Local oscillator power adjustment method and apparatus for radio frequency receiver and electronic device

Abstract

The application provides a local oscillator power adjustment method and device of a radio frequency receiver and electronic equipment, the method comprising: acquiring a power signal of a local oscillator signal in real time, the power signal representing the power of the local oscillator signal inputting a mixer; acquiring preset calibration data, comparing the power signal and the calibration data, and judging whether the error of the power signal and the calibration data exceeds a threshold; if the error of the power signal and the calibration data exceeds the threshold, adjusting the attenuation coefficient of a digital attenuator, so that the error of the power signal and the calibration data does not exceed the threshold; wherein the digital attenuator is arranged in a link before the local oscillator signal inputs the mixer, and is used for adjusting the power of the local oscillator signal inputting the mixer. The application improves the measurement accuracy of the receiver.

Description

Technical Field

[0001] This invention relates to the field of radio frequency signal processing technology, and in particular to a method, apparatus and electronic device for adjusting the local oscillator power of a radio frequency receiver. Background Technology

[0002] As a core module of high-performance spectrum analyzers, the ultra-wideband (UWB) radio frequency receiver's channel amplitude-frequency response, instantaneous analysis bandwidth flatness, and spurious suppression directly determine the test accuracy. In UWB receiver design, due to the need for multiple frequency conversions, the characteristics of the mixer—such as conversion loss, spurious suppression, isolation, and amplitude-frequency response flatness—have a significant impact on the UWB receiver signal performance. As mentioned above, the mixer characteristics are mainly affected by the local oscillator frequency and drive power.

[0003] Based on the above theory, the design of ultra-wideband high-precision test systems faces the following two major challenges in the design of ultra-wideband large-bandwidth receivers.

[0004] Firstly, ultra-wideband receivers have a local oscillator frequency range spanning multiple octaves, making it difficult for traditional driver amplifiers to maintain consistent output performance over such a wide operating range. Secondly, the optimal drive power of the mixer will also vary depending on the local oscillator frequency.

[0005] Secondly, for high-precision test and analysis systems, power calibration under full-temperature conditions is particularly important. However, in addition to environmental factors, components in the link are also affected by many other factors, such as component aging. As a key component in the link, even slight differences in the local oscillator's drive power can alter the mixer's conversion loss, causing the channel gain to deviate from the calibration data, thus affecting the accuracy of power measurement. Therefore, the calibration of the local oscillator's drive power is especially important in high-precision measurement systems.

[0006] To address the two major challenges mentioned above, traditional technical solutions mainly rely on fixed attenuation values ​​for adjusting the driver amplifier. However, due to the inconsistency in amplifier performance across the ultra-wide operating range, it is impossible to meet the requirement that the mixer drive power should dynamically change in real time with variations in local oscillator frequency and ambient temperature, thereby reducing the accuracy of the test system.

[0007] The information disclosed in this background section is intended only to enhance the understanding of the general background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0008] To address the problems existing in the prior art, the present invention provides a method, apparatus, and electronic device for adjusting the local oscillator power of a radio frequency receiver.

[0009] The present invention provides a method for adjusting the local oscillator power of an RF receiver. The method includes: acquiring a power signal of the local oscillator signal in real time, wherein the power signal represents the power of the local oscillator signal when it is input to the mixer; acquiring preset calibration data, comparing the power signal and the calibration data, and determining whether the error between the power signal and the calibration data exceeds a threshold; if the error between the power signal and the calibration data exceeds the threshold, adjusting the attenuation coefficient of a digital attenuator so that the error between the power signal and the calibration data does not exceed the threshold; wherein the digital attenuator is set in the link before the local oscillator signal is input to the mixer, and is used to adjust the power of the local oscillator signal when it is input to the mixer.

[0010] Optionally, preset calibration data can be obtained, including: obtaining the ambient temperature and local oscillator frequency of the current receiver; and reading the corresponding calibration data from a preset mapping table based on the ambient temperature and local oscillator frequency.

[0011] Optionally, each mapping in the mapping table is established during the debugging phase, including: determining the ambient temperature and local oscillator signal frequency; measuring the mixer's multiple corresponding characteristics under multiple drive powers of the local oscillator signal, where multiple drive powers are achieved through multiple different attenuation coefficients of the digital attenuator; selecting the drive power of the local oscillator signal corresponding to the optimal characteristics as calibration data, and simultaneously recording the attenuation coefficient of the corresponding digital attenuator.

