Signal monitoring method and device based on frequency shift technology

Abstract

The invention provides a signal monitoring method and device based on a frequency shift technology. The method comprises the following steps: receiving a to-be-measured frequency band signal; determining a target frequency band and a target local oscillator signal to control an interference index of a frequency mixing signal of the interference frequency band signal and the target local oscillator signal on the target frequency band; performing frequency mixing on the target local oscillator signal and the radio frequency signal to be measured, and outputting a frequency shift signal in a target frequency band; and monitoring the frequency shift signal. By means of the method, full-band accurate monitoring can be achieved with low cost and low frequency interference.

Description

Technical Field

[0001] The invention belongs to the field of signal processing, and in particular relates to a signal monitoring method and device based on frequency shift technology. Background Art

[0002] This section is intended to provide a background or context to embodiments of the invention that are recited in the claims. No description herein is admitted to be prior art by inclusion in this section.

[0003] Indoor distributed antenna monitoring equipment is a key technical equipment used to monitor and manage indoor distributed antenna systems. It is widely used in residential areas, office buildings, large shopping malls and other areas. It can monitor in real time whether each indoor distributed antenna node has any abnormality or failure based on the received signal measurement information, so as to monitor the working status of the indoor distributed antenna in real time.

[0004] However, the traditional indoor distributed system adopts a one-to-one monitoring method for each indoor distributed antenna signal, which has low accuracy and high deployment cost. In particular, the current monitoring methods are prone to mutual interference between frequencies, resulting in reduced monitoring quality.

[0005] Therefore, how to avoid frequency interference at low cost and improve the quality of indoor monitoring is an urgent problem to be solved. Summary of the invention

[0006] In view of the above problems existing in the prior art, a signal monitoring method and device based on frequency shift technology are proposed. By using this method and device, the above problems can be solved.

[0007] The present invention provides the following solutions.

[0008] In a first aspect, a signal monitoring method based on frequency shift technology is provided, comprising:

[0009] Receive a frequency band signal to be tested;

[0010] Obtaining an interference index of a mixed signal of an interference frequency band signal and a target local oscillator signal on a target frequency band, and determining a target frequency band and a target local oscillator signal according to the interference index;

[0011] Mixing the target local oscillator signal and the RF signal to be measured, and outputting a frequency-shifted signal within the target frequency band;

[0012] Monitor the frequency shift signal.

[0013] Preferably, the method further comprises: an interference index of a mixed signal of the interference frequency band signal and the target local oscillator signal on the target frequency band is lower than a preset threshold.

[0014] Preferably, determining the target frequency band and the target local oscillator signal according to the interference index further includes: a mixed signal of the interference frequency band signal and the target local oscillator signal does not fall into the target frequency band.

[0015] Preferably, determining the target frequency band and the target local oscillator signal according to the interference index also includes: determining the target frequency band; determining multiple candidate local oscillator frequencies that can shift the frequency band signal to the target frequency band; determining the interference frequency band signal and the mixed signal of each candidate local oscillator frequency; comparing the mixing signal corresponding to each candidate local oscillator frequency point to fall within the range of the target frequency band, and determining the corresponding interference index; determining the target local oscillator signal according to the interference index corresponding to each candidate local oscillator frequency point.

[0016] Preferably, a candidate local oscillator frequency point with the lowest interference index and / or lower than a preset threshold may be determined as the target local oscillator signal.

[0017] Preferably, the interference index is determined, which is specifically implemented as follows: according to the preset formula FL=m*LO+n*RF, the frequency range of the interference frequency band signal after frequency shifting is calculated, and the interference index is determined by comparing the frequency range with the target frequency band; wherein RF is the interference frequency band signal, LO is the frequency point of the local oscillator signal used for frequency shifting, m is a variable positive integer assignment, n is a variable integer assignment, and FL is the frequency shifted signal of the interference frequency band signal.

[0018] Preferably, the interference frequency band signal falls into the following frequency bands: 3G frequency band and / or its harmonic frequency band, 4G frequency band and / or its harmonic frequency band, 5G frequency band and / or its harmonic frequency band, WiFi frequency band and / or its harmonic frequency band.

