CN119688037A - Pulse signal processing circuit and magnetostrictive liquid level meter - Google Patents

Abstract

The present invention relates to the field of liquid level measurement technology, and in particular to a pulse signal processing circuit and a magnetostrictive liquid level meter. The pulse signal processing circuit comprises: a limiting module, which is used to perform limiting processing on a first voltage signal and a second voltage signal transmitted by an induction coil of a magnetostrictive sensor, wherein the first voltage signal refers to a voltage signal obtained according to an induction pulse signal, and the second voltage signal refers to a voltage signal obtained according to a strain pulse signal; and a signal amplification module, which is connected to the output of the limiting module and amplifies the output and then outputs it to a time-to-digital converter of the magnetostrictive sensor; the pulse signal processing circuit can well reduce the interference of the induction pulse signal on the signal processing process of the time-to-digital converter.

Description

Pulse signal processing circuit and magnetostriction liquid level meter

Technical Field

The invention relates to the technical field of liquid level measurement, in particular to a pulse signal processing circuit and a magnetostrictive liquid level meter.

Background

Magnetostrictive level gauges are precise instruments that measure the height of a liquid using the principle of magnetostriction, and generally include a magnetostrictive sensor, a waveguide (tube), and a floating ball that floats with the liquid surface, etc., in which magnetic steel is provided to generate a magnetic ring magnetic field. During the measurement process, a driving pulse (current pulse) signal is periodically generated in an electronic chamber in the magnetostrictive sensor, and the driving pulse signal is transmitted along the waveguide wire and generates a circumferential magnetic field outside the waveguide wire. When the circumferential magnetic field intersects with the magnetic ring magnetic field, the waveguide wire is deformed due to the magnetostriction, thereby generating a strain pulse signal (strain mechanical wave pulse signal) which is transmitted to the magnetostrictive sensor at a fixed speed. The magnetostrictive sensor converts the strain pulse signal into a voltage signal and determines the height of the liquid surface based on the time at which the drive pulse signal was sent and the time at which the voltage signal was received.

However, the driving pulse signal may induce a sensing pulse signal (current signal) due to a change of a magnetic field in addition to the strain pulse signal generated by the deformation of the waveguide wire, and the sensing pulse signal is far greater than the above-mentioned voltage signal, thereby interfering with the strain pulse signal processing process of the magnetostrictive sensor, resulting in a decrease in measurement accuracy.

Disclosure of Invention

The invention provides a pulse signal processing circuit and a magnetostrictive liquid level meter, which are used for solving the technical problem that the strain pulse signal processing process of a magnetostrictive sensor is easily interfered by an induction pulse signal caused by a driving pulse signal in the prior art, so that the measurement accuracy is reduced.

The invention provides a pulse signal processing circuit which is applied to a magnetostrictive liquid level meter, and comprises a limiting module and a signal amplifying module;

A limiting module for limiting the first voltage signal and the second voltage signal transmitted by the induction coil of the magnetostrictive sensor, wherein the first voltage signal is a voltage signal obtained according to the induction pulse signal, the second voltage signal is a voltage signal obtained according to the strain pulse signal, and

And the signal amplifying module is connected with the output of the amplitude limiting module, amplifies the output of the amplitude limiting module and outputs the amplified output to the time-digital converter of the magnetostrictive sensor.

In one embodiment of the present invention, the pulse signal processing circuit further comprises a sensing pulse cancellation module, wherein the sensing pulse cancellation module comprises a controller and an analog switch;

The controller is used for switching off the analog switch and starting timing when determining that the magnetostrictive sensor sends out a driving pulse signal, and controlling the analog switch to be switched on to finish the elimination of the sensing pulse signal if the accumulated timing time reaches a preset time threshold;

The controller is respectively connected with the magnetostrictive sensor and the signal input end of the circuit board where the analog switch is located, one end of the analog switch is connected with the output end of the signal amplifying module, and the other end of the analog switch is connected with the time-digital converter.

In an embodiment of the present invention, the pulse signal processing circuit further includes a filtering module, configured to perform filtering processing on the signal output by the analog switch;

The input end of the filtering module is connected with the output end of the analog switch, and the output end of the filtering module is connected with the time-digital converter.