[0012] Optionally, before acquiring the power signal of the local oscillator signal in real time, the process includes: determining the real-time ambient temperature and the local oscillator signal frequency; and acquiring the attenuation coefficient of the corresponding digital attenuator during the debugging phase based on the mapping table, as the initial attenuation coefficient of the digital attenuator.

[0013] Optionally, the characteristics include at least one of the following: frequency conversion loss, spurious suppression, isolation, and amplitude-frequency response flatness.

[0014] Optionally, real-time acquisition of the power signal of the local oscillator signal includes: acquiring an analog signal through a detector connected to a broadband coupler, the broadband coupler being coupled to the link before the local oscillator signal input mixer; converting the analog signal into a digital signal through an analog-to-digital converter; and identifying the digital signal as a power signal through a controller.

[0015] Optionally, the radio frequency receiver is an ultra-wideband receiver.

[0016] The present invention also provides a local oscillator power adjustment device for an RF receiver, comprising: a monitoring module for acquiring a power signal of the local oscillator signal in real time, the power signal representing the power of the local oscillator signal when input to the mixer; a judgment module for acquiring preset calibration data, comparing the power signal and the calibration data, and determining whether the error between the power signal and the calibration data exceeds a threshold; and an adjustment module for adjusting the attenuation coefficient of a digital attenuator if the error between the power signal and the calibration data exceeds the threshold, so that the error between the power signal and the calibration data does not exceed the threshold; wherein the digital attenuator is disposed in the link before the local oscillator signal is input to the mixer, and is used to adjust the power of the local oscillator signal when input to the mixer.

[0017] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps of the local oscillator power adjustment method of any of the above-described radio frequency receivers.

[0018] The present invention also provides a non-transitory computer-readable storage medium storing a computer program thereon, wherein the computer program, when executed by a processor, implements the steps of the local oscillator power adjustment method of any of the above-described radio frequency receivers.

[0019] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

[0020] The beneficial effects of this invention are: improved measurement accuracy of the receiver. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 The present invention provides a flowchart illustrating a method for adjusting the local oscillator power of an RF receiver.

[0023] Figure 2 The present invention also provides a local oscillator power adjustment device for a radio frequency receiver.

[0024] Figure 3 This is a schematic diagram of a link for an ultra-wideband receiver designed according to the present invention.

[0025] Figure 4This is a schematic diagram of a local oscillator driving frequency dynamic adjustment process disclosed in the technical solution of this invention.

[0026] Figure 5 This is a calibration flowchart provided for the technical solution of the present invention.

[0027] Figure 6 This is a schematic diagram of the physical structure of an electronic device provided by the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0029] The method for adjusting the local oscillator power of the radio frequency receiver provided in this application will be described in detail below with reference to the accompanying drawings, through specific embodiments and application scenarios.

[0030] Figure 1 The present invention provides a schematic flowchart of a method for adjusting the local oscillator power of an RF receiver, as shown in the technical solution. Figure 1 As shown, the technical solution of the present invention provides a method for adjusting the local oscillator power of an RF receiver. The method includes the following steps: S110 acquiring a power signal of the local oscillator signal in real time, the power signal representing the power of the local oscillator signal when it is input to the mixer; S120 acquiring preset calibration data, comparing the power signal and the calibration data, and determining whether the error between the power signal and the calibration data exceeds a threshold; S130 if the error between the power signal and the calibration data exceeds the threshold, adjusting the attenuation coefficient of the digital attenuator so that the error between the power signal and the calibration data does not exceed the threshold; wherein, the digital attenuator is set in the link before the local oscillator signal is input to the mixer, and is used to adjust the power of the local oscillator signal when it is input to the mixer.

[0031] Optionally, preset calibration data can be obtained, including: obtaining the ambient temperature and local oscillator frequency of the current receiver; and reading the corresponding calibration data from a preset mapping table based on the ambient temperature and local oscillator frequency.

[0032] Optionally, each mapping in the mapping table is established during the debugging phase, including: determining the ambient temperature and local oscillator signal frequency; measuring the mixer's multiple corresponding characteristics under multiple drive powers of the local oscillator signal, where multiple drive powers are achieved through multiple different attenuation coefficients of the digital attenuator; selecting the drive power of the local oscillator signal corresponding to the optimal characteristics as calibration data, and simultaneously recording the attenuation coefficient of the corresponding digital attenuator.

[0033] Optionally, before acquiring the power signal of the local oscillator signal in real time, the process includes: determining the real-time ambient temperature and the local oscillator signal frequency; and acquiring the attenuation coefficient of the corresponding digital attenuator during the debugging phase based on the mapping table, as the initial attenuation coefficient of the digital attenuator.

