JPS60119474A - Test device of dynamic filter - Google Patents

Abstract

PURPOSE:To measure a frequency characteristic in a short time through a simple operation, by repeatedly inputting a pulse signal having many higher harmonic components from the input side while the control voltage of a dynamic filter fluctuates. CONSTITUTION:When a control voltage generating circuit 2 is triggered by a pulse from a clock generating circuit 51, the circuit 2 generates a control voltage whose voltage value gradually rises and the frequency characteristic of a dynamic filter 1 to be tested changes. On the other hand, a pulse signal generated from a pulse generating circuit 52 actuates a waveform generating circuit 32 through a delay circuit 31 and one piece of square wave pulse signal is inputted into the dynamic filter 1 to be tested through an attenuator 34, then, the output signal of the filter 1 is displayed on a memory scope 4. By repeating this operation while changing the delay time of the delay circuit 31, the waveform of answer signals to voltages of plural points of the output of the control voltage generating circuit 2 is compared with the characteristic of a standard dynamic filter. Thus the test of a dynamic filter is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a dynamic filter testing device. In particular, the present invention relates to a dynamic filter testing device installed in a receiver having time-varying frequency characteristics used in radar, sonar, and medical ultrasonic diagnostic equipment.

[Description of prior art]

In radar, sonar, ultrasonic eyelid cutting devices, etc., the frequency characteristics of the receiver are changed over time according to the return of echoes received by the receivers installed in these devices. In order to clearly display images related to echo signals, a dynamic filter whose frequency characteristics change depending on the control input terminal is used. To test and adjust such a device, it is necessary to vary the control voltage applied to the dynamic filter, measure changes in frequency characteristics, and adjust this characteristic to match a reference value. Traditional methods for this are dynamic
The control voltage given to the filter is switched and fixed in stages,
A frequency sweep signal is applied from the input side at each stage, and the signal obtained at the output side is observed on the time axis. Therefore, the same measurement is repeated every time each control voltage is switched, which has the drawback of prolonging the measurement time and complicating the adjustment work. It is also possible to adopt a sampling method and selectively measure each return time of the echo signal, but in this case, there is a drawback that the measuring device becomes complicated.

[Purpose of the invention]

The present invention eliminates the above-mentioned drawbacks, and provides a dynamic filter that can measure the frequency characteristics of a receiver, which has frequency characteristics that change depending on the control voltage, in a short time with simple operations, and that does not require high equipment costs. The purpose is to provide testing equipment for

[Features of the invention]

Rather than fixing the control voltage of the dynamic filter, the present invention provides a signal that changes over time, and during the time when the control voltage is changing, a large number of harmonics are generated from the input side. The characteristics of a dynamic filter can be easily measured by repeatedly inputting a pulse signal having a component and observing the response to the pulse signal on the time axis on the output side.

That is, the present invention provides a control terminal of a dynamic filter under test whose gain frequency characteristic changes from the input terminal to the output terminal according to the voltage applied to the control terminal, and which changes over time according to a predetermined function. In a test device comprising a control voltage generation circuit for supplying a control voltage, an input signal supply means for supplying a test signal to the input terminal, and an output signal measurement means for measuring a signal at the output terminal, "1 input signal The supply means is a pulse generation circuit that supplies a plurality of pulse signals to the input terminal in synchronization with the period in which the control voltage changes, and the output signal measurement means supplies the pulse signal to the output terminal in response to the pulse signal. It is characterized by being a means of viewing the responses that appear from a time axis.

Further, the control voltage is a sawtooth wave, the pulse signal is a repeating square wave, and the observing means is an oscilloscope that can store and sequentially display responses to a plurality of pulse signals. This is desirable.

Further, the control voltage generation circuit is a circuit installed in a device in which the dynamic filter under test is installed, and is a circuit for providing a control voltage in a normal state in which the dynamic filter is used. , the pulse generating circuit can be configured to be activated by a trigger signal common to the 1-trigger signal that activates the control voltage generating circuit.

Furthermore, the means for observing on the time axis can include means for Fourier transforming the response appearing at the output terminal.

[Explanation based on examples]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be explained in detail based on the drawings.

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

To explain the configuration and connections of this first embodiment device, this device connects signals by branching the input 10 and output 1 of the dynamic filter 1 under test, and connects the control voltage generation ports 12 & 2. , an input signal supply means 3, an output signal measurement means 4, and a synchronization signal supply means 5. ”
1 input signal supply means 3 is composed of a delay circuit 31, a waveform generation circuit 32, and an attenuator 34. This delay circuit 3
1 is configured to have a variable delay amount. In this example, the output signal measuring means 4 is a memory oscilloscope. Further, the synchronizing signal supplying means 5 is composed of a clock generation circuit 51 and a pulse generation circuit 52.