[0019] The frequency band signal to be tested includes any one or more of the following: 3G frequency band and / or its harmonic frequency band, 4G frequency band and / or its harmonic frequency band, 5G frequency band and / or its harmonic frequency band, WiFi frequency band and / or its harmonic frequency band.

[0020] In a second aspect, a signal monitoring device based on frequency shift technology is provided, comprising:

[0021] A receiving module, used for receiving a frequency band signal to be tested;

[0022] A control module obtains an interference index of a mixed signal of an interference frequency band signal and a target local oscillator signal on a target frequency band, and determines a target frequency band and a target local oscillator signal according to the interference index;

[0023] The frequency shift module is used to mix the target local oscillator signal and the RF signal to be measured, and output a frequency shift signal within the target frequency band;

[0024] The monitoring unit is used to monitor the frequency shift signal.

[0025] Preferably, the control module is used to control an interference index of a mixed signal of an interference frequency band signal and a target local oscillator signal on a target frequency band to be lower than a preset threshold.

[0026] Preferably, the control module is used to: control a mixed signal of an interference frequency band signal and a target local oscillator signal to not fall into a target frequency band.

[0027] Preferably, the control module is used to: determine the target frequency band; determine multiple candidate local oscillator frequency points that can shift the frequency of the measured frequency band signal to the target frequency band; determine the interference frequency band signal and the mixed signal of each candidate local oscillator frequency point; compare the mixing signal corresponding to each candidate local oscillator frequency point to fall within the range of the target frequency band, and determine the corresponding interference index; determine the target local oscillator signal according to the interference index corresponding to each candidate local oscillator frequency point.

[0028] Preferably, the control module determines a candidate local oscillator frequency point with the lowest interference index and / or lower than a preset threshold as the target local oscillator signal.

[0029] Preferably, the control module calculates the frequency range of the interference frequency band signal after frequency shifting according to the preset formula FL=m*LO+n*RF, compares the overlap between the frequency range and the target frequency band, and determines the interference index; wherein RF is the interference frequency band signal, LO is the frequency point of the local oscillator signal used for frequency shifting, m is a variable positive integer assignment, n is a variable integer assignment, and FL is the frequency shifted signal of the interference frequency band signal.

[0030] Preferably, the interference frequency band signal falls into any one or more of the following: 3G frequency band and / or its harmonic frequency band, 4G frequency band and / or its harmonic frequency band, 5G frequency band and / or its harmonic frequency band, WiFi frequency band and / or its harmonic frequency band.

[0031] One of the advantages of the above embodiment is that when monitoring the signal in the frequency band to be measured, the target frequency band and the target local oscillator signal used to shift the frequency band signal to the target frequency band are first determined, wherein a local oscillator signal with a lower interference index to the target frequency band by the mixed signal that can control the interference frequency band signal and the target local oscillator signal is selected as the target local oscillator signal, and then the target local oscillator signal and the RF signal to be measured are mixed, and the frequency-shifted signal is output for monitoring. In this way, the signal in the frequency band to be measured can be shifted to any frequency band for monitoring under the premise of controlling frequency interference, that is, accurate monitoring of the entire frequency band can be achieved, which has cost advantages.

[0032] Other advantages of the present invention will be explained in more detail with reference to the following description and accompanying drawings.

[0033] It should be understood that the above description is only an overview of the technical solution of the present invention, so that the technical means of the present invention can be more clearly understood and implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described below by way of example. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The advantages and benefits described herein and other advantages and benefits will be apparent to those of ordinary skill in the art by reading the detailed description of the exemplary embodiments below. The accompanying drawings are only used for the purpose of illustrating exemplary embodiments and are not to be considered as limiting the present invention. Moreover, the same reference numerals are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0035] Figure 1 A schematic diagram of a flow chart of a signal monitoring method based on frequency shift technology according to an embodiment of the present invention;

[0036] Figure 2 is another flow chart of a signal monitoring method based on frequency shift technology according to an embodiment of the present invention;

[0037] Figure 3 is a structural schematic diagram of a signal monitoring device based on frequency shift technology according to an embodiment of the present invention;

[0038] Figure 4 FIG. 4 is a schematic diagram of the structure of a signal monitoring system chip based on frequency shift technology according to an embodiment of the present invention.

