A signal spreading circuit

Abstract

This application provides a signal spread spectrum circuit, comprising a pre-processing circuit and a gain compensation circuit connected in sequence. The pre-processing circuit receives a detection signal from a detector, and the gain compensation circuit applies a frequency-varying gain to the detection signal and outputs a spread spectrum signal. The gain compensation circuit is configured such that, within a target compensation frequency band, the amplitude of the gain monotonically increases as the frequency of the detection signal decreases; and, in a frequency range higher than the target compensation frequency band, the rate of monotonic increase of the gain amplitude with decreasing frequency slows down. This application achieves effective compensation for the inherent sensitivity attenuation of the detector in the ultra-low frequency band.

Description

Technical Field

[0001] This application relates to the field of signal processing technology, and more specifically, to a signal spread spectrum circuit. Background Technology

[0002] In low-frequency vibration control applications such as active vibration damping, detectors are needed to detect velocity signals as low as 0.5Hz to form a closed loop. However, commercially available detectors (such as the GEOSPACE GS-ONE LF 4.5Hz model) typically operate at frequencies above 4.5Hz. Above this frequency, their sensitivity remains constant (approximately 89.4 V / m / s); however, in the ultra-low frequency range of 4.5Hz to 0.5Hz, their sensitivity drops exponentially, resulting in a severe deficiency in their ability to detect vibrations in this frequency band. This inherent limitation restricts the application of existing detectors in high-performance vibration damping systems requiring ultra-low frequency detection, constituting a technical bottleneck that urgently needs to be addressed. Summary of the Invention

[0003] In view of this, the purpose of this application is to provide a signal spread spectrum circuit that overcomes at least one of the above-mentioned defects.

[0004] In a first aspect, this application provides a signal spread spectrum circuit, including a pre-processing circuit and a gain compensation circuit connected in sequence. The pre-processing circuit is used to receive a detection signal from a detector, and the gain compensation circuit is used to apply a gain that varies with frequency to the detection signal and output a spread spectrum signal. The gain compensation circuit is configured such that, within the target compensation frequency band, the magnitude of the gain applied by the gain compensation circuit monotonically increases as the frequency of the detected signal decreases, and within a frequency range higher than the target compensation frequency band, the rate at which the magnitude of the gain applied by the gain compensation circuit monotonically increases as the frequency decreases slows down.

[0005] In one possible implementation, the gain compensation circuit includes: The first proportional-integral unit includes a first resistor, a first operational amplifier, and a first RC feedback subunit. The first end of the first resistor is connected to the output of the pre-processing circuit, the second end of the first resistor is connected to the inverting input of the first operational amplifier, the output of the first operational amplifier is connected to the input of the pre-processing circuit, and the first RC feedback subunit is connected in parallel between the inverting input of the first operational amplifier and the output of the first operational amplifier.

[0006] In one possible implementation, the first RC feedback subunit includes a second resistor, a first capacitor, a third resistor, and a second capacitor; The first end of the second resistor is connected to the inverting input terminal of the first operational amplifier, the second end of the second resistor is connected to the output terminal of the first operational amplifier, the first end of the first capacitor is connected to the inverting input terminal of the first operational amplifier, the second end of the first capacitor is connected to the first end of the third resistor, the second end of the third resistor is connected to the output terminal of the first operational amplifier, the first end of the second capacitor is connected to the inverting input terminal of the first operational amplifier, and the second end of the second capacitor is connected to the output terminal of the first operational amplifier.

[0007] In one possible implementation, the gain compensation circuit further includes: The second proportional-integral unit includes a fourth resistor, a second operational amplifier, and a second RC feedback subunit. The first end of the fourth resistor is used to receive the signal processed by the first operational amplifier, and the second end of the fourth resistor is connected to the inverting input of the second operational amplifier. The output of the second operational amplifier is used for the spread spectrum signal. The second RC feedback subunit is connected in parallel between the inverting input of the second operational amplifier and the output of the second operational amplifier.

