Based on ultrasonic ranging method and the ultrasonic sensor of the actual measurement velocity of sound
Technical field
The present invention relates to a kind of ultrasonic ranging method based on the actual measurement velocity of sound and ultrasonic sensor, be specifically related to a kind of can make ultrasonic measurement by ectocine, high stability and high-precision based on the actual measurement ultrasonic ranging method of the velocity of sound and ultrasonic sensor, belong to technical field of ultrasonic measurement.
Background technology
Ultrasonic sensor as non-contacting sensor have easy for installation, stability is high, by the advantage easily such as medium pollution, the occasion of the various level gauging such as industrial, agriculture can be widely applied, particularly in occasion that is poisonous, that have pollution, therefore, ultrasonic sensor has the unrivaled advantage of other kind distance measuring sensors.But because ultrasonic measurement is easily subject to the impact of external environment, compensation way imperfection, causes the not high of measurement reproducibility and precision, therefore can only use when measuring accuracy is less demanding or indoor extraneous environmental change is little.
The principle of ultrasonic sensor is that the transmission speed of time and the sound wave propagated in atmosphere by ultrasound wave calculates distance.But the velocity of sound is not unalterable, it changes to some extent along with the change of external environment, wherein affect sonic velocity change because have temperature, pressure, humidity, air quality etc.
Traditional ultrasonic sensor goes to calculate to be similar to mainly through measuring tempeature and obtains the velocity of sound.The shortcoming that this method exists is:
First, the temperature of measurement can not the correct temperature reflected in air at that time in time;
Secondly, the velocity of sound is not only temperature influence, and it is also by the impact of the aspects such as air humidity, air pressure, air quality.
Therefore the velocity of sound utilizing this kind of method to record goes the impact being still easily subject to external environment during computation and measurement distance, and cause the inaccurate of measuring distance, thus measurement reproducibility is not high, error is large.Therefore, repeatability and the precision of existing ultrasonic sensor measurement are not high, easily by air themperature, and air pressure, air humidity, the impact of the external environments such as air quality.
CN104483380A discloses a kind of ultrasonic gas concentration measuring method based on temperature compensation and measurement mechanism, adopt 1 transmitting-receiving integrated ultrasonic transducer, by transmitting after the reflection of sensor body opposite side inwall, the travel-time of measuring Received signal strength realizes gas concentration measurement, reduce the installation difficulty of ultrasonic transducer, decrease cost; Realize temperature dynamic by built-in temperature sensor to compensate simultaneously, first set up the temperature of gas to be measured under two kinds of concentration and velocity of sound compensated curve; Again according to current observed temperature, temperature and the velocity of sound is utilized to compensate the velocity of propagation of gas to be measured under Current Temperatures instead releasing two kinds of concentration, and the relation curve of real-time foundation place concentration and velocity of propagation; Calculate velocity of propagation according to the travel-time under Current Temperatures, and bring in real-time curve and can calculate real-time concentration, ensure ultrasonic oxygen concentration sensor measurement accuracy at different temperatures.
What ultrasonic wave measuring method disclosed in this documents adopted is traditional mode going to compensate the velocity of sound with measuring tempeature, still easily by the impact of environment.And understand that the velocity of sound is also by the impact of air concentration from the principle.
CN204214517U discloses a kind of ultrasonic liquid level measuring system having automatic calibration function, comprise microcontroller, radiating circuit, receiving circuit and ultrasonic probe, also comprise temperature-compensation circuit, a Metallic rod is provided with between described ultrasonic probe and measured target, automatic calibration is carried out by the actual measurement velocity of sound and temperature survey, measuring accuracy is high, realizes the accurate measurement to liquid level.
Ultrasonic liquid level measuring system disclosed in this documents, although have employed the mode that metal tube compensates, but be still as the criterion with the temperature survey velocity of sound in actual measurement, with metal tube as the compensation after skew, cause measured deviation among a small circle larger like this.In addition, the same time measurement Metallic rod of the ultrasonic probe due to this kind of method and liquid level, so be easy to the interference being subject to spurious echo, cause and measure instability.