[0039] In the drawings, the same or corresponding reference numerals represent the same or corresponding parts. DETAILED DESCRIPTION

[0040] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0041] In the description of the embodiments of the present application, it should be understood that terms such as "including" or "having" are intended to indicate the presence of features, numbers, steps, behaviors, components, parts, or a combination thereof disclosed in this specification, and are not intended to exclude the possibility of the presence of one or more other features, numbers, steps, behaviors, components, parts, or a combination thereof.

[0042] Unless otherwise specified, “ / ” means or. For example, A / B can mean A or B. The “and / or” in this article is merely a way to describe the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone.

[0043] The terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, unless otherwise specified, "plurality" means two or more.

[0044] It should also be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0045] Figure 1 This is a flow chart of a signal monitoring method based on frequency shifting technology according to an embodiment of the present application. In this flow, from the device perspective, the execution subject can be one or more electronic devices; from the program perspective, the execution subject can correspondingly be the program installed on these electronic devices.

[0046] like Figure 1 As shown, the method provided in this embodiment may include the following steps:

[0047] 101. Receive a frequency band signal to be tested;

[0048] The frequency band signal to be measured refers to the frequency band signal to be measured of the received RF signal. For example, when the N41 frequency band (i.e., covering the frequency range of 2515-2675 MHz) needs to be monitored, the N41 frequency band signal of the RF signal is obtained as the frequency band signal to be measured.

[0049] 102. Obtain an interference index of a mixed signal of an interference frequency band signal and a target local oscillator signal on a target frequency band, and determine a target frequency band and a target local oscillator signal according to the interference index;

[0050] The target frequency band refers to the target frequency band where the measured frequency band signal is expected to be shifted. Specifically, it can be a suitable frequency band set as needed. The target local oscillator signal refers to the local oscillator signal used to shift the measured frequency band signal to the target frequency band. Specifically, after mixing the measured frequency band signal and the target local oscillator signal, the frequency-shifted signal of the target frequency band can be obtained. Taking the frequency-shifted signal as the monitoring object can not only eliminate the interference signal to obtain accurate monitoring results, but more importantly, it can realize the monitoring of the full-band signal in this way.

[0051] The frequency band signal to be tested includes any one or more of the following: 3G frequency band and / or its harmonic frequency band, 4G frequency band and / or its harmonic frequency band, 5G frequency band and / or its harmonic frequency band, WiFi frequency band and / or its harmonic frequency band.

[0052] In a possible implementation, within a measurable range, the signal of the frequency band to be measured can be selected to be frequency-shifted to any frequency band within the target frequency band to achieve accurate monitoring of the entire frequency band.

[0053] The interference frequency band signal refers to the frequency band signal with more interference signal noise, which generally includes the public network general frequency band, which usually has more interference signals and easily causes inaccurate monitoring.

[0054] In a possible implementation, the interference frequency band signal may fall into the 3G frequency band and / or its harmonic frequency band, the 4G frequency band and / or its harmonic frequency band, the 5G frequency band and / or its harmonic frequency band, the WiFi frequency band and / or its harmonic frequency band.

[0055] In a possible implementation, in the aforementioned 102, by selecting a suitable target frequency band and a target local oscillator signal, the interference index of the mixed signal of the interfering frequency band signal and the target local oscillator signal, such as a 3G, 4G, 5G or WiFI signal or its harmonic signal, on the target frequency band can be controlled to be limited to a lower level.

[0056] In a possible implementation, in the aforementioned 102, by selecting a suitable target frequency band and a target local oscillator signal, the interference index of the mixed signal of the interference frequency band signal and the target local oscillator signal on the target frequency band can be controlled to be lower than a preset threshold. For example, the frequency range of the mixed signal of the interference frequency band signal and the target local oscillator signal is calculated, and the value of the interference index is determined by the proportion of the frequency range falling into the target frequency band, and the target frequency band and target local oscillator signal with a lower interference index are determined by comparing the value of the interference index with the preset threshold.

