JP2000132907A - Apparatus and method for recording waveform - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow an input signal having a dynamic range larger than that of a recorder to be recorded, and further record information indicating a gain to which the recorded waveform corresponds. SOLUTION: This apparatus comprises a level comparator 2, an attenuator 3, an amplifier 4, and a recorder 5. The level comparator 2 monitors a signal level of an input signal a, and outputs an excessive level detecting signal b only when the signal level exceeds a preset comparison level. The attenuator 3 causes the input signal a to be attenuated at a predetermined amount of attenuation only when the excessive level detecting signal b is being input. The amplifier 4 amplifies an output signal of the attenuator 3 at a predetermined amount of amplification. The recorder 5 records an output signal of the amplifier 4. When the excessive level detecting signal b is also being input from the level comparator 2 to the recorder 5, the recorder 5 simultaneously records gain switching information which indicates that the recorded waveform has been attenuated by the attenuator 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for continuously recording an input signal whose level changes with time.

[0002]

2. Description of the Related Art FIG. 4 shows a schematic configuration of a conventional waveform recording apparatus. The recording circuit includes a recorder amplifier 100 including an amplifier 101, and a recorder 102 to which an input signal is input via the recorder amplifier 100.

The amplifier 101 has an amplification of +40 dB and amplifies an input signal whose level changes with time. The maximum output level of this amplifier 101 is
+20 dBV (0 dBV = 1
VDC, +20 dBV = 10 VDC). Recorder 1
02 is a recording range of 0 to +20 dBV, that is, 20d
It has a dynamic range of B and can record the output signal of the amplifier 101 continuously.

In this recording circuit, for example, when a signal having a change range of −40 to 0 dBV, that is, a dynamic range of 40 dB as shown in FIG. 5 is input, the input signal is amplified by the amplifier 101. Since the maximum output level of the amplifier 101 is +20 dBV, when the amplified output signal exceeds +20 dBV, the output level saturates at +20 dBV, and the waveform in the meantime is clipped. In this case, the output waveform of the amplifier 101 becomes a waveform as shown in FIG.

In order to record a change in the waveform of an input signal having a dynamic range larger than the dynamic range of the recorder, it is necessary to adjust a gain according to the level of the input signal. Japanese Patent Application Laid-Open
Japanese Patent Application Laid-Open No. 7-193446 discloses an automatic gain switching circuit that can automatically set a gain value to an optimum value according to the level of an input signal. In this automatic gain switching circuit, the level of an input signal is determined at N levels, and the gain is switched to N levels according to the level of the determined level.

[0006]

In the above-mentioned conventional waveform recording apparatus, the portion of -20 to 0 dBV in the input signal waveform having the change range of -40 to 0 dBV is converted to the amplifier 10 by the amplifier 10.
Since the output of No. 1 is saturated, it is recorded on the recorder as a waveform having no change. As described above, the conventional waveform recording apparatus cannot record a change in the waveform of an input signal having a dynamic range larger than the dynamic range of the recorder.

In the application of the automatic gain switching circuit disclosed in Japanese Patent Application Laid-Open No. 7-193446, the problem of the dynamic range described above can be solved, but the recorded waveform is at what gain. Is not recorded, so that there is a problem that it becomes very difficult to understand when analyzing the waveform.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problem, to record an input signal having a dynamic range larger than the dynamic range of a recorder, and to determine which gain the recorded waveform has. An object of the present invention is to provide a waveform recording device and a waveform recording method that can record simultaneously.

[0009]

In order to achieve the above object, a waveform recording apparatus of the present invention monitors a signal level of an input signal to be recorded, and the signal level is higher than a preset comparison level. Level comparing means for outputting an excessive level detection signal only when the level is low, and attenuating means for attenuating the signal level of the input signal by a predetermined amount of attenuation only when the excessive level detection signal is input from the level comparing means. Amplifying means for amplifying the output signal of the attenuating means by a predetermined amplification amount, and recording the output signal of the amplifying means, and recording the waveform while the excessive level detection signal is being input from the level comparing means. And recording means for simultaneously recording gain switching information indicating that the gain has been attenuated by the attenuating means.

