A programmable method for amplifying weak signals

Abstract

The present invention provides a weak signal amplification adjustable programmable method, the method includes: a weak signal enters a measured signal channel for preprocessing to remove noise in the weak signal and is amplified; a reference signal enters a reference signal channel for preprocessing; a correlator outputs a difference frequency signal with an improved signal-to-noise ratio; a data acquisition module detects the difference frequency signal with an improved signal-to-noise ratio and converts it into a digital signal, which is then input into an FPGA module to collect and record the signal and output a signal subvalue, superimposing different types of signals; a host computer observes the waveform of the sample, detects the amplitude and frequency of the weak signal, and adjusts the weak signal amplification degree as needed. The weak signal amplification adjustable programmable method provided by the present invention suppresses noise by modulation and demodulation, multiplies a DC or slow-changing signal with a sinusoidal signal or a square wave signal, and migrates the signal spectrum to both sides, thereby eliminating the interference of noise with the same frequency as the signal, and also avoiding the gain of the subsequent amplification circuit to the interference of the same frequency noise.

Description

Technical Field

[0001] The invention belongs to the technical field of signal amplification, and in particular relates to an adjustable program-controlled method for amplifying weak signals. Background Art

[0002] With the advent of the new technological revolution, the world has entered the information age. In the process of using information, the first thing to solve is to obtain accurate and reliable information, and sensors are the main way and means to obtain information in the natural and production fields.

[0003] This technology is the primary link to achieve automatic detection and automatic control. Due to the high output impedance of the sensor, the output electrical signal is often very weak, and sometimes even has strong electromagnetic and external noise interference. Weak signal amplification has always been a difficult problem. Usually, the signals received by the sensor are very weak, and most of the time they are buried in the environmental noise. Therefore, to collect such weak signals, they are generally first amplified and filtered to remove irrelevant interference and noise, and the signal amplification amplitude must reach the signal range that the subsequent data acquisition system can receive. In particular, the initial signal amplitude reaches the microvolt level and the impedance is large. Although the prior art has a reference signal path as a reference, the circuit design is very difficult and the noise is difficult to control. Summary of the invention

[0004] In view of the above-mentioned defects, the present invention provides an adjustable program-controlled method for amplifying a weak signal, which can output a difference frequency signal with a high signal-to-noise ratio.

[0005] The present invention provides the following technical solution: a method for adjustable program-controlled weak signal amplification, comprising the following steps:

[0006] 1) After the weak signal enters the measured signal channel and is pre-processed, the noise in the weak signal is removed and the signal is amplified;

[0007] 2) The reference signal enters the reference signal channel and is preprocessed;

[0008] 3) The pre-processed weak signal and the pre-processed reference signal are input to a correlator, which processes them and outputs a difference frequency signal with an improved signal-to-noise ratio;

[0009] 4) The difference frequency signal with improved signal-to-noise ratio is detected in the data acquisition module and then input into the A / D converter to be converted into an 8-bit or 16-bit digital signal. The digital signal is input into the FPGA module to collect and record the signal and output the signal value, and different types of signals are superimposed and input into the host computer through the USBBlaster driver module;

[0010] 5) The host computer observes the waveform of the sample, detects the amplitude and frequency of the weak signal, and adjusts the amplification degree of the weak signal as needed.

[0011] Furthermore, the weak signal preprocessing step in step 1) comprises the following steps:

[0012] 1.1) A weak signal enters the measured signal channel and is amplified by the preamplifier to a switching level that can be detected by the correlator;

[0013] 1.2) The signal amplified by the preamplifier enters the bandpass filter to filter out the noise in the noise frequency band of the amplified signal;

[0014] 1.3) The amplified signal after filtering and removing noise enters the first amplifier again, and the amplified signal after filtering and removing noise is amplified again.

