CN112305307A - Third-order intermodulation measurement method of spectrum analyzer and spectrum analyzer - Google Patents
Third-order intermodulation measurement method of spectrum analyzer and spectrum analyzer Download PDFInfo
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Abstract
A third order intermodulation measurement method of a spectrum analyzer and the spectrum analyzer, because the third order intermodulation measurement channel is added in the spectrum analyzer, the channel is only used for the third order intermodulation measurement, the spectrum analysis channel and the third order intermodulation measurement channel are switched by a first switch and a second switch, when the signal is subjected to the spectrum analysis, the first switch and the second switch are controlled to connect the signal input end to the input end of the spectrum analysis channel, the output end of the spectrum analysis channel is connected to an analog-to-digital conversion module for output, when the third order intermodulation measurement is carried out on the signal, the first switch and the second switch are controlled to connect the signal input end to the first input end of the third order intermodulation measurement channel, the output end of the third order intermodulation measurement channel is connected to the analog-to-digital conversion module for output, so that the signal does not need to pass through a third order frequency conversion structure of the spectrum analysis channel during the third order, the third-order intermodulation performance of the spectrum analyzer is improved.
Description
Technical Field
The invention relates to the technical field of spectrum analyzers, in particular to a third-order intermodulation measurement method of a spectrum analyzer and a spectrum analyzer.
Background
Third-order intermodulation is a parasitic signal (called third-order intermodulation product) generated by the second harmonic component of one signal and the fundamental component of the other signal caused by nonlinear effects when two signals (with frequencies of f1 and f2, respectively) pass through a nonlinear system, and the frequencies of the two signals are 2f1-f2 and 2f2-f1, respectively. Third-order intermodulation is a very important index in a communication system, and reflects the adjacent channel interference and the adjacent channel interference resistance.
The existing third-order intermodulation measurement method is basically to use a spectrum analyzer for measurement, but the spectrum analyzer is a nonlinear system, and can deteriorate the third-order intermodulation of a signal to be measured (generally, the spectrum analyzer is of a three-stage frequency conversion structure and is provided with three mixers and at least three intermediate frequency amplifiers, and the third-order intermodulation of the signal to be measured can be deteriorated after passing through one mixer or amplifier), so that the measurement of the third-order intermodulation is limited. The adjustable attenuator is arranged in the spectrum analyzer, the attenuation of the adjustable attenuator can be increased to improve the third-order intermodulation measurement range of the spectrum analyzer, but the attenuation is increased to deteriorate the noise coefficient, the noise coefficient deterioration can raise the bottom noise of the spectrum analyzer, and when the bottom noise is higher than the amplitude of the third-order intermodulation component, the third-order intermodulation can not be measured.
Disclosure of Invention
The invention mainly solves the technical problem of improving the measurement performance of the third-order intermodulation of the spectrum analyzer.
According to a first aspect, there is provided in an embodiment a spectrum analyser comprising:
the frequency spectrum analysis channel is used for carrying out three-stage frequency conversion on the frequency of the signal received by the signal input end of the frequency spectrum analyzer to obtain a third intermediate frequency signal;
a third order intermodulation measurement channel for measuring a third order intermodulation product of a signal received at the signal input, the third order intermodulation measurement channel comprising a first input;
a first switch, a first end of which is connected to the signal input, a second end of which switches between the input of the spectral analysis channel and the first input of the third order intermodulation measurement channel;
a first end of the second selector switch is switched between the output end of the spectrum analysis channel and the output end of the third-order intermodulation measurement channel, and a second end of the second selector switch is connected with the input end of the analog-to-digital conversion module;
and the analog-to-digital conversion module is used for performing analog-to-digital conversion on the signal received by the input end of the analog-to-digital conversion module and outputting a digital signal for display.
According to a second aspect, an embodiment provides a third order intermodulation measurement method of a spectrum analyzer, the spectrum analyzer comprising a spectrum analysis channel and a third order intermodulation measurement channel, the method comprising:
determining a local oscillator frequency required by a first mixer during third-order intermodulation measurement to obtain a first local oscillator frequency;
controlling a spectrum analyzer to be switched to a spectrum analysis channel, and acquiring the power of two signals to be detected received by a signal input end of the spectrum analyzer;
acquiring the power of a signal corresponding to the signal frequency received by the signal input end of the spectrum analyzer when the signal frequency is respectively a first preset frequency, a second preset frequency, a third preset frequency and a fourth preset frequency, and acquiring a first power, a second power, a third power and a fourth power of an interference signal;
judging whether the first power, the second power, the third power and the fourth power of the interference signal meet preset conditions or not; if the preset condition is met, configuring a first local oscillation frequency to a first mixer, and controlling the spectrum analyzer to be switched to a third-order intermodulation measurement channel so as to measure a third-order intermodulation component; if the preset condition is not met, correcting the first local oscillation frequency according to a preset rule until the first power, the second power, the third power and the fourth power of the interference signal meet the preset condition, taking the corrected first local oscillation frequency as the second local oscillation frequency, configuring the second local oscillation frequency to a first mixer, and controlling the spectrum analyzer to be switched to a third-order intermodulation measurement channel so as to measure third-order intermodulation components;
the preset conditions are that B1 is not less than A1-10, B2 is not less than A2-10, and B3 and B4 are not more than a preset threshold value; b1 is the first power of the interference signal, B2 is the second power of the interference signal, B3 is the third power of the interference signal, B4 is the fourth power of the interference signal, A1 is the power of one signal to be measured received by the signal input end of the spectrum analyzer, and A2 is the power of another signal to be measured received by the signal input end of the spectrum analyzer, and the unit is dBm.
