JPH01147920A - Quasi-peak value evaluation device - Google Patents

Abstract

PURPOSE:To decrease an overload coefficient considerably in the measurement of a quasi-peak value of a pulse signal at a low frequency by detecting a maximum level of an input signal for evaluation and applying weight operation to the maximum level by a prescribed response coefficient. CONSTITUTION:A selection means 2 extracts an evaluation signal to be evaluated from a pulse input signal 1 and gives it to a peak detection means 4 and a frequency detection means 5. The peak detection means 4 detects the maximum level of an inputted evaluation signal and the frequency detection means 5 detects the frequency of the said evaluation signal. A coefficient output means 6 outputs a response coefficient in response to the detection response of the quasi-peak detection based on the said frequency information. A computing element 7 applies the weighting operation to the said maximum level by the said response coefficient to output the quasi-peak value for the said evaluation signal.

Description

[Detailed Description of the Invention] [Industrial Application Field] The invention of Party B relates to a quasi-peak value evaluation device for determining the quasi-peak value of an input signal, and is particularly applicable to pulse-like noise with a low repetition frequency in the measurement of interference waves. The present invention relates to a quasi-peak value evaluation device that improves quasi-peak value measurement such as the above.

[Conventional technology]

Quasi-peak detectors are used to evaluate the degree of interference to broadcast waves caused by interference waves such as noise.
In other words, the attempt was made to detect waves by making corrections corresponding to the sense of hearing. Therefore, conventionally, to achieve this detection,
A detection circuit having detection characteristics similar to the human auditory characteristics was used, or a circuit was used that detected the envelope and then showed the auditory characteristics. The basic characteristics of a quasi-peak detector with such audible characteristics are determined by the International Special Commission on Radio Interference (CIS).
C [S P R Publ.Published by PI't).

16 (hereinafter referred to as the Cl5PR standard).

Conventionally, such quasi-peak detectors have been constructed with analog circuits and have been installed in interference wave measuring instruments specifically designed to measure interference waves. In recent years, as regulations regarding noise emitted from electronic devices have become stricter, quasi-peak detectors have come to be installed in spectrum analyzers, which are used for general-purpose temperature measurement.

This kind of quasi-peak detector is manufactured by Nikkei McGraw-Hill.
Nikkei Electronics J published on March 23, 1987
No. 417 (the above CI S P I
Some of the information regarding the t standard is published). Here, the configuration of the prior art shown in FIG. 4 will be explained.

Figure 4 shows that, for example, in a spectrum analyzer,
It is a block diagram after conversion to an intermediate frequency by heterodyne etc.

In FIG. 4, 2C is an intermediate frequency signal, 2d is an intermediate frequency filter for band-limiting the required intermediate frequency signal 2C (hereinafter, the bandwidth at this time is referred to as BW), and 30 is a quasi-peak detector. , a detection element and a predetermined charging time constant (T6) and discharging time constant ('1''-) to detect a quasi-peak value.

31 is a display means for displaying the quasi-peak value.

When using these circuits to measure noise in the frequency range of 30 to IO00 MHz, for example, in accordance with the Cl5PR standard, the intermediate frequency signal 2C is band-limited by an intermediate frequency filter 2d having BW = 120 KHz, and the charging time constant is T
c=1 ms and discharge time constant 'ra=55On+s
Detection is performed by a quasi-peak detection device 830 having the following characteristics, and the result is displayed on the display means 31. A specific example of a quasi-peak detector designed to satisfy these basic characteristics is:
There was one disclosed in Japanese Unexamined Patent Publication No. 54-73559. The circuit diagram is shown in FIG.

In FIG. 5, the intermediate frequency signal 2F is envelope-detected by a diode 32 and a smoothing circuit 33 to extract noise amplitude fluctuations, and then a differential amplifier 34 and a diode 35 having a high impedance with respect to the impedance of the diode 32 is used to detect the intermediate frequency signal 2F. The resistors 36, 39 and capacitor 37 were driven to perform quasi-peak detection. That is, when the diode 35 is turned on by the positive voltage of the signal applied to its anode, the output impedance of the cathode can be regarded as a constant voltage source due to feedback, so the charging time constant ゛l' due to the resistor Wi 36 and the capacitor 37. When the diode 35 is turned off by the negative voltage of the signal applied to the anode, the impedance seen from the cathode side becomes very high, so the capacitor 37
The voltage charged in is discharged with a discharge time constant l' determined by its own capacitance and resistor 39.

