JPH083505B2 - Spectrum analyzer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of a spectrum analyzer that performs frequency analysis of a signal under measurement.

[Conventional technology]

As is well known in the art, a spectrum analyzer measures the characteristics of a high-frequency signal under measurement in a relatively high range of, for example, several tens of kHz to several tens to several hundreds GHz, and displays the spectrum intensity at each frequency on the display unit. Is displayed with the horizontal axis as the frequency axis. For example, as shown in FIG. 10, the spectrum analyzer thus configured includes an RF section (high frequency circuit) 1, an IF section (intermediate frequency circuit) 2, a detection section 3, an A / D conversion section 4, a digital memory 5, a display section. 6, a sweep signal generator 7, a data processor / controller 8, and the like.

In such a circuit configuration, the high-frequency signal under measurement a input from the input terminal 9 is input to the RF unit 1 including a mixer and a local oscillator. In the RF unit 1, the input measured signal a is mixed with a local oscillation signal (local signal) of a local oscillator whose oscillation frequency changes according to the signal level of the sweep signal b output from the sweep signal generation unit 7. By doing so, the frequency is converted into the intermediate frequency signal c.
The intermediate frequency signal c output from the RF unit 1 is input to the IF unit 2 incorporating the next band pass filter (BPF).
Then, only the frequency component that matches the pass frequency of the bandpass filter passes through the IF section 2, is input to the next detection section 3, and is output as a DC detection signal d corresponding to its magnitude. This detected signal d is processed by the next A / D converter 4 such as a data processor formed of, for example, a microprocessor.
After being converted into digital data in response to the cycle of the sampling signal e output from the control unit 8, for example, a RAM
And the like are stored in the digital memory 5 formed by the above.

The digital data of the detection signal d stored in the digital memory 5 at each sampling cycle is also read in a fixed order and displayed in response to the read signal f having a constant cycle output from the data processing / control unit 8. It is sent to the unit 6. The display unit 6 has, for example, an image memory for one screen which can be displayed on the display screen at a time. After storing each sequentially input data value in the image memory, the image memory for the one screen is stored. Display image information on the display screen. Then, the spectrum distribution data as shown in FIG. 11 is displayed on the display screen of the display unit 6.

Each spectrum in FIG. 11 is shown as an ideal linear shape having no area. However, it is actually displayed as a spectrum having a width corresponding to the bandwidth of the bandpass filter of the IF unit 2.

The data processing / control section 8 controls the sweep interval and sweep speed of the sweep signal generating section 7 so that the spectrum distribution data shown in FIG. 11 is displayed on the display section 6, and
The sampling signal e is sent to the A / D converter 4, and the read signal f is sent to the digital memory 5. In addition, the spectrum value of the desired frequency value is displayed on the display unit 6,
Perform the necessary arithmetic processing.

[Problems to be Solved by the Invention]

However, the spectrum analyzer configured as shown in FIG. 10 still has the following problems. That is, in order to investigate the property of the measured signal a, the distribution data of the spectrum value of each frequency included in the signal is accurately grasped, and the total sum of the spectrum values, that is, the power value of the input measured signal a is input. There are many cases where it is necessary to understand at the same time.

When the input signal under test a includes a spectrum component that spreads over the bandwidth of the bandpass filter of the IF section 2, its power value is measured using a conventional spectrum analyzer as shown in FIG. For example, if the data value obtained for each cycle of each sampling signal e in the A / D conversion unit 4 in the period from the start of the sweep of one sweep signal b to the end of the sweep is integrated in the data / control unit 8, for example, Good. Then, in order to accurately integrate the power values of the input signal under test a, it is premised that each spectrum value over all frequencies included in the signal under test a is accurately measured. However, it is generally difficult to predict the spread of the spectrum component included in the input measured signal in advance. In addition, a complicated correction calculation is required when correcting and integrating an error amount according to the bandwidth of the bandpass filter of the IF unit 2 included in the spectrum measured as described above. Therefore, it is almost impossible to measure the power value accurately by the integration method as described above.

