Same-precision measuring device and method for wide-range frequency signals

Abstract

The invention discloses a same-precision measurement device and method for wide-range frequency signals in the technical field of vehicle engineering. The device comprises a first filter circuit, a clamping circuit, a conditioning circuit, a second filter circuit and a microprocessor which are electrically connected in sequence, the first filter circuit and the second filter circuit are both used for filtering electrostatic interference and low-frequency noise; the clamping circuit is used for protecting a rear-end circuit; the conditioning circuit comprises a non-inverse Schmitt trigger and is used for eliminating signal noise interference; the microprocessor comprises a timer and is used for carrying out frequency counting on the frequency signal; the method comprises the steps that when a measurement result exceeds a preset frequency threshold value, an improved M / T method is adopted for frequency measurement, and when the measurement result does not exceed the preset frequency threshold value, an improved T method is adopted for frequency measurement; according to the invention, the same measurement precision can be maintained in a wide frequency range, and the real-time performance is good.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle engineering, and in particular to a device and method for measuring wide-range frequency signals with the same precision. Background Art

[0002] There are three commonly used speed measurement methods at present, namely M method, T method and M / T method. Among them, M method is also called frequency method, which calculates the rotation speed by measuring the number of pulses of the measured signal within a fixed time interval; T method is also called period method, which calculates the rotation speed by measuring the time interval between two adjacent pulses of the measured signal; M / T method is a method of measuring speed by counting the measured signal and the reference pulse signal at the same time within a certain time interval. M method is suitable for high-speed measurement occasions, T method is suitable for low-speed measurement occasions, and M / T method takes into account the advantages of both M method and T method, with the advantages of high precision and wide range, but because the sampling time interval is fixed, its real-time performance will deteriorate when running at low speed, and it cannot meet the scenarios with high real-time requirements. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art, to provide a device and method for measuring wide-range frequency signals with the same precision, and to solve the technical problem that the M / T method cannot meet the requirements of high real-time scenarios.

[0004] To achieve the above object, the present invention is implemented by adopting the following technical solutions: In the first aspect, the present invention provides a device for measuring wide-range frequency signals with the same precision, comprising a first filter circuit, a clamp circuit, a conditioning circuit, a second filter circuit and a microprocessor electrically connected in sequence; the first filter circuit and the second filter circuit are both used to filter out electrostatic interference and low-frequency noise; the clamp circuit is used to protect its back-end circuit; the conditioning circuit includes a non-inverting Schmitt trigger for eliminating signal noise interference; the microprocessor includes a timer for counting the frequency signal.

[0005] Optionally, the first filtering circuit includes a TVS tube D2, a capacitor C2 and a resistor R3, one end of the TVS tube D2, the capacitor C2 and the resistor R3 are connected and serve as the input end of the first filtering circuit, the other ends of the TVS tube D2 and the capacitor C2 are connected and grounded, and the other end of the resistor R3 serves as the output end of the first filtering circuit.

[0006] Optionally, the clamping circuit includes a diode D1 and a diode D3, the cathode of the diode D1 is connected to the power supply VDD1, the anode of the diode D1 is connected to the cathode of the diode D3, the anode of the diode D3 is grounded, and the common end of the diode D1 and the diode D3 serves as the input and output end of the clamping circuit.

[0007] Optionally, the non-inverting Schmitt trigger includes a resistor R1 and an operational amplifier U1A, the positive input terminal and the output terminal of the operational amplifier U1A are connected in series via the resistor R1, and the negative input terminal of the operational amplifier U1A is connected to an adjustable threshold signal.

[0008] Optionally, the conditioning circuit also includes an RC filter circuit and a resistor R2, the RC filter circuit includes a resistor R4 and a capacitor C1, the input end of the RC filter circuit serves as the input end of the conditioning circuit, and the output end of the RC filter circuit is connected to the positive input end of the operational amplifier U1A; the output end of the operational amplifier U1A is pulled up to the power supply VDD2 via the resistor R2, and the output end of the operational amplifier U1A serves as the output end of the conditioning circuit.