[Problem that the invention seeks to solve]

For example, when measuring pulse-like noise with a low repetition frequency and a long time interval, the quasi-peak detector 30 has a high peak value. The longer the repetition time interval, the lower the level occupied by the discharged and output level during that time, which has the disadvantage of requiring a large dynamic range from a high level to a low level. As a result, the quasi-peak detector 30 and its preceding circuit are likely to become saturated, making it impossible to widen the measurement range. In addition, because the measurement range was narrow, it was necessary to adjust the input noise level to the measurement range using an input attenuator, making the measurement procedure complicated. For example, in the case of a measurement frequency range of 30 to 1000 MHz, the quasi-peak detector 30, as shown in FIG. An extra dynamic range (hereinafter referred to as overload coefficient) is required for the reduction.When detecting an isolated pulse, a maximum overload coefficient of 44 dB is required.1 These dynamic range, overload coefficient, and measurement range FIG. 7 is a diagram that clearly shows the relationship between the two values using the measurement of an isolated pulse as an example.

From the diagram in Figure B, to measure low repetition frequency i <, t less, the overload coefficient is 44 dB, and if we take 10 dB as the measurement range, the minimum (when S/N = 12) is 6
A dynamic range of 6 dB is required.

Therefore, even in the conventional example shown in Fig. 5, the dynamic range is approximately 56 dB, and there is almost no measurement range for isolated pulses, etc. It was not possible to measure unless the values matched.

Further, the internal resistance (resistance when ON and OFF) of the detection diode 35 of the quasi-peak detector 3o shown in FIG. 5 changes depending on the level of the input signal. Although various devices such as applying feedback have been devised in the past, it is difficult to maintain this internal resistance at a constant value over a range of (56 dB1 measurement range). This change in internal resistance is a drawback that reduces detection accuracy.

Furthermore, if you try to apply the conventional quasi-peak detector 30 like Otsu to a spectrum analyzer, the spectrum
The level diagram of the circuits before the intermediate frequency of the analyzer, such as the mixer and the input amplifier before it, also had to be changed to cover the dynamic range including the overload factor mentioned above (see 1 above). (See Figure 17 on page 367 of ``Nikkei Electronics'').

Note that when a random signal is subjected to quasi-peak detection, the overload coefficient of the detection circuit may be smaller than that for an isolated pulse signal.

This invention was made to solve the above-mentioned conventional problems. Conventionally, it was a pulse-like signal with a low repetition frequency that required the maximum overload coefficient. The purpose of the present invention is to provide a quasi-peak value evaluation device that greatly reduces the overload coefficient during quasi-peak value measurement, widens the measurement range, and makes it possible to easily measure pulsed signals with a low repetition frequency. .

Another invention of the present invention is that in addition to the above-mentioned purpose, quasi-peak values of random signals or high frequency signals can also be evaluated, and measurement instruments with different purposes such as spectrum analyzers can also be used with a dynamic range. I'm going to hang out with you (,
It is an object of the present invention to provide a quasi-peak value evaluation device that can be used as an additional device.

[Means for solving problems]

The quasi-peak value evaluation device according to the present invention includes a selection means for extracting and outputting an evaluation signal to be evaluated from a pulse-shaped input signal, and a peak value for detecting the maximum level of the evaluation signal and outputting the value. a detection means, a frequency detection means for detecting the repetition frequency of the input signal and outputting it as frequency information, a coefficient output means for outputting a response coefficient corresponding to a detection response of quasi-peak detection based on the frequency information, and a maximum level. The device is equipped with an arithmetic unit that performs a weighting operation on the value of , using a response coefficient, and outputs a quasi-peak value of the evaluation signal.