Further, in such a spectrum analyzer, only the signal component within the specific frequency sweep range selected and set by the data processing / control unit 8 is displayed on the display unit 6.
In reality, there may be a high-level spectrum value (frequency component) in the frequency region outside this frequency sweep range. However, the operator often does not notice the existence of the high-level frequency component. Also, RF unit 1
However, there is a concern that measurement may be performed with a large error without noticing that saturation has occurred. Moreover, there is a concern that the RF unit 1 may be damaged by excessive input. In particular, when measuring a signal with a wide spectrum distribution such as a noisy signal or RF pulse signal, the total power value and pulse peak power are much larger than the individual spectrum values. Is likely to occur.

Furthermore, the whole spectrum is like a continuous wave (CW) signal.
Even if the power value can be measured within the pass band of the band pass filter of the IF unit 2 in principle, a large error is involved because it passes through the complicated signal circuit of the RF unit 1 and the IF unit 2. Is normal. Therefore, in order to accurately measure the power value of a continuous wave signal, input a signal whose power value is known in advance as a reference signal and set the spectrum analyzer's indicated value to the operating frequency. It was necessary to calibrate in. However, this calibration work is a very laborious work, and the measurement work efficiency is significantly reduced. Also, as a practical matter, a calibration signal source whose power value is accurately known at the frequency to be measured,
Or, it is almost impossible and inadequate to have a continuous wave signal source (regardless of power value) and a high-precision level meter (especially equipped with the same temperature conditions as the spectrum analyzer) that measures the level at all times. There is a problem that the power value must be measured with high measurement accuracy.

Therefore, it is an object of the present invention to provide a spectrum analyzer that can easily and accurately display the power value of normal spectrum distribution data.

[Means for solving problems]

In order to solve the above problems, according to the present invention, of the measurement frequency range of the signal under measurement input from the input terminal, the signal under measurement is processed by sequentially sweeping a desired partial frequency sweep range, A signal processing section (101) for outputting a spectrum of a signal under measurement corresponding to a swept frequency sweep range; a first A / D conversion section (102) for converting the spectrum into first digital data; A first memory (103) for storing one digital data; a signal branching or switching circuit (105) inserted between the input terminal and the signal processing section; A power sensor (106) that detects the power of the signal under measurement, a second A / D conversion unit (107) that converts the output of the power sensor into second digital data, and the second digital data Second to remember A memory (108), a spectrum analyzer having a display unit (104) for displaying said second digital data together with the first digital data is provided.

Further, according to the second aspect of the present invention, a continuous wave signal whose entire spectrum falls within the pass band of the band pass of the intermediate frequency section (IF section) in the signal processing section is input to the input terminal as a calibration signal. In this case, a detection means (109) for detecting a difference between the first digital data stored in the first memory and the second digital data stored in the second memory, A third memory (110) for storing correction data which is a difference between the first digital data and the second digital data detected by the detecting means; and a first signal when the measured signal is input to the input terminal. The spectrum analyzer according to claim 1, further comprising: a correction unit (111) that corrects the first digital data stored in the memory of the display device based on the correction data and displays the correction data on the display unit. Be served.

According to a third aspect of the present invention, a variable attenuator (114) provided between the input terminal and the signal processing unit for varying the input level, and based on the second digital data are used. And further controlling the variable attenuator to a desired value, and further comprising a data processing control (112) for calculating a spectrum value of the signal under measurement from the first digital data and the value of the variable attenuator. A spectrum analyzer according to claim 1 is provided.

Furthermore, according to a fourth aspect of the present invention, the first A /
The D conversion unit and the second A / D conversion unit are configured by a single shared A / D conversion unit, and the first memory and the second memory are separate memories in the single shared memory. A switching means (13) configured by an area for switching between a signal from the signal processing unit and a signal from the power sensor and supplying the signal to the one A / D conversion unit; and a sweep period and a reset period of the sweep signal. The spectrum analyzer according to claim 1, further comprising: a control means (8) for controlling the switching means in synchronization with the spectrum analyzer.

[Action]

In the first mode, the observed frequency range out of the measured frequency range of the signal under measurement is swept and the spectrum is displayed. On the other hand, the power sensor measures and displays the power in the measurement frequency range. Therefore, even if no spectrum is displayed in a sweep of a certain observation frequency range,
By looking at the level of the power display, you can see that the spectrum exists in different frequency ranges, and you can sweep different frequency ranges.