[0008] In one possible implementation, the second RC feedback subunit includes a fifth resistor, a third capacitor, and a sixth resistor; The first end of the fifth resistor is connected to the inverting input of the second operational amplifier, the second end of the fifth resistor is connected to the output of the second operational amplifier, the first end of the third capacitor is connected to the inverting input of the second operational amplifier, the second end of the third capacitor is connected to the first end of the sixth resistor, and the second end of the sixth resistor is connected to the output of the second operational amplifier.

[0009] In one possible implementation, the gain compensation circuit further includes: The seventh capacitor, the first terminal of which is connected to the output terminal of the first operational amplifier; The eighth resistor has its first end connected to the second end of the seventh capacitor, and its second end is grounded. The third operational amplifier has its non-inverting input connected to the second terminal of the seventh capacitor and the first terminal of the eighth resistor, its inverting input shorted to its output, and its output connected to the first terminal of the fourth resistor.

[0010] In one possible implementation, the preprocessing circuit includes a protection sub-circuit, a low-pass filter sub-circuit, and a differential amplifier sub-circuit connected in sequence. The protection sub-circuit is used to provide electrostatic protection and transient overvoltage protection for the differential detection signal output by the detector. The low-pass filter sub-circuit is used to filter out high-frequency noise in the differential detection signal. The differential amplifier sub-circuit is used to amplify the filtered differential detection signal with high precision and fixed gain.

[0011] In one possible implementation, the protection sub-circuit includes: A ninth resistor, the two ends of which are used to connect to the detector; A protector, which is connected in parallel with the ninth resistor.

[0012] In one possible implementation, the low-pass filter sub-circuit includes a tenth resistor, an eleventh resistor, an eighth capacitor, a ninth capacitor, and a tenth capacitor. The first end of the tenth resistor is connected to the positive output terminal of the protection sub-circuit, the second end of the tenth resistor is connected to the inverting input terminal of the differential amplifier sub-circuit, the first end of the eleventh resistor is connected to the negative output terminal of the protection sub-circuit, the second end of the eleventh resistor is connected to the non-inverting input terminal of the differential amplifier sub-circuit, the first end of the eighth capacitor is grounded, the second end of the eighth capacitor is connected to the second end of the tenth resistor, the first end of the ninth capacitor is connected to the second end of the tenth resistor, the second end of the ninth capacitor is connected to the second end of the eleventh resistor, the first end of the tenth capacitor is grounded, and the second end of the tenth capacitor is connected to the second end of the eleventh resistor.

[0013] In one possible implementation, the differential amplifier sub-circuit includes an instrumentation amplifier and a twelfth resistor; The inverting input terminal of the instrumentation amplifier is connected to the second terminal of the tenth resistor, the non-inverting input terminal of the instrumentation amplifier is connected to the second terminal of the eleventh resistor, the twelfth resistor is connected between the two gain setting pins of the instrumentation amplifier, and the output terminal of the instrumentation amplifier is connected to the gain compensation circuit.

[0014] This application provides a signal spread spectrum circuit, comprising a pre-processing circuit and a gain compensation circuit connected in sequence. The pre-processing circuit receives a detection signal from a detector, and the gain compensation circuit applies a frequency-varying gain to the detection signal and outputs a spread spectrum signal. The gain compensation circuit is configured such that, within a target compensation frequency band, the amplitude of the gain monotonically increases as the frequency of the detection signal decreases; and, in a frequency range higher than the target compensation frequency band, the rate of monotonic increase of the gain amplitude with decreasing frequency slows down. This application achieves effective compensation for the inherent sensitivity attenuation of the detector in the ultra-low frequency band.

