CN218041406U

CN218041406U - Remote amplitude-frequency characteristic tester

Info

Publication number: CN218041406U
Application number: CN202222660463.3U
Authority: CN
Inventors: 石文强; 周宇; 王锡坤; 张秀丽
Original assignee: Zhejiang Wanli University
Current assignee: Zhejiang Wanli University
Priority date: 2022-10-10
Filing date: 2022-10-10
Publication date: 2022-12-13
Anticipated expiration: 2032-10-10

Abstract

The utility model discloses a remote amplitude-frequency characteristic tester, which comprises a microcontroller module, a DDS signal generator module, an AGC signal amplifier module and an amplitude detection module; the microcontroller module controls the DDS signal generator module to output sine frequency sweeping signals required by amplitude-frequency characteristic testing, the sine frequency sweeping signals are amplified by the AGC signal amplifier module and then are connected to the input end of the circuit to be tested after the amplitude is stable, the output signals of the circuit to be tested are converted into direct current voltage containing sine frequency sweeping signal amplitude information through the amplitude detection module and are transmitted to the microcontroller module, and the microcontroller module samples and calculates the amplitude of the sine frequency sweeping signals output by the circuit to be tested. The utility model discloses a high performance singlechip STM32F407ZET6 control AD9959 signal generator module has realized constant amplitude sweep frequency signal output, through amplitude detection circuit and WIFI module, has realized short range and long-range amplitude frequency characteristic test, and it is simple to have hardware, and is with low costs, characteristics such as small.

Description

Remote amplitude-frequency characteristic tester

Technical Field

The utility model relates to a rack technical field for the refrigerator specifically is a long-range amplitude-frequency characteristic test appearance.

Background

The amplitude-frequency characteristic tester is an instrument for measuring the transmission characteristics of various devices, and is one of important instruments for measuring the frequency domain of a linear system. The traditional analog amplitude-frequency characteristic tester is large in size and cannot store an amplitude-frequency characteristic curve, thousands of digital amplitude-frequency characteristic testers are very expensive for users in low-end application occasions, the hardware design is complex, the power consumption is high, and a signal generator capable of outputting a sweep frequency signal is required to be arranged during use; the existing amplitude-frequency characteristic tester has the problems of high price, large volume, inconvenience in use and the like.

SUMMERY OF THE UTILITY MODEL

In order to solve the technical problem, the utility model provides a following technical scheme:

the utility model relates to a remote amplitude-frequency characteristic tester, which comprises a microcontroller module, a DDS signal generator module, an AGC signal amplifier module and an amplitude detection module; the AGC signal amplifier module is connected with the microcontroller module through the DDS signal generator module, and the amplitude detection module is connected with the microcontroller module; the amplitude detection module is used for collecting amplitude information of the output end of the circuit to be detected;

the DDS signal generator module is controlled by the microcontroller module to output sine frequency sweeping signals required by amplitude-frequency characteristic testing, the sine frequency sweeping signals are amplified by the AGC signal amplifier module and then are connected to the input end of the circuit to be tested after the amplitude is stable, the output signals of the circuit to be tested are converted into direct current voltage containing sine frequency sweeping signal amplitude information through the amplitude detection module and are transmitted to the microcontroller module, and the microcontroller module samples and calculates the amplitude of the sine frequency sweeping signals output by the circuit to be tested;

the intelligent control system also comprises a communication module connected with the microcontroller module, and the microcontroller module is connected with the upper computer through the communication module.

As a preferred technical scheme of the utility model, still include the liquid crystal display module of being connected with the microcontroller module.

As a preferred technical scheme of the utility model, what microcontroller module adopted is STM32F407ZET6 handles the chip.

As a preferred technical scheme of the utility model, what DDS signal generator module adopted is AD9959 integrated chip, and what adopt between AD9959 integrated chip and the STM32F407ZET6 processing chip is SPI bus communication mode.