In the second aspect, the accuracy of the spectrum analyzer is equal to the accuracy of the power sensor.

In the third mode, the attenuation value of the variable attenuator (ATT) 114 is changed according to the level measured by the power sensor 106,
The level input to the signal processing unit 101 can be controlled to an appropriate level that does not saturate. Further, since the ATT 114 does not have frequency characteristics, the ATT 114 does not change to the level input to the signal processing 101.
By correcting the attenuation value of 114, the level of each spectrum can be accurately obtained.

In the fourth mode, one A / D converter can be shared.

〔Example〕

First, the outline of the present invention will be described. According to the present invention, as shown in FIG. 1, a signal under measurement input from an input terminal IN is processed by a sweep signal from a sweep signal generator 100 to obtain a spectrum of the signal under measurement. Signal processing unit 101 for outputting a signal corresponding to the first digital signal, a first A / D conversion unit 102 for converting the corresponding signal into first digital data, and a first A / D conversion unit for storing the first digital data. Memory 103,
The present invention is applied to a spectrum analyzer including a display unit 104 that displays the first digital data.

According to the present invention, the input terminal IN and the signal processing unit 101
A signal demultiplexing circuit (or a signal switching circuit) 105, a power sensor 106 for detecting the power of the signal under measurement, and an output of the power sensor 106 converted into second digital data. The second A / D converter 107 and the second
A second memory 108 for storing the output of the A / D conversion unit 107, and the display unit displays the second digital data and the first digital data together on the same screen of the display unit 104. There is provided a spectrum analyzer having a peculiar structure characterized in that

Further, according to the present invention, in addition to the above-described unique configuration, a calibration signal is input instead of the signal under measurement to calibrate the signal processing unit. Specifically, for example, a 50 MHz continuous wave (CW) signal (power value does not matter) is input to the input terminal IN. The entire spectrum of the CW signal falls within the pass band of the band pass filter of the IF section that constitutes the signal processing section 101. The first memory 103 and the second memory 103 are input by the same means as when the CW signal is input and the signal under measurement is input.
Stored in the memory 108. Then, the first memory 103
A correction data detector 109 for detecting a difference between the first digital data stored therein and the second digital data stored in the second memory 108 as correction data; It has a third memory 110 for storing correction data that is the difference between the first and second digital data detected by the detection unit 109. Then, when the signal under measurement is input and the spectrum of the signal under measurement is measured, the first digital data stored in the first memory is corrected based on the correction data and displayed on the display unit 104. A spectrum analyzer including the unit 111 is provided. In FIG. 1, the correction data detection unit 109, the third memory 110, and the correction unit 111 are built in a data processing / control unit 112 similar to that of FIG.

Furthermore, according to the present invention, in addition to the above-mentioned unique configuration,
The first A / D conversion unit 102 and the second A / D conversion unit 107 are configured by a single shared A / D conversion unit 102, and the signal from the signal processing unit and the power sensor 106 are used. And a switching unit 113 which supplies the signal to the one A / D conversion unit 102 by switching the signal of the above, and which controls the switching unit 113 in synchronization with the sweep period and the reset period of the sweep signal. To be done. In this aspect, the first memory 103 and the second memory 108 should be understood as separate memory areas within the same memory.

Furthermore, according to the present invention, in addition to the above-mentioned unique configuration, a variable attenuator 114 for varying the input level provided between the signal branch circuit (or signal switching circuit) 105 and the signal processing unit 101. And a spectrum analyzer for controlling the attenuation value of the attenuator to a desired value based on the second digital data. This allows
The excessive input level can be suppressed to a proper level.

Next, some embodiments of the present invention based on the above outline will be described with reference to the drawings.