[0015] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is one of the structural schematic diagrams of a signal spread spectrum circuit provided in the embodiments of this application; Figure 2 This is one of the structural schematic diagrams of the gain compensation circuit provided in the embodiments of this application; Figure 3 This is a second schematic diagram of the gain compensation circuit provided in the embodiments of this application; Figure 4 This is one of the schematic diagrams of the pre-processing circuit provided in the embodiments of this application; Figure 5 This is a second schematic diagram of the pre-processing circuit provided in the embodiments of this application; Figure 6 This is a schematic diagram of the amplitude-frequency and phase-frequency characteristic curves of the spread-spectrum detection signal provided in the embodiments of this application; Figure 7 This is a schematic diagram comparing the sensitivity curves before and after spread spectrum provided in the embodiments of this application. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. Based on the embodiments of this application, every other embodiment obtained by those skilled in the art without inventive effort falls within the scope of protection of this application.

[0019] First, the applicable scenarios for this application will be introduced. This application can be applied to the field of signal processing technology.

[0020] Research has revealed that active vibration damping systems typically use geophones to detect velocity signals in a closed-loop configuration, requiring the detection of vibration frequencies as low as 0.5Hz. However, most geophones on the market do not cover frequencies down to 0.5Hz. For example, the GEOSPACE GS-ONE LF 4.5Hz geophone, according to its datasheet, operates at frequencies greater than 4.5Hz, and its sensitivity curve is shown below. Figure 1 As shown; from Figure 1 It can be seen that when the operating frequency is greater than 4.5Hz, the sensitivity of the GS-ONE LF 4.5Hz Geophone is basically constant at 89.4V / m / s±10%; when the operating frequency is in the range of 4.5Hz to 0.5Hz, the sensitivity of the GS-ONE LF 4.5Hz Geophone drops exponentially, which means that its detection capability in the ultra-low frequency range (4.5Hz to 0.5Hz) is seriously insufficient.

[0021] Based on this, this application provides a signal spread spectrum circuit, which aims to achieve accurate frequency compensation of the detector output signal while maintaining stable gain of the high-frequency signal, thereby meeting the requirements of active vibration reduction systems for ultra-low frequency vibration detection.

[0022] Please see Figure 1 , Figure 1 This is one of the structural schematic diagrams of a signal spread spectrum circuit provided in an embodiment of this application. For example... Figure 1 As shown in the figure, the signal spread spectrum circuit provided in this application embodiment includes a pre-processing circuit 100 and a gain compensation circuit 200.

[0023] The preprocessing circuit 100 is used to receive the detection signal from the detector, and the gain compensation circuit 200 is used to apply a gain that varies with frequency to the detection signal and output a spread spectrum signal.

[0024] The gain compensation circuit 200 is configured such that, within the target compensation frequency band, the magnitude of the gain applied by the gain compensation circuit 200 increases monotonically as the frequency of the detected signal decreases, and within a frequency range higher than the target compensation frequency band, the rate at which the magnitude of the gain applied by the gain compensation circuit 200 increases monotonically as the frequency decreases slows down.

[0025] Here, the target frequency band is 0.5Hz to 4.5Hz. The principle behind its spread spectrum function lies in the fact that the gain compensation circuit 200 is endowed with a gain-frequency characteristic completely opposite to the inherent defects of the target detector. Specifically, in the frequency range above 4.5Hz, due to the effect of a specific zero point in the circuit, the rate at which the gain monotonically increases with decreasing frequency gradually slows down and eventually tends to a stable value determined by the internal resistance ratio. This design ensures that high-frequency signals still receive sufficient amplification while avoiding excessive gain increases that could introduce noise or cause system instability. However, within the target compensation frequency band of 0.5Hz to 4.5Hz, the sensitivity of the target detector decreases sharply with decreasing frequency, resulting in excessively small amplitude of the low-frequency output signal. The gain compensation function of this circuit is manifested in that its voltage gain monotonically increases with decreasing input signal frequency within the same frequency band, and the rate of increase is significantly higher than in the high-frequency band. Therefore, when the signal output from the detector, which has already undergone low-frequency attenuation, passes through this circuit, its low-frequency component (e.g., 0.5Hz) will receive a higher amplification factor than its high-frequency component (e.g., 4.5Hz), resulting in a signal with uniform and sufficient amplitude across the entire target frequency band. The ultimate effect is that the overall effective operating bandwidth of the detector-spread spectrum circuit is successfully extended towards the low-frequency end, achieving spread spectrum while ensuring stable transmission of high-frequency signals and overall system reliability.