Summary of the invention
Technical matters to be solved by this invention is, provide a kind of make ultrasonic measurement by ectocine, high stability and high-precision based on the actual measurement ultrasonic ranging method of the velocity of sound and ultrasonic sensor.
For solving technical matters of the present invention, the technical scheme adopted is as follows:
Based on the ultrasonic ranging method of the actual measurement velocity of sound, specifically comprise the following steps:
A, known fixed distance L is set, utilizes ultrasonic probe to measure real velocity of sound V at that time
real;
B, utilize the real velocity of sound V recorded in steps A
realmeasure the distance L ' of ultrasonic probe bottom surface and determinand, step B specifically comprises:
B1. sent by central processing unit and transmit, transmit through transformer drive circuit boosting rear drive ultrasonic probe transmission ultrasound wave, time during ultrasonic probe transmission ultrasound wave is t1 ';
The ultrasound wave that ultrasonic probe sends is reflected back after running into determinand, the ultrasonic echo be reflected back is received by described ultrasonic probe, and convert it into ultrasonic echo signal, ultrasonic echo signal is returned to central processing unit and triggers sampling after amplification, filtering, shaping circuit process, and the time that ultrasonic probe receives ultrasonic echo is t2 ';
Central processing unit calculates the t ' during this period of time that ultrasonic probe sends ultrasound wave and receives ultrasonic echo, described t '=t2 '-t1 ';
Time (namely sending the time of drive singal) when t1 ' is ultrasonic probe transmitting ultrasound wave, t2 ' is the time (namely central processing unit receives the time of echoed signal) that ultrasonic probe receives the ultrasonic echo reflected, wherein ultrasonic probe ultrasonic signal is transformed into the amplification of electric signal, then signal, filtering, shaping these time compole short, can ignore.
B2. central processing unit obtains real velocity of sound V
real, and according to formula: L '=V
real× (1/2t ')=1/2V
real(t2 '-t1 '), calculate the distance L ' of ultrasonic probe bottom surface and determinand.
Further, described steps A specifically comprises:
A1. the known fixed distance L place immediately below ultrasonic probe one arranges a reverberation;
A2. sent by central processing unit and transmit, transmitting sends ultrasound wave through the transformer drive circuit one rear drive ultrasonic probe one that boosts, and time when ultrasonic probe one sends ultrasound wave is t1;
The ultrasound wave that ultrasonic probe one sends out is reflected back after the reverberation running into fixed range L place, the ultrasonic echo be reflected back is by the reception of described ultrasonic probe one, and convert it into ultrasonic echo signal, ultrasonic echo signal is returned to central processing unit through amplification, filtering, shaping circuit one and triggers sampling after processing, the time that ultrasonic probe one receives ultrasonic echo is t2;
Central processing unit calculates the t during this period of time that ultrasonic probe one sends ultrasound wave and receives ultrasonic echo, described t=t2-t1;
T1 is the time (namely send the time of drive singal) of ultrasonic probe one when launching ultrasound wave, t2 is the time (namely central processing unit receives the time of echoed signal) that ultrasonic probe one receives the ultrasonic echo reflected, wherein ultrasonic probe one ultrasonic signal is transformed into the amplification of electric signal, then signal, filtering, shaping these time compole short, can ignore.
A3. central processing unit is according to formula: V
real=s/t=2L/ (t2-t1), calculates real velocity of sound V at that time
real, and the velocity of sound recorded is stored in central processing unit;
Ultrasonic probe in step B is ultrasonic probe two, and accordingly, the transformer drive circuit in described step B is transformer drive circuit two, and amplification, filtering, shaping circuit are amplification, filtering, shaping circuit two.
