Simple radio frequency signal detection device

Abstract

The utility model discloses a simple radio frequency signal detection device, which comprises a local oscillator source module, a variable gain programmable amplifier module, a frequency mixing module, a filtering module and a main controller, the local oscillator source module, the variable gain programmable amplifier module and the filtering module are all connected with the main controller; the local oscillation source module, the variable gain program control amplifier module, the frequency mixing module and the filtering module are connected in sequence; the local oscillation source module and the variable gain program control amplifier module form a phase-locked loop, and the main controller controls and can adjust the frequency of an output signal of the local oscillation source module in a stepping manner, controls the voltage amplitude of the output signal of the variable gain program control amplifier module, collects the voltage of a high-frequency signal subjected to multi-point filtering processing, and restores the waveform of the signal; the frequency mixing module mixes the radio frequency signal with the local oscillator signal, outputs a signal when the mixing frequency is equal to the intermediate frequency, and filters and amplifies the signal through the filtering module; the volume of the spectrum analyzer is reduced, and the spectrum analyzer is simple in circuit, good in stability and programmable.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of spectrum analysis technology more particularly to a simple radio frequency signal detection device. BACKGROUND

[0002] The spectrum analyzer is a necessary means for measuring radio signals, an instrument for studying the spectral structure of electrical signals, and is used for measuring signal parameters such as signal distortion, modulation degree, spectral purity, frequency stability, and intermodulation distortion. It can be used to measure certain parameters of circuit systems such as amplifiers and filters, and is a multi-purpose electronic measuring tool and a commonly used tool for electronic product research and development, production, and testing.

[0003] At present, most spectrum analyzers are composed of discrete components, and the hardware circuit is complex, which requires high production technology, has low stability, and is uncontrollable. The discrete components are large in size, and when the circuit scale is large and the frequency is high, the distribution parameters have a great impact, making the design and debugging very difficult. The spectrum analyzer made of discrete components is heavy and inconvenient, and lacks flexibility or multifunctionality.

[0004] Therefore, how to simplify the circuit component structure of the spectrum analyzer, improve the stability and programmable control, and improve the flexibility or multifunctionality, is a problem that needs to be solved by those skilled in the art. INVENTION CONTENTS

[0005] Therefore, the utility model provides a simple radio frequency signal detection device to solve part of the technical problems mentioned in the background art.

[0006] In order to achieve the above purpose, the utility model adopts the following technical scheme:

[0007] A simple radio frequency signal detection device, comprising: a local oscillator source module, a variable gain programmable amplifier module, a mixing module, a filtering module, and a main controller MCU;

[0008] The local oscillator source module, the variable gain programmable amplifier module, and the filtering module are connected with the main controller MCU;

[0009] The local oscillator source module, the variable gain programmable amplifier module, the mixing module, and the filtering module are connected in sequence;

[0010] The local oscillator source module and the variable gain programmable amplifier module constitute a phase-locked loop for outputting a signal with step-adjustable frequency and voltage amplitude adjustable;

[0011] The main controller MCU is used to control and step-adjust the frequency of the local oscillator source module output signal, control the voltage amplitude of the variable gain programmable amplifier module output signal, and collect the voltage of the high-frequency signal after filtering and processing, and restore the waveform of the signal.

[0012] a mixing module, configured to mix the received radio frequency signal with an output signal of the local oscillator source module, and output a signal when the mixed frequency is equal to the intermediate frequency;

[0013] a filtering module, configured to filter and amplify the mixed signal.

[0014] Preferably, the main controller MCU adopts an STM32 main control board data sampling driving board.

[0015] Preferably, the local oscillator source module adopts ADF4351, and the output signal frequency is 90MHz-110MHz and can be step-adjusted; the variable gain programmable amplifier module adopts VCA824, and the output signal amplitude is 10mV-100mV.

[0016] Preferably, the main controller MCU includes a built-in high-speed AD acquisition module, which is configured to perform peak detection on the output signal of the filtering module, acquire the voltage of the high-frequency signal after filtering, and upload the analog signal converted into a digital signal.

[0017] Preferably, the mixing module is an MCL SBL-1 mixer.

[0018] Preferably, the local oscillator source module further includes an LED display lamp, which is configured to show the locking condition of the phase-locked loop on the frequency through lightening.

[0019] Preferably, the simple radio frequency signal detection device further includes a TFT display module connected with the main controller, configured to display the output frequency of the phase-locked loop and the local oscillator source module.