In one embodiment of the present invention, the clipping module includes a first diode and a second diode;

The positive pole of first diode with induction coil's negative output end is connected, the negative pole of first diode with induction coil's positive output end is connected, the positive pole of second diode with induction coil's positive output end is connected, the negative pole of second diode with induction coil's negative output end is connected, in order to constitute two-way amplitude limiting, the negative pole of first diode is the negative output end of amplitude limiting module, the negative pole of second diode is the positive output end of amplitude limiting module.

In an embodiment of the invention, the signal amplifying module comprises a biasing unit, a filtering unit and a signal amplifying unit which are sequentially connected.

In an embodiment of the present invention, the bias unit includes a first resistor, a second resistor, and a third resistor, and the filter unit includes a fourth resistor, a fifth resistor, a first capacitor, a second capacitor, and a third capacitor;

the first end of the first resistor is connected with the negative electrode of an external power supply, the second end of the first resistor is connected with the first end of the second resistor and the positive output end of the amplitude limiting module respectively, the second end of the second resistor is connected with the first end of the third resistor and the negative output end of the amplitude limiting module respectively, and the second end of the third resistor is connected with the positive electrode of the external power supply;

One end of the fourth resistor is connected with the second end of the first resistor, the other end of the fourth resistor, the first capacitor, the second capacitor and the fifth resistor are sequentially connected, the fifth resistor is connected with the negative output end of the amplitude limiting module, a grounding node is arranged between the first capacitor and the second capacitor, a first connecting point is arranged between the fourth resistor and the first capacitor, a second connecting point is arranged between the fifth resistor and the second capacitor, the first end of the third capacitor is connected with the first connecting point, the second end of the third capacitor is connected with the second connecting point, the first end of the third capacitor is connected with the negative input end of the signal amplifying unit, and the second end of the third capacitor is connected with the positive input end of the signal amplifying unit.

In an embodiment of the invention, the signal amplifying unit comprises a sixth resistor and an instrument operational amplifier;

One end of the third capacitor is connected with the positive input end of the instrument operational amplifier, the other end of the third capacitor is connected with the negative input end of the instrument operational amplifier, the instrument operational amplifier is externally connected with the sixth resistor, and the resistance value of the sixth resistor is inversely proportional to the gain of the instrument operational amplifier.

In an embodiment of the invention, the inductive pulse cancellation module further includes a noise reduction unit and a bias resistor, where the noise reduction unit includes a seventh resistor and a fourth capacitor;

One end of the seventh resistor is connected with the output end of the controller, the other end of the seventh resistor is connected with the signal input end of the circuit board where the analog switch is located, one end of the seventh resistor far away from the controller is connected with the fourth capacitor, and one end of the fourth capacitor far away from the seventh resistor is grounded;

One end of the bias resistor is connected with the output end of the analog switch, and the other end of the bias resistor is grounded.

In an embodiment of the invention, the filtering module includes an operational amplifier, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a fifth capacitor, and a sixth capacitor;

One end of the eighth resistor is an input end of the filter module, the other end of the eighth resistor, the ninth resistor and the in-phase input end of the operational amplifier are sequentially connected, one end of the fifth capacitor is connected with the in-phase input end of the operational amplifier, the other end of the fifth capacitor is grounded, one end of the tenth resistor is connected with the inverting input end of the operational amplifier, the other end of the tenth resistor is grounded, one end of the eleventh resistor is connected with the inverting input end of the operational amplifier, the other end of the eleventh resistor is connected with the output end of the operational amplifier, one end of the sixth capacitor is connected with one end of the eighth resistor, which is close to the ninth resistor, the other end of the sixth capacitor is connected with the output end of the operational amplifier, and the output end of the operational amplifier is the output end of the filter module.

The invention also provides a magnetostrictive liquid level meter, which comprises the pulse signal processing circuit.