A waveform recording method according to the present invention is a waveform recording method for amplifying and recording a signal level of an input signal to be recorded by a predetermined amplification amount, wherein the signal level of the input signal is monitored. When the level is equal to or higher than a preset level, the signal level of the input signal is attenuated by a predetermined amount to perform gain switching, and when the gain switching is performed, gain switching information indicating the effect is provided together with the waveform. It is characterized by recording.

(Operation) In the present invention as described above, when the signal level of an input signal exceeds a preset level, the signal level of the input signal is attenuated by a predetermined amount. Therefore, the output of the amplifier does not saturate.

Further, in the present invention, when gain switching is performed, gain switching information indicating the effect is recorded together with the waveform. You can know what it is.

[0013]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of a waveform recording apparatus according to the present invention. This waveform recording device comprises a recorder amplifier 1 comprising a level comparator 2, an attenuator 3, and an amplifier 4, and a recorder 5.

The level comparator 2 monitors the signal level of the input signal a, and outputs an excessive level detection signal b only when the signal level is equal to or higher than a preset level (comparison level). The comparison level of the level comparator 2 is
The dynamic range (dB value) of the recorder 4 is added to the lowest level (dBV value) of the input signal a.

The attenuator 3 attenuates the input signal a, and attenuates the input signal a by a predetermined amount only when receiving the excessive level detection signal b from the level comparator 2.
During other periods, the input signal a is not attenuated. The amount of attenuation of the attenuator 3 when receiving the excessive level detection signal b is a value of the dynamic range (dB value) of the recorder 5.

The amplifier 4 amplifies the output signal of the attenuator 3, and its maximum output level is the same as the maximum input level of the recorder 5. The amplification degree of the amplifier 4 is a value obtained by subtracting the lowest level (dBV value) of the input signal a from the lowest input level (dBV value) of the recorder 5.

The recorder 5 records the output signal of the amplifier 4 and outputs the excessive level detection signal b from the level comparator 2.
During this time, gain switching information indicating that the recorded waveform has been attenuated by the attenuator 3 is simultaneously recorded.

Next, the recording operation of the waveform recording apparatus will be specifically described. Here, the comparison level of the level comparator 2 is -20 dBV, and the attenuation of the attenuator 3 is 0 dB.
A description will be given of a recording operation when a signal having a dynamic range of 40 dB as shown in FIG. 2 is input as 20 dB, the amplification amount of the amplifier 4 is +40 dB, the dynamic range of the recorder 5 is 20 dB, and the input signal a is shown in FIG.

In the portion of the waveform of the input signal a having a change range of -40 to 0 dBV, the level comparator 2 does not output the excessive level detection signal b in a portion of less than -20 dBV.
The attenuation of the attenuator 3 is 0 dB. Therefore, the input signal a
Is directly input to the amplifier 4 and amplified by +40 dB.
Recorded by the recorder 5.

-20 to 0 dB of the waveform of the input signal a
In the part of V, since the excessive level detection signal b is output from the level comparator 2, the attenuation of the attenuator 3 is switched to -20 dB. Therefore, the input signal a is-
After being attenuated by 20 dB, the signal is input to the amplifier 4 and +40 dB
B is amplified and recorded by the recorder 5. During this recording, since the recorder 5 receives the excessive level detection signal b from the level comparator 2, information (mark) indicating that the recorded waveform has been attenuated by -20 dB by the attenuator 3 ) Is recorded together with the waveform.

As described above, in this embodiment, when the level of the input signal a exceeds -20 dBV, the signal is attenuated by -20 dB in the attenuator 3, so that the amplifier 4 for the input signal a shown in FIG. The output has the waveform shown in FIG.
The output of the amplifier 4 does not saturate in the portion of -20 to 0 dBV of the input signal waveform unlike the related art. Therefore, an input signal having a larger dynamic range than the dynamic range of the recorder 5 can be recorded.

Further, -20 to 0d of the input signal waveform
Since the mark indicating that the BV portion has been attenuated by -20 dB in the attenuator 3 is recorded at the same time, when the operator later looks at the recording waveform, the portion of the recording waveform where the gain is Whether the switching has been performed can be easily determined.

The setting values of the level comparator 2, the attenuator 3, the amplifier 4, and the recorder 5 of the waveform recording apparatus described above are merely examples, and are not particularly limited, and may be variously selected according to the design. be able to.