As an optimized technical scheme of the utility model, communication module is wiFi communication module.

The utility model has the advantages that:

this kind of long-range amplitude-frequency characteristic tester passes through high performance singlechip STM32F407ZET6 control AD9959 signal generator module, has realized constant amplitude sweep frequency signal output, through amplitude detection circuitry and WIFI module, has realized short range and long-range amplitude-frequency characteristic test, has that hardware is simple, and is with low costs, characteristics such as small.

Drawings

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 is a system block diagram of a remote amplitude-frequency characteristic tester of the present invention;

fig. 2 is a circuit diagram of a microcontroller module of a remote amplitude-frequency characteristic tester of the present invention;

fig. 3 is a circuit diagram of an AD9959 of a remote amplitude-frequency characteristic tester of the present invention;

fig. 4 is a circuit diagram of an AGC signal amplifier module of a remote amplitude-frequency characteristic tester of the present invention;

fig. 5 is a circuit diagram of an amplitude detection module of the remote amplitude-frequency characteristic tester of the present invention;

fig. 6 is a flowchart of a main program of a remote amplitude-frequency characteristic tester according to the present invention;

fig. 7 is a frequency sweep signal generation interface of a remote amplitude-frequency characteristic tester of the present invention;

fig. 8 is an amplitude-frequency characteristic curve measured by the remote amplitude-frequency characteristic tester of the present invention.

In the figure: 1. a microcontroller module; 2. a DDS signal generator module; 3. an AGC signal amplifier module; 4. an amplitude detection module; 5. a circuit to be tested; 6. a communication module; 7. a liquid crystal display module.

Detailed Description

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are presented herein only to illustrate and explain the present invention, and not to limit the present invention.

Example (b): as shown in fig. 1, the utility model relates to a remote amplitude-frequency characteristic tester, which comprises a microcontroller module 1, a DDS signal generator module 2, an AGC signal amplifier module 3 and an amplitude detection module 4; the AGC signal amplifier module 3 is connected with the microcontroller module 1 through the DDS signal generator module 2, and the amplitude detection module 4 is connected with the microcontroller module 1; the amplitude detection module 4 is used for collecting amplitude information of the output end of the circuit to be tested 5;

the microcontroller module 1 controls the DDS signal generator module 2 to output sine frequency sweeping signals required by amplitude-frequency characteristic test, the sine frequency sweeping signals are amplified by the AGC signal amplifier module 3 and then have stable amplitude and are connected to the input end of the circuit to be tested 5, the output signals of the circuit to be tested 5 are converted into direct current voltage containing sine frequency sweeping signal amplitude information through the amplitude detection module 4 and are transmitted to the microcontroller module 1, and the microcontroller module 1 samples and calculates the amplitude of the sine frequency sweeping signals output by the circuit to be tested;

the device also comprises a communication module 6 connected with the microcontroller module 1, wherein the communication module 6 is a WiFi communication module; the microcontroller module 1 is connected with an upper computer through a communication module 6. Through high performance singlechip STM32F407ZET6 control AD9959 signal generator module, realized the constant amplitude sweep frequency signal output, through amplitude detection circuitry and WIFI module, realized short range and long-range amplitude-frequency characteristic test, have that hardware is simple, with low costs, characteristics such as small. The microcontroller module controls the AD9959 signal generator module to output sine sweep frequency signals required by the amplitude-frequency characteristic test, the amplitude of the sweep frequency signals is stabilized to 1V after the sweep frequency signals are amplified by the AGC signal amplifier module, the sweep frequency signals are connected to the input end of the circuit to be tested, the output signals of the circuit to be tested are converted into direct current voltage containing sine sweep frequency signal amplitude information through the amplitude detection module, the microcontroller module carries out AD sampling and calculates the amplitude of the sine sweep frequency signals output by the circuit to be tested, gain data of the circuit to be tested under corresponding frequency are obtained through calculation of the microcontroller module, finally gain data of the circuit to be tested under different frequency are obtained through multiple tests, the amplitude-frequency characteristic curve of the circuit to be tested is drawn according to the gain data, the gain data are displayed on a liquid crystal display screen or are uploaded to an upper computer, and the upper computer can be a PC.