The pulse signal processing circuit and the magnetostrictive liquid level meter have the beneficial effects that the amplitude limiting module and the signal amplifying module are arranged, the amplitude limiting module is used for carrying out amplitude limiting processing on the first voltage signal and the second voltage signal transmitted by the induction coil of the magnetostrictive sensor, the first voltage signal is the voltage signal obtained according to the induction pulse signal, the second voltage signal is the voltage signal obtained according to the strain pulse signal, the signal amplifying module is connected with the output of the amplitude limiting module, the signal amplifying module is used for amplifying the output of the amplitude limiting module and then outputting the amplified output to the time-digital converter of the magnetostrictive sensor, and the interference of the induction pulse signal on the signal processing process of the time-digital converter can be well reduced. It can be understood that the first voltage signal corresponding to the induction pulse signal is far greater than the second voltage signal corresponding to the strain pulse signal, so that the voltage signal output by the induction coil is limited, the larger first voltage signal can be clamped in a fixed voltage range, so that the interference of the first voltage signal/the induction pulse signal to the signal processing process of the time-to-digital converter is reduced, and the accuracy of the signal processing of the time-to-digital converter (the height of the liquid level is determined according to the time of sending the driving pulse signal and the time of receiving the voltage signal corresponding to the strain pulse signal) is improved to a certain extent.

And, because the second voltage signal that the strain pulse signal corresponds to is less, so the second voltage signal can pass through the amplitude limiting module smoothly, and enter the signal amplification module. By amplifying the second voltage signal, the signal recognition and processing of the subsequent time-to-digital converter can be facilitated.

In addition, compared with the method that the first voltage signal and the second voltage signal output by the induction coil are directly input into the signal amplifying module, the stability and the safety of the device provided by the invention are stronger. It will be appreciated that since the induction pulse signal is a current signal and the strain pulse signal is a mechanical wave signal, the induction pulse signal reaches the induction coil faster than the strain pulse signal. The induction coil can firstly convert the induction pulse signal into a first voltage signal, and then convert the strain pulse signal arriving later into a second voltage signal. On the basis, if the first voltage signal generated first is directly input to the signal amplifying module, the response time of the signal amplifying module to the second voltage signal may be reduced (after the larger first voltage signal is input to the signal amplifying module, the amplifier in the signal amplifying module is saturated, the time required for recovering from the saturated state to the linear state is longer), and the larger first voltage signal is easy to damage the amplifier in the signal amplifying module, the pulse signal processing circuit in the invention can better solve the problem by arranging the amplitude limiting circuit between the induction coil and the signal amplifying module, and can realize the amplification of the second voltage signal while reducing the interference of the larger first voltage signal to the signal processing process of the time-to-digital converter, thereby being beneficial to improving the processing accuracy of the time-to-digital converter to the strain pulse signal, better protecting devices in the signal amplifying module and improving the stability of the whole circuit.

Drawings

FIG. 1 is a schematic diagram of a magnetostrictive sensor according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a pulse signal processing circuit according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of another structure of a pulse signal processing circuit according to an embodiment of the present invention;

Fig. 4 is a schematic structural diagram of an amplitude limiting module and a signal amplifying module in a pulse signal processing circuit according to an embodiment of the present invention;

FIG. 5 is a schematic diagram illustrating a structure of an inductive pulse cancellation module in a pulse signal processing circuit according to an embodiment of the present invention;

fig. 6 is a schematic diagram of a filtering module in a pulse signal processing circuit according to an embodiment of the invention.

Detailed Description

Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention. It should be noted that the following embodiments and features in the embodiments may be combined with each other without conflict.

It should be noted that the illustrations provided in the following embodiments merely illustrate the basic concept of the present invention by way of illustration, and only the components related to the present invention are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complicated.

In the following description, numerous details are set forth in order to provide a more thorough explanation of embodiments of the present invention, it will be apparent, however, to one skilled in the art that embodiments of the present invention may be practiced without these specific details, in other embodiments, well-known structures and devices are shown in block diagram form, rather than in detail, in order to avoid obscuring the embodiments of the present invention.

In order to facilitate understanding of the pulse signal processing circuit and the magnetostrictive liquid level meter provided by the invention, the working principle of the magnetostrictive sensor is explained below.