[0026] Please see Figure 2 , Figure 2 This is one of the structural schematic diagrams of a gain compensation circuit 200 provided in an embodiment of this application. Figure 2 As shown, the gain compensation circuit 200 includes a first proportional-integral unit 201, a filter unit 202, and a second proportional-integral unit 203.

[0027] The first proportional-integral unit 201 includes a first resistor R9, a first operational amplifier, and a first RC feedback subunit. The first end of the first resistor R9 is connected to the output of the pre-processing circuit 100, the second end of the first resistor R9 is connected to the inverting input of the first operational amplifier, the output of the first operational amplifier is connected to the input of the output conditioning circuit, and the first RC feedback subunit is connected in parallel between the inverting input of the first operational amplifier and the output of the first operational amplifier.

[0028] The first proportional-integral unit 201, through its unique feedback network structure, achieves a compensation function where the gain increases at lower frequencies within the target frequency band of 0.5Hz to 4.5Hz. This is based on the principle that the gain of an inverting amplifier is determined by the impedance of its feedback network. The first RC feedback subunit is not a single component but a combination of resistors and capacitors, and its total impedance exhibits a significant frequency dependence: since the impedance of the capacitor increases as the frequency decreases, the equivalent impedance of the entire network also increases accordingly.

[0029] Specifically, the filter unit 202 is a first-order high-pass filter, which is used to filter out DC bias and buffer isolation, to filter out DC offset generated by the preceding circuit and protect the following stage; at the same time, it acts as a voltage follower to isolate the active circuits of the preceding and following stages and ensure stable signal transmission.

[0030] The second proportional-integral unit 203 includes a fourth resistor R17, a second operational amplifier, and a second RC feedback subunit. The first end of the fourth resistor R17 is used to receive the signal processed by the first operational amplifier, and the second end of the fourth resistor R17 is connected to the inverting input of the second operational amplifier. The output of the second operational amplifier is used for spread spectrum signal. The second RC feedback subunit is connected in parallel between the inverting input of the second operational amplifier and the output of the second operational amplifier.

[0031] Specifically, the second proportional-integral unit 203 is the second frequency-selective amplifier stage of this circuit. Through the design of its own second RC feedback sub-unit, it also achieves the characteristic that the gain increases as the frequency decreases. Its core function is to work in conjunction with the first stage. By cascading the two stages with similar characteristics, it can finely control and superimpose the shape of the compensation curve and the overall gain, thereby accurately achieving the final amplitude-frequency characteristic required to extend the detector's detection lower limit to 0.5Hz.

[0032] Please see Figure 3 , Figure 3 This is a second schematic diagram of a gain compensation circuit 200 provided in an embodiment of this application. Figure 2 As shown, the first RC feedback subunit includes a second resistor R11, a first capacitor C11, a third resistor R13, and a second capacitor C13. The first end of the second resistor R11 is connected to the inverting input terminal of the first operational amplifier, and the second end of the second resistor R11 is connected to the output terminal of the first operational amplifier. The first end of the first capacitor C11 is connected to the inverting input terminal of the first operational amplifier, and the second end of the first capacitor C11 is connected to the first end of the third resistor R13. The second end of the third resistor R13 is connected to the output terminal of the first operational amplifier, and the first end of the second capacitor C13 is connected to the inverting input terminal of the first operational amplifier, and the second end of the second capacitor C13 is connected to the output terminal of the first operational amplifier.

[0033] Specifically, the first proportional-integral unit 201 achieves its core compensation function through the precise parameterization design of its feedback network. In this feedback network, the second capacitor C13 is preferably 2.2nF in capacitance and is connected in parallel with the second resistor R11, preferably 470kΩ in resistance, to jointly form the main feedback path; the first capacitor C11 is preferably 100pF in capacitance and is connected in series with the third resistor R13, preferably approximately 36kΩ in resistance, to form a feedforward compensation branch.