According to the third order intermodulation measurement method of a spectrum analyzer and the spectrum analyzer of the above embodiment, since the third order intermodulation measurement channel is added in the spectrum analyzer, the channel is only used for the third order intermodulation measurement, the spectrum analysis channel and the third order intermodulation measurement channel are switched by the first switch and the second switch, when the spectrum analyzer is used for spectrum analysis of signals, the first switch and the second switch are controlled to connect the signal input end to the input end of the spectrum analysis channel, the output end of the spectrum analysis channel is connected to the analog-to-digital conversion module for output, when the spectrum analyzer is used for the third order intermodulation measurement of signals, the first switch and the second switch are controlled to connect the signal input end to the first input end of the third order intermodulation measurement channel, and the output end of the third order intermodulation measurement channel is connected to the analog-to-digital conversion module for output, the signal does not need to pass through a three-level frequency conversion structure of the frequency spectrum analysis channel during three-level intermodulation measurement, the three-level intermodulation of the signal is not deteriorated, and the measurement performance of the three-level intermodulation of the frequency spectrum analyzer is improved.
Drawings
FIG. 1 is a schematic diagram of a conventional spectrum analyzer;
FIG. 2 is a schematic diagram of an exemplary spectrum analyzer;
FIG. 3 is a flowchart of a third order intermodulation measurement method of a spectrum analyzer according to an embodiment;
fig. 4 is a flowchart of a third order intermodulation measurement method of a spectrum analyzer according to another embodiment.
Detailed Description
The present invention will be described in further detail with reference to the following detailed description and accompanying drawings. Wherein like elements in different embodiments are numbered with like associated elements. In the following description, numerous details are set forth in order to provide a better understanding of the present application. However, those skilled in the art will readily recognize that some of the features may be omitted or replaced with other elements, materials, methods in different instances. In some instances, certain operations related to the present application have not been shown or described in detail in order to avoid obscuring the core of the present application from excessive description, and it is not necessary for those skilled in the art to describe these operations in detail, so that they may be fully understood from the description in the specification and the general knowledge in the art.
Furthermore, the features, operations, or characteristics described in the specification may be combined in any suitable manner to form various embodiments. Also, the various steps or actions in the method descriptions may be transposed or transposed in order, as will be apparent to one of ordinary skill in the art. Thus, the various sequences in the specification and drawings are for the purpose of describing certain embodiments only and are not intended to imply a required sequence unless otherwise indicated where such sequence must be followed.
The numbering of the components as such, e.g., "first", "second", etc., is used herein only to distinguish the objects as described, and does not have any sequential or technical meaning. The term "connected" and "coupled" when used in this application, unless otherwise indicated, includes both direct and indirect connections (couplings).
Referring to fig. 1, fig. 1 is a schematic structural diagram of a conventional spectrum analyzer, which includes a signal input terminal 101, a variable attenuator 102, a first low-pass filter 103, a first frequency conversion module 104, a second frequency conversion module 105, a third frequency conversion module 106, and an analog-to-digital conversion module 107. The first frequency conversion module 104, the second frequency conversion module 105, and the third frequency conversion module 106 have the same structure, and the first frequency conversion module 104 is exemplified, and the first frequency conversion module 104 includes a first local oscillator 1041, a first mixer 1042, a first amplifier 1043, and a first bandpass filter 1044. The signal received by the signal input terminal 101 is attenuated by the variable attenuator 102 and the first low pass filter 103, and then is subjected to three-time frequency conversion by the first frequency conversion module 104, the second frequency conversion module 105 and the third frequency conversion module 106 in sequence to obtain a frequency-converted intermediate frequency signal, and the frequency-converted intermediate frequency signal is converted into a digital intermediate frequency signal by the analog-to-digital conversion module 107 and displayed by the display module.
The first frequency conversion module 104 mixes the frequency of the signal received by the signal input end 101 into a first intermediate frequency, and outputs a local oscillation signal with a local oscillation frequency to the first frequency mixer 1042 through the first local oscillation 1041, the first frequency mixer 1042 mixes the frequency of the signal received by the signal input end 101 with the frequency of the local oscillation signal to obtain an intermediate frequency signal with the first intermediate frequency, and the intermediate frequency signal with the first intermediate frequency is amplified and filtered by the first amplifier 1043 and the first band pass filter 1044 to obtain the first intermediate frequency signal. In this embodiment, the working principle of the second frequency conversion module 105, the third frequency conversion module 106 and the first frequency conversion module 104 are the same, and are not described herein again.
To sum up, the existing spectrum analyzer has a three-level frequency conversion structure composed of the first frequency conversion module 104, the second frequency conversion module 105 and the third frequency conversion module 106, and if the received signal is subjected to three-level intermodulation measurement by the spectrum analyzer, the three-level frequency conversion structure can deteriorate the three-level intermodulation of the signal, which affects the performance of the spectrum analyzer in the three-level intermodulation measurement.