(Other Embodiments) In the above description, the attenuator 3 is configured to switch the attenuation from 0 dB to -20 dB when it receives the excessive level detection signal b. It can be performed in stages.

For example, the level comparator 2 determines the level of the input signal based on the levels of N stages, and outputs the excessive level detection signals b1 to bN corresponding to the level of the determined level. The attenuator 3 outputs the excessive level detection signal b1
A different amount of attenuation is set for each of .about.bN. When the recorder 5 receives the excessive level detection signals b1 to bN, it records the corresponding gain information together with the waveform. According to this configuration, by switching the gain in multiple stages, it is possible to obtain a finer recording waveform, and it is also possible to know at the same time which waveform the recorded waveform has.

[0027]

According to the present invention configured as described above, even for an input signal having a dynamic range larger than the dynamic range of the recorder, the output of the amplifier does not saturate. It can be recorded accurately.

In addition, according to the present invention, when gain switching is performed, gain switching information indicating that fact is recorded together with the waveform, so that when viewing the recorded waveform, It is easy to determine at which gain the part was recorded.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a waveform recording apparatus according to the present invention.

FIG. 2 is a diagram illustrating an example of a signal having a dynamic range of 40 dB.

FIG. 3 is a diagram showing an example of an output waveform of the amplifier shown in FIG.

FIG. 4 is a block diagram showing a schematic configuration of a conventional waveform recording device.

FIG. 5 is a diagram illustrating an example of a signal having a dynamic range of 40 dB.

6 is a diagram showing an example of an output waveform of the amplifier shown in FIG.

[Explanation of symbols]

 Reference Signs List 1 amplifier for recorder 2 level comparator 3 attenuator 4 amplifier 5 recorder

Claims (5)

[Claims] 1. A level comparing means for monitoring a signal level of an input signal to be recorded and outputting an excessive level detection signal only when the signal level is equal to or higher than a preset comparison level, and said level comparing means. An attenuating means for attenuating the signal level of the input signal by a predetermined amount of attenuation only when an excessive level detection signal is input from: an amplifying means for amplifying an output signal of the attenuating means by a predetermined amount of amplification; While the output signal of the amplifying means is recorded, while the excessive level detection signal is being input from the level comparing means, the gain switching information indicating that the recorded waveform has been attenuated by the attenuating means. Recording means for recording simultaneously. 2. The waveform recording apparatus according to claim 1, wherein the level comparing unit is set such that a comparison level is a value obtained by adding a dynamic range of the recording unit to a minimum level of the input signal. The attenuating means is set so that the amount of attenuation when receiving the excessive level detection signal becomes a value of the dynamic range of the recording means, and the amplifying means has a maximum output level equal to a maximum input level of the recording means. Wherein the amplification degree is set to a value obtained by subtracting the lowest level of the input signal from the lowest input level of the recording means. 3. A level comparing means for judging a signal level of an input signal to be recorded at a plurality of levels and outputting an excessive level detection signal corresponding to the judgment level, and an excessive level inputted from the level comparing means. Attenuating means for attenuating the signal level of the input signal by a different amount of attenuation in accordance with a level detection signal; amplifying means for amplifying an output signal of the attenuating means by a predetermined amount of amplification; and recording an output signal of the amplifying means. In addition, based on the excessive level detection signal inputted from the level comparing means, the recording for simultaneously recording the gain switching information indicating the amount of attenuation of the recorded waveform by the attenuation means. Means for recording a waveform. 4. A waveform recording method for amplifying and recording a signal level of an input signal to be recorded by a predetermined amplification amount, wherein the signal level of the input signal is monitored, and the input signal level is equal to or higher than a preset level. In this case, the signal level of the input signal is attenuated by a predetermined amount to perform gain switching, and when the gain switching is performed, gain switching information indicating the effect is recorded together with the waveform. Waveform recording method. 5. A waveform recording method for amplifying and recording a signal level of an input signal to be recorded by a predetermined amplification amount, wherein the signal level of the input signal is determined by a plurality of levels.
A gain switching is performed by attenuating the signal level of the input signal with a different amount of attenuation according to the determination level. Based on the determination level, it is determined at which attenuation amount the recorded waveform is attenuated. And recording the gain switching information shown together with the waveform.