[0034] This parameter combination sets a low-frequency pole of approximately 0.3 Hz and a high-frequency zero of approximately 4.5 Hz in the circuit's transfer function. Within the frequency range between the zero and the pole, the circuit gain exhibits a characteristic of decreasing with increasing frequency. Therefore, within the target compensation frequency range of 0.5 Hz to 4.5 Hz, the design requirement of "voltage gain monotonically increasing with decreasing signal frequency" is achieved, thereby directly eliminating the sensitivity attenuation of the detector in this frequency range and extending the effective detection lower limit of the system to 0.5 Hz.

[0035] Specifically, the transfer function H1(s) of the first proportional-integral unit 201 is:

[0036]

[0037] The filter unit 202 includes a seventh capacitor C19, an eighth resistor R15, and a third operational amplifier. The first terminal of the seventh capacitor C19 is connected to the output terminal of the first operational amplifier. The first terminal of the eighth resistor R15 is connected to the second terminal of the seventh capacitor C19, and the second terminal of the eighth resistor R15 is grounded. The non-inverting input terminal of the third operational amplifier is connected to the second terminal of the seventh capacitor C19 and the first terminal of the eighth resistor R15. The inverting input terminal of the third operational amplifier is shorted to the output terminal. The output terminal of the third operational amplifier is connected to the first terminal of the fourth resistor R17.

[0038] The transfer function H of filter unit 202 HP (s) is:

[0039] After substituting the optimal parameters, it can be simplified to:

[0040] The second RC feedback subunit includes a fifth resistor R19, a third capacitor C21, and a sixth resistor R21. The first end of the fifth resistor R19 is connected to the inverting input of the second operational amplifier, and the second end of the fifth resistor R19 is connected to the output of the second operational amplifier. The first end of the third capacitor C21 is connected to the inverting input of the second operational amplifier, and the second end of the third capacitor C21 is connected to the first end of the sixth resistor R21. The second end of the sixth resistor R21 is connected to the output of the second operational amplifier.

[0041] The second proportional-integral unit 203 achieves further frequency-selective amplification of the compensated signal through the precise parameterization design of its feedback network. In this feedback network, the fifth resistor R19 is preferably 560kΩ, forming the main feedback path; the third capacitor C21 is preferably 100pF, and is connected in series with the sixth resistor R21, preferably 75kΩ, to form an additional frequency compensation branch.

[0042] This parameter combination gives its transfer function a specific zero-pole distribution. Within the target frequency band of 0.5Hz to 4.5Hz, the voltage gain of this unit also shows a trend of increasing as the signal frequency decreases. Therefore, it further amplifies the signal that has already undergone the first-stage main compensation with a specific frequency response law, working in conjunction with the first stage to shape the compensation curve required by the entire system, ensuring that the final output spread spectrum signal obtains sufficient and accurate gain enhancement within the target frequency band.

[0043] The transfer function H2(s) of the second proportional-integral unit 203 is:

[0044] Please see Figure 4 , Figure 4 This is one of the structural schematic diagrams of the pre-processing circuit 100 provided in an embodiment of this application. For example... Figure 4 As shown, the preprocessing circuit 100 includes a protection sub-circuit 101, a low-pass filter sub-circuit 102, and a differential amplifier sub-circuit 103 connected in sequence. The protection sub-circuit 101 is used to perform electrostatic protection and transient overvoltage protection on the differential detection signal output by the detector. The low-pass filter sub-circuit 102 is used to filter out high-frequency noise in the differential detection signal. The differential amplifier sub-circuit 103 is used to perform high-precision fixed-gain amplification on the filtered differential detection signal.