The embodiment of the invention provides a spectrum analyzer, which is additionally provided with a third-order intermodulation measurement channel on the basis of the existing spectrum analysis channel, wherein the third-order intermodulation measurement channel does not have a frequency conversion structure, only has a first-order amplifier and has small influence on third-order intermodulation measurement, and the channel of the spectrum analyzer and the third-order intermodulation measurement channel are switched by a first switch and a second switch, so that the spectrum analyzer has the original spectrum analysis function and improves the third-order intermodulation performance of the spectrum analyzer.
Referring to fig. 2, fig. 2 is a schematic structural diagram of a spectrum analyzer according to an embodiment, the spectrum analyzer includes a signal input terminal 201, a variable attenuator 202, a first low pass filter 203, a first switch 204, a spectrum analysis channel 205, a third order intermodulation measurement channel 206, a second switch 207, and an analog-to-digital conversion module 208.
The signal input terminal 201 is used for receiving an externally input signal.
The variable attenuator 202 is used to attenuate the signal received at the signal input by an amount of attenuation.
The first low pass filter 203 is used to low pass filter the signal received at the signal input.
The spectrum analysis channel 205 is configured to perform three-stage frequency conversion on the frequency of the signal received by the signal input terminal 201 to obtain a third intermediate frequency signal.
The spectrum analysis channel 205 includes a first frequency conversion module, a second frequency conversion module, and a third frequency conversion module. The first frequency conversion module is used for converting the frequency of the received signal into a first intermediate frequency to obtain a first intermediate frequency signal, the second frequency conversion module is used for converting the frequency of the first intermediate frequency signal into a second intermediate frequency to obtain a second intermediate frequency signal, and the third frequency conversion module is used for converting the frequency of the second intermediate frequency signal into a third intermediate frequency to obtain a third intermediate frequency signal.
In this embodiment, the first frequency conversion module includes a first local oscillator 213, a first mixer 214, a first amplifier 215, a first band-pass filter 216, and a frequency divider 221, where the first local oscillator 213 is configured to generate a first local oscillator signal, the first mixer 214 is configured to mix a frequency of a received signal with a frequency of the first local oscillator signal to output a signal having a first intermediate frequency, the first amplifier 215 is configured to amplify a signal output by the first mixer, the first band-pass filter 216 is configured to filter the signal output by the first amplifier and output the first intermediate frequency signal, and the frequency divider 221 is configured to divide the frequency of the first local oscillator signal and output a divided frequency signal of the first local oscillator signal when the frequency of the first local oscillator signal is greater than the local oscillator frequency required by the first mixer.
In this embodiment, the second frequency conversion module and the third frequency conversion module have the same structure, and this embodiment is described by taking the second frequency conversion module as an example, where the second frequency conversion module includes a second local oscillator 217, a second mixer 218, a second amplifier 219 and a second band-pass filter 220, the second local oscillator 217 is configured to output a second local oscillator signal, the second mixer 218 is configured to mix the second local oscillator signal with the first intermediate frequency signal to obtain a signal having a second intermediate frequency, and the second amplifier 219 and the second band-pass filter 220 are configured to amplify and filter the signal having the second intermediate frequency, and output the second intermediate frequency signal.
The third order intermodulation measurement channel 206 is used to measure the third order intermodulation products of the signal received at the signal input 201.
The third-order intermodulation measurement channel in this embodiment has two input ends, which are the first input end and the second input end respectively.
The third order intermodulation measurement channel 206 comprises a fourth switch 210, a fourth amplifier 222, and a second low pass filter 223; a first end of the fourth switch 210 is switched between a first input end and a second input end of the third-order intermodulation measurement channel 206, a second end of the fourth switch 210 is connected to an input end of a fourth amplifier 222, an input end of the fourth amplifier 222 is connected to an input end of a second low-pass filter 223, and an output end of the second low-pass filter 223 is an output end of the third-order intermodulation measurement channel 206.
The fourth amplifier 222 is configured to amplify a signal received at an input end of the third-order intermodulation measurement channel; the second low-pass filter 223 is used for low-pass filtering the signal output by the fourth amplifier, and the second low-pass filter in this embodiment is an existing anti-aliasing low-pass filter.
A first end of the first switch 204 is connected to the signal input end 201 through the variable attenuator 202 and the first low pass filter 203, a second end of the first switch 204 is switched between the input end of the spectrum analysis channel 205 and the first input end of the third order intermodulation measurement channel 206, and when a signal received at the signal input end needs to be subjected to spectrum analysis, the second end of the first switch 204 is switched to the input end of the spectrum analysis channel 205, so that the signal input end 201 is connected to the input end of the spectrum analysis channel 205 through the variable attenuator 202 and the first low pass filter 203, in other words, the signal received at the signal input end 201 is subjected to three-stage frequency conversion through the spectrum analysis channel 205 to obtain the spectrum characteristics of the signal. When the third-order intermodulation measurement needs to be performed on the signal received by the signal input terminal, the second terminal of the first switch 204 is switched to the first input terminal of the third-order intermodulation measurement channel 206, so that the signal input terminal 201 is connected to the first input terminal of the third-order intermodulation measurement channel 206 through the variable attenuator 202 and the first low-pass filter 203, in other words, the signal received by the signal input terminal 201 is subjected to the measurement of the third-order intermodulation component of the signal through the third-order intermodulation measurement channel 206.
