JPS58215711A - Processor for reproducing digital signal - Google Patents

Abstract

PURPOSE:To discriminate the maximum level of an analog signal being an output of a processor for reproduction, by providing an analog signal generator generating a reference signal having a level corresponding to a full scale value of a digital signal. CONSTITUTION:A digital signal reproducer 11 detects and corrects data errors by inputting a digitized signal and reproducing it with a demodulating system. Before an analog reproducing output is recorded, an output of a reference signal generator 15 is selected with a switch 13 and an attenuator 22 is adjusted so that this reference signal becomes an approximate maximum point of the linear region of the recording system. Since this reference signal level is set so as to represent the maximum level of the analog output of a reproducing processing circuit 1, even if the output of a D/A converter 12 selected by the switch 13 is inputted to the recording system 2, the recording system including a tape is not saturated at all. Thus, the nonlinear operation of the processor for reproduction is prevented in advance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a digital signal reproduction processing device, and more particularly to a digital signal reproduction processing device that converts a digitally encoded signal into an analog signal.

A digital signal reproducing circuit including a digital processor reproduces a digitally encoded signal based on a predetermined format using a predetermined demodulation method, and performs processing such as error detection and correction using a predetermined method.

The reproduced signal obtained in this way is converted into a D/A (digital
An analog converter restores the signal to an analog signal, which is the original signal, and sends it to, for example, an audio amplifier or the like to drive a speaker or the like.

Analog signals obtained by these digital signal reproducing circuits and D/A converters may be recorded onto a recording medium such as a magnetic tape using a tape recorder. In such a case, depending on the adjustment of the recording system, the recorded analog signal may be recorded with distortion due to the characteristics of the recording medium. To be more specific, if the recording key is a dog,
In areas where the recorded analog signal level is high, it is recorded in a saturated state due to the magnetic saturation characteristics of the magnetic tape.
As a result, non-linear distortion will occur.

Such a phenomenon occurs not only in the recording system but also generally in circuits connected to the next stage. That is, this is not preferable because it causes saturation operation of the next stage circuit in response to an excessive input and generates unnecessary distortion.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a digital signal reproduction processing device that can prevent the use of circuit equipment in a nonlinear region and eliminate the occurrence of nonlinear distortion.

According to the present invention, the digital signal reproduction processing device is configured to generate a reference signal having a level corresponding to the full scale value of the digital signal, and the maximum level of the analog signal output from this reproduction processing device can be identified. It is characterized by what it did.

For example, when recording the analog signal on a magnetic tape, etc., this reference signal is input into the recording system in advance to adjust the overall r-in of the recording system, and the magnetic tape is adjusted to the level of this reference signal. It becomes possible to make adjustments so that saturation does not occur.

Since an analog signal input higher than this reference signal level is never applied to the recording system, it is possible to prevent non-linear distortion from occurring when recording analog signals.

The present invention will be explained below using the drawings.

FIG. 1 is a block diagram when an embodiment of the present invention is used in a recording system for recording onto a magnetic tape using a tape recorder. Reference numeral 11 denotes a digital signal regenerator, which has the function of inputting a digitally encoded signal, reproducing it using a predetermined demodulation method, and detecting and correcting data errors. The digital reproduction signal thus obtained is converted into an analog signal by the D/A converter (2) and inputted to the output amplifier (4) via the switch I3. The above circuit constitutes the digital signal reproduction processing circuit 1, but this circuit 1 further includes an analog reference signal generator 15, for example, 1&
Generates a reference signal of ±5 VC or +tOV) at Hz. The level of this signal corresponds to the full scale value of the digital data input to the reproduction processing circuit 1.

This reference signal is selected by the switch 13 and becomes the input to the output amplifier 14. The amplified output of the output amplifier 14 becomes the output of the reproduction processing circuit 1 and is supplied to the tape recorder 2 via the connection cord 3. The tape recorder 2 includes an input amplifier 21, an attenuator 22 for adjusting the output level of the input amplifier 21, and a recording amplifier 23.
The output of this recording amplifier 23 is supplied to a recording head 24 and recorded on a tape 25.

Before recording the analog reproduction output, the output of the reference signal generator 15 is selected by the switch 13, and the attenuator 22 is set so that this reference signal becomes approximately the maximum point of the linear region of the recording system.
Since this reference signal level indicates the maximum level of the analog output of the reproduction processing circuit 1, the output of the D/A converter 12 is selected by the switch 13 and inputted to the recording system 2. However, the recording system including the tape never reaches saturation.

FIG. 2 is a block diagram when another embodiment of the present invention is used in a recording system for recording onto a magnetic tape using a tape recorder, and parts equivalent to those in FIG. 1 are designated by the same reference numerals. The explanation will be omitted.

In this example, the digital signal regenerator 11 and the D/A converter 1
A switch 13 is provided between the two and a digital reference signal generator 16 is added. The output of this digital reference signal generator 16 is a Noculus train corresponding to the full scale of the digital output of the digital signal regenerator 11. When this pulse train is input to the D/A converter 12 via the switch 13, it is equivalent to selecting the output of the analog reference signal generator 15 as in the example of FIG. It has the same effect as in the case of .

The level (amplitude) is more stable both in terms of temperature and over time if the reference signal generator is a digital oscillator rather than an analog oscillator, so it is better to use the example in Figure 2. It is possible to identify the maximum level more accurately than in the illustrated example.

As described above, according to the present invention, the maximum output level of the digital signal reproduction processing device can be identified with an extremely simple configuration, so that non-linear operation of the next stage circuit can be avoided.

[Brief explanation of drawings]

FIGS. 1 and 2 are block diagrams showing embodiments of the present invention, respectively. Explanation of symbols of main parts■...Dizotal signal reproduction processing circuit 2...Tape recorder 11...Digital signal regenerator 12...D/A converter 15, 1.6...Reference signal Generator 22... Attenuator 25... Magnetic tape Applicant No. 4 Motohiko Fujimura, patent attorney representing Ionia Co., Ltd.

Claims (1)

[Claims] A digital signal reproduction processing device for converting a signal encoded into a digital signal into an analog signal, the device comprising means for generating as an output an analog reference signal having a level corresponding to the full scale value of the digital signal at a desired time. A digital signal reproduction processing device characterized in that the maximum level of the analog signal output from the reproduction processing device can be identified.