[0045] Please see Figure 5 , Figure 5 This is a second schematic diagram of the pre-processing circuit 100 provided in an embodiment of this application. Figure 5 As shown, the protection sub-circuit 101 includes a ninth resistor R1 and a protector D1. The two ends of the ninth resistor R1 are used to connect to the detector, and the protector D1 is connected in parallel with the ninth resistor R1.

[0046] The protection sub-circuit 101 is used to provide electrostatic discharge (ESD) protection and transient overvoltage protection for the differential detection signal output by the detector. The ninth resistor, R1, is the load resistor of the detector. The protector D1 is an ESD protection device (such as ESDCAN24), which internally contains two bidirectional TVS diodes. This device is connected across the differential signal path in a specific configuration, providing nanosecond-level fast clamping protection for both differential-mode overvoltage (between signal lines) and common-mode overvoltage (between signal lines and ground), thereby ensuring that the subsequent precision amplifier circuit is protected from abnormal high-voltage surges.

[0047] The low-pass filter sub-circuit 102 includes a tenth resistor R3, an eleventh resistor R5, an eighth capacitor C1, a ninth capacitor C3, and a tenth capacitor C5. The first end of the tenth resistor R3 is connected to the positive output terminal of the protection sub-circuit 101, and the second end of the tenth resistor R3 is connected to the inverting input terminal of the differential amplifier sub-circuit 103. The first end of the eleventh resistor R5 is connected to the negative output terminal of the protection sub-circuit 101, and the second end of the eleventh resistor R5 is connected to the non-inverting input terminal of the differential amplifier sub-circuit 103. The first end of the eighth capacitor C1 is grounded, and the second end of the eighth capacitor C1 is connected to the second end of the tenth resistor R3. The first end of the ninth capacitor C3 is connected to the second end of the tenth resistor R3, and the second end of the ninth capacitor C3 is connected to the second end of the eleventh resistor R5. The first end of the tenth capacitor C5 is grounded, and the second end of the tenth capacitor C5 is connected to the second end of the eleventh resistor R5.

[0048] The low-pass filter sub-circuit 102 employs a first-order RC structure to filter out high-frequency noise in the differential detection signal. Resistors R3 and R5, along with capacitors C1, C3, and C5, form a passive filter network. Specifically, capacitors C1 and C5 bypass the high-frequency common-mode noise of the positive and negative terminals of the signal to ground, respectively; capacitor C3, connected between the differential signal lines, filters out differential-mode high-frequency noise between the lines. Resistors R3 and R5 simultaneously serve to limit current and match the impedance of subsequent circuits.

[0049] The differential amplifier sub-circuit 103 includes an instrumentation amplifier U1, a twelfth resistor R7, an inverting input terminal of the instrumentation amplifier U1 connected to the second terminal of the tenth resistor R3, a non-inverting input terminal of the instrumentation amplifier U1 connected to the second terminal of the eleventh resistor R5, a twelfth resistor R7 connected between the two gain setting pins of the instrumentation amplifier U1, and an output terminal of the instrumentation amplifier U1 connected to a gain compensation circuit 200.

[0050] The differential amplifier sub-circuit 103 is used to perform high-precision fixed-gain amplification of the filtered differential detection signal. Its core is the instrumentation amplifier U1 (such as the LT1167). The gain of this amplifier is precisely set by a single external resistor R7. By optimizing the value of R7 (preferably 150Ω), the gain can be configured to approximately 330.3 times. The instrumentation amplifier has extremely high input impedance, extremely high common-mode rejection ratio, and excellent linearity, enabling it to stably, with low noise and high fidelity amplify the weak millivolt-level differential signal output from the detector to the volt level, providing a sufficiently large and high signal-to-noise ratio input signal for the subsequent gain compensation circuit 200.

[0051] Transfer function of differential amplifier circuit 103 for:

[0052] This gain is constant and does not change with frequency, providing a fixed signal amplification reference for subsequent compensation.