Referring to fig. 1, the induction coil in the magnetostrictive sensor can be equivalent to an inductance, such as the inductance on the right part in fig. 1. The waveguide wire may be equivalently a resistor, such as the resistor on the left hand side of fig. 1. When the induction pulse signal (current signal) or the strain pulse signal is transmitted to the induction coil, the induction coil can convert the induction signal into a voltage signal, so that a subsequent Time-to-Digital Converter (TDC) is convenient for signal processing, namely, the height of the liquid level is determined according to the Time of sending the driving pulse signal and the Time of receiving the voltage signal corresponding to the strain pulse signal. The arrow in fig. 1 indicates the propagation direction of the signal, I indicates the induced pulse signal, a indicates the strain pulse signal, and V1 indicates the voltage signal of the induction coil obtained by converting the induced pulse signal or the strain pulse signal.

Referring to fig. 2, fig. 2 is a schematic structural diagram of a pulse signal processing circuit according to an embodiment of the present invention, as shown in fig. 2, the pulse signal processing circuit is applied to a magnetostrictive liquid level meter, and includes:

A limiting module for limiting the first voltage signal and the second voltage signal transmitted by the induction coil of the magnetostrictive sensor, wherein the first voltage signal is a voltage signal obtained according to the induction pulse signal, the second voltage signal is a voltage signal obtained according to the strain pulse signal, and

And the signal amplifying module is connected with the output of the amplitude limiting module, amplifies the output of the amplitude limiting module and outputs the amplified output to the time-digital converter of the magnetostrictive sensor.

The input end of the amplitude limiting module is connected with the induction coil, the output end of the amplitude limiting module is connected with the input end of the signal amplifying module, and the output end of the signal amplifying module is connected with the time-digital converter of the magnetostriction sensor.

It will be appreciated that the electronics in the magnetostrictive sensor periodically generate a drive pulse signal that propagates along the waveguide wire and creates a circumferential magnetic field outside the waveguide wire. When the circumferential magnetic field intersects with the magnetic field of the magnetic ring of the floating ball, an induction pulse signal is generated due to the magnetic field change. And, the waveguide wire is deformed due to the magnetostriction, thereby generating a strain pulse signal. The propagation speed of the induction pulse signal is faster than that of the strain pulse signal, so that the induction pulse signal and the strain pulse signal are returned to the induction coil after the waveguide wire is sequentially extended. When the induction coil detects the induction pulse signal, the induction pulse signal is converted into a first voltage signal. When the induction coil detects the strain pulse signal, the strain pulse signal is converted into a second voltage signal. The first voltage signal and the second voltage signal are transmitted to a time-digital converter of the magnetostrictive sensor for signal processing so as to realize liquid level measurement. The time-to-digital converter determines the height of the liquid level according to the time of sending the driving pulse signal and the time of receiving the voltage signal corresponding to the strain pulse signal.

It should be noted that, by setting the amplitude limiting module, the amplitude of the voltage signal input to the signal amplifying module can be limited, so that the amplifier (i.e. the instrument operational amplifier) in the signal amplifying module is prevented from entering a saturated state, and the response speed of the signal amplifying module to the second pulse signal is ensured. And, effectively avoid high voltage (first voltage signal) to cause the damage to the amplifier. And, the clipping module can clamp the first voltage signal within a fixed voltage range, thereby reducing subsequent interference of the first voltage signal with the processing of the time-to-digital converter.

The signal amplifying module is arranged to amplify the limited second voltage signal, so that the time-digital converter of the magnetostrictive sensor can conveniently recognize and process the signal.

It can be understood that, although the first voltage signal still enters the signal amplifying module to be amplified after being limited by the limiting module, the amplified signal is still lower than the original first voltage signal, so that the interference of the first voltage signal to the signal processing process of the time-to-digital converter can be reduced.

In order to further eliminate the interference of the induced pulse signal to the signal processing process of the time-to-digital converter, and in order to reduce the signal noise, an induced pulse eliminating module and a filtering module are sequentially introduced in the following embodiments, and the connection relationship between the circuits is shown in fig. 3. As shown in fig. 3, the induction coil, the amplitude limiting module, the signal amplifying module, the induction pulse eliminating module, the filtering module and the time-to-digital converter are sequentially connected.