A first end of a third switch 209 is connected to the output end of the first mixer, a second end of the third switch is switched between the input end of the first amplifier and the second input end of the third order intermodulation measurement channel, and the third switch 209 is configured to switch the second end of the third switch 209 to the input end of the first amplifier when a signal needs to be subjected to spectrum analysis, so that the output end of the first mixer is connected to the input end of the first amplifier. When a third order intermodulation measurement of signals is required, the second terminal of the third switch 209 is switched to the second input terminal of the third order intermodulation measurement channel 206, so that the output terminal of the first mixer is connected to the second input terminal of the third order intermodulation measurement channel 206.
A first end of the second switch 207 switches between an output end of the spectrum analysis channel 205 and an output end of the third-order intermodulation measurement channel 206, a second end of the second switch 207 is connected to an input end of the analog-to-digital conversion module 208, and the second switch 207 is configured to switch the first end of the second switch 207 to the output end of the spectrum analysis channel 205 when a signal received by the signal input end needs to be subjected to spectrum analysis, so that the output end of the spectrum analysis channel 205 is connected to the input end of the analog-to-digital conversion module 208, in other words, after an intermediate frequency signal output by the spectrum analysis channel 205 is converted into a digital intermediate frequency signal by the analog-to-digital conversion module 208, a spectrum characteristic of the signal is displayed. When the third-order intermodulation measurement needs to be performed on the signal received by the signal input terminal, the first terminal of the second switch 207 is switched to the output terminal of the third-order intermodulation measurement channel 206, so that the output terminal of the third-order intermodulation measurement channel 206 is connected to the input terminal of the analog-to-digital conversion module 208, in other words, the third-order intermodulation component of the measured signal is displayed after the signal output by the third-order intermodulation measurement channel 206 is converted into a digital signal by the analog-to-digital conversion module 208.
The present embodiment further includes a fifth switch 212 and a sixth switch 211, a first end of the fifth switch 212 is connected to the output end of the first local oscillator 213, and a second end of the fifth switch 212 switches between the first end of the sixth switch 211 and the input end of the frequency divider; a first terminal of the sixth switch 211 is switched between the output terminal of the frequency divider 221 and a second terminal of the fifth switch 212, and the second terminal of the sixth switch 211 is connected to the first mixer 214.
The analog-to-digital conversion module 206 is configured to perform analog-to-digital conversion on the signal received by the input end thereof, and output a digital signal for display.
The embodiment further includes a processor, configured to determine a local oscillation frequency required by the first mixer during third-order intermodulation measurement, and obtain the first local oscillation frequency.
In this embodiment, determining a local oscillation frequency required by the first mixer during third-order intermodulation measurement to obtain a first local oscillation frequency includes: controlling a spectrum analyzer to be switched to a spectrum analysis channel, and respectively acquiring the power (A1 and A2, the unit is dBm) and the frequency (f1 and f2, wherein f1 is less than f2) of two signals to be measured received by a signal input end; determining the center frequencies f0= (f1+ f2)/2 of the two signals to be tested based on the frequencies (f1 and f2) of the two signals to be tested; based on the central frequency f0, determining a local oscillation frequency flo = f0+0.375 × fc/2 required by the first mixer when measuring third-order intermodulation, and obtaining a first local oscillation frequency flo, wherein fc is a sampling frequency of the analog-to-digital conversion module. The two signals to be measured in this embodiment are to-be-measured diphone signals.
The processor is further configured to control the spectrum analyzer to switch to a spectrum analysis channel, and obtain corresponding signal powers when the frequencies of the signals received by the spectrum analyzer are a first preset frequency (2 flo-f 1), a second preset frequency (2 flo-f 2), a third preset frequency (2 flo- (2 f1-f 2)) and a fourth preset frequency (2 flo- (2 f2-f 1)), so as to obtain a first power B1, a second power B2, a third power B3 and a fourth power B4 (unit is dBm) of the interference signals. It should be noted that, at this time, the signal input to the spectrum analyzer is a signal of a first preset frequency, a second preset frequency, a third preset frequency and a fourth preset frequency, which are obtained by respectively calculating the frequencies of the two signals to be measured according to different relations, that is, the frequencies of the signal (the first preset frequency, the second preset frequency, the third preset frequency and the fourth preset frequency) have a certain relation with the frequencies of the two signals to be measured.
Judging whether the first power B1, the second power B2, the third power B3 and the fourth power B4 of the interference signal meet preset conditions or not; if the preset conditions that B1 is not less than A1-10, B2 is not less than A2-10 and B3 and B4 are not more than the preset threshold values are met, configuring a first local oscillation frequency flo to a first mixer, and controlling a spectrum analyzer to be switched to a third-order intermodulation measurement channel so as to measure third-order intermodulation products; if the first power B1 and the second power B2 do not satisfy the relational expression or B3 and B4 are larger than a preset threshold value, the first local oscillation frequency is corrected according to a preset rule until the first power B1, the second power B2, the third power B3 and the fourth power B4 of the interference signal satisfy the preset condition, the corrected first local oscillation frequency is obtained, the corrected first local oscillation frequency is configured as the second local oscillation frequency and is configured to the first frequency conversion module, the spectrum analyzer is controlled to be switched to a third-order intermodulation measurement channel, and third-order intermodulation components are measured.