FIG. 2 is a block diagram showing a schematic configuration of the spectrum analyzer of the first embodiment. The same parts as those of the conventional spectrum analyzer shown in FIG. 10 are designated by the same reference numerals. In this embodiment, the input terminal 9 and the mixer 1a
Signal branch circuit between the RF unit 1 and the RF oscillator 1 which is composed of the local oscillator 1b.
11 are inserted. The RF unit 1 is connected to one output terminal of the signal branch circuit 11, and the power detector 12 is connected to the other output terminal. Then, this signal branch circuit 11
Is composed of, for example, a resistance division type divider, and the measured signal a input from the input terminal 9 is supplied to the RF unit 1 and the power source with a power distribution ratio (for example, 1: 1) determined in advance by the voltage division ratio of the resistance. Distribute to detector 12.

The power detector 12 is composed of a normal high frequency power detector using a thermocouple element, a diode element and an averaging circuit or a power detector using a wide band amorphous power sensor technique, and has a wide frequency range from direct current to high frequency. It is possible to accurately detect the power value of the signal including the signal. As the latter power detector, the power measuring device of International Patent Application PCT / JP87 / 00812 by the same applicant as this application can be used. DC power value signal g output from the power detector 12
Is input to the A / D converter 4 via the switching circuit 13. The detection signal d from the detection unit 3 is also input to the switching circuit 13. Then, the signal input to the A / D converter is switched to the detection signal d or the power value signal g by the switching signal h sent from the data processing / control unit 8 '.

It is assumed that the digital memory 5'has first and second memory areas corresponding to the first and second memories 103 and 108 in FIG.

In addition, RF section 1, IF section 2, detection section 3, A / D conversion section 4,
The configurations of the display section 6 and the sweep signal generating section 7 are the same as in FIG. As will be described later, the data processing / control unit 8'is different from the case of FIG. 10 in control of each unit.

A variable attenuator 114 similar to that of FIG.
It is controlled by the control unit 8.

Next, the operation of the spectrum analyzer configured as described above will be described using a time chart of a general sweep signal b output from the sweep signal generator 7 shown in FIG. That is, at time t _0, the sweep signal b for sweeping the frequency of the local oscillation signal i output from the local oscillator 1b of the RF unit 1 starts to increase from the lowest value corresponding to the lowest measurement frequency, and the sweep period A After reaching the maximum value corresponding to the measured maximum frequency at elapsed time t _1, the signal level is lowered, the next sweep period from the time t ₂ has elapsed reset period B from the lowest value corresponding to the original measurements lowest frequency Start the sweep for A.

Then, the data processing / control unit 8 ′ is configured to perform the sweep period A
In the inside, the detection signal d is sent to the switching circuit 13 by the A / D converter 4
The switching signal h to be input to the
Inside, a switching signal h for inputting the power value signal g to the A / D converter 4 is sent to the switching circuit 13.

Then, during the sweep period A, the high frequency signal under test a input from the input terminal 9 is input to the mixer 1a of the RF unit 1 and mixed with the local oscillation signal i which is frequency swept by the sweep signal b. As a result, the frequency is converted into the intermediate frequency signal c. In the IF circuit 2, the intermediate frequency signal c output from the RF unit 1 is extracted only in the frequency component that matches the pass frequency of the bandpass filter (BPF), and is input to the next detection unit 3. Then, it is converted into a DC detection signal d corresponding to the magnitude, and the switching circuit
It is input to the A / D conversion unit 4 via 13. Detection signal d is A / D
After being converted into digital data by the conversion unit 4 in response to the cycle of the sampling signal e output from the data processing / control unit 8 ', it is stored in the first memory area of the digital memory 5'.

The digital data of the detection signal d stored in the first memory area of the digital memory 5'at each sampling cycle is also responsive to the read signal f having a constant cycle output from the data processing / control section 8 ', The data is read out in a fixed order and sent to the display unit 6. Then, as shown in FIG. 4, the spectrum value at each frequency, that is, the spectrum distribution data D1 is displayed on the display unit 6. The spectrum distribution data is held until the next reset period B ends.

In the reset period B, the power value signal g output from the power detector 12 is converted into a digital value by the A / D converter 4 via the switching circuit 13. This digital value is stored in the second memory area, which is a dedicated area for the power value in the next digital memory 5 ', and then read out from the digital memory 5'and in the numerical character data format as shown in FIG. The average power value P1 is displayed in the empty area of the spectrum distribution data on the CRT display unit 6. The numerical character data of this power value is held until the end of the next sweep period A.

