CN110780117A - Simple spectrum analyzer - Google Patents
Simple spectrum analyzer Download PDFInfo
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- CN110780117A CN110780117A CN201911174915.3A CN201911174915A CN110780117A CN 110780117 A CN110780117 A CN 110780117A CN 201911174915 A CN201911174915 A CN 201911174915A CN 110780117 A CN110780117 A CN 110780117A
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
- G01R23/16—Spectrum analysis; Fourier analysis
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Abstract
The invention discloses a simple spectrum analyzer, relates to the technical field of spectrum analyzers, and solves the technical problems that the existing spectrum analyzer is complicated in operation and cannot automatically switch sampling frequency. It includes host system and display module, display module is used for showing the information of being carried by host system, still includes signal frequency acquisition module, decay module, AD sampling module and signal processing module, signal frequency acquisition module is connected with signal processing module, the decay module passes through AD sampling module and is connected with signal processing module, signal processing module is connected with host system, host system is connected with display module. The invention has simple structure, simple operation, wide measurement range and high measurement precision, and is suitable for teaching experiments; and the sampling frequency can be automatically switched to realize automatic measurement.
Description
Technical Field
The invention relates to the technical field of spectrum analyzers, in particular to a simple spectrum analyzer.
Background
The spectrum analyzer is a commonly used signal measuring instrument, and is mainly used for analyzing and processing audio signals and radio frequency signals, and the content of the spectrum analyzer mainly comprises the frequency, power, phase, distortion degree and the like of the measured signals. However, the existing spectrum analyzer generally has the problems of complex structure and function, high price and complex operation. Before use, a large amount of description data needs to be read or more time is spent on learning operation control; in the teaching experiment, the special guidance and teaching are needed for guiding the operation, the application range is small, and the teaching experiment is not beneficial to being used. In addition, most of the existing spectrum analyzers also need to artificially adjust the sampling frequency to obtain better display parameters, and the operation mode is inconvenient to use in the measurement process.
Disclosure of Invention
The invention aims to solve the technical problem of the prior art, and provides a simple spectrum analyzer which can automatically switch sampling frequency and is simple to operate.
The technical scheme of the invention is as follows: a simple spectrum analyzer comprises a main control module and a display module, wherein the display module is used for displaying information transmitted by the main control module, and also comprises a signal frequency acquisition module, an attenuation module, an AD sampling module and a signal processing module;
the signal frequency acquisition module carries out shaping processing on the acquired input signal to generate a frequency signal and transmits the frequency signal to the signal processing module;
the attenuation module attenuates the acquired input signal so that the voltage of the input signal after attenuation is adaptive to the sampling voltage of the AD sampling module, generates a differential signal according to the input signal after attenuation, and transmits the differential signal to the AD sampling module;
the AD sampling module generates a digital signal according to the differential signal and transmits the digital signal to the signal processing module;
the signal processing module stores and FFT conversion operation digital signals, the digital signals are transmitted to the main control module after FFT conversion operation, the signal processing module generates AD sampling frequency signals according to the frequency signals and transmits the AD sampling frequency signals to the AD sampling module, and the AD sampling module automatically switches sampling frequencies according to the AD sampling frequency signals.
The signal frequency acquisition module comprises a comparator, the input signal is connected with the forward input end of the comparator through a first resistor, the forward input end of the comparator is further connected with the output end of the comparator through a third resistor, the output end of the comparator is connected with the signal processing module through a fourth resistor, the output end of the comparator is further connected with the power supply end of the comparator through a fifth resistor, and the reverse output end of the comparator is grounded through a second resistor.
Further, the type adopted by the comparator is a TLV3501 comparator.
Furthermore, the attenuation module comprises a pi-type attenuation unit and a differential output unit, wherein the pi-type attenuation unit attenuates an input signal by at least 5 times and transmits the attenuated input signal to the differential output unit, and the differential output unit generates a differential signal according to the attenuated input signal.