The device also comprises a liquid crystal display screen module 7 connected with the microcontroller module 1 and capable of carrying out short-range display.

The microcontroller module 1 adopts an STM32F407ZET6 processing chip, belongs to an STM32F4 series single chip microcomputer, adopts a 90nm NVM process, is internally provided with a 512KB FLASH program memory and has (192 + 4) KB SRAM, and is a high-performance single chip microcomputer. The microcontroller module 1 is the core of the system and controls the DDS signal generator module to output sine signals required by testing and complete human-computer interaction and other operations of liquid crystal display control. The circuit diagram of the microcontroller module 1 is shown in fig. 2, JP1 is an interface for connecting a 2.8-inch TFT-LCD resistive touch screen, and JP2 is an interface for connecting an AD9959 signal generation module.

The DDS signal generator module adopts an AD9959 integrated chip, and an SPI bus communication mode is adopted between the AD9959 integrated chip and an STM32F407ZET6 processing chip. It is composed of AD9959 integrated chip, peripheral circuit and low-pass filter. The microcontroller module 1 controls the AD9959 to output a series of sinusoidal signals of different frequencies, i.e. frequency sweep signals. The circuitry of the DDS signal generator module is shown in FIG. 3. In the design, an SPI bus communication mode is adopted between an AD9959 single chip microcomputer and an STM32 single chip microcomputer, wherein AD59_ SCLK is an SPI clock signal line; AD59_ CS is the chip select signal line of the SPI bus; AD59_ SD0 is two-way data pin line, and AD59_ CS, AD59_ SD0 and AD59_ SCLK link to each other with singlechip PC5, PB12 and PC4 respectively. The AD9959 can output 4 signals at most, which are respectively CH0, CH1, CH2 and CH3 ports. In order to filter out high-frequency clutter, the signal output end is connected with a 4-order low-pass filter.

Because the amplitude of the sweep frequency signal output by the AD9959 is only 0.5v at most, the driving capability is weak, and the amplitude fluctuation is large, the amplitude can be used for the amplitude-frequency characteristic test after the signal amplification is carried out by the AGC signal amplifier module. In order to obtain a sine wave signal with a stable voltage amplitude in the frequency range of 10KHz-10MHz, the project adopts an Automatic Gain Control (AGC) amplifier module consisting of a VCA821 voltage-controlled gain amplification chip, an OPA695 current feedback operational amplifier chip and an OPA820 voltage feedback operational amplifier, and the circuit of the amplifier module is shown in FIG. 4. In fig. 4, the OPA695 constitutes a non-inverting amplifier, which is mainly used for improving the load capacity of the overall circuit; the circuit composed of the OPA820 inverse integrator and the diode D1 mainly generates an AGC control voltage, when the peak value of the output voltage of the OPA695 is lower than the OPA820_ VREF, the diode is reverse biased, at this time, although the diode is cut off, because the diode forms reverse leakage under the action of the reverse voltage, the currents charge the integrating capacitor, the charging direction is from left to right, so that the output voltage of the integrator is increased, the voltage of the Vg end (control end) of the VCA821 is increased, the gain of the voltage-controlled gain amplifier can be increased accordingly, and the purpose of increasing the amplitude of the output signal is achieved, and vice versa. It can be seen that the amplification of the entire amplification circuit can be varied in this module by adjusting the voltage of OPA820_ VREF. The design mainly aims to test the gain conditions of the circuit to be tested under different frequencies, and for convenience of calculation, the amplitude of a sinusoidal frequency sweeping signal Vout1 output after the amplification of the AGC amplification circuit is stabilized to be 1V.