[0020] Preferably, the simple radio frequency signal detection device further includes a key module connected with the main controller, configured to realize step control of the output frequency, adjust the output voltage and realize the sweep frequency function through the cross-rectangular keys and the main controller.

[0021] Preferably, the simple radio frequency signal detection device further includes a power module connected with the main controller MCU and the filtering module respectively.

[0022] Preferably, the simple radio frequency signal detection device is connected with an upper computer, configured to use graphical display for the digital signal converted by the high-speed AD acquisition module.

[0023] As can be seen from the above technical solution, compared with the prior art, this utility model discloses a simple radio frequency signal detection device. It uses a local oscillator with adjustable output frequency and amplitude, and a crystal mixer to achieve mixing. The output signal of the local oscillator is superimposed with other signals and passes through a bandpass filter circuit to obtain a mixed sine wave signal. The data acquisition and driving board realizes AD conversion to measure the amplitude of the mixed waveform and uploads it to the host computer for display. This utility model uses a highly integrated chip to simplify the size of the spectrum analyzer. It has the advantages of simple circuit, good stability, and programmability. It also realizes functions such as frequency measurement and display, step control, and amplitude control, which helps to increase its flexibility or multi-functionality. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model 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 only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0025] Figure 1 The attached figure is a schematic diagram of a simple radio frequency signal detection device provided by this utility model;

[0026] Figure 2 The attached figure is a schematic diagram of the ADF4351 circuit used in the local oscillator module provided by this utility model;

[0027] Figure 3 The attached figure is a schematic diagram of the MCL SBL-1 circuit used in the mixing module provided by this utility model. Detailed Implementation

[0028] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0029] This utility model discloses a simple radio frequency signal detection device, such as... Figure 1 As shown, it includes: a local oscillator module, a variable gain programmable amplifier module, a mixer module, a filter module, and a main controller MCU;

[0030] The local oscillator module, variable gain programmable amplifier module, and filter module are all connected to the main controller MCU.

[0031] The local oscillator module, the variable gain programmable amplifier module, the mixing module and the filtering module are connected in sequence.

[0032] The local oscillator module and the variable gain programmable amplifier module constitute a phase-locked loop, which is used for outputting a signal with frequency step adjustable and voltage amplitude adjustable;

[0033] The main controller MCU is used for controlling and step adjusting the frequency of the signal output by the local oscillator module, controlling the voltage amplitude of the signal output by the variable gain programmable amplifier module, and collecting and filtering the high-frequency signal voltage and restoring the waveform of the signal.

[0034] The mixing module is used for mixing the received radio frequency signal with the signal output by the local oscillator module, and outputting a signal when the mixed frequency is equal to the intermediate frequency.

[0035] The filtering module is used for filtering and amplifying the mixed signal.

[0036] In order to further implement the above technical scheme, the main controller MCU adopts an STM32 main control board data acquisition driving board.

[0037] In order to further implement the above technical scheme, the local oscillator module adopts ADF4351, the output signal frequency is 90MHz-110MHz, and it can be step adjusted; the variable gain programmable amplifier module adopts VCA824, and the amplitude of the output signal is 10mV-100mV.

[0038] In actual application, for example, Figure 2 ADF4351 has an integrated voltage controlled oscillator VCO, the fundamental output frequency range is 2200MHz to 4400MHz, when combined with an external loop filter and a reference frequency, a fractional N frequency divider or an integer N frequency divider phase-locked loop (PLL) frequency synthesizer can be realized; a three-state frequency discriminator phase discriminator is adopted, the phase discrimination linear range is-2π-2π, and it has the characteristics of large capture range, simple circuit structure, short locking time, etc.

[0039] The frequency discriminator phase discriminator (PFD) and the charge pump of the built-in delay element of ADF4351, the digital part includes a 10-bit RF R counter, a 16-bit RF N counter, a 12-bit FRAC counter and a 12-bit analog-digital counter, data is input into a 32-bit shift register at each rising edge of CLK, the data input mode is MSB first, and at the rising edge of LE, the data is transmitted from the shift register to one of the six latches; the VCO core of ADF4351 is composed of three independent VCOs, each VCO uses 16 overlapping frequency bands;

[0040] The principle of the output signal frequency of the ADF4351 frequency synthesizer within a reasonable error range is as follows:

[0041] RF out = [INT + (FRAC / MOD)] x (f PFD / RFDivider)

[0042] Wherein, RF out is RF frequency output, INT is integer frequency coefficient, FRAC is the numerator of decimal frequency (0 to MOD-1), MOD is the preset decimal modulus (2-4095), RFDivider is the sub VCO output frequency divider;

[0043] f PFD = REF N x [(1+D) / (1+T)]

[0044] Wherein, REF N is the reference frequency input, D is the RF REFIN frequency multiplier bit (0 or 1), T is the RF reference frequency coefficient (1-1023).