In some embodiments, the pulse signal processing circuit further comprises a sense pulse cancellation module comprising a controller and an analog switch.

The controller is used for switching off the analog switch and starting timing when determining that the magnetostrictive sensor sends out a driving pulse signal, and controlling the analog switch to be switched on to finish the elimination of the sensing pulse signal if the accumulated timing time reaches a preset time threshold.

The controller is respectively connected with the magnetostrictive sensor and the signal input end of the circuit board where the analog switch is located, one end of the analog switch is connected with the output end of the signal amplifying module, and the other end of the analog switch is connected with the time-digital converter.

Since the induction pulse signal is a current signal and the strain pulse signal is a mechanical wave signal, the induction pulse signal reaches the induction coil faster than the strain pulse signal. Therefore, by providing the above-described inductive pulse cancellation module between the signal amplification module and the time-to-digital converter, cancellation of the inductive pulse signal can be achieved. The duration threshold may be determined from a difference between a time of transmission of the induction pulse signal to the induction coil and a time of transmission of the strain pulse signal to the induction coil. For example, assuming that the difference between the time of transmission of the induction pulse signal to the induction coil and the time of transmission of the strain pulse signal to the induction coil is 20 microseconds (the time of transmission of the driving pulse signal to the floating ball is relatively fast and negligible here), the duration threshold may be 20 microseconds, etc. It can be understood that when the electronic chamber of the magnetostrictive sensor sends out a driving pulse signal, the controller of the sensing pulse eliminating module controls the analog switch to be turned off, so that the sensing pulse signal (sensing pulse signal after amplitude limiting and signal amplification) which is firstly reached cannot pass through the analog switch, and is eliminated. After 20 microseconds, the controller controls the analog switch to be turned on, and the arriving strain pulse signal (the strain pulse signal after amplitude limiting and signal amplification) can directly pass through the analog switch.

The inductive pulse eliminating module in the embodiment can well eliminate inductive pulse signals, avoid interference to the signal processing process of the time-to-digital converter, and avoid false triggering of the time-to-digital converter.

In some embodiments, the pulse signal processing circuit further comprises a filtering module for filtering the signal output by the analog switch.

The input end of the filtering module is connected with the output end of the analog switch, and the output end of the filtering module is connected with the time-digital converter.

It should be noted that, by setting the filtering module, noise, burrs and the like in the signal can be eliminated, thereby being beneficial to improving the signal processing accuracy of the subsequent time digital converter.

Fig. 4 is a schematic structural diagram of a clipping module and a signal amplifying module in a pulse signal processing circuit according to an embodiment of the present invention, referring to fig. 4, in some embodiments, the clipping module includes a first diode D1 and a second diode D2.

The positive pole of first diode D1 with induction coil's negative output (MRX-) is connected, first diode D1's negative pole with induction coil's positive output is connected, second diode D2's positive pole with induction coil's positive output (MRX+) is connected, second diode D2's negative pole with induction coil's negative output is connected, in order to constitute two-way amplitude limiting, first diode D1's negative pole is the negative output of amplitude limiting module, second diode D2's negative pole is the positive output of amplitude limiting module.

It should be noted that, the first diode D1 and the second diode D2 are both amplitude limiting diodes. Based on the unidirectional conduction characteristic of the diode, when the signal output by the induction coil is a positive voltage signal, the second diode D2 is turned on, and the first diode D1 is in a reverse off state, so that the voltage passing through the second diode D2 is clamped/limited within the conduction voltage of the second diode D2, i.e., the maximum value of the voltage signal output by the second diode D2 does not exceed the conduction voltage of the second diode D2. When the signal output by the induction coil is a negative voltage signal, the first diode D1 is turned on, and the second diode D2 is in a reverse cut-off state, so that the voltage passing through the first diode D1 is clamped/limited within the reverse breakdown voltage of the first diode D1, i.e. the maximum value of the voltage signal output by the first diode D1 does not exceed the reverse breakdown voltage of the first diode D1. For example, assuming that the on voltage of the second diode D2 is 0.2V and the reverse breakdown voltage of the first diode D1 is-0.2V, the voltage signal output from the clipping module will be clamped within [ -0.2V,0.2V ], which is the clipping range of the clipping module.