[0057] In a possible implementation, in the aforementioned 102, when a high monitoring accuracy is required, it may be required that a mixed signal of an interference frequency band signal and a selected target local oscillator signal does not fall into a target frequency band.

[0058] In one possible implementation, reference Figure 2 In the aforementioned 102, the following steps may be further included:

[0059] 1021. Determine a target frequency band; wherein the target frequency band may be a freely set frequency band range.

[0060] 1022. Determine a plurality of candidate local oscillator frequency points that can shift the frequency of the signal in the frequency band to be measured to the target frequency band;

[0061] 1023. Determine a mixed signal generated by an interference frequency band signal and a local oscillator signal corresponding to each candidate local oscillator frequency point;

[0062] 1024. Compare the mixing signal corresponding to each candidate local oscillator frequency point to a range within the target frequency band, and determine the corresponding interference index;

[0063] 1025. Determine a target local oscillator signal according to an interference index corresponding to each candidate local oscillator frequency point.

[0064] Specifically, a local oscillator signal corresponding to a candidate local oscillator frequency point having the lowest interference index and / or lower than a preset threshold may be determined as a target local oscillator signal.

[0065] After selecting the appropriate target frequency band and target LO signal, perform the following steps:

[0066] 103. Mixing the target local oscillator signal and the radio frequency signal to be measured, and outputting a frequency-shifted signal within the target frequency band;

[0067] 104. Monitor the frequency shift signal.

[0068] Specifically, a power detection device may be used to directly detect the power of the frequency-shifted signal to achieve detection of the frequency band to be tested.

[0069] In this way, the signal in the frequency band to be measured can be converted into a frequency-shifted signal of the target frequency band for power detection. In the frequency shifting process, by selecting a suitable target frequency band and target local oscillator signal, it is possible to avoid or reduce the frequency shifting of the interference frequency band signal to the target frequency band, thereby causing frequency interference, and achieve accurate monitoring of the entire frequency band.

[0070] The present application is described in detail below with reference to specific embodiments:

[0071] In one example, the frequency shift to the target frequency band (600M~700M) is used to detect the monitored frequency band signal in the frequency range of 2515M~2675M. It can be understood that due to the existence of the interference frequency band signal, when detecting the monitored frequency band signal, it is necessary to consider the adverse interference of public frequency band signals such as 4G, 5G, WiFi, etc. (interference frequency band signals) and their harmonics to the target frequency band after frequency shift. For example, the main frequency bands of 4G and 5G mobile networks of various operators are distributed in the following frequency bands (band) range B28 / B8 / B3 / B39 / B34 / B1 / B40 / B77 / B78 / B79. Therefore, when determining the frequency point of the target local oscillator signal, it is necessary to calculate the situation where the mixing products of each frequency band signal and its harmonics and the local oscillator signal and its harmonics fall within the range of the target frequency band (600M~700M). For example, the preset formula FL=m*LO+n*RF can be used to calculate the frequency range of the interference frequency band signal after frequency shifting, wherein RF is the interference frequency band signal to be monitored, LO is the frequency point of the local oscillator signal used for frequency shifting, m is a variable positive integer value, which can be 1, 2, 3, ..., n is a variable integer value, which can be 1, -1, 2, -2, 3, -3, ..., and FL is the signal of the interference frequency band signal after frequency shifting.

[0072] The applicant has verified that if the LO is selected as the 3115M frequency point, the second harmonic of the first interference frequency band (1830M~1880M) and the second interference frequency band (1880M~1920M) will be mixed with the LO 3115M, which will fall into the monitoring range of the target frequency band (600M~700M), and the signal strength is strong, which will affect the monitoring results. If the LO is changed to 1915M, the amplitude of the signal of the interference frequency band and the mixed product of the LO falling into the target frequency band (600M~700M) will be very small and can be ignored, thus minimizing the interference of other frequency band signals on the frequency band to be measured.