Then, the spectrum distribution data and the power value are displayed on the display unit 6 as the same screen as shown in FIG. As described above, by providing the signal branching circuit 11 and the power detector 12, it becomes possible to simultaneously obtain each spectrum value and power value at each frequency of the signal under measurement a.

In addition, as described above, the signal branch circuit 11 and the power detector.
The 12 has a simple structure, can be constructed at a low price, and can have a wide frequency characteristic. Therefore, the tenth
The manufacturing cost does not rise significantly compared to the conventional spectrum analyzer shown in the figure.

In addition, the measurement accuracy can be significantly improved as compared with the case where the power values are calculated by adding the spectrum values.

Furthermore, in the first embodiment of FIG. 2, the sweep signal b
Since the power value is measured by using the reset period B of 1., by measuring the power value,
Compared to the conventional spectrum analyzer that obtains only the spectrum distribution data, the total measurement time is not extended. That is, the power value is also measured within the conventional measurement time.

FIG. 5 is a block diagram showing a spectrum analyzer according to the second embodiment of the present invention. The same parts as those in the first embodiment shown in FIG. 2 are designated by the same reference numerals.

In the second embodiment, an RF (high frequency) switch circuit 11a is used as a signal switching circuit inserted between the input terminal 9 and the RF section 1. Then, this RF switch circuit 11a outputs the signal under measurement a inputted from the input terminal 9 to the R
Whether the signal is sent to the F section 1 or the power detector 12 is switched by a switching signal h from the data processing / control section 8 '. The switching timing is the same as the switching circuit.
It is synchronized with the switching timing of 13.

That is, when the sweep signal b in FIG. 3 is in the sweep period A, the data processing / control unit 8 ′ changes the
The RF switch circuit 11a is switched to the RF section 1 side and the switching circuit 13 is switched to the detection signal d side. In the reset period B, the RF switch circuit 11a is switched to the power detector 12 side and the switching circuit 13 is switched to the power value signal g side.

Then, each spectrum value is measured during the sweep period A, and the power value is measured during the reset period B. Therefore,
Also in the second embodiment, the spectrum distribution data and the power value of the signal under measurement a can be measured and can be displayed on the display unit 6 as the same screen. As a result, the first
It is possible to obtain substantially the same effect as the embodiment.

Furthermore, by using the RF switch circuit 11a as the signal branch circuit, compared to other signal branch circuits using the above-mentioned resistive divider or directional coupler, the loss of the signal under measurement is small, the signal It is possible to prevent the sensitivity of the entire spectrum analyzer from being lowered due to the insertion of the branch circuit.

FIG. 6 is a block diagram showing a spectrum analyzer according to the third embodiment of the present invention. The same parts as those in the embodiment of FIG. 2 are designated by the same reference numerals.

In the third embodiment, the switching circuit shown in FIG.
13 is removed, and the detection signal d output from the detection unit 3 is directly
Input to the A / D converter 4. Further, the power value signal g output from the power detector 12 is input to another A / D conversion unit 4a. Then, the digital data obtained by each A / D converter 4, 4a is written in the first and second memory areas of the digital memory 5 '. A / D
Although the same sampling signal e is input to the conversion units 4 and 4a, it is not always necessary to match them.

Even with such a configuration, it is possible to obtain the spectrum distribution data and the power value of the signal under measurement a, so that it is possible to obtain substantially the same effect as the embodiment of FIG.

Further, in the third embodiment, the detection signal d and the power value signal g are converted into digital data values by using the dedicated A / D converters 4 and 4a, respectively, so that the sweep period A in FIG. Also in, it is possible to measure the power value. Therefore, even when the sweep period A for spectrum measurement is long, the input power value of the signal under measurement a can be monitored in real time on the display screen of the display unit 6. In this way, not only during the reset period B but also during the sweep period A, that is, because the power value of the signal under measurement a can be constantly monitored, an alarm output is immediately generated when excessive power is input, and a warning display or alarm sound is generated. be able to. It is also possible to use the power value signal g so that the input attenuator 114 inserted in front of the RF section 1 is automatically adjusted as in FIG. 2 to obtain a correct display value. That is,
This spectrum analyzer can be protected from damage due to excessive signal input.