Furthermore, the pi-type attenuation unit comprises a sixth resistor, a seventh resistor, an eighth resistor and a ninth resistor, the input signal is grounded through the eighth resistor, the input signal is also connected with one end of the ninth resistor through the sixth resistor and the seventh resistor which are connected in series, and the other end of the ninth resistor is grounded;
the differential output unit comprises an operational amplifier, the connecting end of the ninth resistor and the seventh resistor is connected with the positive input end of the operational amplifier through a tenth resistor, the positive input end of the operational amplifier is further connected with the first differential output end of the operational amplifier through an eleventh resistor, the first differential output end of the operational amplifier is further connected with one input end of the AD sampling module through a fifteenth resistor, and the connecting end of the fifteenth resistor and the AD sampling module is further grounded through a second capacitor; the reverse input end of the operational amplifier is grounded through a twelfth resistor and a thirteenth resistor which are connected in series, the reverse input end of the operational amplifier is further connected with a second differential output end of the operational amplifier through a fourteenth resistor, the second differential output end of the operational amplifier is further connected with another input end of the AD sampling module through a sixteenth resistor, the connecting end of the sixteenth resistor and the AD sampling module is grounded through a fourth capacitor, and a third capacitor is further connected between the connecting end of the sixteenth resistor and the AD sampling module and the connecting end of the fifteenth resistor and the AD sampling module.
Further, the operational amplifier is an OPA690 operational amplifier.
Furthermore, the AD sampling module comprises an AD sampling chip, a twenty-third pin of the AD sampling chip is connected with one end of a fifteenth resistor, a twenty-fourth pin of the AD sampling chip is connected with one end of a sixteenth resistor, the twentieth pin and the twenty-first pin of the AD sampling chip are connected with a noise suppression unit, and a data output pin of the AD sampling chip is connected with the signal processing module through exclusion.
Furthermore, the AD sampling chip adopts an AD9226 operational amplifier.
Advantageous effects
The invention has the advantages that: this spectral analysis appearance passes through signal frequency acquisition module and generates frequency signal according to input signal to carry it to signal processing module, signal processing module switches sampling frequency according to frequency signal control AD sampling module, so that the adoption frequency adaptation of AD sampling module is in input signal's frequency, thereby realized the automatic switching sampling frequency of this spectral analysis appearance, make its operation simpler, change in the use. The attenuation module attenuates the input signal and transmits the attenuated input signal to the AD sampling module in a differential signal mode, so that the spectrum analyzer is wider in measurement range and higher in practicability; the differential signal is generated into a digital signal through the AD sampling module and is transmitted to the signal processing module, so that the measurement precision of the spectrum analyzer is higher. In addition, the spectrum analyzer realizes measurement processing of input signals through the signal frequency acquisition module, the attenuation module, the AD sampling module, the signal processing module, the main control module and the display module, so that the circuit structure is simple, and the overall specification of the spectrum analyzer is effectively reduced.
Drawings
FIG. 1 is a block schematic of the present invention;
FIG. 2 is a schematic diagram of a circuit structure of a signal frequency acquisition module according to the present invention;
FIG. 3 is a schematic circuit diagram of an attenuating module according to the present invention;
fig. 4 is a schematic circuit diagram of an AD sampling module according to the present invention.
Detailed Description
The invention is further described below with reference to examples, but not to be construed as being limited thereto, and any number of modifications which can be made by anyone within the scope of the claims are also within the scope of the claims.
Referring to fig. 1, the simple spectrum analyzer of the present invention includes a main control module and a display module, wherein the display module is used for displaying information transmitted by the main control module. The main control module comprises an STM32 main control chip and is used for receiving the data information sent by the signal processing module and transmitting the data information to the TFT screen of the display module for display. The spectrum analyzer also comprises a signal frequency acquisition module, an attenuation module, an AD sampling module and a signal processing module.