In an embodiment, the modifying the first local oscillation frequency according to a preset rule until the first power B1, the second power B2, the third power B3, and the fourth power B4 of the interference signal satisfy the preset condition to obtain a modified first local oscillation frequency includes:
the initial value of the first local oscillation frequency is flo = f0+0.375 × fc/2;
the first local oscillation frequency flo = f0+0.475 × fc/2 after the first correction, based on the first local oscillation frequency after the first correction, whether the first power, the second power, the third power and the fourth power of the interference signal at the time meet preset conditions is judged, and if the preset conditions are met, the first local oscillation frequency after the first correction is configured to the first frequency conversion module;
and if the first local oscillation frequency does not meet the preset condition, performing secondary correction on the first local oscillation frequency, wherein the first local oscillation frequency after secondary correction flo = f0+0.275 × fc/2, judging whether the first power, the second power, the third power and the fourth power of the interference signal at the moment meet the preset condition or not based on the first local oscillation frequency after secondary correction, and if the first local oscillation frequency after secondary correction meets the preset condition, configuring the first local oscillation frequency after secondary correction to the first frequency conversion module.
And if the first local oscillation frequency after the third correction is not satisfied with the preset condition, performing third correction on the first local oscillation frequency, wherein the first local oscillation frequency after the third correction is flo = f0+0.575 fc/2, judging whether the first power, the second power, the third power and the fourth power of the interference signal at the moment satisfy the preset condition or not based on the first local oscillation frequency after the third correction, and if the first local oscillation frequency after the third correction is satisfied with the preset condition, configuring the first local oscillation frequency after the third correction to the first frequency conversion module.
And if the preset condition is not met, performing four times of correction on the first local oscillation frequency, wherein the four times of corrected first local oscillation frequency flo = f0+0.175 fc/2, judging whether the first power, the second power, the third power and the fourth power of the interference signal at the moment meet the preset condition or not based on the four times of corrected first local oscillation frequency, and if the preset condition is met, configuring the four times of corrected first local oscillation frequency to the first frequency conversion module.
And if the preset condition is not met, performing five times of correction on the first local oscillation frequency, wherein the five times of corrected first local oscillation frequency flo = f0+0.675 fc/2, judging whether the first power, the second power, the third power and the fourth power of the interference signal at the moment meet the preset condition or not based on the five times of corrected first local oscillation frequency, and if the preset condition is met, configuring the five times of corrected first local oscillation frequency to the first frequency conversion module.
In this embodiment, the first local oscillator is implemented by a phase-locked loop, and the first local oscillator may be configured to continuously correct the first local oscillator frequency.
It should be noted that, in this embodiment, the first local oscillation frequency may be modified according to the preset rule, and may also be modified according to other preset rules, so that the first power, the second power, the third power, and the fourth power of the interference signal meet the preset condition.
The size of the preset threshold in this embodiment is set by a user, and the lower the value of the preset threshold is, the larger the interference-free dynamic range of the third-order intermodulation measurement is.
In this embodiment, when the first power, the second power, the third power, and the fourth power of the interference signal are measured to satisfy the preset condition, the spectrum analyzer switches to the third-order intermodulation measurement channel, and selects the switching states of the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch according to the frequencies of the two signals to be measured by the spectrum analysis channel, where the selection mode is as follows:
when 2f2-f1<0.75 × fc/2, the second end of the first switch is switched to the first input end of the third-order intermodulation measurement channel, the first end of the fourth switch is also switched to the first input end of the third-order intermodulation measurement channel, at this time, the signal input port of the third-order intermodulation measurement channel is located before the first mixer, and the second end of the second switch is switched to the output end of the third-order intermodulation measurement channel, that is, the input channel of the analog-to-digital conversion module is selected as the third-order intermodulation measurement channel. At the moment, the two signals to be detected are directly sampled and output by the analog-to-digital conversion module without passing through a three-level frequency conversion structure.
When 2f2-f1 is greater than or equal to 0.75 × fc/2, the second end of the first switch is switched to the input end of the spectrum analysis channel, the first end of the fourth switch is switched to the second input end of the third-order intermodulation measurement channel, at this time, the signal input port of the third-order intermodulation measurement channel is located behind the first mixer, and the second end of the second switch is switched to the output end of the third-order intermodulation measurement channel, that is, the input channel of the analog-to-digital conversion module is selected as the third-order intermodulation measurement channel. At the moment, the two signals to be measured are sampled and output by the analog-to-digital conversion module after being subjected to frequency mixing once.
Finally, the analog-to-digital conversion module samples the power of the two signals to be detected to be A3 and a4 and the power of the third-order intermodulation product to be a5 and a6, and obtains the gain difference of the channel to be a = (a1+ a2)/2- (A3+ a4)/2, so that the actual power of the third-order intermodulation product is a + a5 and a + a 6. And finally, displaying the power A1 and the power A2 of the two signals to be tested and the power A + A5 and the power A + A6 of the third-order intermodulation products on a display screen.