It should be mentioned that the useful signal of the strained pulse signal is within the clipping range of the clipping module. The strain pulse signal, after being converted into the second voltage signal, typically contains a useful signal of around 100mV (millivolts), and the limiting range of the limiting module can be set based on the value of the second voltage signal, so as to avoid the distortion of the useful signal.

In some embodiments, the signal amplification module comprises a bias unit, a filtering unit and a signal amplification unit which are connected in sequence.

It should be noted that, through setting up the biasing unit in the signal amplification module, can avoid induction coil short circuit, guarantee the security of whole circuit. In addition, by arranging the filtering unit in the signal amplifying module, noise in the signal can be reduced, and the accuracy of the signal can be improved.

In some embodiments, the bias unit comprises a first resistor R1, a second resistor R2 and a third resistor R3, and the filter unit comprises a fourth resistor R4, a fifth resistor R5, a first capacitor C1, a second capacitor C2 and a third capacitor C3;

The first end of the first resistor R1 is connected with a negative electrode (NVCC) of an external power supply, the second end of the first resistor R1 is respectively connected with the first end of a second resistor R2 and the positive output end of the amplitude limiting module, the second end of the second resistor R2 is respectively connected with the first end of a third resistor R3 and the negative output end of the amplitude limiting module, and the second end of the third resistor R3 is connected with the positive electrode (VDD) of the external power supply;

One end R4 of the fourth resistor is connected with the second end of the first resistor R1, the other end of the fourth resistor R4, the first capacitor C1, the second capacitor C2 and the fifth resistor R5 are sequentially connected, the fifth resistor R5 is connected with the negative output end of the clipping module, a grounding node is arranged between the first capacitor C1 and the second capacitor C2, a first connection point is arranged between the fourth resistor R4 and the first capacitor C1, a second connection point is arranged between the fifth resistor R5 and the second capacitor C2, the first end of the third capacitor C3 is connected with the first connection point, the second end of the third capacitor C3 is connected with the second connection point, the first end of the third capacitor C3 is connected with the negative input end of the signal amplifying unit, and the second end of the third capacitor is connected with the positive input end of the signal amplifying unit.

The grounding node is used for grounding. Through the arrangement, the signal filtering is realized while the safe conduction of the circuit is ensured.

In some embodiments, the signal amplifying unit comprises a sixth resistor R6 and a meter operational amplifier U1;

One end of the third capacitor C3 is connected to the positive input end (e.g., the "+" port of U1 in fig. 4) of the instrument operational amplifier U1, the other end of the third capacitor C3 is connected to the negative input end (e.g., the "-" port of U1 in fig. 4) of the instrument operational amplifier U1, the instrument operational amplifier U1 is externally connected with the sixth resistor R6, and the resistance value of the sixth resistor R6 is inversely proportional to the gain of the instrument operational amplifier U1.

As shown in fig. 4, the instrument op-amp U1 is connected to the sixth resistor R6 through a preset resistor port (RG). The "v+" port in the instrument op-amp U1 in fig. 4 represents a positive power supply port, "V-" represents a negative power supply port, "VOUT" represents an output port, and "REF" represents a ground port. "sig_vo" represents a voltage signal output by the meter op-amp U1.

The gain of the instrumentation op-amp U1 can be adjusted by adjusting the resistance of the sixth resistor R6.

Fig. 5 is a schematic structural diagram of a sensing pulse cancellation module in a pulse signal processing circuit according to an embodiment of the present invention, referring to fig. 5, in some embodiments, the sensing pulse cancellation module further includes a noise reduction unit and a bias resistor R', where the noise reduction unit includes a seventh resistor R7 and a fourth capacitor C4.

One end of the seventh resistor R7 is connected with the output end of the controller, the other end of the seventh resistor R7 is connected with the signal input end of the circuit board where the analog switch is located, one end of the seventh resistor R7 far away from the controller is connected with the fourth capacitor C4, and one end of the fourth capacitor C4 far away from the seventh resistor R7 is grounded.