[0045] ADF4351-based local oscillator source module using 20M active vibration, through the resistance capacitor combination of its peripheral circuit, combined with variable gain programmable amplifier VCA824 and its combination circuit design out of the complete output frequency 90M-110M step.

[0046] The precision of the local oscillator source can reach 100KHz; the output signal amplitude of the local oscillator source is adjustable from 10mV to 100mV, and the control function of the data sampling driving board is used in combination with the feedback mechanism to process the output voltage amplitude. In the design, in order to realize the correct locking of the phase-locked loop to the frequency, a light-emitting diode is added at pin 25 of ADF4351. According to the working characteristics of ADF4351, when the phase-locked loop correctly locks the frequency, the 25th pin is high, and the diode is turned on at this time. The brightness of the light-emitting diode can be observed to directly see the frequency locking condition of the phase-locked loop.

[0047] In order to further implement the above technical scheme, the main controller MCU includes a built-in high-speed AD acquisition module for peak detection of the filter module output signal, multi-point acquisition of the voltage of the high-frequency signal after filtering processing, and uploading of the analog signal converted into a digital signal.

[0048] In the embodiment, the filter module adopts an active filter, which combines the amplification and switching functions of a triode and the filtering characteristics of a resistor and a capacitor, can stably realize signal filtering and amplification, has a good voltage response, can maintain the filtering effect in a wide voltage range, has high stability and is not easily affected by external environment changes; compared with a capacitor filter, the triode filter has a better suppression effect on high-frequency interference, but the capacitor filter has a better frequency response in a low-frequency band; in terms of cost budget, the active filter has a low cost; through multiple simulation debugging and actual circuit testing, it is found that when the cutoff frequency is set to 500 kHz, a better filtering effect can be achieved, and finally through actual circuit debugging, the requirements can be completely met, high-frequency signals superimposed in a low-frequency signal can be effectively filtered out, and the output signal becomes a stable 500 kHz sine wave.

[0049] In order to further implement the above technical solutions, the mixing frequency module is an MCL SBL-1 mixer, which mixes the high-frequency signal and the local oscillator signal to realize frequency down-conversion of the signal, generates a new frequency output, and the output frequency is usually the sum or difference of the input signal and the local oscillator signal frequency.

[0050] In the embodiment, as Figure 3 , the working principle of the mixer is that two signals of different frequencies are input into a nonlinear device to generate sum frequency and difference frequency signals through frequency conversion, and the difference frequency signal is usually selected as the required intermediate frequency signal;

[0051] Specifically, the mixer mixes the signal received by the antenna (whose frequency is fs) with the signal generated by the local oscillator circuit (whose frequency is fl), that is, the product of two sine signals will generate signals with frequencies of the sum and difference of the two, and the difference frequency signal is taken in the mixer, and the frequency is fi=fs-fl, which is the required intermediate frequency signal.

[0052] When the mixing frequency is equal to the intermediate frequency, the signal can be amplified through the intermediate frequency amplifier, and then peak detection is performed, the detected signal is amplified through the video amplifier, and finally displayed.

[0053] In order to further implement the above technical solutions, the local oscillator source module further includes an LED display lamp for displaying the locking condition of the phase-locked loop on the frequency.

[0054] In order to further implement the above technical solutions, a simple radio frequency signal detection device further includes a TFT display module connected with the main controller and used for displaying the output frequency of the phase-locked loop and the local oscillator source module.

[0055] In order to further implement the above technical solutions, the simple radio frequency signal detection device further comprises a key module connected with the main controller, and the stepping control of the output frequency is realized through the main controller by the cross-rectangular key, the output voltage is adjusted, and the frequency sweeping function is realized.

[0056] In order to further implement the above technical solutions, the simple radio frequency signal detection device further comprises a power module connected with the main controller MCU and the filter module respectively.

[0057] In order to further implement the above technical solutions, the simple radio frequency signal detection device is connected with the upper computer, and is used for converting the digital signal converted by the high-speed AD acquisition module by using the graphic display.