Referring to fig. 3, fig. 3 is a flowchart illustrating a third order intermodulation measurement method of a spectrum analyzer according to an embodiment, wherein the method includes steps 301 to 305, which are described in detail below.
And 306, if the preset condition is not met, correcting the first local oscillation frequency according to a preset rule until the first power, the second power, the third power and the fourth power of the interference signal meet the preset condition, taking the corrected first local oscillation frequency as the second local oscillation frequency, configuring the second local oscillation frequency to the first frequency mixer, and controlling the frequency spectrum analyzer to be switched to a third-order intermodulation measurement channel so as to measure the third-order intermodulation component.
The preset conditions are that B1 is not less than A1-10, B2 is not less than A2-10, and B3 and B4 are not more than a preset threshold value; b1 is the first power of the interference signal, B2 is the second power of the interference signal, B3 is the third power of the interference signal, B4 is the fourth power of the interference signal, A1 is the power of one signal to be measured received by the signal input end of the spectrum analyzer, and A2 is the power of another signal to be measured received by the signal input end of the spectrum analyzer, and the unit is dBm.
In an embodiment, the determining a local oscillation frequency required by the first mixer during the third-order intermodulation measurement in step 301 to obtain the first local oscillation frequency includes:
controlling the spectrum analyzer to switch to a spectrum analysis channel, and respectively acquiring the power and the frequency of two signals to be detected received by a signal input end;
determining the central frequencies of the two signals to be measured based on the frequencies of the two signals to be measured;
and determining the local oscillation frequency required by the first frequency mixer during the third-order intermodulation based on the central frequency to obtain the first local oscillation frequency.
Referring to fig. 4, fig. 4 is a flowchart of a third order intermodulation measurement method of a spectrum analyzer according to another embodiment, where the third order intermodulation measurement method includes:
And 406, controlling the spectrum analyzer to switch to a third-order intermodulation measurement channel and enter a third-order intermodulation measurement mode.
In step 408, when 2f2-f1<0.75 × fc/2, the second terminal of the first switch is switched to the first input terminal of the third order intermodulation measurement channel, and the first terminal of the fourth switch is also switched to the first input terminal of the third order intermodulation measurement channel.
In step 409, when 2f2-f1 is greater than or equal to 0.75 × fc/2, the second end of the first switch is switched to the input end of the spectrum analysis channel, and the first end of the fourth switch is switched to the second input end of the third-order intermodulation measurement channel.
And step 410, sampling the signals output by the third-order intermodulation measurement channel through the analog-to-digital conversion module, and measuring to obtain the power of the two signals to be measured, namely A3 and A4, and the power of the third-order intermodulation component, namely A5 and A6.
At step 412, the actual magnitudes of the third order intermodulation products are determined to be a + a5 and a + a 6.
And 413, displaying the power A1 and the power A2 of the two signals to be detected and the power A + A5 and the power A + A6 of the third-order intermodulation products on a display screen.
Those skilled in the art will appreciate that all or part of the functions of the various methods in the above embodiments may be implemented by hardware, or may be implemented by computer programs. When all or part of the functions of the above embodiments are implemented by a computer program, the program may be stored in a computer-readable storage medium, and the storage medium may include: a read only memory, a random access memory, a magnetic disk, an optical disk, a hard disk, etc., and the program is executed by a computer to realize the above functions. For example, the program may be stored in a memory of the device, and when the program in the memory is executed by the processor, all or part of the functions described above may be implemented. In addition, when all or part of the functions in the above embodiments are implemented by a computer program, the program may be stored in a storage medium such as a server, another computer, a magnetic disk, an optical disk, a flash disk, or a removable hard disk, and may be downloaded or copied to a memory of a local device, or may be version-updated in a system of the local device, and when the program in the memory is executed by a processor, all or part of the functions in the above embodiments may be implemented.
The present invention has been described in terms of specific examples, which are provided to aid understanding of the invention and are not intended to be limiting. For a person skilled in the art to which the invention pertains, several simple deductions, modifications or substitutions may be made according to the idea of the invention.
Claims (10)
1. A spectrum analyzer, comprising:
the frequency spectrum analysis channel is used for carrying out three-stage frequency conversion on the frequency of the signal received by the signal input end of the frequency spectrum analyzer to obtain a third intermediate frequency signal;
a third order intermodulation measurement channel for measuring a third order intermodulation product of a signal received at the signal input, the third order intermodulation measurement channel comprising a first input;
a first switch, a first end of which is connected to the signal input, a second end of which switches between the input of the spectral analysis channel and the first input of the third order intermodulation measurement channel;
a first end of the second selector switch is switched between the output end of the spectrum analysis channel and the output end of the third-order intermodulation measurement channel, and a second end of the second selector switch is connected with the input end of the analog-to-digital conversion module;
and the analog-to-digital conversion module is used for performing analog-to-digital conversion on the signal received by the input end of the analog-to-digital conversion module and outputting a digital signal for display.