The utility model discloses a full wave rectification filter circuit who comprises OPA365 low noise single power rail to rail operational amplifier, resistance and electric capacity realizes the sinusoidal frequency sweep signal's of the circuit output that awaits measuring amplitude detects. The sinusoidal signal is converted into a direct-current voltage signal related to the amplitude of the sinusoidal signal after full-wave rectification and filtering, and then the sinusoidal signal at the input end of the amplitude detection module, namely the amplitude of the signal at the output end of the circuit to be detected, is obtained through sampling and calculation of an ADC port of the STM 32. The amplitude detection circuit is shown in fig. 5.

In fig. 5, when the voltage value of the signal at the input port Vin1 is greater than or equal to 0V, the OPA365 (U1) of the first stage constitutes a single power supply voltage follower circuit, and the voltage output from the port Vout _1 of the first stage is equal to the voltage value of the signal at the input port Vin 1. The second stage is composed of OPA365 (U2) and resistor R ₁ And R ₂ The non-inverting amplifier circuit is formed, and the calculation formula of the voltage value of the output port of the second stage Vout _2 at the time is shown as (3).

The utility model discloses get R1= R2, so Vout-2= Vin1, the signal of Vout_2 output port is the sinusoidal signal's of amplitude detection module input positive half cycle signal promptly this moment.

When the voltage value of the signal input to the Vin1 port is smaller than 0V, the voltage output from the first stage Vout _1 port is constantly 0V since the OPA365 (U1) is a single-power operational amplifier chip. At this time, the second stage constitutes a negative feedback amplifying circuit, and the calculation formula of the voltage value at the output port of the second stage Vout _2 is shown in (4). Due to R ₁ ＝R ₂ Therefore, the amplification factor of the amplification circuit is-1.

As can be seen from equations (3) and (4), fig. 5 realizes full-wave rectification. Full-wave rectified and passed through C ₁ And R ₃ And filtering to obtain a stable direct current signal. In circuit D ₁ Is a diode for preventing the output voltage from being less than C when Vout _2 is lower than C ₁ Capacitor voltage time C ₁ The capacitor voltage flows backward to cause the failure of the full-wave rectifying circuit. The calculation formula of the dc voltage value at the output terminal Vout2 of the amplitude detection circuit shown in fig. 5 is shown in equation (5) [7 ]]Namely, the input signal amplitude detection is realized.

In formula (5): uout2 is a direct-current voltage value after full-wave rectification and filtration; uin1 is the effective value of the input signal of the amplitude detection module.

In addition the utility model discloses use Keil uVision5 to carry out system function development as development software to STM32F407ZET6 programming. The touch screen is used as an operation structure of the human-computer interaction center, different module programs are packaged into functions, and the functions are called and executed by the main program to realize the design function. The software design mainly comprises a main program, an operating system function, an AD9959 control function, a touch screen driving function, an ADC sampling function, an amplitude-frequency characteristic calculation function and a WIFI communication program design.

The main program flow chart is shown in fig. 6. The main program firstly initializes each module to ensure the normal operation of the single chip system according to the expected purpose. And then calling a touch screen driving function, and realizing the design of sine signals, frequency sweeping signals and amplitude-frequency characteristic test parameters through the touch screen.

The graphical display interface designs 1 menu interface and 3 work interfaces according to functions. The working interfaces are respectively as follows: the device comprises a sine wave signal generator interface, a sweep frequency signal generator interface and an amplitude-frequency characteristic test interface. And each function interface is flexibly switched through a menu interface. In the interface of the sinusoidal signal generator, the parameters of the output sinusoidal signal can be adjusted by inputting frequency, phase and amplitude data through a numeric keyboard. In the interface of the sweep signal generator, the initial frequency, the final frequency, the step frequency and the time parameter of the frequency change are input through a numeric keyboard, and the sweep signal meeting the test requirement is output, and the interface is shown in fig. 7. The amplitude-frequency characteristic test interface displays the amplitude-frequency characteristic curve of the tested network, and the initial frequency, the stepping frequency, the frequency change time parameters and the like are input through a digital keyboard, and the interface is shown in an experimental result part.