[0073] It should be noted that the steps not described in detail in this embodiment can be referred to Figure 1 The description of the relevant steps in the illustrated embodiment will not be repeated here.

[0074] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code that includes one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present invention belong.

[0075] Based on the same technical concept, an embodiment of the present invention further provides a signal monitoring device based on frequency shift technology, which is used to execute the signal monitoring method based on frequency shift technology provided by any of the above embodiments. Figure 3 A schematic structural diagram of a signal monitoring device based on frequency shift technology provided by an embodiment of the present invention.

[0076] It should be noted that the monitoring device can be integrated into the system chip SOC, refer to Figure 4 In some feasible embodiments, it can be integrated into a high-performance, highly integrated 4G / 5G baseband demodulation SOC based on the RISC-V architecture. The SOC can integrate MCU, baseband processor and on-chip SRAM in a single chip, and support a flexible and upgradeable software reconfigurable architecture. It can be widely used in 4G and 5G indoor signal detection, repeater TDD synchronization, and customized 5G private networks such as satellite IoT applications.

[0077] See also Figure 3 , a signal monitoring device based on frequency shift technology, comprising:

[0078] The receiving module 301 is used to receive the frequency band signal to be measured;

[0079] The control module 302 obtains an interference index of a mixed signal of an interference frequency band signal and a target local oscillator signal on a target frequency band, and determines a target frequency band and a target local oscillator signal according to the interference index;

[0080] The frequency shift module 303 is used to mix the target local oscillator signal and the radio frequency signal to be measured, and output a frequency shift signal within the target frequency band;

[0081] The monitoring unit 304 is used to monitor the frequency shift signal.

[0082] Preferably, the control module 302 is used to determine a target frequency band and a target local oscillator signal to control an interference index of a mixed signal of an interference frequency band signal and a target local oscillator signal on the target frequency band to be lower than a preset threshold.

[0083] Preferably, the control module 302 is used to determine a target frequency band and a target local oscillator signal to control a mixed signal of an interference frequency band signal and a target local oscillator signal not to fall into the target frequency band.

[0084] Preferably, the control module 302 is used to: determine the target frequency band; determine multiple candidate local oscillator frequencies that can shift the frequency of the measured frequency band signal to the target frequency band; determine the mixed signal of the interference frequency band signal and the local oscillator signal corresponding to each candidate local oscillator frequency point; compare the range of the mixed signal corresponding to each candidate local oscillator frequency point falling into the target frequency band, and determine the corresponding interference index; determine the target local oscillator signal according to the interference index corresponding to each candidate local oscillator frequency point.

[0085] Preferably, the control module 303 determines the candidate local oscillator frequency point with the lowest interference index and / or lower than a preset threshold as the target local oscillator signal.

[0086] Preferably, the control module 303 uses the formula FL=m*LO+n*RF to calculate the frequency range of the interference frequency band signal after frequency shifting, compares the overlap between the frequency range and the target frequency band, and determines the interference index; wherein RF is the interference frequency band signal, LO is the frequency point of the local oscillator signal used for frequency shifting, m is a variable positive integer assignment, n is a variable integer assignment, and FL is the frequency shifted signal of the interference frequency band signal.

[0087] Preferably, the interference frequency band signal may fall into the 3G frequency band and / or its harmonic frequency band, the 4G frequency band and / or its harmonic frequency band, the 5G frequency band and / or its harmonic frequency band, the WiFi frequency band and / or its harmonic frequency band.

[0088] Preferably, the frequency band signal to be tested includes any one or more of the following: 3G frequency band and / or its harmonic frequency band, 4G frequency band and / or its harmonic frequency band, 5G frequency band and / or its harmonic frequency band, WiFi frequency band and / or its harmonic frequency band.

[0089] The target frequency band includes any one or more of the following: 3G frequency band and / or its harmonic frequency band, 4G frequency band and / or its harmonic frequency band, 5G frequency band and / or its harmonic frequency band, WiFi frequency band and / or its harmonic frequency band.

[0090] It should be noted that the device in the embodiment of the present application can implement the various processes of the embodiment of the aforementioned method and achieve the same effects and functions, which will not be repeated here.