Referring to fig. 2, the signal frequency acquisition module shapes the acquired input signal to generate a frequency signal, and transmits the frequency signal to the signal processing module. Specifically, the signal frequency acquisition module comprises a comparator U1. Preferably, the comparator U1 is a TLV3501 comparator. The input signal is connected to the positive input terminal of the comparator U1 through the first resistor R1, and the positive input terminal of the comparator U1 is also connected to the output terminal thereof through the third resistor R3. The third resistor R3 is a positive feedback resistor. The output end of the comparator U1 is connected with the signal processing module through a fourth resistor R4, and the output end of the comparator U1 is also connected with the power supply end thereof through a fifth resistor R5. The fifth resistor R5 is a pull-up resistor. The inverting output of the comparator U1 is connected to ground through a second resistor R2. Because the TLV3501 comparator is a single-limit comparator, a positive feedback network and a pull-up resistor which are formed by positive feedback resistors are introduced on the TLV3501 comparator, so that the threshold voltage of the TLV3501 comparator changes along with the change of the output voltage of the output end of the TLV3501 comparator, the TLV3501 comparator avoids the phenomenon of multiple triggering at the zero crossing point, the anti-interference capability of the TLV3501 comparator is improved, and the frequency signals acquired by the signal frequency acquisition module are more stable and reliable; and the signal processing module can more accurately measure the frequency of the frequency signal, and the measured frequency error is greatly reduced. In the embodiment, the signal frequency acquisition unit formed by the TLV3501 comparator and the peripheral devices thereof processes the input signal, so that the absolute error of the frequency of the input signal measured by the signal processing module is about 0.1Hz, and the measurement accuracy is greatly improved.
The attenuation module attenuates the acquired input signal so that the voltage of the attenuated input signal is adapted to the sampling voltage of the AD sampling module, and the attenuation module generates a differential signal according to the attenuated input signal and transmits the differential signal to the AD sampling module. Specifically, the attenuation module comprises a pi-type attenuation unit and a differential output unit, wherein the pi-type attenuation unit attenuates an input signal by at least 5 times and transmits the attenuated input signal to the differential output unit, and the differential output unit generates a differential signal according to the attenuated input signal. Preferably, the pi-type attenuation unit attenuates the input signal by 5 times, thereby making the frequency range of the input signal wider.
Referring to fig. 3, in the present embodiment, the pi attenuation unit includes a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, and a ninth resistor R9, the input signal is grounded through the eighth resistor R8, the input signal is further connected to one end of the ninth resistor R9 through the sixth resistor R6 and the seventh resistor R7 connected in series, and the other end of the ninth resistor R9 is grounded. The differential output unit includes an operational amplifier U2. Preferably, operational amplifier U2 is an OPA690 operational amplifier. The connection end of the ninth resistor R9 and the seventh resistor R7 is connected with the positive input end of the operational amplifier U2 through a tenth resistor R10, the positive input end of the operational amplifier U2 is further connected with the first differential output end thereof through an eleventh resistor R11, the first differential output end of the operational amplifier U2 is further connected with an input end of the AD sampling module through a fifteenth resistor R15, and the connection end of the fifteenth resistor R15 and the AD sampling module is further grounded through a second capacitor C2. The inverting input end of the operational amplifier U2 is grounded through a twelfth resistor R12 and a thirteenth resistor R13 which are connected in series, the inverting input end of the operational amplifier U2 is further connected with the second differential output end thereof through a fourteenth resistor R14, the second differential output end of the operational amplifier U2 is further connected with the other input end of the AD sampling module through a sixteenth resistor R16, and the connection end of the sixteenth resistor R16 and the AD sampling module is further grounded through a fourth capacitor C4. And a third capacitor C3 is connected between the connection end of the sixteenth resistor R16 and the AD sampling module and the connection end of the fifteenth resistor R15 and the AD sampling module. The ground terminal of the operational amplifier U2 is grounded through the first capacitor C1. In the embodiment, the input signal is attenuated by the attenuation module, so that the frequency range of the input signal can reach 1Hz-1MHz, and the frequency range of the input signal is greatly improved.