[0015] Furthermore, the reference signal preprocessing in step 2) includes the following steps:

[0016] 2.1) The reference signal entering the reference signal channel is processed by a second amplifier to amplify the reference signal to meet the starting level in the correlator;

[0017] 2.2) The amplified reference signal enters the phase shifter, and the phase of the amplified reference signal is adjusted to ensure that the phase difference between the preprocessed reference signal and the weak signal preprocessed in step 1) meets the processing requirements of the correlator.

[0018] Further, the step 3) comprises the following steps:

[0019] 3.1) performing a multiplication operation on the preprocessed input signal obtained in step 1) and the preprocessed reference signal obtained in step 2) to output a frequency multiplication signal and a frequency difference signal;

[0020] 3.2) After the frequency doubling signal and the difference frequency signal are filtered out by a low-pass filter module in the correlator, a difference frequency signal with improved signal-to-noise ratio is output.

[0021] Furthermore, the reference signal is a sine wave or a square wave.

[0022] The present invention also provides a weak signal amplification adjustable program-controlled system using the above method, the system comprising a weak signal detection module, the system also comprising a measured signal channel composed of a preamplifier, a bandpass filter and a first amplifier connected in sequence, a reference signal channel composed of a second amplifier and a phase shifter, a correlator connected to the measured signal channel and the reference signal channel, and a data acquisition module connected to the correlator; the data acquisition module comprises an A / D conversion module, an FPGA module, a USB Blaster driver module and a host computer connected in sequence to the correlator.

[0023] Furthermore, the correlator includes a phase-sensitive detection module and a low-pass filtering module. The phase-sensitive detection module is used to multiply the preprocessed input signal and the preprocessed reference signal to output a frequency doubled signal and a frequency difference signal; the low-pass filtering module is used to filter out the high-frequency signal in the output signal of the phase-sensitive detection module and only output a DC voltage signal.

[0024] Furthermore, the phase-sensitive detection module is one of LZX1C, AD630, HJ002C or MXT002.

[0025] Furthermore, the bandpass filter is an active filter.

[0026] Furthermore, the model of the active filter is one of MAX7480ESA+T, MAX275BCWP+, MAX274ACNG or MAX7408CUA+.

[0027] The beneficial effects of the present invention are:

[0028] 1. The adjustable programmable method for weak signal amplification provided by the present invention can effectively preprocess the reference signal and the input weak signal respectively, and then use the correlator to multiply the two preprocessed reference signals and the weak signal, and finally eliminate the high-frequency signal in the output signal of the phase-sensitive detection module through the low-pass filter module, and only output the DC voltage signal, that is, the difference frequency signal with a high signal-to-noise ratio, thereby improving the accuracy of the waveform analysis performed by the host computer.

[0029] 2. The adjustable programmable method for weak signal amplification provided by the present invention suppresses noise through modulation and demodulation methods, multiplies a DC or slow-changing signal with a sinusoidal signal or a square wave signal, and migrates the signal's spectrum to both sides, thereby eliminating the noise interference of the same frequency as the signal and avoiding the gain of the subsequent amplification circuit to the same frequency noise interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be described in more detail below based on embodiments and with reference to the accompanying drawings, wherein:

[0031] Figure 1A schematic diagram of the process flow of the adjustable program-controlled method for weak signal amplification provided by the present invention;

[0032] Figure 2 A schematic diagram of a weak signal preprocessing process provided by the present invention;

[0033] Figure 3 A schematic diagram of a reference signal preprocessing process provided by the present invention;

[0034] Figure 4 A schematic diagram of a process flow of a correlator provided by the present invention processing a pre-processed weak signal and a pre-processed reference signal;

[0035] Figure 5 This is a schematic diagram of the structure of the adjustable program-controlled system for weak signal amplification provided by the present invention. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Example 1

[0038] like Figure 1 As shown, a weak signal amplification adjustable program control method provided by the present invention comprises the following steps:

[0039] 1) After the weak signal enters the measured signal channel and is pre-processed, the noise in the weak signal is removed and the signal is amplified;