Further, a quasi-peak value evaluation device according to another invention of the present invention includes:
a selection means for extracting and outputting an evaluation signal to be evaluated from an input signal; a peak detection means for detecting the maximum level of the evaluation signal and outputting that value; and a peak detection means for detecting the repetition frequency of the input signal and using it as frequency information. A frequency detection means for outputting, a coefficient output means for outputting a response coefficient corresponding to a detection response of quasi-peak detection based on frequency information, and a coefficient output means for performing a weighting operation on the maximum level value with a response coefficient to generate an evaluation signal. an arithmetic unit that outputs a quasi-peak value; a quasi-peak value detector that detects an evaluation signal and outputs a quasi-peak value; Comparing the quasi-peak value outputted by the arithmetic unit and the quasi-peak value outputted by the quasi-peak value detector based on the frequency information outputted by the detection means,
It is equipped with a comparison switching means that sets one of them to a quasi-peak value.

[Effect]

In this invention, an evaluation signal to be evaluated is selected and extracted from a pulsed input signal, and the maximum level value of the evaluation signal is determined. A response coefficient corresponding to the detection response is determined, a weighting operation is performed on the maximum level value by the response coefficient, and a quasi-peak value is output.

Further, in another aspect of the present invention, the evaluation signal to be evaluated is extracted from the input signal, and the quasi-peak value of the evaluation signal B is obtained by calculation as described above. On the other hand, the evaluation signal was detected by a quasi-peak value detector consisting of a detection element and a time constant circuit that determines the charging and discharging time constants to obtain the quasi-peak value, which was calculated by calculation based on the repetition frequency of the input signal. The quasi-peak value is compared with the quasi-peak value obtained by detection, and one of these quasi-peak values is output.

〔Example〕

FIG. 1 shows the configuration of an embodiment of the present invention. This configuration makes it possible to measure, for example, noise components in the frequency band of 30 to 1000 MHz, which are included in noise whose amplitude fluctuates in a pulse-like manner with a low repetition frequency, in accordance with the above-mentioned CISI R standard. This is what was done.

In FIG. 1, 1 is the input signal, which in this example represents noise. 2 is a selection means for extracting the noise component as an evaluation signal to be evaluated;
a, a local oscillator 2b, an intermediate frequency filter 2d, and an envelope detector 2e. 3 is an evaluation signal; 4 is a peak detection means; an A/D conversion circuit 4a for converting the evaluation No. 48 3 into a digital signal;
D conversion #! It consists of a peak search circuit 4b which detects the maximum level value while comparing the digital signals sequentially sent from I4a one by one. Reference numeral 5 denotes frequency detection means, which is comprised of a waveform shaping circuit 5a and a counter 56 for counting the repetition frequency of the evaluation signal 3. 6 is a coefficient output means, and the above CI SP
) is calculated based on the quasi-peak value response conditions in the standard, and the value is calculated according to the frequency information output by the frequency detection means 5, which is held as an OM table. Outputs the detection efficiency as a response coefficient. 7 is a digital arithmetic unit which calculates the response coefficient output by the coefficient output means 6 as the maximum level value output from the peak detection means 4.
Then, the quasi-peak value of the evaluation signal 3 is output. Here, peak detection means 4. The coefficient output means 6 and the arithmetic unit 7 are configured to perform consistent operations by being scheduled by a CPU (not shown) or the like.

With this configuration, we will take as an example a platform that receives a thin pulse-like noise with 1011 z repetitions as input signal 1 and evaluates the quasi-peak value of the noise component near 80 MHz from this noise. Explain the operation.