Referring to fig. 4, the AD sampling module generates a digital signal according to the differential signal and transmits the digital signal to the signal processing module. Specifically, the AD sampling module includes an AD sampling chip U3. Preferably, the model of the AD sampling chip U3 is an AD9226 operational amplifier. The twenty-third pin of the AD sampling chip U3 is connected to one end of the fifteenth resistor R15, and the twenty-fourth pin of the AD sampling chip U3 is connected to one end of the sixteenth resistor R16, so that the differential signal is transmitted to the AD sampling chip U3. And the twentieth pin and the twenty-first pin of the AD sampling chip U3 are connected with a noise suppression unit. The noise suppression unit comprises a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7 and an eighth capacitor C8. The twentieth pin of the AD sampling chip U3 is grounded through a seventh capacitor C7, the twenty-first pin of the AD sampling chip U3 is grounded through an eighth capacitor C8, and a fifth capacitor C5 and a sixth capacitor C6 which are connected in parallel are further connected between the twentieth pin and the twenty-first pin of the AD sampling chip U3. The data output pin of the AD sampling chip U3 is connected with the signal processing module through the exclusion Rp 1.
The signal processing module stores and FFT conversion operation is carried out on the digital signal, and information obtained after the FFT conversion operation is carried out on the digital signal is transmitted to the main control module. Specifically, the signal processing module comprises a programmable device FPGA, which is of the model EP4CE6E22C 8. And reading a digital signal of a data output pin on the AD sampling chip U3 through a fifty-ninth pin, a sixty-sixth pin and a sixty-fifth to seventy-fourth pin of the FPGA, storing the digital signal and performing FFT conversion operation on the digital signal, and then transmitting the operated information to the STM32 main control chip through an SPI protocol.
The FPGA used in this embodiment is a programmable device with an FFT IP core already designed. Therefore, the number of data bits used on the FPGA is determined, the acquired digital signals are converted through FFT change operation, and then the driver for driving the FFT IP core is downloaded into the FPGA. The input signal is processed by the FPGA adopting the FFT IP core, so that the development time is greatly reduced, the later maintenance is facilitated, and the maintenance difficulty is reduced.
The signal processing module also generates an AD sampling frequency signal according to the frequency signal, and transmits the AD sampling frequency signal to the AD sampling module, so that the AD sampling module can automatically switch the sampling frequency. Specifically, the TLV3501 comparator transmits the frequency signal to the one hundred forty one pin of the FPGA through the fourth resistor R4, so as to complete the collection of the frequency signal. The FPGA segments the acquired frequency signals according to set time, and performs mean value processing on the frequency signals in each segment to obtain a frequency mean value, wherein the frequency mean value is the frequency value of the AD sampling frequency signals. And a seventeenth pin of the FPGA is connected with the first pin of the AD sampling chip U3 through a seventeenth resistor R17, so that the AD sampling frequency signal is transmitted to the AD sampling chip U3. The frequency value of the AD sampling frequency signal is used as the frequency of the AD sampling chip U3.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can make various changes and modifications without departing from the structure of the invention, which will not affect the effect of the invention and the practicability of the patent.
Claims (8)
1. A simple spectrum analyzer comprises a main control module and a display module, wherein the display module is used for displaying information transmitted by the main control module, and is characterized by further comprising a signal frequency acquisition module, an attenuation module, an AD sampling module and a signal processing module;
the signal frequency acquisition module carries out shaping processing on the acquired input signal to generate a frequency signal and transmits the frequency signal to the signal processing module;
the attenuation module attenuates the acquired input signal so that the voltage of the input signal after attenuation is adaptive to the sampling voltage of the AD sampling module, generates a differential signal according to the input signal after attenuation, and transmits the differential signal to the AD sampling module;
the AD sampling module generates a digital signal according to the differential signal and transmits the digital signal to the signal processing module;
the signal processing module stores and FFT conversion operation digital signals, information after the FFT conversion operation of the digital signals is transmitted to the main control module, the signal processing module generates AD sampling frequency signals according to the frequency signals and transmits the AD sampling frequency signals to the AD sampling module, and the AD sampling module automatically switches sampling frequencies according to the AD sampling frequency signals to adapt to the frequency of the input signals.