Further, in each of the embodiments shown in FIGS. 2, 5, and 6, the relationship between the detection signal d and the power value signal g is accurately obtained in advance in accordance with a specific operation (calibration command CALIB) of the operation part OP. The data processing / control section 8'uses each of the data so that each data value obtained by the signal under measurement a and displayed on the display section 6 becomes a correct value by using the calibration signal thus obtained. It is possible to calibrate the value. In this case, when a continuous wave (CW) signal is used as the calibration signal, its power value does not have to be known in advance.

Further, in this case, the data processing / control unit 8'can perform calibration (correction) using the correction data detection unit 109, the third memory 110 and the correction unit 111 shown in FIG.

In the above description, it has been assumed that the power detector 12 is configured to detect the average power value. However,
In particular, when it is necessary to detect the peak power in the spectrum measurement of the pulse modulated wave, the power detector 12 detects the input signal from the signal branch circuit 11 or the signal switching circuit 11a as shown in FIG. The diode element 12a and the peak hold circuit 12b that holds the peak value of the detection output of the diode element 12a may be provided. A reset signal is supplied to the peak hold circuit 12b from the data processing / control unit 8'at each measurement cycle. The power detector 12 of FIG. 7 is provided with an averaging circuit 12c for averaging the detection output from the diode element 12a in order to detect the above-mentioned average power value. Further, the power detector 12 includes an averaging circuit 12c and the peak hold circuit 1 described above.
Switch 12 to change the output of 2b according to the purpose of use
d is also provided.

Figure 8 shows a display example of a pulse modulation wave spectrum distribution data D2 and peak power (P _2).

FIG. 9 shows a block configuration applied to an optical spectrum analyzer as a fourth embodiment. In FIG. 9, the second
The same parts as those in the figure are designated by the same reference numerals and the description thereof will be omitted. That is, the signal to be measured a ', which is incident on the optical signal input terminal 9', is branched into two by the optical signal branching unit 11 'which is, for example, a half mirror. One of these optical signals enters the half mirror 1a 'of the RF unit 1'. An optical local oscillation signal from an electro-optical converter 1b 'such as a light emitting diode which responds to the electrical sweep signal from the sweep signal generator 7 is incident on the half mirror 1a'. Therefore, this half mirror
1a 'acts as a mixer equivalent to an electric mixer,
Outputs an optical intermediate frequency signal. This optical intermediate frequency signal is converted into an electrical intermediate frequency signal by the photoelectric converter 1c such as a photodiode. Therefore, the processing thereafter is performed in the same manner as in FIG.

The other optical signal from the optical signal branching unit 11 'is photoelectrically converted by the optical power sensor 12' including a light receiving element such as a photodiode, and at the same time, its optical power is detected. Therefore, after that, the power value signal g in FIG. 2 is read as the optical power value signal g and the same processing is performed.

Therefore, according to this fourth embodiment, FIGS.
Similar to the figure, the optical spectrum distribution data and the optical power value are displayed on the same screen.

The application to the optical spectrum analyzer can be similarly applied to FIGS. 5 to 7 according to the embodiment of FIG.

Incidentally, 1d in FIG. 9 is a programmable optical attenuator controlled by the data processing / control section 8 '. The optical attenuator 1d suppresses an excessive input level to an appropriate level, like the variable attenuator 114 shown in FIG.

As described above, according to the present invention, since the signal under measurement is distributed to the signal processing unit and the power detection unit via the signal branching unit, along with the normal spectrum distribution data, It is possible to provide a spectrum analyzer which can easily and accurately display its power value and can be applied to a wide range including electric signals and optical signals.

That is, in the first aspect of the present invention, a certain observation frequency range of the measurement frequency range of the signal under measurement is swept and the spectrum thereof is displayed. On the other hand, the power sensor measures and displays the power in the measurement frequency range. Therefore, even if no spectrum is displayed in the sweep of a certain observation frequency range, it is possible to sweep the different frequency range by observing the level of the power display and finding that the spectrum exists in the different frequency range.

Further, in the second aspect, the accuracy of the spectrum analyzer is equal to the accuracy of the power sensor.