[0009] Optionally, the second filtering circuit includes a resistor R5 and a capacitor C3, one end of the resistor R5 and the capacitor C3 are connected and serve as the output end of the second filtering circuit, the other end of the resistor R5 serves as the input end of the second filtering circuit, and the other end of the capacitor C3 is grounded.

[0010] In a second aspect, the present invention provides a method for measuring a wide range frequency signal with the same precision, using the same precision measuring device as described above, the same precision measuring method comprising: Step S1: Use the improved T method to measure the frequency and obtain the measurement result: frequency ; like , then continue to use the improved T method to measure the frequency, like , then proceed to step S2; Step S2: Use the improved M / T method to measure the frequency and obtain the measurement result: frequency ; like , then continue to use the improved M / T method to measure the frequency, like , then go to step 1; Among them, the frequency is the preset frequency threshold.

[0011] Optionally, the frequency , To preset the measurement accuracy, is the frequency of the high-frequency reference frequency signal.

[0012] Optionally, the frequency measurement using the improved T method includes: A counter is used to count the frequency signal to be measured and the high-frequency reference frequency signal respectively, and a count value N of the high-frequency reference frequency signal is obtained within one cycle of the frequency signal to be measured; Calculate the frequency based on the count value N , For measurement accuracy The adjustment coefficient under is the frequency of the high-frequency reference frequency signal; by adjusting the adjustment coefficient , keep the count value N the same under different frequency signals to be measured, and maintain the same measurement accuracy of different frequency signals to be measured.

[0013] Optionally, the frequency measurement using the improved M / T method includes: A counter is used to count the frequency signal to be measured and the high-frequency reference frequency signal respectively, and within a preset time interval, count values ​​M and N of the frequency signal to be measured and the high-frequency reference frequency signal are obtained; Calculate the frequency based on the values ​​N and M , For measurement accuracy The count value below, is the frequency of the high-frequency reference frequency signal; by adjusting the count value M, the count value N is kept the same under different frequency signals to be measured, and the measurement accuracy of different frequency signals to be measured is maintained the same.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a device and method for measuring wide-range frequency signals with the same precision. The device has a simple structure and can achieve strong anti-interference ability by filtering and conditioning the wide-range frequency signals, thereby improving the measurement precision. The method ensures that the acquisition precision of the entire frequency band remains unchanged by adjusting the parameters M and k on the basis of the device, and the real-time performance of the entire frequency band is also enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural block diagram of a device for measuring wide-range frequency signals with the same precision provided by an embodiment of the present invention; Figure 2 It is a circuit principle diagram of a device for measuring wide-range frequency signals with the same precision provided by an embodiment of the present invention; Figure 3 It is a flow chart of a method for measuring wide-range frequency signals with the same precision provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0017] Embodiment 1:

[0018] like Figure 1As shown, an embodiment of the present invention provides a same-precision measurement device for a wide range of frequency signals, including a first filter circuit, a clamp circuit, a conditioning circuit, a second filter circuit and a microprocessor electrically connected in sequence; the first filter circuit and the second filter circuit are both used to filter out electrostatic interference and low-frequency noise; the clamp circuit is used to protect its back-end circuit; the conditioning circuit includes a non-inverting Schmitt trigger for eliminating signal noise interference; the microprocessor includes a timer for counting the frequency signal.

[0019] like Figure 2 As shown, this embodiment provides a circuit schematic diagram of a device for measuring a wide range of frequency signals with the same precision, wherein the first filter circuit includes a TVS tube D2, a capacitor C2 and a resistor R3, one end of the TVS tube D2, the capacitor C2 and the resistor R3 are connected and used as the input end of the first filter circuit, the other end of the TVS tube D2 and the capacitor C2 are connected and grounded, and the other end of the resistor R3 is used as the output end of the first filter circuit. The clamp circuit includes a diode D1 and a diode D3, the cathode of the diode D1 is connected to the power supply VDD1, the anode of the diode D1 is connected to the cathode of the diode D3, the anode of the diode D3 is grounded, and the common end of the diode D1 and the diode D3 is used as the input and output end of the clamp circuit. The non-inverting Schmitt trigger includes a resistor R1 and an op amp U1A, the positive input end and the output end of the op amp U1A are connected in series via the resistor R1, and the negative input end of the op amp U1A is connected to the adjustable threshold signal Vref_PI. The conditioning circuit also includes an RC filter circuit and a resistor R2. The RC filter circuit includes a resistor R4 and a capacitor C1. The input end of the RC filter circuit serves as the input end of the conditioning circuit. The output end of the RC filter circuit is connected to the positive input end of the operational amplifier U1A. The output end of the operational amplifier U1A is pulled up to the power supply VDD2 via the resistor R2. The output end of the operational amplifier U1A serves as the output end of the conditioning circuit. The second filter circuit includes a resistor R5 and a capacitor C3. One end of the resistor R5 and the capacitor C3 are connected and serve as the output end of the second filter circuit. The other end of the resistor R5 serves as the input end of the second filter circuit. The other end of the capacitor C3 is grounded.