2. The spectrum analyzer of claim 1, wherein the spectrum analysis channel comprises:
the first frequency conversion module is used for converting the frequency of the signal received by the signal input end into a first intermediate frequency and outputting a first intermediate frequency signal; the first frequency conversion module comprises a first local oscillator, a first frequency mixer, a first amplifier and a first band-pass filter, wherein the first local oscillator is used for generating a first local oscillator signal, and the first frequency mixer is used for mixing the frequency of a received signal with the frequency of the first local oscillator signal and outputting a signal with a first intermediate frequency; the first amplifier is used for amplifying the signal output by the first mixer; the first band-pass filter is used for filtering a signal output by the first amplifier;
the second frequency conversion module is used for converting the frequency of the first intermediate frequency signal into a second intermediate frequency and outputting a second intermediate frequency signal;
and the third frequency conversion module is used for converting the frequency of the third intermediate frequency signal into a third intermediate frequency and outputting the third intermediate frequency signal.
3. The spectrum analyzer of claim 2, further comprising a third switch;
the third order intermodulation measurement channel also comprises a second input end
The first end of the third switch is connected with the output end of the first mixer, and the second end of the third switch is switched between the input end of the first amplifier and the second input end of the third-order intermodulation measurement channel.
4. The spectrum analyzer of claim 3, wherein the third order intermodulation measurement channel comprises a fourth switch, a fourth amplifier, and a second low pass filter;
the first end of the fourth switch is switched between the second end of the first switch and the second end of the third switch, and the second end of the fourth switch is connected with the input end of the fourth amplifier;
the fourth amplifier is used for amplifying signals received by the third-order intermodulation measurement channel;
the second low-pass filter is used for low-pass filtering the signal output by the fourth amplifier.
5. The spectrum analyzer of claim 2, further comprising a frequency divider configured to divide the frequency of the first local oscillator signal to output a divided signal of the first local oscillator when the frequency of the first local oscillator signal is greater than a desired local oscillator frequency of the first mixer.
6. The spectrum analyzer of claim 5, further comprising a fifth switch and a sixth switch;
the first end of the fifth change-over switch is connected with the output end of the first local oscillator, and the second end of the fifth change-over switch is switched between the first end of the sixth change-over switch and the input end of the frequency divider;
and the first end of the sixth change-over switch is switched between the output end of the frequency divider and the second end of the fifth change-over switch, and the second end of the sixth change-over switch is connected with the first mixer.
7. The spectrum analyzer of claim 2, further comprising:
the processor is used for determining the local oscillation frequency required by the first frequency mixer during the third-order intermodulation measurement to obtain a first local oscillation frequency;
the processor is also used for controlling the spectrum analyzer to be switched to a spectrum analysis channel, and acquiring the power of two signals to be detected received by the signal input end of the spectrum analyzer;
acquiring the power of a signal corresponding to the signal frequency received by the signal input end of the spectrum analyzer when the signal frequency is respectively a first preset frequency, a second preset frequency, a third preset frequency and a fourth preset frequency, and acquiring a first power, a second power, a third power and a fourth power of an interference signal;
judging whether the first power, the second power, the third power and the fourth power of the interference signal meet preset conditions or not; if the preset condition is met, configuring a first local oscillation frequency to a first mixer, and controlling the spectrum analyzer to be switched to a third-order intermodulation measurement channel so as to measure a third-order intermodulation component; if the preset condition is not met, correcting the first local oscillation frequency according to a preset rule until the first power, the second power, the third power and the fourth power of the interference signal meet the preset condition, taking the corrected first local oscillation frequency as the second local oscillation frequency, configuring the second local oscillation frequency to a first mixer, and controlling the spectrum analyzer to be switched to a third-order intermodulation measurement channel so as to measure third-order intermodulation components;
the preset conditions are that B1 is not less than A1-10, B2 is not less than A2-10, and B3 and B4 are not more than a preset threshold value; b1 is the first power of the interference signal, B2 is the second power of the interference signal, B3 is the third power of the interference signal, B4 is the fourth power of the interference signal, A1 is the power of one signal to be measured received by the signal input end of the spectrum analyzer, and A2 is the power of another signal to be measured received by the signal input end of the spectrum analyzer, and the unit is dBm.
8. The spectrum analyzer of claim 7, wherein determining the local frequency required by the first mixer for the third order intermodulation measurement to obtain the first local frequency comprises:
controlling the spectrum analyzer to switch to a spectrum analysis channel, and respectively acquiring the frequencies of two signals to be detected received by a signal input end;
determining the central frequencies of the two signals to be measured based on the frequencies of the two signals to be measured;
and determining the local oscillation frequency required by the first frequency mixer when measuring the third-order intermodulation based on the central frequency to obtain the first local oscillation frequency.