[0034] Optionally, the characteristics include at least one of the following: frequency conversion loss, spurious suppression, isolation, and amplitude-frequency response flatness.

[0035] Optionally, real-time acquisition of the power signal of the local oscillator signal includes: acquiring an analog signal through a detector connected to a broadband coupler, the broadband coupler being coupled to the link before the local oscillator signal input mixer; converting the analog signal into a digital signal through an analog-to-digital converter; and identifying the digital signal as a power signal through a controller.

[0036] Optionally, the radio frequency receiver is an ultra-wideband receiver.

[0037] The local oscillator power adjustment device for an RF receiver provided by the present invention will be described below. The local oscillator power adjustment device for the RF receiver described below can be referred to in correspondence with the local oscillator power adjustment method for the RF receiver described above. It should be noted that the device described herein includes a virtual device on a program running device such as a computer or processor.

[0038] Figure 2 The present invention also provides a local oscillator power adjustment device for a radio frequency receiver, such as... Figure 2 As shown, the technical solution of the present invention also provides a local oscillator power adjustment device for an RF receiver. The device includes: a monitoring module, which is used to acquire a power signal of the local oscillator signal in real time, the power signal representing the power of the local oscillator signal when it is input to the mixer; a judgment module, which is used to acquire preset calibration data, compare the power signal and the calibration data, and determine whether the error between the power signal and the calibration data exceeds a threshold; and an adjustment module, which is used to adjust the attenuation coefficient of a digital attenuator if the error between the power signal and the calibration data exceeds the threshold, so that the error between the power signal and the calibration data does not exceed the threshold; wherein, the digital attenuator is set in the link before the local oscillator signal is input to the mixer, and is used to adjust the power of the local oscillator signal when it is input to the mixer.

[0039] This embodiment improves the measurement accuracy of the receiver.

[0040] In one embodiment, Figure 3 This is a schematic diagram of a link for an ultra-wideband high-bandwidth receiver designed according to the present invention, as shown below. Figure 3As shown, the main function of an ultra-wideband receiver is to mix the input radio frequency signal with the local oscillator signal via a mixer and output the required intermediate frequency signal.

[0041] The RF signal input link includes: signal generator ---> single-pole double-throw switch ---> digital attenuator ---> low-noise amplifier ---> bandpass filter ---> mixer. The input signal, generated by the signal generator, is input to the receiver via a single-pole double-throw switch (SPDT). It first passes through a digital attenuator, which precisely adjusts the input signal strength while preventing signal damage to the next stage low-noise amplifier. Compared to traditional stepped attenuators, this embodiment uses a digital attenuator at the RF front end, reducing transient glitches introduced by the attenuator. Furthermore, the digital attenuator ensures consistent attenuation of the input RF signal across octave bands, solving the frequency response fluctuation problem of traditional amplifiers. The main function of the bandpass filter is to preprocess the RF signal input to the mixer, eliminating out-of-band interference and selecting only signals within the desired frequency range.

[0042] The local oscillator input signal link includes: local oscillator source signal ---> digital attenuator ---> driver amplifier ---> mixer; among which, the digital attenuator works with other modules to dynamically and precisely control the local oscillator signal (LO) drive power. Figure 4 This is a schematic diagram of a local oscillator driving frequency dynamic adjustment process disclosed in the technical solution of this invention, as shown below. Figure 4 As shown, the local oscillator signal is input to the mixer through a digital attenuator, a driver amplifier, and a broadband coupler. The coupler extracts the feedback signal and enters a high-precision detector, which converts the power signal into a quantifiable voltage signal. The signal is then converted into a digital signal by an analog-to-digital converter and transmitted to the controller. The controller uses the feedback signal to control the digitally controlled attenuator to dynamically adjust the local oscillator drive power.

[0043] The intermediate frequency (IF) output signal link includes: mixer ---> bandpass filter ---> low noise amplifier ---> digital attenuator ---> ADCRX (sampling interface of the controller); after the radio frequency signal and the local oscillator signal are mixed by the mixer, the intermediate frequency signal is output. The bandpass filter removes out-of-band interference, and the low noise amplifier is set to compensate for the mixer loss, ensuring the response to test and analysis of weak signals.