[0020] like Figure 3 As shown, based on the above-mentioned same-precision measurement device, an embodiment of the present invention also provides a same-precision measurement method for a wide range frequency signal, comprising the following steps: Step S1: Use the improved T method to measure the frequency and obtain the measurement result: frequency ; like , then continue to use the improved T method to measure the frequency, like , then proceed to step S2; Step S2: Use the improved M / T method to measure the frequency and obtain the measurement result: frequency ; like , then continue to use the improved M / T method to measure the frequency, like , then go to step 1; Among them, the frequency is the preset frequency threshold.

[0021] Among them, the frequency , To preset the measurement accuracy, is the frequency of the high-frequency reference frequency signal.

[0022] (1) Frequency measurement using the improved T method includes: A counter is used to count the frequency signal to be measured and the high-frequency reference frequency signal respectively, and a count value N of the high-frequency reference frequency signal is obtained within one cycle of the frequency signal to be measured (the cycle can be determined by the rising edge); Calculate the frequency based on the count value N , For measurement accuracy The adjustment coefficient under is the frequency of the high-frequency reference frequency signal.

[0023] Adjustment coefficient Ways to obtain include: Select a known frequency signal, whose frequency , set its corresponding adjustment coefficient ; Take the known frequency to be measured as the frequency signal to be measured and obtain the count value of the corresponding high-frequency reference frequency signal ,but: ; According to frequency and frequency We can get: ; By adjusting the coefficient Take a positive integer value and get the corresponding frequency , and then define the adjustment coefficient The corresponding frequency The adjustment coefficient of the range interval is determined according to the initial frequency. , and substitute it into Calculate and take the adjustment coefficient each time , then according to the frequency measured in the previous round .

[0024] (2) Frequency measurement using the improved M / T method includes: A counter is used to count the frequency signal to be measured and the high-frequency reference frequency signal respectively, and within a preset time interval, count values ​​M and N of the frequency signal to be measured and the high-frequency reference frequency signal are obtained; Calculate the frequency based on the values ​​N and M , For measurement accuracy The count value below, is the frequency of the high-frequency reference frequency signal.

[0025] Methods for obtaining the count value M include: Select a known frequency signal, whose frequency , set its corresponding count value ; Take the known frequency to be measured as the frequency signal to be measured and obtain the count value of the corresponding high-frequency reference frequency signal ,but: ; According to frequency and frequency We can get: ; By counting the value Take a positive integer value and get the corresponding frequency , and then define the count value The corresponding frequency The range interval. Determine the count value of the range interval according to the initial frequency , and substitute it into Calculate and take the count value each time , then according to the frequency measured in the previous round .

[0026] The same-precision measurement device provided by the embodiment of the present invention has a simple structure and strong anti-interference ability. The same-precision measurement method provided by the embodiment of the present invention, based on the same-precision measurement device, ensures that the acquisition accuracy of the entire frequency band remains unchanged by adjusting the parameters k and M, and the real-time performance of the entire frequency band is also enhanced.

[0027] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0028] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0029] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0030] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0031] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A device for measuring wide range frequency signals with the same precision, characterized in that: It includes a first filter circuit, a clamp circuit, a conditioning circuit, a second filter circuit and a microprocessor which are electrically connected in sequence; the first filter circuit and the second filter circuit are both used to filter out electrostatic interference and low-frequency noise; the clamp circuit is used to protect its back-end circuit; the conditioning circuit includes a non-inverting Schmitt trigger for eliminating signal noise interference; the microprocessor includes a timer for counting the frequency of the frequency signal.

