JPS5848067B2 - Noise intensity measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a noise intensity measuring device that is applied to, for example, an electric field intensity measuring device and can also measure the electric field intensity of noise.

When the electric field strength of continuous waves is measured by pressing a button on the electric field strength measurement device, average value detection is performed and the result is supplied to the display, but in the case of noise electric field strength, quasi-peak value detection is used.

This quasi-peak detection is standardized.

With quasi-peak detection, the output is averaged to a certain extent, and in this case, it is easier to hear the signal due to noise than with normal average detection, which extracts a single radial line. Affect corresponds well to sensation.

When using a conventional field strength measurement device to measure both noise field strength and continuous wave field strength, the dynamic range of the amplifier, etc. at the stage before the detector is was not used effectively.

That is, in the conventional electric field strength measuring device, as shown in FIG. 1, a signal from an antenna 11 is level-adjusted by a high frequency attenuator 12, further amplified by a high frequency amplifier 13, and then supplied to a frequency converter 14.

The oscillation output from the variable frequency local oscillator 15 is supplied to the frequency converter 14, and frequency mixed with the signal from the high frequency amplifier 13 to obtain an intermediate frequency output.

The intermediate frequency output is amplified by an intermediate frequency amplifier 16, further level-adjusted by a variable gain amplifier 17, and the output is supplied to an intermediate frequency detector 18.

The detected output is supplied to the display 19.

A detection characteristic switching knob 21 is attached to the detector 18, and when the knob 21 is switched to the M side, the detector 18 becomes an average value detection, a detection that extracts a single radial line, and is switched to the Q side. If so, the charging/discharging time constant of the detector 18 is switched so as to perform quasi-peak detection, which averages the output with an appropriate time constant.

The charging/discharging time constant of quasi-peak detection is standardized for measuring this type of noise field strength.

In the case of quasi-peak detection, the output is averaged to a certain extent, so the output level is considerably lower than that of average detection, for example, about 40 bB lower.

A field strength measuring device that measures the noise field strength requires an overload coefficient of about 40 dB in the section before the detector 18, in accordance with a field strength measuring device that does not measure the noise field strength.

When the continuous wave input is average detected and the display 19 shows full scale, the level of each stage before the detector 18 will be about 40 dB lower than the maximum allowable level when the button is pressed for that stage. .

In other words, when displaying continuous wave input with average value detection, the maximum allowable level that can be pressed on each stage before the detector is 40 d.
B The display 19 becomes full scale at a low point 1
cormorant.

Therefore, if a continuous wave input is applied, each stage before the detector 18 cannot be used up to its maximum permissible level, and the dynamic range decreases by about 40 dB, reducing the input level range that can be measured. Become.

The purpose of this invention is to be able to fully use each stage before the detector up to its maximum allowable level, and to also measure the noise intensity and display the quasi-peak detection output. The purpose of the present invention is to provide a noise intensity measuring device that can perform the following.

According to this invention, when the charging/discharging time constant of the intermediate frequency detector is switched to quasi-peak detection, the auxiliary amplifier is inserted after the frequency converter.

This auxiliary amplifier compensates for the drop in level when pressing the quasi-peak detection button and supplies it to the display, so the display can display the full scale when the button is pressed, and the detector is used for average detection. When switched, the auxiliary amplifier is automatically removed, thus allowing each stage before the detector to operate up to its maximum allowable level; The range can be used effectively, and the input signal can be measured from a low level to a high level, and a sufficiently large dynamic range can be obtained.

Since the auxiliary amplifier is inserted or removed in this manner, the converted value of the input relative to the reference level applied to the display changes.

Therefore, the display buttoned on the second display indicating the converted value of the input is automatically switched in accordance with switching between average value detection and quasi-peak value detection in the intermediate frequency detector.

A second display is supplied with a signal indicating a setting value of a level adjustment means for adjusting the signal level supplied to the first display, and a signal indicating a gain of the auxiliary amplifier.