First, the noise around 80 MHz is mixed with the signal from the local oscillator 2b by the mixer 2a and received by the local oscillator 2b.
For example, it is converted into an intermediate frequency signal 2c having an intermediate frequency of 10M1lz. This intermediate frequency signal 2c is band-limited by an intermediate frequency filter 2d and output. This intermediate frequency filter 2d is recommended by the BWEat CI SPR standard, and is set to 120 KHz in this example. Therefore, noise between 10 MHz ± 60 kHz (noise components are distributed every 1 OHz in this BW) is input to the intermediate frequency filter 2d at intervals of 0.1 seconds (1710 Hz), and this intermediate Frequency filter BW
In response to a time response determined by 120 KHz, an intermediate frequency signal 2f having a rounded envelope is generated and output to the next stage envelope detector 2e. The envelope detector 2e performs envelope detection on the input intermediate frequency signal 2f and outputs 10 M
60 KHz on llz is converted to direct current, and the amplitude fluctuation of the envelope is outputted as evaluation signal 3. Here, although the repetition frequency of the evaluation signal 3 is determined by the input signal 1, its waveform is the intermediate frequency filter 2d(7)BW12
It is determined at 0 KHz and its level is the noise component 80 M
The amplitude is determined at Hz±60KHz. In other words, a difference in the waveform such as the pulse width of the input signal 1 directly affects the amplitude of the evaluation signal 3, and does not result in a difference in the shape of the waveform.

The 1# return frequency of this evaluation signal 3 is detected by the frequency detection means 5, and the value is sent to the coefficient output means 6. The coefficient output means 6 calculates in advance the detection efficiency y of quasi-peak detection with respect to the repetition frequency using the following approximate expression, and stores the value in a ROM table.

2n'I' 5, l iy=〒■
Tt (TTzysy4t y') where 't'c: Charging time constant Td: Discharging time constant n: Repetition frequency B: W of intermediate frequency filter 2d Therefore, the coefficient output means 6 is 1
When a frequency of 0 Hz is input, n =
10 Hz, 'l' from CI SPR standard.

=1@5. 'l', = 550ms, B = 120
The value determined as KHz (0.058 in this case) is output to the calculation Wil as a response coefficient.

The arithmetic unit 7 receives the evaluation signal 3 detected by the peak detection means 4.
The value of the maximum level is multiplied by the response coefficient output by the coefficient output means 6, and the resulting value is output as the quasi-peak value 8.The quasi-peak value 8 is established by this operation as follows. As mentioned above, the waveform of the evaluation signal 3 is the same as that of the intermediate frequency filter 2.
This is because it depends on d. If the shape of the waveform of the evaluation signal 3 is directly influenced by the waveform of the input signal 1, the response coefficient (the response coefficient) cannot be determined solely by the approximation formula described above.

In addition, in the above embodiment, the next pulse does not arrive even after an appropriate time elapses, for example, 5 seconds, after the input signal 1 receives all (in the case of one isolated pulse, the counter 5b is 0) one pulse. If not, set the repetition frequency of this pulse to 0.
211z to the coefficient output means 6. Although some errors occur due to the time limit, there is no practical problem.

In the quasi-peak value evaluation device of the present invention, since the detection efficiency is calculated by calculation, the overload coefficient shown in FIG. 6 and FIG. This has the great effect of eliminating the need for a range and allowing the measurement range to be used instead. At the same time, since no diode is used, accuracy is also improved.

Note that in the above embodiment, the envelope detector 2e is not necessarily required.1. However, in this case, the next stage Al1) conversion circuit 4a must respond to the intermediate frequency. Also,
The frequency detection means 5 may also detect the repetition frequency directly from the input signal 1. Further, when the selection means 2 measures the quasi-peak value 8 of only fixed frequency components, it can be done by using a narrow band filter.

Furthermore, the peak detection means 4 of the above embodiment. The coefficient output means 6 and the arithmetic unit 7 can be constructed from analog circuits. For example, the arithmetic unit 7 can be configured by passing the evaluation signal 3 through a diode and charging a capacitor connected to the input of a high-impedance human-powered operational amplifier. The coefficient output means 6 may generate a DC voltage according to the detection efficiency y. Arithmetic V! An analog multiplier may be used for g7.

Next, another embodiment of this invention is shown in FIG.

FIG. 2 shows an example of a configuration in which random noise and noise having a high repetition frequency can also be measured.