[0040] 2) The reference signal enters the reference signal channel and is preprocessed;

[0041] 3) The pre-processed weak signal and the pre-processed reference signal are input to the correlator, which processes them and outputs a difference frequency signal with improved signal-to-noise ratio;

[0042] 4) The difference frequency signal with improved signal-to-noise ratio is detected in the data acquisition module and then input into the A / D converter to be converted into an 8-bit or 16-bit digital signal. The digital signal is input into the FPGA module to collect and record the signal and output the signal value, superimpose different types of signals, and input into the host computer through the USBBlaster driver module;

[0043] 5) The host computer observes the waveform of the sample, detects the amplitude and frequency of the weak signal, and adjusts the amplification degree of the weak signal as needed.

[0044] Example 2

[0045] As a preferred embodiment of the present invention, based on Embodiment 1, the weak signal method adjustable program control method provided by the present invention comprises the following steps:

[0046] 1) If Figure 2 As shown, a weak signal enters the measured signal channel and is amplified by the preamplifier to a switch level that can be detected by the correlator; the signal amplified by the preamplifier enters the bandpass filter to filter out the noise of the noise frequency band in the amplified signal; the amplified signal after filtering and removing the noise enters the first amplifier again, and the amplified signal after filtering and removing the noise is amplified again;

[0047] 2) The reference signal enters the reference signal channel and is preprocessed;

[0048] 3) The pre-processed weak signal and the pre-processed reference signal are input to the correlator, which processes them and outputs a difference frequency signal with improved signal-to-noise ratio;

[0049] 4) The difference frequency signal with improved signal-to-noise ratio is detected in the data acquisition module and then input into the A / D converter to be converted into an 8-bit or 16-bit digital signal. The digital signal is input into the FPGA module to collect and record the signal and output the signal value, superimpose different types of signals, and input into the host computer through the USBBlaster driver module;

[0050] 5) The host computer observes the waveform of the sample, detects the amplitude and frequency of the weak signal, and adjusts the amplification degree of the weak signal as needed.

[0051] Example 3

[0052] As a preferred embodiment of the present invention, based on Embodiment 1, the weak signal method adjustable program control method provided by the present invention comprises the following steps:

[0053] 1) If Figure 2 As shown, a weak signal enters the measured signal channel and is amplified by the preamplifier to a switch level that can be detected by the correlator; the signal amplified by the preamplifier enters the bandpass filter to filter out the noise of the noise frequency band in the amplified signal; the amplified signal after filtering and removing the noise enters the first amplifier again, and the amplified signal after filtering and removing the noise is amplified again;

[0054] 2) If Figure 3 As shown, the reference signal entering the reference signal channel is processed by the second amplifier, and the reference signal is amplified to meet the starting level of the phase-sensitive detection module in the correlator; the amplified reference signal enters the phase shifter, and the phase of the amplified reference signal is adjusted to ensure that the phase difference between the preprocessed reference signal and the weak signal preprocessed in step 1) meets the processing requirements of the correlator.

[0055] 3) The pre-processed weak signal and the pre-processed reference signal are input to the correlator, which processes them and outputs a difference frequency signal with improved signal-to-noise ratio;

[0056] 4) The difference frequency signal with improved signal-to-noise ratio is detected in the data acquisition module and then input into the A / D converter to be converted into an 8-bit or 16-bit digital signal. The digital signal is input into the FPGA module to collect and record the signal and output the signal value, superimpose different types of signals, and input into the host computer through the USBBlaster driver module;

[0057] 5) The host computer observes the waveform of the sample, detects the amplitude and frequency of the weak signal, and adjusts the amplification degree of the weak signal as needed.