2. The simple spectrum analyzer as claimed in claim 1, wherein the signal frequency acquisition module comprises a comparator (U1), the input signal is connected to the positive input terminal of the comparator (U1) through a first resistor (R1), the positive input terminal of the comparator (U1) is further connected to the output terminal of the comparator (U3) through a third resistor (R3), the output terminal of the comparator (U1) is connected to the signal processing module through a fourth resistor (R4), the output terminal of the comparator (U1) is further connected to the power supply terminal of the comparator (U5) through a fifth resistor (R5), and the reverse output terminal of the comparator (U1) is grounded through a second resistor (R2).
3. The simple spectrum analyzer as claimed in claim 2, wherein the comparator (U1) is a TLV3501 comparator.
4. The simple spectrum analyzer as claimed in claim 1, wherein the attenuation module comprises a pi-type attenuation unit and a differential output unit, the pi-type attenuation unit attenuates an input signal by at least 5 times and transmits the attenuated input signal to the differential output unit, and the differential output unit generates a differential signal according to the attenuated input signal.
5. The simplified spectrum analyzer as claimed in claim 4, wherein the pi-type attenuation unit comprises a sixth resistor (R6), a seventh resistor (R7), an eighth resistor (R8) and a ninth resistor (R9), the input signal is grounded through the eighth resistor (R8), the input signal is further connected with one end of the ninth resistor (R9) through the sixth resistor (R6) and the seventh resistor (R7) which are connected in series, and the other end of the ninth resistor (R9) is grounded;
the differential output unit comprises an operational amplifier (U2), the connection end of the ninth resistor (R9) and the seventh resistor (R7) is connected with the positive input end of the operational amplifier (U2) through a tenth resistor (R10), the positive input end of the operational amplifier (U2) is further connected with the first differential output end thereof through an eleventh resistor (R11), the first differential output end of the operational amplifier (U2) is further connected with one input end of the AD sampling module through a fifteenth resistor (R15), and the connection end of the fifteenth resistor (R15) and the AD sampling module is further grounded through a second capacitor (C2); the inverting input end of the operational amplifier (U2) is grounded through a twelfth resistor (R12) and a thirteenth resistor (R13) which are connected in series, the inverting input end of the operational amplifier (U2) is also connected with the second differential output end of the operational amplifier through a fourteenth resistor (R14), the second differential output end of the operational amplifier (U2) is also connected with the other input end of the AD sampling module through a sixteenth resistor (R16), the connection end of the sixteenth resistor (R16) and the AD sampling module is also grounded through a fourth capacitor (C4), and a third capacitor (C3) is further connected between the connection end of the sixteenth resistor (R16) and the AD sampling module and the connection end of the fifteenth resistor (R15) and the AD sampling module.
6. The simple spectrum analyzer as claimed in claim 5, wherein the operational amplifier (U2) is an OPA690 operational amplifier.
7. The simple spectrum analyzer as claimed in claim 1, wherein the AD sampling module comprises an AD sampling chip (U3), the twenty-third pin of the AD sampling chip (U3) is connected with one end of a fifteenth resistor (R15), the twenty-fourth pin of the AD sampling chip (U3) is connected with one end of a sixteenth resistor (R16), the twentieth pin and the twenty-first pin of the AD sampling chip (U3) are connected with a noise suppression unit, and the data output pin of the AD sampling chip (U3) is connected with the signal processing module through a resistor (Rp 1).
8. The simple spectrum analyzer as claimed in claim 7, wherein the AD sampling chip (U3) is an AD9226 operational amplifier.
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| CN201911174915.3A CN110780117A (en) | 2019-11-26 | 2019-11-26 | Simple spectrum analyzer |
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| CN201911174915.3A CN110780117A (en) | 2019-11-26 | 2019-11-26 | Simple spectrum analyzer |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111932861A (en) * | 2020-07-16 | 2020-11-13 | 国网湖北省电力有限公司宜昌供电公司 | Multifunctional power carrier concentrator |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111932861A (en) * | 2020-07-16 | 2020-11-13 | 国网湖北省电力有限公司宜昌供电公司 | Multifunctional power carrier concentrator |
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