In FIG. 2, the same symbols as in FIG. 1 indicate the same parts,
9 is a quasi-peak detector, for example, the differential amplifier 34 in FIG. Diode 35. Consists of resistors 36, 39, capacitors 37, etc., and consists of a detection circuit 9a that outputs a quasi-peak value, and an Al1) conversion web that converts the quasi-peak value into a digital signal and outputs a quasi-peak value 11. Reference numerals 3 and 12 are comparing and switching means, which compare the quasi-peak value 8 outputted by the arithmetic unit 7 based on the frequency information from the frequency detection means 5 and the quasi-peak value 11 outputted by the quasi-peak value detector 9. While comparing the magnitudes of each, output the quasi-peak value of either one. Since the operation of the quasi-peak detector 9 is the same as that described in the prior art section, the operation of this embodiment will be explained based on the operation of the comparison switching means 12.

The comparing and switching means 12 operates based on the frequency information received from the frequency detecting means 5, and FIG. 3 shows the flowchart 1. at that time. In FIG. 3, (1) to (5) indicate each step of the operation. Note that the frequency detecting means 5 uses random noise W as the noise to be determined.

Or, if the noise is a mixture of random noise and pulse-like noise, and the counter 5b does not operate, it will output zero as frequency information, and if the noise to be measured is mainly pulse-like noise, the counter 5b will operate and the pulse-like noise will be output. When the repetition frequency of noise is counted, the value is output as frequency information. Therefore, the comparison switching means 12 operates as follows and outputs either the quasi-peak value 8 or 11 described above.

(a) First, it is determined whether the frequency information is zero (step (1)). If it is zero, that is, if it is mainly random noise as described above, a quasi-peak value of 11 is output (
Step (5)).

(b) When the frequency information is a certain repetition frequency f, that is, it is mainly a pulsed noise field &, f) 20 H
Step (2)), f ) 20
If it is Hz, a quasi-peak value of 11 is output (step (5)
).

(c) If f < 20 Hz, compare quasi-peak value 8 and quasi-peak value 11 (step (3)), select and output the larger quasi-peak value (step (4) and (5)), In this case, the larger value is selected when the pulse-like noise includes random noise, and as the magnitude approaches the pulse-like noise, the peak value 8 is selected. This is because 9° indicates a value lower than the actual value.
In this case, since the effective overload coefficient required for the quasi-peak detector 9 to operate is lowered by random noise, there is no problem with the value of the quasi-peak value 11.

In this embodiment, one of the criteria for determining whether to select quasi-peak value 8 or 11 is when the frequency output by the frequency detection means 5 is 20 Hz. This is because when the repetition frequency of pulse-like noise becomes around 20 Hz, the overload coefficient of the detection circuit 9a performing quasi-peak detection is halved compared to the overload coefficient of isolated pulses, as shown in Fig. 6.
In the example of Party B, 20 II F is used as the cutoff point for judgment. 1. In this way, this frequency may be selected at a value where the overload coefficient of the detection circuit 9a does not become large. Along with this,
The overload coefficient of the circuit before selection means 2 is also reduced, and the measurement range can be expanded by that amount.

In the two embodiments described above, the measurement target is not limited to noise.

〔Effect of the invention〕

As explained above, the present invention includes a selection means for extracting and outputting an evaluation signal to be evaluated from a pulse-shaped input signal, and a peak detection means for detecting the maximum level of the evaluation signal and outputting the value. , a frequency detection means for detecting the repetition frequency of the human signal and outputting it as frequency information, a coefficient output means for outputting a response coefficient corresponding to a detection response of quasi-peak detection based on the frequency information, and a maximum level value. Equipped with a calculator that performs weighting calculations using response coefficients and outputs the quasi-peak value of the evaluation signal, greatly reducing the overload coefficient when measuring the quasi-peak value of pulsed signals at low frequencies. This has the effect of widening the measurement range and making the measurement itself easier. Furthermore, since the measurement range is expanded and it is not necessary to use a diode, accuracy is improved.