[0053] The overall transfer function H(s) of this signal spread spectrum circuit is obtained by cascading and multiplying the transfer functions of the differential amplifier sub-circuit 103 in the pre-processing circuit 100, the first proportional-integral unit 201 in the gain compensation circuit 200, the filter unit 202, and the second proportional-integral unit 203:

[0054] After substituting the transfer function expressions and optimal parameters for each part, the overall transfer function can be simplified as follows:

[0055] The overall transfer function fully describes the overall frequency response characteristics of this circuit from the detector signal input to the spread spectrum signal output. Within the target compensation frequency band of 0.5Hz to 4.5Hz, the amplitude-frequency characteristic of H(s) exhibits a monotonically decreasing trend, that is, the voltage gain increases precisely as the frequency decreases, and its slope is complementary to the slope of the detector's sensitivity attenuation in this frequency band.

[0056] Please see Figure 6 and Figure 7 , Figure 6 This is a schematic diagram of the amplitude-frequency and phase-frequency characteristic curves of the spread-spectrum detection signal provided in the embodiments of this application; Figure 7 This is a schematic diagram comparing the sensitivity curves before and after spread spectrum provided in the embodiments of this application.

[0057] Figure 6 The amplitude-frequency response curve and phase-frequency response curve corresponding to the total transfer function H(s) of the signal spread spectrum circuit of this application are shown. The amplitude-frequency response curve shows that within the target compensation frequency band of 0.5Hz to 4.5Hz, the circuit gain exhibits a monotonically decreasing trend, meaning the gain is higher at lower frequencies. Above 4.5Hz, the rate of decrease in the gain curve gradually slows down and eventually flattens out, reflecting the combined effect of zero-point effects and the resistance ratio on the high-frequency gain.

[0058] Figure 7 The sensitivity curves of the detector (taking the GS-ONE LF 4.5Hz Geophone as an example) before and after spread spectrum were compared. The solid line in the figure represents the original sensitivity curve before spread spectrum, and it can be clearly seen that the sensitivity across the entire frequency band has been significantly improved. This comparison intuitively demonstrates that the circuit of this application achieves effective detection of ultra-low frequency vibration signals.

[0059] Compared with existing technologies, this application successfully achieves active compensation for the inherent frequency response defects of the detector through the transfer function cascade architecture of this design, extending the effective detection frequency lower limit of the detector from 4.5Hz to 0.5Hz, thereby solving the technical problem that existing detectors cannot meet the requirements of ultra-low frequency vibration detection.

[0060] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0061] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the coupling or direct coupling or communication connection shown or discussed may be through some communication interface; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0062] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0063] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0064] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0065] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The scope of protection of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this application. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A signal spread spectrum circuit, characterized in that, It includes a pre-processing circuit and a gain compensation circuit connected in sequence. The pre-processing circuit is used to receive the detection signal from the detector, and the gain compensation circuit is used to apply a gain that varies with frequency to the detection signal and output a spread spectrum signal. The gain compensation circuit is configured such that, within the target compensation frequency band, the magnitude of the gain applied by the gain compensation circuit monotonically increases as the frequency of the detected signal decreases, and within a frequency range higher than the target compensation frequency band, the rate at which the magnitude of the gain applied by the gain compensation circuit monotonically increases as the frequency decreases slows down.

2. The circuit according to claim 1, characterized in that, The gain compensation circuit includes: The first proportional-integral unit includes a first resistor, a first operational amplifier, and a first RC feedback subunit. The first end of the first resistor is connected to the output of the pre-processing circuit, the second end of the first resistor is connected to the inverting input of the first operational amplifier, the output of the first operational amplifier is connected to the input of the pre-processing circuit, and the first RC feedback subunit is connected in parallel between the inverting input of the first operational amplifier and the output of the first operational amplifier.