[0044] The adjustment method for the local oscillator of the ultra-wideband receiver described above is as follows: During the debugging process, the influence of the local oscillator drive frequency and power on the output characteristics of the receiving channel is tested under the same input conditions. Combined with the real-time data transmission between the receiver temperature sensor and the controller, the optimal drive power at different temperatures and different local oscillator frequencies is determined.

[0045] By adjusting the high-precision digitally controlled attenuator in the local oscillator channel, the receiver performance is optimized. The above states are recorded and stored in the controller as a mapping table. During the actual operation of the test system, the data can be retrieved by looking up the table according to the test conditions set by the user and the ambient temperature identified by the temperature control sensor. The digitally controlled attenuator is controlled by the SPI (Serial Peripheral Interface) of the controller (such as a microcontroller), thereby realizing precise power control of the local oscillator.

[0046] During user operation, the testing system can support calibration of the receiver's local oscillator drive power. Figure 5 A calibration process flowchart is provided for the technical solution of this invention, such as... Figure 5 As shown, under different temperature and local oscillator frequency test conditions, the local oscillator signal enters a high-precision detector through a broadband coupler, converting the power signal into a voltage signal. This signal is sampled by a 12-bit analog-to-digital converter, and the data is transmitted to the controller for analysis to form calibration data. The test system automatically reads the corresponding calibration data according to the test conditions set by the user, and compares the current local oscillator signal detector output voltage with the value recorded in the calibration table. When the error between the two sets of data exceeds the set maximum error threshold, the power difference is calculated by the algorithm, thereby controlling the digitally controlled attenuator to adjust the local oscillator power. This process is repeated until the difference between the acquired data and the calibration data is less than the error threshold. Relying on the controller's powerful data processing capabilities, real-time monitoring and adjustment of the power can be achieved, thereby improving the measurement accuracy of the spectrum analyzer.

[0047] The ultra-wideband receiver designed in this embodiment of the invention solves the problem that traditional drive amplifiers have difficulty maintaining consistent output performance over such a wide operating range because the local oscillator frequency range spans multiple octaves.

[0048] This invention enables real-time monitoring and adjustment of the local oscillator drive power under test conditions of different temperatures and frequencies, thereby ensuring that the spectrum analyzer's receiving channel is always in optimal working condition and improving the accuracy of the test system.

[0049] Figure 6 A schematic diagram of the physical structure of an electronic device provided by the present invention, such as... Figure 6As shown, the electronic device may include a processor 810, a communications interface 820, a memory 830, and a communication bus 840, wherein the processor 810, the communications interface 820, and the memory 830 communicate with each other via the communication bus 840. The processor 810 can call logic instructions in the memory 830 to execute a local oscillator power adjustment method for an RF receiver. The method includes: acquiring a power signal of the local oscillator signal in real time, the power signal representing the power level of the local oscillator signal when input to the mixer; acquiring preset calibration data; comparing the power signal and the calibration data; determining whether the error between the power signal and the calibration data exceeds a threshold; if the error between the power signal and the calibration data exceeds the threshold, adjusting the attenuation coefficient of a digital attenuator so that the error between the power signal and the calibration data does not exceed the threshold; wherein the digital attenuator is disposed in the link before the local oscillator signal is input to the mixer, and is used to adjust the power level of the local oscillator signal when input to the mixer.

[0050] Furthermore, the logical instructions in the aforementioned memory 830 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0051] On the other hand, the present invention also provides a computer program product, the computer program product comprising a computer program stored on a non-transitory computer-readable storage medium, the computer program comprising program instructions, wherein when the program instructions are executed by a computer, the computer is able to execute the local oscillator power adjustment method for the radio frequency receiver provided by the above methods, the method comprising: acquiring a power signal of the local oscillator signal in real time, the power signal representing the power of the local oscillator signal when input to a mixer; acquiring preset calibration data, comparing the power signal and the calibration data, and determining whether the error between the power signal and the calibration data exceeds a threshold; if the error between the power signal and the calibration data exceeds the threshold, adjusting the attenuation coefficient of a digital attenuator so that the error between the power signal and the calibration data does not exceed the threshold; wherein the digital attenuator is disposed in the link before the local oscillator signal is input to the mixer, for adjusting the power of the local oscillator signal when input to the mixer.