Further, in the third aspect, the attenuation value of the variable attenuator (ATT) 114 is varied according to the level measured by the power sensor 106, and the level input to the signal processing unit 101 is set to an appropriate level that does not saturate. You can control. Further, since the ATT 114 has no frequency characteristic, the level of each spectrum can be accurately obtained by correcting the attenuation value of the ATT 114 to the level input to the signal processing 101.

Further, in the fourth mode, one A / D converter can be shared.

[Brief description of drawings]

1 is a block diagram showing an outline of a spectrum analyzer according to the present invention, FIG. 2 is a block diagram showing a spectrum analyzer according to a first embodiment of the present invention, and FIG. 3 is a time chart showing the operation of the same embodiment. FIG. 4 is a diagram illustrating a display screen of the same embodiment, and FIGS. 5 and 6 are second and third of the present invention, respectively.
FIG. 7 is a block diagram showing a spectrum analyzer according to an embodiment, FIG. 7 is a diagram showing a concrete example of a power detector used in each embodiment, and FIG. 8 is an example of a display screen when the power detector shown in FIG. 7 is used. FIG. 9, FIG. 9 is a block diagram showing an optical spectrum analyzer according to a fourth embodiment of the present invention, FIG. 10 is a block diagram showing a conventional spectrum analyzer, and FIG. 11 is a general block diagram displayed on a display unit. It is a figure which shows spectrum distribution data. 1 ... RF section, 2 ... IF section, 3 ... Detection section, 4, 4a ... A / D conversion section,
5 ... Digital memory, 6 ... Display unit, 7,100 ... Sweep signal generating unit, 8,112 ... Data processing / control unit, 9 ... Input terminal, 1
1,105 ... Signal branch circuit (or signal switching circuit), 11a ... RF
Switch circuit (signal switching circuit), 12 ... Power detector, 12 '
... optical power sensor, 106 ... power sensor, 13 ... switching circuit, a ... measured signal, b ... sweep signal, d ... detection signal, g
… Power value signal.

Claims (4)

[Claims] 1. A measurement frequency range of a signal to be measured input from an input terminal, wherein a desired partial frequency sweep range is sequentially swept to process the signal to be measured to correspond to the swept frequency sweep range. A signal processing unit (101) for outputting a spectrum of a signal under measurement, a first A / D conversion unit (102) for converting the spectrum into first digital data, and a first A / D conversion unit for storing the first digital data. No. 1 memory (103), a signal branching or switching circuit (105) interposed between the input terminal and the signal processing unit, and the power of the signal under measurement from the signal branching or switching circuit is detected. A power sensor (106), a second A / D converter (107) for converting the output of the power sensor into second digital data, and a second memory (108) for storing the second digital data. ) And the second data A spectrum analyzer having a display unit (104) for displaying digital data together with the first digital data. 2. When a continuous wave signal whose entire spectrum falls within the pass band of the band pass of the intermediate frequency section (IF section) in the signal processing section is input to the input terminal as a calibration signal, The first digital data stored in the memory and the second digital data stored in the second memory.
Detecting means for detecting the difference from the digital data of (109)
And a third memory (110) for storing correction data which is a difference between the first digital data and the second digital data detected by the detection means, and when a signal under measurement is input to the input terminal. The spectrum analyzer according to claim 1, further comprising: a correction unit (111) that corrects the first digital data stored in the first memory based on the correction data and displays the corrected data on the display unit. 3. A variable attenuator (114) provided between the input terminal and a signal processing unit for varying an input level.
And controlling the variable attenuator to a desired value based on the second digital data, and calculating the spectrum value of the signal under measurement from the first digital data and the value of the variable attenuator. The spectrum analyzer according to claim 1, further comprising a data processing control (112). 4. The first A / D conversion unit and the second A / D conversion unit are configured by a single shared A / D conversion unit, and the first memory and the second memory are combined. Is composed of separate memory areas in one shared memory, and switching means (13) for switching between the signal from the signal processing section and the signal from the power sensor and supplying the signal to the one A / D conversion section. The spectrum analyzer according to claim 1, further comprising: a control means (8) for controlling the switching means in synchronization with a sweep period and a reset period of the sweep signal.