The output of the clock generation circuit 51 of this device is connected to the input of the pulse generation circuit 52, and the output of the pulse generation circuit 52 is connected to the input of the delay circuit 31 of the input signal supply means 3. The output of the delay circuit 3I is connected to the timing input of the waveform generation circuit 32 and the trigger input of the output signal measuring means 4. The test waveform output of the waveform generating circuit 32 is connected to the input of an attenuator 34, and the output of the attenuator 34 is connected to the input of the dynamic filter 1 under test. The clock generation circuit 51 is also connected to the input of the control voltage generation circuit 2, and the control output of the control voltage generation circuit 2 is connected to the control input of the dynamic filter 1 under test. The output of the dynamic filter under test 1 is connected to the response signal input of the output signal measuring means 4.

Next, the operation of this first embodiment device will be explained.

When the clock generation circuit 51 generates a clock pulse,
The control voltage generation circuit 2 is triggered by this clock and generates a control voltage whose voltage gradually increases. Accordingly, the dynamic filter 1 under test is gently swept from the state of the minimum value of the control voltage to the state of the maximum value of the control voltage, and its frequency characteristics change. Clock generation circuit 51
This change is complete by the time that the next clock pulse occurs, and the next clock pulse causes the control voltage to change from the minimum state to the maximum state again.

On the other hand, this clock pulse causes the pulse generation circuit 52 to generate one short pulse signal, which passes through the delay circuit 31 and activates the waveform generation circuit 32. generates a square wave pulse signal. This pulse signal is adjusted to an appropriate level by an attenuator 34 and then applied to the dynamics under test.

is given to the input of the filter. The dynamic filter under test sends out an output signal in response to this input pulse signal, which is displayed on the screen of the memory scope.

Now, if the delay circuit 31 is set to a small value and corresponds to the time at the beginning of the voltage generated by the control voltage generation circuit 2 that gradually increases by 1, then the value for the control voltage at this time is The response signal of the dynamic filter under test is displayed on the time axis.

By comparing the waveform of this response signal with the characteristics of a separately prepared standard dynamic filter shown in FIG. 2, the characteristics of the dynamic filter 1 under test can be determined. For example, the gain can be determined by the amplitude of the waveform of the response signal, and the phase can be determined by its time position.

Next, the delay circuit 31 is set to a medium value to correspond to the time of the medium voltage generated by the control voltage generating circuit 2, and the waveform of the response signal is similarly obtained on the memory scope. By comparing this waveform with the waveform of a standard dynamic filter for a moderate control voltage, the characteristics of the dynamic filter 1 under test can be known.

Next, by setting the delay circuit 31 to a long time, the characteristics of the dynamic filter 1 under test corresponding to the high voltage of the control voltage generating circuit 2 can be similarly determined.

When the dynamic filter 1 under test is manufactured to have almost the same characteristics as a standard dynamic filter, the response waveform on the memory scope appears almost the same as the standard waveform. By comparing the waveforms,
The elements of the dynamic filter under test I can be fine-tuned to bring its characteristics closer to those of a standard dynamic filter.

Next, a second embodiment of the apparatus will be explained. FIG. 30 is a block diagram showing the configuration of the second embodiment apparatus, and fal to fdl in FIG.
al~(dl) This is a signal waveform diagram of each part. This embodiment device is the same as the above-mentioned first embodiment device except for the input signal supply means 3. This input signal supply means 3 is as follows. The input of the repetitive square wave generating circuit 33 is connected to the output of the pulse generating circuit 52, and the output of the repetitive square wave generating circuit 33 is connected to the attenuator 34 and the output signal. It is connected to the input of the measuring means 4. The output of the attenuator 34 is connected to the input of the dynamic filter under test l.

The repetitive square wave generation circuit 33 of the input signal supply means 3 is
When the impulse signal shown in FIG. 4 (a) is input from the synchronization signal supply means 5, a repetitive square wave pulse signal shown in FIG. The level is adjusted and becomes the input signal of the dynamic filter under test 1. On the other hand, the state of the control voltage output from the control type 1 pressure generation circuit 2 is determined by the impulse signal output from the pulse generation circuit 52 shown in FIG. is shown in Figure 4 (C
), the state changes from the minimum value to the maximum value. Therefore, the dynamic filter 1 under test is
At the rising and falling parts of the repetitive square wave, Figure 4 Fd
A response waveform as shown in 1 is output. This series of response waveforms is stored in the output signal measuring means 4 and can be displayed individually at desired times. From these displays, it is possible to know the frequency characteristics when a plurality of control voltages are applied to the dynamic filter 1 under test. By comparing this displayed waveform showing the frequency characteristics with the characteristics of a separately prepared standard dynamic filter, the suitability of the frequency characteristics of the dynamic filter under test 1 is tested. Fine tuning of the elements of the filter can be made to bring its characteristics closer to those of a standard dynamic filter.