Further, as explained above, another invention of the present invention includes a selection means for extracting and outputting an evaluation signal to be evaluated from an input signal, and a peak detecting means for detecting the maximum level of the evaluation signal and outputting the value. a detection means, a frequency detection means for detecting the repetition frequency of the human signal and outputting it as frequency information, a coefficient output means for outputting a response coefficient corresponding to a detection response of quasi-peak detection based on the frequency information, and a maximum level. It has a calculation unit that weights the value of the evaluation signal with a response coefficient and outputs the quasi-peak value of the evaluation signal, a detection element, and a time constant element that determines the charging and discharging time constants. A quasi-peak value detector outputs a peak value, a quasi-peak value outputted by an arithmetic unit based on frequency information outputted by the frequency detection means, and a quasi-peak value outputted by the quasi-peak value detector. Since it is equipped with a comparison switching means that compares them and sets one of them as a quasi-peak value, it is possible to detect unspecified signals other than pulse-like signals with a low repetition frequency more accurately than conventional quasi-peak detection. It has a measurable effect. Furthermore, since the overload coefficient has been significantly increased, it has the effect of being able to be added to general-purpose measuring instruments such as spectrum analyzers without placing a large burden on them.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment according to the present invention, FIG. 2 is a diagram showing the configuration of an embodiment according to another invention of the invention, and FIG. 3 is a flowchart of the operation of another invention of the invention. 4 is a diagram showing the configuration of a conventional example in which quasi-peak detection is performed after frequency conversion. FIG. 5 is a circuit diagram showing a specific example of a conventional quasi-peak detector. 7 and 7 are diagrams for explaining the characteristics of the conventional example. In the figure, 1 is an input signal, 2 is a selection means, 2a is a mixer, 2
b is a local oscillator, 2C is an intermediate frequency signal, 2d is an intermediate frequency signal, 2e is an envelope detector, 3 is an evaluation signal, 4 is a peak detection means, 4a and 9b are A/D converters, 4b is a peak search circuit, 5 is a frequency detection means, 5a is a waveform shaping circuit, 5b is a counter, 6 is a coefficient output means, 7 is an arithmetic unit, 8
, 10°11 is a quasi-peak value, 9.30 is a quasi-peak value detector,
9a is a detection circuit, 12 is a comparison switching means, 31 is a display means, 32.35 is a diode, 33 is a smoothing circuit, 34 is a differential amplifier, 36 and 39 are resistors, and 37 is a capacitor. . Figure 3

Claims (3)

[Claims] (1) Selection means (2) for extracting and outputting an evaluation signal to be evaluated from a pulsed input signal; and peak detection means (4) for detecting the maximum level of the evaluation signal and outputting the value. , a frequency detection means (5) that detects the repetition frequency of the input signal and outputs it as frequency information, and a coefficient output means (5) that outputs a response coefficient corresponding to a detection response of quasi-peak detection based on the frequency information. 6), and a calculator (7) that performs a weighting operation on the maximum level value using the response coefficient and outputs a quasi-peak value of the evaluation signal. . (2) A patent characterized in that the selection means (2) heterodyne receives the frequency component to be evaluated from the pulsed input signal, band-limits it with an intermediate frequency filter, and outputs this signal as an evaluation signal. A quasi-peak value evaluation device according to claim (1). (3) Selection means (2) for extracting and outputting the evaluation signal to be evaluated from the input signal; and peak detection means (4) for detecting the maximum level of the evaluation signal and outputting the value.
, a frequency detection means (5) that detects the repetition frequency of the input signal and outputs it as frequency information, and a coefficient output means (5) that outputs a response coefficient corresponding to a detection response of quasi-peak detection based on the frequency information. 6), a computing unit (7) that performs a weighting operation on the maximum level value using the response coefficient and outputs a quasi-peak value of the evaluation signal, a detection element, and a time constant that determines charging and discharging time constants. a quasi-peak value detector (9) which has an element and detects the evaluation signal and outputs a quasi-peak value;
), and compares the quasi-peak value outputted by the arithmetic unit and the quasi-peak value outputted by the quasi-peak value detector based on the frequency information outputted by the frequency detection means, and determines which one of them A quasi-peak value evaluation device characterized by comprising a comparison switching means (12) for determining the quasi-peak value as a quasi-peak value.