output decoder of the encoder is provided, an arbitrary audio signal is supplied from the line input to the encoder via AD conversion, the encoded output is supplied to the decoder, and the decoded output is supplied via DA conversion. A method has also been proposed in which the signal is taken out to the line output and compared with the signal supplied to the line input. However, in the case of this method, the signal supplied to the line input is not immediately taken out to the line output due to the processing time of the encoder / decoder or the like, and a time difference occurs, so that it is not easy to compare the listening and listening. At the same time, there is a possibility that detection cannot be performed with sufficient accuracy by comparison with listening by a human ear.

On the other hand, the applicant of the present application has previously proposed a method of supplying random data to an encoder, supplying the encoded output to a decoder, and observing the decoded output via DA conversion to detect a defect (special method). See JP-A-58-130415).

That is, the signal when the random data is DA-converted should have a constant frequency spectrum over the entire range that can be transmitted by the system. Therefore, when there is a defect in the encoder decoder by the above-described method, a change occurs in the frequency spectrum, and the defect can be detected by observing the fluctuation.

However, this method requires a special configuration for observing the frequency spectrum, and may not be able to detect when a random defect occurs in the encoder decoder.

[Problems to be solved by the invention]

As described above, the conventional technique has a problem that the function diagnosis of the digital recorder cannot be easily performed.

[Means for Solving the Problems] The present invention reproduces a recorded (tape (1)) digital signal (head (2)), decodes the reproduced signal at least (7), and encodes (15). In a digital recorder provided with a system for performing re-recording (head (17)), a line (selector (5)) for feeding back the output of the encoder to the input of the decoder is provided, and a test signal ( A generator circuit (18)) is supplied (selector (14)), and the period of this check signal is equal to the total processing time of signal processing from the input of the encoder through the feedback line and at least the system including the decoder. The test signal is compared with an output signal passed through a signal processing system including at least the encoder and the decoder (circuit (19)) to determine at least A digital recorder to perform the function diagnosis of over motor and encoder.

[Action]

According to this, accurate signal comparison can be performed by electrical comparison, and signal comparison can be performed very easily by comparing the encoded and decoded signal with the signal one cycle later. This makes it possible to detect a functional failure extremely easily and accurately.

〔Example〕

In FIG. 1, a digital signal recorded on a tape (1) is reproduced by a reproducing head (2), and the reproduced signal is transmitted through a reproducing and equalizing amplifier (3) to a PLL (4).
And a data clock is generated to be digital data. The digital signal from the PLL (4) is passed through a selector (5) to a decoder (7) through a time base collector (6) for removing fluctuations in the tape running system.
To perform interleave demodulation and error correction.

A signal from the decoder (7) is supplied to a crossfader (9) via a muting circuit (8), and another signal supplied to a terminal (10) is supplied to an AD conversion circuit (11) to be formed. Cross-fade with the digital signal. The signal from this fader (9) is a DA conversion circuit (12)
Through the selector (14), the signal from the fader (9) is supplied to the encoder (15) via the selector (14), and interleaving and addition of an error correction code are performed. It is supplied to the recording head (17) through 16) and is recorded on the tape (1).

With the above circuit, reproduction of the digital signal recorded on the tape (1) to the terminal (13) and digital recording of the signal supplied to the terminal (10) to the tape (1) are performed.

On the other hand, in the above-described apparatus, a signal from the inspection signal generation circuit (18) is supplied to the encoder (15) via the selector (14), and the encoded output is supplied to the time base collector via the selector (5). (6), the signal which is fed back and taken out from the fader (9) and the signal from the generation circuit (18) are supplied to a digital signal comparison circuit (19), and the comparison output is supplied to a terminal ( Retrieved at 20).

In the above-described inspection signal generation circuit (18), a digital signal generated at a period equal to the sum of each signal processing time from the input of the encoder (15) to the output of the fader (9) is fed back. This signal is supplied to the selector (14) and the comparison circuit (19).

Therefore, in this device, the period s equal to the total processing time t as shown in FIG.
Digital signal equivalent to the sine waveform of the selector (14)
, This signal is taken out of the fader (9) after a time t via the encoder (15), the decoder (7) and the like as shown in FIG. At this time, completely equal signals delayed by one cycle are extracted from the generation circuit (18), and these are relatively supplied to the circuit (19) to detect mismatch.

That is, in the above-described apparatus, if the functions of the encoder (15) and the decoder (7) are normal, a signal exactly equal to the signal supplied to the encoder (15) is extracted from the output of the fader (9) with a delay of t time. And if this signal and the signal from the generator circuit (18) are exactly the same,
It can be determined that there is no defect in the function of each circuit.

In this way, the function of the digital recorder is diagnosed. According to the above-described device, accurate signal comparison can be performed by electrical comparison, and the encoded decoded signal and the signal one cycle later can be compared with each other. Are compared, signals can be compared very easily, and malfunctions can be detected very easily and accurately.

Although the above-described example describes a one-channel signal system, the present invention can also be applied to a multi-channel recorder in which a plurality of channels are provided in parallel. In that case, the system from the time base collector (6) to the encoder (15) can process each channel with a time-division serial signal. In this case, too, the cycle of the inspection signal is adjusted to the entire delay time. As a result, inspection of each channel is performed, and an inspection result can be obtained for each channel by providing a serial-parallel conversion circuit on the output side of the comparison circuit (19).

〔The invention's effect〕

According to the present invention, accurate signal comparison can be performed electrically by comparison, and signal comparison can be performed very easily by comparing the encoded decoded signal with the signal one cycle later. This makes it possible to extremely easily and accurately detect malfunctions.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an example of the present invention, and FIG. 2 is a diagram for explaining the configuration. (1) is a tape, (2) is a reproducing head, (5) and (14) are selectors, (7) is a decoder, (9) is a crossfader, (15) is an encoder, (17) is a recording head, and (18) )
Is a test signal generation circuit, (19) is a digital signal comparison circuit,
(20) is an inspection result output terminal.

Claims (1)

(57) [Claims] 1. A digital recorder provided with a system for reproducing a recorded digital signal, decoding the reproduced signal at least, and encoding and re-recording the reproduced signal, a line for returning an output of the encoder to an input of the decoder. A test signal is supplied to the input of the encoder, and the period of the test signal is set to a time equal to the total processing time of signal processing from the input of the encoder through the feedback line to at least the system including the decoder. A digital recorder configured to compare the inspection signal with an output signal passed through a signal processing system including at least the encoder and the decoder to perform at least a function diagnosis of the data and the encoder;