One end of the bias resistor R 'is connected with the output end of the analog switch, and the other end of the bias resistor R' is grounded.

By arranging the noise reduction unit, the noise of the signal output by the controller can be eliminated, and the accurate control is realized. By setting the bias resistor R', normal conduction of the circuit can be ensured.

The switch IN fig. 5 is an analog switch, a box outside the switch is a circuit board where the switch is located, a 'COM/D' port IN the circuit board is a port for connecting with a signal amplifying module, a 'NO/S' port is an output port, an 'IN' port is a signal input end for receiving a control signal of a controller, so that the opening or closing control of the analog switch is realized, a 'GND' port is a ground port, a 'v+' port represents a positive power port, and a 'V-' represents a negative power port. "sig_fin" is a signal that passes through an analog switch. SPST in fig. 5 represents a control signal.

Fig. 6 is a schematic diagram of a filtering module in a pulse signal processing circuit according to an embodiment of the present invention, referring to fig. 6, in some embodiments, the filtering module includes an operational amplifier, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a fifth capacitor C5, and a sixth capacitor C6;

One end of the eighth resistor R8 is an input end of the filtering module, the other end of the eighth resistor R8, the ninth resistor R9 and the non-inverting input end of the operational amplifier are sequentially connected, one end of the fifth capacitor C5 is connected with the non-inverting input end of the operational amplifier, the other end of the fifth capacitor C5 is grounded, one end of the tenth resistor R10 is connected with an inverting input end of the operational amplifier, the other end of the tenth resistor R10 is grounded, one end of the eleventh resistor R11 is connected with the inverting input end of the operational amplifier, the other end of the eleventh resistor R11 is connected with an output end of the operational amplifier, one end of the sixth capacitor C6 is connected with one end of the eighth resistor R8, which is close to the non-inverting input end of the ninth resistor R9, the other end of the sixth capacitor C6 is connected with the output end of the operational amplifier, and the output end of the operational amplifier is the output end of the filtering module.

By means of the circuit structure, noise and burrs in signals can be reduced well, the signal-to-noise ratio of useful signals is improved, and therefore the signal processing accuracy of the subsequent time digital converter is improved. "sig_fout" in fig. 6 refers to a signal output from the filtering module.

In order to verify the signal processing effect of the pulse signal processing circuit in the above embodiment, after a plurality of experiments, it is determined that the induction pulse signal and most of other noises can be eliminated when the signal output by the induction coil is processed by the pulse signal processing circuit, so that the signal processing accuracy of the time-to-digital converter is improved.

The embodiment also provides a magnetostrictive liquid level meter which is characterized by comprising the pulse signal processing circuit. It should be noted that, the magnetostrictive liquid level meter in this embodiment can achieve the technical effects achieved by any one of the embodiments described above, and will not be described herein again.

The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.

Claims (10)

1. A pulse signal processing circuit, characterized in that it is applied to a magnetostrictive liquid level meter, comprising:

A limiting module for limiting the first voltage signal and the second voltage signal transmitted by the induction coil of the magnetostrictive sensor, wherein the first voltage signal is a voltage signal obtained according to the induction pulse signal, the second voltage signal is a voltage signal obtained according to the strain pulse signal, and

And the signal amplifying module is connected with the output of the amplitude limiting module, amplifies the output of the amplitude limiting module and outputs the amplified output to the time-digital converter of the magnetostrictive sensor.

2. The pulse signal processing circuit of claim 1, further comprising a sense pulse cancellation module comprising a controller and an analog switch;

The controller is used for switching off the analog switch and starting timing when determining that the magnetostrictive sensor sends out a driving pulse signal, and controlling the analog switch to be switched on to finish the elimination of the sensing pulse signal if the accumulated timing time reaches a preset time threshold;

The controller is respectively connected with the magnetostrictive sensor and the signal input end of the circuit board where the analog switch is located, one end of the analog switch is connected with the output end of the signal amplifying module, and the other end of the analog switch is connected with the time-digital converter.

3. The pulse signal processing circuit according to claim 2, further comprising a filter module for performing a filter process on the signal output from the analog switch;

The input end of the filtering module is connected with the output end of the analog switch, and the output end of the filtering module is connected with the time-digital converter.