2. The same-precision measurement device for wide-range frequency signals according to claim 1, characterized in that: The first filter circuit includes a TVS tube D2, a capacitor C2 and a resistor R3. One ends of the TVS tube D2, the capacitor C2 and the resistor R3 are connected and serve as the input end of the first filter circuit. The other ends of the TVS tube D2 and the capacitor C2 are connected and grounded. The other end of the resistor R3 serves as the output end of the first filter circuit.

3. The same-precision measurement device for wide-range frequency signals according to claim 1, characterized in that: The clamp circuit includes a diode D1 and a diode D3, wherein the cathode of the diode D1 is connected to the power supply VDD1, the anode of the diode D1 is connected to the cathode of the diode D3, the anode of the diode D3 is grounded, and the common end of the diode D1 and the diode D3 serves as the input and output end of the clamp circuit.

4. The same-precision measurement device for wide-range frequency signals according to claim 1, characterized in that: The non-inverting Schmitt trigger includes a resistor R1 and an operational amplifier U1A, the positive input terminal and the output terminal of the operational amplifier U1A are connected in series via the resistor R1, and the negative input terminal of the operational amplifier U1A is connected to an adjustable threshold signal.

5. The same-precision measurement device for wide-range frequency signals according to claim 4, characterized in that: The conditioning circuit also includes an RC filter circuit and a resistor R2. The RC filter circuit includes a resistor R4 and a capacitor C1. The input end of the RC filter circuit serves as the input end of the conditioning circuit. The output end of the RC filter circuit is connected to the positive input end of the operational amplifier U1A. The output end of the operational amplifier U1A is pulled up to the power supply VDD2 via the resistor R2. The output end of the operational amplifier U1A serves as the output end of the conditioning circuit.

6. The same-precision measurement device for wide-range frequency signals according to claim 1, characterized in that: The second filter circuit includes a resistor R5 and a capacitor C3. One end of the resistor R5 and the capacitor C3 are connected and serve as the output end of the second filter circuit. The other end of the resistor R5 serves as the input end of the second filter circuit. The other end of the capacitor C3 is grounded.

7. A method for measuring a wide range of frequency signals with the same precision, characterized in that: Using the same-precision measurement device as described in any one of claims 1 to 6, the same-precision measurement method includes: Step S1: Use the improved T method to measure the frequency and obtain the measurement result: frequency ; like , then continue to use the improved T method to measure the frequency, like , then proceed to step S2; Step S2: Use the improved M / T method to measure the frequency and obtain the measurement result: frequency ; like , then continue to use the improved M / T method to measure the frequency, like , then go to step 1; Among them, the frequency is the preset frequency threshold.

8. The method for measuring wide-range frequency signals with the same precision according to claim 7, characterized in that: The frequency , To preset the measurement accuracy, is the frequency of the high-frequency reference frequency signal.

9. The method for measuring wide-range frequency signals with the same precision according to claim 7, characterized in that: The frequency measurement using the improved T method includes: A counter is used to count the frequency signal to be measured and the high-frequency reference frequency signal respectively, and a count value N of the high-frequency reference frequency signal is obtained within one cycle of the frequency signal to be measured; Calculate the frequency based on the count value N , For measurement accuracy The adjustment coefficient under is the frequency of the high-frequency reference frequency signal; by adjusting the adjustment coefficient , keep the count value N the same under different frequency signals to be measured, and maintain the same measurement accuracy of different frequency signals to be measured.

10. The method for measuring wide-range frequency signals with the same precision according to claim 7, characterized in that: The frequency measurement using the improved M / T method includes: A counter is used to count the frequency signal to be measured and the high-frequency reference frequency signal respectively, and within a preset time interval, count values ​​M and N of the frequency signal to be measured and the high-frequency reference frequency signal are obtained; Calculate the frequency based on the values ​​N and M , For measurement accuracy The count value below, is the frequency of the high-frequency reference frequency signal; by adjusting the count value M, the count value N is kept the same under different frequency signals to be measured, and the measurement accuracy of different frequency signals to be measured is maintained the same.

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