[0052] In another aspect, the present invention also provides a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the local oscillator power adjustment method of the aforementioned radio frequency receivers. The method includes: acquiring a power signal of a local oscillator signal in real time, the power signal representing the power level of the local oscillator signal when input to a mixer; acquiring preset calibration data; comparing the power signal and the calibration data; and determining whether the error between the power signal and the calibration data exceeds a threshold. If the error between the power signal and the calibration data exceeds the threshold, adjusting the attenuation coefficient of a digital attenuator so that the error between the power signal and the calibration data does not exceed the threshold. The digital attenuator is disposed in the link before the local oscillator signal is input to the mixer, and is used to adjust the power level of the local oscillator signal when input to the mixer.

[0053] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0054] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for adjusting the local oscillator power of an RF receiver, characterized in that, The method includes: The power signal of the local oscillator signal is acquired in real time, and the power signal represents the power of the local oscillator signal when it is input to the mixer; Obtain preset calibration data, compare the power signal with the calibration data, and determine whether the error between the power signal and the calibration data exceeds a threshold. If the error between the power signal and the calibration data exceeds a threshold, adjust the attenuation coefficient of the digital attenuator so that the error between the power signal and the calibration data does not exceed the threshold. The digital attenuator is located in the link before the local oscillator signal is input to the mixer, and is used to adjust the power of the local oscillator signal when it is input to the mixer. The acquisition of preset calibration data includes: Obtain the current ambient temperature of the receiver and the frequency of the local oscillator signal; Based on the ambient temperature and the local oscillator signal frequency, the corresponding calibration data is read from a preset mapping table; Each mapping in the mapping table is established during the debugging phase, including: The ambient temperature and local oscillator signal frequency are determined, and the mixer is measured to have multiple corresponding characteristics under multiple drive powers of the local oscillator signal. The multiple drive powers are achieved by multiple different attenuation coefficients of the digital attenuator. The driving power of the local oscillator signal corresponding to the optimal characteristic is selected as the calibration data, and the attenuation coefficient of the corresponding digital attenuator is recorded at the same time.

2. The method for adjusting the local oscillator power of an RF receiver according to claim 1, characterized in that, Before acquiring the power signal of the local oscillator signal in real time, the following steps are included: Determine the real-time ambient temperature and local oscillator signal frequency; Based on the mapping table, the attenuation coefficient of the corresponding digital attenuator during the debugging phase is obtained and used as the initial attenuation coefficient of the digital attenuator.

3. The method for adjusting the local oscillator power of an RF receiver according to claim 1, characterized in that, The characteristics include at least one of the following: frequency conversion loss, spurious suppression, isolation, and amplitude-frequency response flatness.

4. The method for adjusting the local oscillator power of an RF receiver according to claim 1, characterized in that, The real-time acquisition of the power signal related to the local oscillator signal includes: The analog signal is acquired by a detector, which is connected to a broadband coupler, and the broadband coupler is coupled to the link before the local oscillator signal is input to the mixer; The analog signal is converted into a digital signal using an analog-to-digital converter; The controller identifies the digital signal as the power signal.

5. The method for adjusting the local oscillator power of an RF receiver according to claim 1, characterized in that, The radio frequency receiver is an ultra-wideband receiver.

6. A local oscillator power adjustment device for a radio frequency receiver, characterized in that, The device includes: A monitoring module is used to acquire the power signal of the local oscillator signal in real time, the power signal representing the power of the local oscillator signal when it is input to the mixer; The judgment module is used to acquire preset calibration data, compare the power signal and the calibration data, and determine whether the error between the power signal and the calibration data exceeds a threshold. An adjustment module is configured to adjust the attenuation coefficient of a digital attenuator if the error between the power signal and the calibration data exceeds a threshold, so that the error between the power signal and the calibration data does not exceed the threshold. The digital attenuator is located in the link before the local oscillator signal is input to the mixer, and is used to adjust the power of the local oscillator signal when it is input to the mixer. The acquisition of preset calibration data includes: Obtain the current ambient temperature of the receiver and the frequency of the local oscillator signal; Based on the ambient temperature and the local oscillator signal frequency, the corresponding calibration data is read from a preset mapping table; Each mapping in the mapping table is established during the debugging phase, including: The ambient temperature and local oscillator signal frequency are determined, and the mixer is measured to have multiple corresponding characteristics under multiple drive powers of the local oscillator signal. The multiple drive powers are achieved by multiple different attenuation coefficients of the digital attenuator. The driving power of the local oscillator signal corresponding to the optimal characteristic is selected as the calibration data, and the attenuation coefficient of the corresponding digital attenuator is recorded at the same time.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the local oscillator power adjustment method of the radio frequency receiver as described in any one of claims 1-5.

8. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the local oscillator power adjustment method of the radio frequency receiver as described in any one of claims 1-5.

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