At this time, the signal indicating the gain of the auxiliary amplifier in the average value detection is blocked, and the converted value of the input corresponding to the reference level of the first display is displayed on the second display.

When the quasi-peak detection button is pressed, a signal indicating the gain of the auxiliary amplifier is also added, and the auxiliary amplifier 9 gain is subtracted from the first signal.
The input conversion value of the reference level of the display device is displayed on the second display device.

For example, an auxiliary amplifier 23 is provided as shown in FIG. 2, in which parts corresponding to those in FIG.

In this example, the output of the variable gain amplifier 17 is supplied to the input side of the auxiliary amplifier 23.

Furthermore, a changeover switch 24 is provided, and the changeover switch 24
The output side of the variable gain amplifier 17 and the auxiliary amplifier 23 are
The output side of the intermediate frequency detector 18 is connected to the input side of the intermediate frequency detector 18 by switching.

The changeover switch 24 is linked to the switching operation of the switching knob 21 between average value detection and quasi-peak detection in the intermediate frequency detector 18, and when the knob 21 is set on the average value detection M side, the switch 24 is When the switch 24 is connected to the variable gain amplifier 17 side and the knob 21 is set to the quasi-peak detection Q side, the switch 24 is connected to the auxiliary amplifier 23 side.

The auxiliary amplifier 23 is an overload amplifier having a gain larger than the overload coefficient of the stage before the detector 18, for example, about 40 dB.

The level of the signal supplied to the first display 19 can be adjusted by adjusting the high frequency variable attenuator 12 or by adjusting the intermediate frequency variable gain amplifier 11.

Signals indicating these level adjustment setting values are displayed on the second display 2.
5.

Along with this, a signal indicating the gain of the auxiliary amplifier 23 is also connected to the terminal 26.
The signal is then supplied to the second display 25.

That is, the variable resistor 27 is adjusted in conjunction with the attenuation amount means of the high frequency variable attenuator 12, and a constant voltage is applied across the variable resistor 27, and the setting of the high frequency variable attenuator 12 is controlled by the movable element. A signal indicating the value is taken out and added to the adder circuit 2.
8.

Similarly, a variable resistor 29 is provided which interlocks with the gain adjustment knob of the intermediate frequency variable gain amplifier 17, and the variable resistor 29
A constant voltage is applied to both ends of the movable element, and the output of the movable element is used as a signal indicating the adjustment gain of the variable gain amplifier 17 in the adder circuit 2.
given to 8.

A constant value indicating the gain of the auxiliary amplifier 23 provided to the terminal 26 is also provided to the adder circuit 28 through a switch 31.

The switch 31 is turned on when the detection characteristics of the detector 18 are set to the quasi-peak detection Q side, but is turned off when the knob 21 is set to the average detection M side. It is said to be linked so that.

The output of the adder circuit 28 is supplied to the second display 25.

Since the reception characteristics of the antenna 11 have frequency characteristics, the level adjustment power has the same setting value, and even if the display on the first display 19 is the same, the input level differs depending on the reception frequency.

Therefore, the reference level of the first display 19, for example, the display of the second display 25 that displays the input level corresponding to the full scale, must be corrected in accordance with the frequency of the received signal.

For this correction, the adjustment circuit 33 for adjusting the oscillation frequency of the variable frequency local oscillator 15 includes, for example, a variable resistor 34.
The local oscillation frequency is adjusted by applying a constant voltage to both ends of the movable element and applying the output of the movable element to the frequency control terminal of the local oscillator 15 to adjust the movable element of the variable resistor 34.
The output of the movable element of the variable resistor 34 is branched and supplied to the correction signal generator 35.

The input/output characteristics of the correction signal generator 35 are based on the antenna 1 used.
For example, when the antenna is a dipole antenna, a logarithmic amplifier is used.