The signal generator of the instrument is used as a signal source, the amplitude of a sine wave signal at the output end of the AGC signal amplifier module is calibrated to be 1V, and then a circuit is connected: connecting the output end Vout1 of the signal amplifier to the input end Vin of the circuit to be tested; the output end Vout of the circuit to be tested is connected to the input end Vin1 of the amplitude detection module, and then the output end Vout2 of the amplitude detection module is connected to the ADC sampling port of the instrument.

And then testing the amplitude-frequency characteristic curve of the circuit to be tested by using a frequency sweeping method. Adjusting the parameters of the start frequency, the end frequency, the sweep frequency stepping and the like of the sweep frequency signal source carried by the instrument, starting to measure and drawing an amplitude-frequency characteristic curve, and referring to fig. 8, the actually measured amplitude-frequency characteristic curve is drawn.

The tester uses an STM32F407ZET6 single chip microcomputer as a control and data processing core. The high-performance AD9959DDS chip and the VCA821 automatic gain balance amplifier generate a constant amplitude sweep frequency signal, the amplitude signal is detected by the OPA365 module, and finally the amplitude-frequency characteristic of the circuit to be detected is obtained through ADC sampling and data processing. On the output display terminal of the amplitude-frequency characteristic: the TFT type display screen is selected by proximity. The WIFI circuit module ESP8266 which has a longer and more stable signal transmission distance is selected remotely, and the information of the signal source to be tested and the amplified information are displayed on a computer through an upper computer through an amplitude-frequency characteristic testing device. The test result shows that the amplitude-frequency characteristic tester designed by the method can generate sine signals and frequency sweeping signals with stable amplitude and smooth waveforms, and local test and remote test of the amplitude-frequency characteristic are realized.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described in the foregoing embodiments, or equivalents may be substituted for elements thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A long-range amplitude-frequency characteristic tester is characterized in that: the device comprises a microcontroller module (1), a DDS signal generator module (2), an AGC signal amplifier module (3) and an amplitude detection module (4); the AGC signal amplifier module (3) is connected with the microcontroller module (1) through the DDS signal generator module (2), and the amplitude detection module (4) is connected with the microcontroller module (1); the amplitude detection module (4) is used for collecting amplitude information of the output end of the circuit to be detected (5);

the method comprises the following steps that a microcontroller module (1) controls a DDS signal generator module (2) to output sine frequency sweeping signals required by amplitude-frequency characteristic testing, the sine frequency sweeping signals are amplified by an AGC signal amplifier module (3) and then are connected to the input end of a circuit to be tested (5), the output signals of the circuit to be tested (5) are converted into direct current voltages containing sine frequency sweeping signal amplitude information through an amplitude detection module (4) and are transmitted to the microcontroller module (1), and the microcontroller module (1) samples and calculates the amplitude of the sine frequency sweeping signals output by the circuit to be tested;

still include communication module (6) be connected with microcontroller module (1), microcontroller module (1) is connected with the host computer through communication module (6).

2. A remote amplitude-frequency characteristic tester as claimed in claim 1, characterized by further comprising a liquid crystal display screen module (7) connected to the microcontroller module (1).

3. A remote amplitude-frequency characteristic tester as claimed in claim 1, characterized in that the microcontroller module (1) uses STM32F407ZET6 processing chip.

4. The remote amplitude-frequency characteristic tester as claimed in claim 3, wherein the DDS signal generator module adopts an AD9959 integrated chip, and an SPI bus communication mode is adopted between the AD9959 integrated chip and the STM32F407ZET6 processing chip.

5. The remote amplitude-frequency characteristic tester as claimed in claim 1, wherein the communication module (6) is a WiFi communication module.