4. The pulse signal processing circuit according to claim 1, wherein the clipping module comprises a first diode and a second diode;

The positive pole of first diode with induction coil's negative output end is connected, the negative pole of first diode with induction coil's positive output end is connected, the positive pole of second diode with induction coil's positive output end is connected, the negative pole of second diode with induction coil's negative output end is connected, in order to constitute two-way amplitude limiting, the negative pole of first diode is the negative output end of amplitude limiting module, the negative pole of second diode is the positive output end of amplitude limiting module.

5. The pulse signal processing circuit according to claim 1 or 4, wherein the signal amplifying module comprises a bias unit, a filter unit, and a signal amplifying unit connected in sequence.

6. The pulse signal processing circuit according to claim 5, wherein the bias unit comprises a first resistor, a second resistor, and a third resistor, and the filter unit comprises a fourth resistor, a fifth resistor, a first capacitor, a second capacitor, and a third capacitor;

the first end of the first resistor is connected with the negative electrode of an external power supply, the second end of the first resistor is connected with the first end of the second resistor and the positive output end of the amplitude limiting module respectively, the second end of the second resistor is connected with the first end of the third resistor and the negative output end of the amplitude limiting module respectively, and the second end of the third resistor is connected with the positive electrode of the external power supply;

One end of the fourth resistor is connected with the second end of the first resistor, the other end of the fourth resistor, the first capacitor, the second capacitor and the fifth resistor are sequentially connected, the fifth resistor is connected with the negative output end of the amplitude limiting module, a grounding node is arranged between the first capacitor and the second capacitor, a first connecting point is arranged between the fourth resistor and the first capacitor, a second connecting point is arranged between the fifth resistor and the second capacitor, the first end of the third capacitor is connected with the first connecting point, the second end of the third capacitor is connected with the second connecting point, the first end of the third capacitor is connected with the negative input end of the signal amplifying unit, and the second end of the third capacitor is connected with the positive input end of the signal amplifying unit.

7. The pulse signal processing circuit according to claim 6, wherein the signal amplifying unit comprises a sixth resistor and an instrumentation operational amplifier;

One end of the third capacitor is connected with the positive input end of the instrument operational amplifier, the other end of the third capacitor is connected with the negative input end of the instrument operational amplifier, the instrument operational amplifier is externally connected with the sixth resistor, and the resistance value of the sixth resistor is inversely proportional to the gain of the instrument operational amplifier.

8. The pulse signal processing circuit of claim 2, wherein the inductive pulse cancellation module further comprises a noise reduction unit and a bias resistor, the noise reduction unit comprising a seventh resistor and a fourth capacitor;

One end of the seventh resistor is connected with the output end of the controller, the other end of the seventh resistor is connected with the signal input end of the circuit board where the analog switch is located, one end of the seventh resistor far away from the controller is connected with the fourth capacitor, and one end of the fourth capacitor far away from the seventh resistor is grounded;

One end of the bias resistor is connected with the output end of the analog switch, and the other end of the bias resistor is grounded.

9. The pulse signal processing circuit according to claim 3, wherein the filter module comprises an operational amplifier, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a fifth capacitor, and a sixth capacitor;

One end of the eighth resistor is an input end of the filter module, the other end of the eighth resistor, the ninth resistor and the in-phase input end of the operational amplifier are sequentially connected, one end of the fifth capacitor is connected with the in-phase input end of the operational amplifier, the other end of the fifth capacitor is grounded, one end of the tenth resistor is connected with the inverting input end of the operational amplifier, the other end of the tenth resistor is grounded, one end of the eleventh resistor is connected with the inverting input end of the operational amplifier, the other end of the eleventh resistor is connected with the output end of the operational amplifier, one end of the sixth capacitor is connected with one end of the eighth resistor, which is close to the ninth resistor, the other end of the sixth capacitor is connected with the output end of the operational amplifier, and the output end of the operational amplifier is the output end of the filter module.

10. A magnetostrictive level meter comprising a pulse signal processing circuit according to any one of claims 1 to 9.