The output of this correction signal generator 35 is supplied to an adder 28.

As a result, as described above, correction is performed in line with the input conversion with respect to the reference level according to the frequency characteristics of the antenna used.

According to the structure shown in Fig. 2, the detection characteristic setting knob 21
When the switch 24 is switched to the average value detection M side, the switch 24 is connected to the variable gain amplifier 17 side, so each stage before the detector 18 must be operated to its maximum allowable level. I can do it.

Setting value of level adjustment means, single variable resistor 27.29
The output of the movable element is supplied to the second display 25, and the converted value of the reference level input of the first display 19 is displayed.

Based on the display on the second display 25 and the display on the first display 19, the level of the input signal and the electric field strength of the input signal can be measured.

Furthermore, each stage before the detector 18 can be operated up to its maximum allowable level, which increases the ability to measure over a wide level range of input signals.

When measuring the noise electric field strength, press the button and switch the knob 21 to the quasi-peak detection Q side.

Therefore, the switch 24 is switched to the output side of the auxiliary amplifier 23.

Therefore, the drop in output level due to quasi-peak detection is compensated for by the auxiliary amplifier 23, and each stage before it is saturated or not, and it is possible to operate up to the maximum allowable level.

Also, at this time, the switch 31 is turned on, and a signal indicating the gain of the auxiliary amplifier 23 is input to the adder circuit 28, where the gain of the auxiliary amplifier 23 is subtracted, and the display on the second display 25 becomes smaller.

By inserting the switching auxiliary amplifier 23, even if the input signal is at a lower level, the first display 19 is turned on and reaches the reference level, so that the adder circuit 28 is turned on to perform subtraction.

Therefore, the second display 25 showing the input signal level corresponding to the reference level pressed on the first display 19 is automatically and correctly displayed regardless of the setting of the detection characteristic setting knob 21.

Due to the presence of the auxiliary amplifier 23, the signal level at each stage before the dividing detector 18 becomes low, and the overload coefficient is ensured without saturation and summation.

For example, if the overload coefficient at the front stage of detector 1B is 40 dB,
Also, assuming that the maximum allowable level of the stage before the detector is 110 dBμ, the electric field strength at full scale for the device shown in FIG. 1 is 70 dBμ. The gain of the variable gain amplifier 17 is set to the maximum gain.

However, in the embodiment shown in FIG. 2, in the case of quasi-peak detection, the display 1
At full scale of 9, the input is 70 dBμ, and in the case of average value detection, it is possible to measure up to 110 dBμ.

When the display on the display 19 is a dB display, the signal supplied to the intermediate frequency detector 18 is amplified by a certain number of times when the button is pressed.

A part of the power amplifier can also be used as the auxiliary amplifier 23.

For example, as shown in FIG. 3, a logarithmic amplifier 37 is inserted on the output side of the variable gain amplifier 17.

The column number amplifier 37 includes, for example, a plurality of amplifiers 38 having a gain of 10 dB connected in series, and the output of each amplifier stage is connected to the adder circuit 3.
9 and is added and output.

A plurality of these amplification stages 38 are also used as the auxiliary amplifier 23.

The output side of the fourth stage from the first stage of the cascade-connected amplification stages is connected to one fixed terminal of the switch 24.

The switch 24 connects the output side of this fourth stage, the output side of the amplifier 37, and the output side of the adder 39? It is connected to the detector 18 by switching between the two.

In the detector 18, the output of the switch 24 is supplied to one end of a detection element 41 such as a diode, and the other end of the detection element 41 is grounded through a high-frequency bypass capacitor 42, and is switched when the intermediate frequency signal is grounded. switch 43
through the selector switch 44, and the first display 19 through the changeover switch 44.
connected directly to.

A series circuit including a time constant circuit 45 and a DC column amplifier 46 is connected between the other contacts of the changeover switches 43 and 44.

The switches 43 and 44 are switched by the detection switching knob 21.