[0091] The apparatus and method provided in the embodiments of the present application correspond one to one, and therefore, the apparatus also has similar beneficial technical effects as the corresponding method. Since the beneficial technical effects of the method have been described in detail above, the beneficial technical effects of the apparatus, device and computer-readable storage medium will not be repeated here.

[0092] Although the spirit and principle of the present invention have been described with reference to several specific embodiments, it should be understood that the present invention is not limited to the disclosed specific embodiments, and the division of various aspects does not mean that the features in these aspects cannot be combined to benefit, and such division is only for the convenience of expression. The present invention is intended to cover various modifications and equivalent arrangements included in the spirit and scope of the attached claims.

Claims

1. A signal monitoring method based on frequency shift technology, characterized in that: include: Receive a frequency band signal to be tested; Obtaining an interference index of a mixed signal of an interference frequency band signal and a target local oscillator signal on the target frequency band, and determining a target frequency band and a target local oscillator signal according to the interference index; Mixing the target local oscillator signal with the radio frequency signal to be measured, and outputting a frequency-shifted signal within the target frequency band; The frequency shifted signal is monitored.

2. The method according to claim 1, characterized in that Also includes: An interference index of a mixed signal of the interference frequency band signal and the target local oscillator signal on the target frequency band is lower than a preset threshold.

3. The method according to claim 1, characterized in that Determining the target frequency band and the target local oscillator signal according to the interference index is specifically implemented as follows: A mixed signal of the interference frequency band signal and the target local oscillator signal does not fall into the target frequency band.

4. The method according to claim 1, characterized in that: Determining a target frequency band and a target local oscillator signal according to the interference index also includes: Determine the target frequency band; Determine a plurality of candidate local oscillator frequency points that can shift the frequency of the signal in the frequency band to be measured to the target frequency band; Determine a mixed signal of the interference frequency band signal and the local oscillator signal corresponding to each candidate local oscillator frequency point; Compare the mixing signal corresponding to each candidate local oscillator frequency point to a range within the target frequency band, and determine the corresponding interference index; The target local oscillator signal is determined according to the interference index corresponding to each candidate local oscillator frequency point.

5. The method according to claim 4, characterized in that Also includes: A candidate local oscillator frequency point with the lowest interference index and / or lower than a preset threshold is determined as the target local oscillator signal.

6. The method according to claim 2, characterized in that Also includes: Determine the interference index, which is specifically implemented as follows: The frequency range of the interference frequency band signal after frequency shift is calculated according to the preset formula FL=m*LO+n*RF, and the interference index is determined by comparing the frequency range with the target frequency band; Among them, RF is the interference frequency band signal, LO is the frequency point of the local oscillator signal used for frequency shifting, m is a variable positive integer assignment, n is a variable integer assignment, and FL is the frequency shift signal of the interference frequency band signal.

7. The method according to claim 1, characterized in that The interference frequency band signal falls into any one or more of the following frequency bands: 3G frequency band and / or its harmonic frequency band, 4G frequency band and / or its harmonic frequency band, 5G frequency band and / or its harmonic frequency band, WiFi frequency band and / or its harmonic frequency band.

8. The method according to claim 1, characterized in that The frequency band signal to be tested includes any one or more of the following: 3G frequency band and / or its harmonic frequency band, 4G frequency band and / or its harmonic frequency band, 5G frequency band and / or its harmonic frequency band, WiFi frequency band and / or its harmonic frequency band.

9. A signal monitoring device based on frequency shift technology, characterized in that: According to any one of claims 1 to 8, the monitoring device is configured as follows: A receiving module, used for receiving a frequency band signal to be tested; A control module, which obtains an interference index of a mixed signal of an interference frequency band signal and a target local oscillator signal on the target frequency band, and determines a target frequency band and a target local oscillator signal according to the interference index; A frequency shift module, used for mixing a target local oscillator signal with the radio frequency signal to be measured, and outputting a frequency shift signal within the target frequency band; A monitoring unit is used to monitor the frequency shift signal.

Images