[0058] Example 4

[0059] As a preferred embodiment of the present invention, based on Embodiment 1, the weak signal method adjustable program control method provided by the present invention comprises the following steps:

[0060] 1) If Figure 2 As shown, a weak signal enters the measured signal channel and is amplified by the preamplifier to a switch level that can be detected by the correlator; the signal amplified by the preamplifier enters the bandpass filter to filter out the noise of the noise frequency band in the amplified signal; the amplified signal after filtering and removing the noise enters the first amplifier again, and the amplified signal after filtering and removing the noise is amplified again;

[0061] 2) If Figure 3 As shown, the reference signal entering the reference signal channel is processed by the second amplifier, and the reference signal is amplified to meet the starting level of the phase-sensitive detection module in the correlator; the amplified reference signal enters the phase shifter, and the phase of the amplified reference signal is adjusted to ensure that the phase difference between the preprocessed reference signal and the weak signal preprocessed in step 1) meets the processing requirements of the correlator.

[0062] 3) If Figure 4 The preprocessed input signal obtained in step 1) and the preprocessed reference signal obtained in step 2) are multiplied to output a frequency-doubled signal and a frequency difference signal; after the frequency-doubled signal and the frequency difference signal are filtered out by a low-pass filter module in the correlator, a frequency difference signal with an improved signal-to-noise ratio is output;

[0063] 4) The difference frequency signal with improved signal-to-noise ratio is detected in the data acquisition module and then input into the A / D converter to be converted into an 8-bit or 16-bit digital signal. The digital signal is input into the FPGA module to collect and record the signal and output the signal value, superimpose different types of signals, and input into the host computer through the USBBlaster driver module;

[0064] 5) The host computer observes the waveform of the sample, detects the amplitude and frequency of the weak signal, and adjusts the amplification degree of the weak signal as needed.

[0065] Furthermore, the reference signal is a sine wave or a square wave.

[0066] Example 5

[0067] like Figure 5 As shown, a weak signal amplification adjustable programmable system provided by the present invention using the method provided by any one of embodiments 1-4, the system includes a weak signal detection module, the system also includes a measured signal channel composed of a preamplifier, a bandpass filter and a first amplifier connected in sequence, a reference signal channel composed of a second amplifier and a phase shifter, a correlator connected to the measured signal channel and the reference signal channel, and a data acquisition module connected to the correlator; the data acquisition module includes an A / D conversion module, an FPGA module, a USBBlaster driver module and a host computer connected to the correlator in sequence.

[0068] The preamplifier is used to amplify weak signals and make the amplified signals reach the switching level of the correlator phase-sensitive detection module;

[0069] A bandpass filter is used to filter out the noise in the noise frequency band of the amplified signal;

[0070] The first amplifier is used to amplify the signal after filtering and amplification.

[0071] The purpose of the reference signal channel is to amplify the reference signal and output a reference signal with low noise and high open-loop gain. After amplification by the second amplifier, the preprocessed reference signal is adjusted to meet the starting level of the phase-sensitive detection module. The adjustment multiple of the second amplifier can be adjusted within a controllable range as needed. The phase shifter adjusts the phase of the amplified reference signal to ensure that the phase difference between the preprocessed input weak signal and the reference signal meets the multiplication operation requirements of the phase-sensitive detection module in the correlator.

[0072] Furthermore, the correlator includes a phase-sensitive detection module and a low-pass filtering module. The A / D conversion module in the data acquisition module is connected to the low-pass filtering module. The phase-sensitive detection module is used to multiply the preprocessed input signal and the preprocessed reference signal to output a frequency multiplication signal and a difference frequency signal; the low-pass filtering module is used to filter out the high-frequency signal in the output signal of the phase-sensitive detection module and only output a DC voltage signal.

[0073] Optionally, the phase-sensitive detection module is one of LZX1C, AD630, HJ002C or MXT002.

[0074] Optionally, the bandpass filter is an active filter.

[0075] Optionally, the active filter is one of the MAX7480ESA+T, MAX275BCWP+, MAX274ACNG, or MAX7408CUA+.