The filter switches 43 and 44 are the time constant circuit 45 and the amplifier 4.
The time constant circuit 45 is selected so that when connected to the 6 side, quasi-peak detection is performed.

The switch 24 is connected to the fourth stage output side of the amplification stage 38 in the case of quasi-peak detection.

In this way, in the case of average value detection, the variable gain amplifier 17
The output is logarithmically converted by a gain amplifier 37, and the output is sent to a detector 18 through a switch 24 for average value detection and supplied to a display 19 for so-called dB display.

When switching to quasi-peak detection, a part of the amplification stage 38 in the logarithmic amplifier 37 is also used as the auxiliary amplifier 23,
The output is supplied to the detector 18 through the switch 24, subjected to quasi-peak detection, and displayed on the display 19.

In that case, the power is logarithmically converted by the amplifier 46 and expressed in dB;
It will be done.

In addition, in the above-mentioned case, the auxiliary amplifier 23 is replaced by the intermediate frequency detector 18.
Although this auxiliary amplifier and 1- are inserted immediately before, a DC amplifier may be used and inserted on the output side of the wave detector 18.

However, in that case the detector 18 needs to operate well at relatively low levels.

Furthermore, even if an AC amplifier is used as the auxiliary amplifier 23, the frequency converter 14 is generally the one placed before the detector 18 and has the smallest dynamic range, so the button placed after the frequency converter 14 is Auxiliary amplifier 2
Just insert 3.

As the display 19, an analog meter display or a cathode ray tube display may be used.

When displaying on a single cathode ray tube display, the horizontal axis may be swept at a constant frequency and the vertical axis may be deflected by the output of the detector 18.

In this way, horizontal displays appear at different heights on the display surface that can be pressed on the cathode ray tube display depending on the output level of the detector 18.

As the second display 25, an analog meter display, a dial display, a digital display, etc. can be used.

Furthermore, although the above-mentioned button assumes input from the antenna 11, it is not necessarily necessary to do so, and it can be used for general noise measurement, that is, for measuring the intensity of a signal source or noise.

In that case, it is a matter of course that the correction signal generator 35 is omitted.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a conventional field strength measuring device, Fig. 2 is a block diagram showing an example of a noise field strength measuring device to which the present invention is applied, and Fig. 3 shows a part of a logarithmic amplifier used as an auxiliary amplifier. It is a connection diagram showing an example of utilization. 12: High frequency variable attenuator, 14... frequency converter, 1
5: Variable frequency local oscillator, 17: Variable gain amplifier, 1
8: Intermediate frequency detector, 19: First indicator, 21: Detection characteristic switching knob, 23: Auxiliary amplifier, 25: Second indicator, 2
6: signal input terminal indicating the gain of the auxiliary amplifier; 27: signal generator generating a signal indicating the setting value of the variable attenuator 12;
28: Adder, 29: Signal generator that generates a signal indicating the setting value of the variable gain amplifier, 33: Control signal generator for variable frequency local oscillator, 37 Two-column amplifier, 38: Amplification stage,
39: adder circuit, 41: detection element, 45: time constant circuit,
46: DC logarithmic amplifier.

Claims (1)

[Claims] 1. A variable frequency local oscillator, a frequency converter that mixes the oscillation output of the variable frequency local oscillator and an input signal to obtain an intermediate frequency output of a constant frequency, and the intermediate frequency output is supplied to perform average value detection and standard An intermediate frequency detector capable of switching the number of charging/discharging times between peak detection and peak detection; a first display that displays the magnitude of the output of the intermediate frequency detector; an auxiliary amplifier inserted after the frequency converter when switched to a value frequency, a level adjustment means for adjusting the level of the signal supplied to the first display, and setting of the level adjustment means. and a second display to which a signal indicating the gain of the auxiliary amplifier is supplied and displays a converted input level to be applied to the reference level of the first display.