In the following explanation, the input waveform given to the dynamic filter 1 under test is an impulse signal in the first embodiment, but it may also be a step signal. In the embodiment device, a repetitive square wave signal is used, but a repetitive sawtooth wave signal may be used.

Further, although the output signal measuring means 4 displays the output of the dynamic filter under test 1 as it is, it is also possible to display a signal obtained by performing fast Fourier transform on the input signal in decibels on the frequency axis. (11) in Figure 6 represents the output waveform amplitude of the device under test in the time domain;
(bl in the figure is the decibel representation of each output waveform amplitude in the frequency domain. ul, u of fal in Figure 6
2, ua and U.

The respective waveforms of vl and %V in FIG. 6(b)
This corresponds to the waveforms of 2, v3, and 4.

Further, although the output of the dynamic filter 1 under test in the embodiment device is the output of the echo amplifier or the echo intermediate amplifier after hetero gain conversion, the video signal after detecting this output can be the object of measurement. The waveform of the response signal in this case is shown in FIG. Waveform Zl in Fig. 7,
Z2 and Z3 correspond to waveforms X1, X2 and X3 in FIG. 5, respectively. However, the test input signal given to the dynamic filter under test 1 is a step signal. The vertical axis in FIG. 7 represents the amplitude of the waveform, and the horizontal axis represents the elapsed time.

Furthermore, the present invention can be implemented by using, as the control voltage control circuit 2 installed in the devices of these embodiments, a circuit installed in the device in which the dynamic filter under test is installed. However, in this case, it is assumed that the pulse generation circuit 52 is activated by a trigger signal that is common to the trigger signal that activates the control voltage generation circuit 2.

〔Effect of the invention〕

As described above, the present invention has the advantage of being able to test dynamic filters with simple operations and in a short time.

Moreover, the equipment cost required for this is also low.

Furthermore, uniform adjustment can be performed by setting standard frequency characteristics for mass-produced products.

Furthermore, when the measurement signal is subjected to Fourier transform processing, changes in the center frequency and bandwidth can be detected, making it possible to automate the measurement.

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram showing a first embodiment circuit. FIG. 2 is a schematic diagram showing a waveform sample for verifying the output of the device under test. FIG. 3 is a block configuration diagram showing a second embodiment circuit. FIG. 4 is a waveform diagram showing signal waveforms at various parts of the circuit of the second embodiment. FIG. 5 is a waveform diagram showing a response waveform displayed on the output signal measuring means of the second embodiment circuit. FIG. 6 is a waveform diagram showing waveforms before and after Fourier transform processing. FIG. 7 is a waveform diagram showing a response waveform displayed on the output signal measuring means when a video signal output is input. DESCRIPTION OF SYMBOLS 1... Dynamic filter under test, 2... Control 5 voltage generation circuit, 3... Input signal supply means, 4... Output signal measurement means, 5... Synchronization signal supply means, 10.1
1... Dynamic filter terminal under test, 31...
- Delay circuit, 32... Waveform generation circuit, 33... Repetitive square wave generation circuit, 34... Attenuator, 51... Clock generator, 52... Pulse generation circuit. Patent applicant Yokogawa Medical System Co., Ltd. Agent
Patent attorney Nao Takashi Ide, '. 6 Excitement 4 Diagram x 3 5th day M 6.

Claims (1)

[Scope of Claims] (]) A control terminal of a dynamic filter under test whose gain frequency characteristics change from the input terminal to the output terminal according to the voltage applied to the control terminal is applied over time according to a predetermined function. A test device comprising: a control voltage generation circuit that provides a control voltage that varies depending on the input terminal; input signal supply means that supplies a test signal to the input terminal; and output signal measurement means that measures a signal at the output terminal. The signal supply means is a pulse generation circuit that supplies a plurality of pulse signals to the input terminal in synchronization with the period in which the control voltage changes, and the output signal measurement means is a pulse generation circuit that supplies a plurality of pulse signals to the input terminal in synchronization with the period in which the control voltage changes. A dynamic filter testing device characterized by being a means for observing a response appearing at an output terminal on a time axis. (2) A patent claim in which the control voltage is a sawtooth wave, the pulse signal is a repetitive square wave, and the observing means is an oscilloscope that can store and sequentially display responses to multiple pulse signals. A testing device for a dynamic filter according to item (1). (3) The control voltage generation circuit is a circuit installed in the device in which the dynamic filter under test is installed, and is a circuit for providing a control voltage in the normal state in which the dynamic filter is used; The dynamic filter testing device according to claim 1, wherein the pulse generation circuit is configured to be activated by a trigger signal common to the trigger signal that activates the control voltage generation circuit. (4) The means for observing on the time axis includes means for Fourier transforming the response appearing at the output terminal.
The dynamic filter test device described in item 1).