9. A method of third order intermodulation measurement in a spectrum analyzer, the spectrum analyzer comprising a spectrum analysis channel and a third order intermodulation measurement channel, the method comprising:
determining a local oscillator frequency required by a first mixer during third-order intermodulation measurement to obtain a first local oscillator frequency;
controlling a spectrum analyzer to be switched to a spectrum analysis channel, and acquiring the power of two signals to be detected received by a signal input end of the spectrum analyzer;
acquiring the power of a signal corresponding to the signal frequency received by the signal input end of the spectrum analyzer when the signal frequency is respectively a first preset frequency, a second preset frequency, a third preset frequency and a fourth preset frequency, and acquiring a first power, a second power, a third power and a fourth power of an interference signal;
judging whether the first power, the second power, the third power and the fourth power of the interference signal meet preset conditions or not; if the preset condition is met, configuring a first local oscillation frequency to a first mixer, and controlling the spectrum analyzer to be switched to a third-order intermodulation measurement channel so as to measure a third-order intermodulation component; if the preset condition is not met, correcting the first local oscillation frequency according to a preset rule until the first power, the second power, the third power and the fourth power of the interference signal meet the preset condition, taking the corrected first local oscillation frequency as the second local oscillation frequency, configuring the second local oscillation frequency to a first mixer, and controlling the spectrum analyzer to be switched to a third-order intermodulation measurement channel so as to measure third-order intermodulation components;
the preset conditions are that B1 is not less than A1-10, B2 is not less than A2-10, and B3 and B4 are not more than a preset threshold value; b1 is the first power of the interference signal, B2 is the second power of the interference signal, B3 is the third power of the interference signal, B4 is the fourth power of the interference signal, A1 is the power of one signal to be measured received by the signal input end of the spectrum analyzer, and A2 is the power of another signal to be measured received by the signal input end of the spectrum analyzer, and the unit is dBm.
10. The method of claim 9, wherein determining the local frequency required by the first mixer for the third order intermodulation measurement to obtain the first local frequency comprises:
controlling the spectrum analyzer to switch to a spectrum analysis channel, and respectively acquiring the frequencies of two signals to be detected received by a signal input end;
determining the central frequencies of the two signals to be measured based on the frequencies of the two signals to be measured;
and determining the local oscillation frequency required by the first frequency mixer when measuring the third-order intermodulation based on the central frequency to obtain the first local oscillation frequency.
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Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101478353A (en) * | 2009-01-20 | 2009-07-08 | 信息产业部通信计量中心 | Radio frequency unit capable of being used in wireless communication base station radio frequency automatic test |
| US20100156438A1 (en) * | 2008-12-19 | 2010-06-24 | Gorin Joseph M | Spectrum analyzers with dynamic range indicator and methods of use |
| CN202818313U (en) * | 2012-09-07 | 2013-03-20 | 苏州市大富通信技术有限公司 | Detection system for intermodulation signal |
| US8706434B1 (en) * | 2013-09-12 | 2014-04-22 | King Fahd University Of Petroleum And Minerals | Nonlinear systems measurement system and method |
| US20150177296A1 (en) * | 2010-02-12 | 2015-06-25 | Test Equipment Plus, Inc. | Spectrum analyzer using multiple intermediate frequencies and multiple clock configurations for residual, spurious and image signal reduction |
| CN105323015A (en) * | 2014-06-18 | 2016-02-10 | 中国移动通信集团公司 | Device for realizing passive device testing |
| CN105577294A (en) * | 2014-10-13 | 2016-05-11 | 罗森伯格技术（昆山）有限公司 | Multifunctional handheld passive intermodulation analyzer |
| CN108833029A (en) * | 2018-05-30 | 2018-11-16 | 中国电力科学研究院有限公司 | A kind of 1800M RF consistency transmitting intermodulation testing method and device |
| CN110568283A (en) * | 2019-08-12 | 2019-12-13 | 中电科仪器仪表有限公司 | Active device intermodulation test device and test method |
| CN110672920A (en) * | 2019-12-06 | 2020-01-10 | 深圳市鼎阳科技股份有限公司 | Spectrum analyzer with temperature compensation function |
-
2020
- 2020-12-21 CN CN202011513248.XA patent/CN112305307B/en active Active
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100156438A1 (en) * | 2008-12-19 | 2010-06-24 | Gorin Joseph M | Spectrum analyzers with dynamic range indicator and methods of use |
| CN101478353A (en) * | 2009-01-20 | 2009-07-08 | 信息产业部通信计量中心 | Radio frequency unit capable of being used in wireless communication base station radio frequency automatic test |
| US20150177296A1 (en) * | 2010-02-12 | 2015-06-25 | Test Equipment Plus, Inc. | Spectrum analyzer using multiple intermediate frequencies and multiple clock configurations for residual, spurious and image signal reduction |
| CN202818313U (en) * | 2012-09-07 | 2013-03-20 | 苏州市大富通信技术有限公司 | Detection system for intermodulation signal |
| US8706434B1 (en) * | 2013-09-12 | 2014-04-22 | King Fahd University Of Petroleum And Minerals | Nonlinear systems measurement system and method |
| CN105323015A (en) * | 2014-06-18 | 2016-02-10 | 中国移动通信集团公司 | Device for realizing passive device testing |
| CN105577294A (en) * | 2014-10-13 | 2016-05-11 | 罗森伯格技术（昆山）有限公司 | Multifunctional handheld passive intermodulation analyzer |
| CN108833029A (en) * | 2018-05-30 | 2018-11-16 | 中国电力科学研究院有限公司 | A kind of 1800M RF consistency transmitting intermodulation testing method and device |
| CN110568283A (en) * | 2019-08-12 | 2019-12-13 | 中电科仪器仪表有限公司 | Active device intermodulation test device and test method |
| CN110672920A (en) * | 2019-12-06 | 2020-01-10 | 深圳市鼎阳科技股份有限公司 | Spectrum analyzer with temperature compensation function |
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| Publication number | Publication date |
|---|---|
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