[0058] The working principle of the simple radio frequency signal detection device is as follows:

[0059] The ADF4351 module outputs a signal at a frequency of 90MHz-110MHz and a voltage amplitude of 200MV under the control of the single-chip microcomputer, controls the output signal voltage amplitude through the variable gain programmable amplifier, mixes the high-frequency signal and the local oscillator signal through the frequency mixer to generate a new frequency output, the output frequency is usually the sum or difference of the input signal and the local oscillator signal frequency, then the output frequency is filtered through the band-pass filter, and the frequency is transmitted to the single-chip microcomputer for demodulation processing, and then the signal collected by the single-chip microcomputer AD acquisition is transmitted to the upper computer for display.

[0060] In another embodiment, the frequency range and stepping test of the local oscillator source are carried out:

[0061] The maximum frequency and minimum frequency of the local oscillator source output signal frequency are observed by the oscilloscope through the single-chip microcomputer changing the frequency division coefficient in the phase-locked loop, then the output frequency is controlled to step from 90MHz to 110MHz by 100KHz each time, and whether the frequency of the oscilloscope output waveform meets the frequency requirement is observed, and part of the measurement results are as follows:

[0062] Set frequency / MHz Output frequency / MHz Set frequency / MHz Output frequency / MHz 90 90.1 105 104.0 95 95.2 110 111.0 102 101.0

[0063] Through actual circuit system test, the local oscillator source can output a standard stable sine wave, and the stepping of the frequency and the amplitude control of the output signal can obtain a relatively ideal effect; in actual test, after the input signal is given, the input signal is mixed with the signal output by the local oscillator source through the AD835 multiplier, and after filtering through the filter circuit, the system can obtain a stable standard sine wave.

[0064] The various embodiments described in this specification are presented by way of example, and each embodiment is presented for the purpose of conveying the novelty and inventive aspects of the present patent application. Each embodiment is presented in a progressive and explanatory manner, and each embodiment highlights differences from other embodiments. The same or similar parts and / or functions between embodiments are to be understood as mutual references among the embodiments.

[0065] The above description of disclosed embodiments enables one of ordinary skill in the art to make and use the patent application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the patent application. Thus, the present patent application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A simple radio frequency signal detection device, characterized by, It comprises: The local oscillator module, variable gain programmable amplifier module, mixing module, filtering module and main controller MCU; The local oscillator module, variable gain programmable amplifier module and filtering module are connected with the main controller MCU; The local oscillator module, variable gain programmable amplifier module, mixing module and filtering module are connected in sequence; The local oscillator module and the variable gain programmable amplifier module constitute a phase-locked loop for outputting frequency step adjustable and voltage amplitude adjustable signals; The main controller MCU is used for controlling and step adjusting the frequency of the local oscillator module output signal, controlling the voltage amplitude of the variable gain programmable amplifier module output signal, and collecting the voltage of the high frequency signal after filtering and processing, and restoring the waveform of the signal; The mixing module is used for mixing the received radio frequency signal with the output signal of the local oscillator module, and outputting the signal when the frequency of the mixing is equal to the intermediate frequency; The filtering module is used for filtering and amplifying the mixed signal.

2. The simple radio frequency signal detection device of claim 1, wherein, The main controller MCU adopts STM32 main control board data acquisition driving board.

3. The simple radio frequency signal detection device of claim 1, wherein, The local oscillator module adopts ADF4351, and the output signal frequency is 90MHz-110MHz, which can be step adjusted; the variable gain programmable amplifier module adopts VCA824, and the amplitude of the output signal is 10mV-100mV.

4. The simple radio frequency signal detection device of claim 1, wherein, The main controller MCU comprises a built-in high-speed AD acquisition module, which is used for peak detection of the output signal of the filtering module, multi-point collection of the voltage of the high frequency signal after filtering and processing, and conversion of the analog signal into digital signal and uploading.

5. The simple radio frequency signal detection device of claim 1, wherein, The mixing module is MCLSBL-1 mixer.

6. The simple radio frequency signal detection device of claim 1, wherein, The local oscillator module further comprises an LED display lamp connected with the main controller, which is used for displaying the locking condition of the phase-locked loop to the frequency by lighting and extinguishing.

7. The simple radio frequency signal detection device of claim 1, wherein, It further comprises a TFT display module for displaying the output frequency of the phase-locked loop and the local oscillator module.

8. The simple radio frequency signal detection device of claim 1, wherein, It further comprises a key module connected with the main controller, which realizes step control of the output frequency, adjustment of the output voltage and realization of the sweep function through the cross rectangular key and the main controller.

9. The simple radio frequency signal detection device of claim 1, wherein, It further comprises a power module connected with the main controller MCU and the filtering module respectively.

10. The simple radio frequency signal detection device of claim 4, wherein, It is connected with the upper computer, and is used for using the graphical display of the digital signal converted by the high-speed AD acquisition module.

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