[0076] Although the present invention has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there is no conflict of technical solutions. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A programmable method for weak signal amplification, characterized in that: The following steps are involved: 1) After the weak signal enters the measured signal channel and is pre-processed, the noise in the weak signal is removed and the signal is amplified; 2) The reference signal enters the reference signal channel and is preprocessed; 3) The pre-processed weak signal and the pre-processed reference signal are input to the correlator, which processes them and outputs a difference frequency signal with improved signal-to-noise ratio. The following steps are involved: 3.1) performing a multiplication operation on the preprocessed input signal obtained in step 1) and the preprocessed reference signal obtained in step 2) to output a frequency multiplication signal and a frequency difference signal; 3.2) After the frequency-doubled signal and the difference frequency signal are filtered out by the low-pass filter module in the correlator, the difference frequency signal with improved signal-to-noise ratio is output; 4) The difference frequency signal with improved signal-to-noise ratio is detected in the data acquisition module and then input into the A / D converter to be converted into an 8-bit or 16-bit digital signal. The digital signal is input into the FPGA module to collect and record the signal and output the signal secondary value, and different types of signals are superimposed and input into the host computer through the USBBlaster driver module; 5) The host computer observes the waveform of the sample, detects the amplitude and frequency of the weak signal, and adjusts the amplification degree of the weak signal as needed.

2. The adjustable program-controlled method for weak signal amplification according to claim 1 is characterized in that: The weak signal preprocessing step in step 1) comprises the following steps: 1.1) A weak signal enters the measured signal channel and is amplified by the preamplifier to a switching level that can be detected by the correlator; 1.2) The signal amplified by the preamplifier enters the bandpass filter to filter out the noise in the noise frequency band of the amplified signal; 1.3) The amplified signal after filtering and removing noise enters the first amplifier again, and the amplified signal after filtering and removing noise is amplified again.

3. The adjustable program-controlled method for weak signal amplification according to claim 1 is characterized in that: The reference signal preprocessing in step 2) includes the following steps: 2.1) The reference signal entering the reference signal channel is processed by the second amplifier, and the reference signal is amplified to meet the starting level in the correlator; 2.2) The amplified reference signal enters the phase shifter, and the phase of the amplified reference signal is adjusted to ensure that the phase difference between the preprocessed reference signal and the weak signal preprocessed in step 1) meets the processing requirements of the correlator.

4. The adjustable program-controlled method for weak signal amplification according to claim 1 is characterized in that: The reference signal is a sine wave or a square wave.

5. A weak signal amplification adjustable program-controlled system according to any one of the methods described in claims 1-4, the system comprising a weak signal detection module, characterized in that: The system includes a measured signal channel composed of a preamplifier, a bandpass filter and a first amplifier connected in sequence, a reference signal channel composed of a second amplifier and a phase shifter, a correlator connected to the measured signal channel and the reference signal channel, and a data acquisition module connected to the correlator; the data acquisition module includes an A / D conversion module, an FPGA module, a USB Blaster driver module and a host computer connected to the correlator in sequence.

6. The adjustable program-controlled system for weak signal amplification according to claim 5 is characterized in that: The correlator includes a phase-sensitive detection module and a low-pass filtering module. The phase-sensitive detection module is used to multiply the preprocessed input signal and the preprocessed reference signal to output a frequency-doubled signal and a frequency difference signal; the low-pass filtering module is used to filter out the high-frequency signal in the output signal of the phase-sensitive detection module and only output a DC voltage signal.

7. The adjustable program-controlled system for weak signal amplification according to claim 6 is characterized in that: The phase-sensitive detection module is one of LZX1C, AD630, HJ002C or MXT002.

8. The adjustable program-controlled system for weak signal amplification according to claim 5 is characterized in that: The bandpass filter is an active filter.

9. The adjustable program-controlled system for weak signal amplification according to claim 8 is characterized in that: The model of the active filter is one of MAX7480ESA+T, MAX275BCWP+, MAX274ACNG or MAX7408CUA+.

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