3. The circuit according to claim 2, characterized in that, The first RC feedback subunit includes a second resistor, a first capacitor, a third resistor, and a second capacitor. The first end of the second resistor is connected to the inverting input terminal of the first operational amplifier, the second end of the second resistor is connected to the output terminal of the first operational amplifier, the first end of the first capacitor is connected to the inverting input terminal of the first operational amplifier, the second end of the first capacitor is connected to the first end of the third resistor, the second end of the third resistor is connected to the output terminal of the first operational amplifier, the first end of the second capacitor is connected to the inverting input terminal of the first operational amplifier, and the second end of the second capacitor is connected to the output terminal of the first operational amplifier.

4. The circuit according to claim 2, characterized in that, The gain compensation circuit also includes: The second proportional-integral unit includes a fourth resistor, a second operational amplifier, and a second RC feedback subunit. The first end of the fourth resistor is used to receive the signal processed by the first operational amplifier, and the second end of the fourth resistor is connected to the inverting input of the second operational amplifier. The output of the second operational amplifier is used for the spread spectrum signal. The second RC feedback subunit is connected in parallel between the inverting input of the second operational amplifier and the output of the second operational amplifier.

5. The circuit according to claim 4, characterized in that, The second RC feedback subunit includes a fifth resistor, a third capacitor, and a sixth resistor. The first end of the fifth resistor is connected to the inverting input of the second operational amplifier, the second end of the fifth resistor is connected to the output of the second operational amplifier, the first end of the third capacitor is connected to the inverting input of the second operational amplifier, the second end of the third capacitor is connected to the first end of the sixth resistor, and the second end of the sixth resistor is connected to the output of the second operational amplifier.

6. The circuit according to claim 4, characterized in that, The gain compensation circuit also includes: The seventh capacitor, the first terminal of which is connected to the output terminal of the first operational amplifier; The eighth resistor has its first end connected to the second end of the seventh capacitor, and its second end is grounded. The third operational amplifier has its non-inverting input connected to the second terminal of the seventh capacitor and the first terminal of the eighth resistor, its inverting input shorted to its output, and its output connected to the first terminal of the fourth resistor.

7. The circuit according to claim 1, characterized in that, The pre-processing circuit includes a protection sub-circuit, a low-pass filter sub-circuit, and a differential amplifier sub-circuit connected in sequence. The protection sub-circuit is used to provide electrostatic protection and transient overvoltage protection for the differential detection signal output by the detector. The low-pass filter sub-circuit is used to filter out high-frequency noise in the differential detection signal. The differential amplifier sub-circuit is used to amplify the filtered differential detection signal with high precision and fixed gain.

8. The circuit according to claim 7, characterized in that, The protection sub-circuit includes: A ninth resistor, the two ends of which are used to connect to the detector; A protector, which is connected in parallel with the ninth resistor.

9. The circuit according to claim 7, characterized in that, The low-pass filter sub-circuit includes a tenth resistor, an eleventh resistor, an eighth capacitor, a ninth capacitor, and a tenth capacitor. The first end of the tenth resistor is connected to the positive output terminal of the protection sub-circuit, the second end of the tenth resistor is connected to the inverting input terminal of the differential amplifier sub-circuit, the first end of the eleventh resistor is connected to the negative output terminal of the protection sub-circuit, the second end of the eleventh resistor is connected to the non-inverting input terminal of the differential amplifier sub-circuit, the first end of the eighth capacitor is grounded, the second end of the eighth capacitor is connected to the second end of the tenth resistor, the first end of the ninth capacitor is connected to the second end of the tenth resistor, the second end of the ninth capacitor is connected to the second end of the eleventh resistor, the first end of the tenth capacitor is grounded, and the second end of the tenth capacitor is connected to the second end of the eleventh resistor.

10. The circuit according to claim 9, characterized in that, The differential amplifier sub-circuit includes an instrumentation amplifier and a twelfth resistor. The inverting input terminal of the instrumentation amplifier is connected to the second terminal of the tenth resistor, the non-inverting input terminal of the instrumentation amplifier is connected to the second terminal of the eleventh resistor, the twelfth resistor is connected between the two gain setting pins of the instrumentation amplifier, and the output terminal of the instrumentation amplifier is connected to the gain compensation circuit.

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