In another kind of scheme, described steps A specifically comprises:
A1. send signal to the gear train be connected with central processing unit by central processing unit, the reverberation be connected with gear train is moved to the known fixed distance L place immediately below ultrasonic probe by drive transmission device;
A2. sent by central processing unit and transmit, transmit through transformer drive circuit boosting rear drive ultrasonic probe transmission ultrasound wave, time during ultrasonic probe transmission ultrasound wave is t1;
The ultrasound wave that ultrasonic probe sends out is reflected back after the reverberation running into known fixed distance L place, the ultrasonic echo be reflected back is received by described ultrasonic probe, and convert it into ultrasonic echo signal, ultrasonic echo signal is returned to central processing unit and triggers sampling after amplification, filtering, shaping circuit process, and the time that ultrasonic probe receives ultrasonic echo is t2;
Central processing unit calculates the t during this period of time that ultrasonic probe sends ultrasound wave and receives ultrasonic echo, described t=t2-t1;
Time (namely sending the time of drive singal) when t1 is ultrasonic probe transmitting ultrasound wave, t2 is the time (namely central processing unit receives the time of echoed signal) that ultrasonic probe receives the ultrasonic echo reflected, wherein ultrasonic probe ultrasonic signal is transformed into the amplification of electric signal, then signal, filtering, shaping these time compole short, can ignore.
A3. central processing unit is according to formula: V
real=s/t=2L/ (t2-t1), calculates real velocity of sound V at that time
real, and the velocity of sound recorded is stored in central processing unit;
Before step B, comprise step B0: send signal by central processing unit and regain to gear train drive transmission device, described reverberation is shifted out hyperacoustic measurement range;
Ultrasonic probe in described steps A and step B is same ultrasonic probe, and accordingly, the transformer drive circuit in described steps A and step B and amplification, filtering, shaping circuit are respectively same circuit.
Further, the described ultrasonic ranging method based on the actual measurement velocity of sound comprises:
Repeating said steps A and step B, realizes the distance L ' of Real-Time Monitoring determinand.
The alarming value preset in the data recorded in real time and central processing unit is compared by central processing unit, if exceed default alarming value will send signal to warning device by central processing unit, realizes the Real-Time Monitoring to thing distance to be measured.
The data repeating to record can also be kept in internal memory by central processing unit, and carry out intelligent algorithm filtering process within a period of time of setting, reduce the interference that the flowing because of determinand surface wave or propagation medium causes, make the more stable more realistic value of data.
Described intelligent algorithm filtering process refers to, central processing unit sets a time period, if the time period of setting is 1 second, if ultrasonic measurement can measure 10 times in 1 second, so can record 10 data in 1 second, and it is just enough fast within reality 1 second, to record 1 data, therefore data processing is carried out by central processing unit, remove some interfering datas, such as: remove 3 large data, 3 little data, 4 then remaining data are asked for and are averaged, therefore the data drawn can be more accurate, improves the precision measured.
The present invention also provides a kind of ultrasonic sensor adopting the above-mentioned ultrasonic ranging method based on the actual measurement velocity of sound, and described ultrasonic sensor comprises:
Ultrasonic probe one, for measuring real velocity of sound;
Ultrasonic probe two, for measuring the distance of determinand;
Central processing unit is connection transformer driving circuit one and amplification respectively, filtering, shaping circuit one, central processing unit sends pwm signal and drives ultrasonic probe one to launch ultrasound wave through transformer drive circuit one, ultrasound wave fires back after running into the reverberation being arranged on known fixed distance, the ultrasonic echo be reflected back is by the reception of described ultrasonic probe one, and convert it into ultrasonic echo signal, ultrasonic echo signal is through amplifying, filtering, after shaping circuit one processes, become the signal that central processing unit can catch sampling to be received by central processing unit, real velocity of sound is at that time drawn by central processing unit internal calculation,
Central processing unit is connection transformer driving circuit two and amplification respectively also, filtering, shaping circuit two, central processing unit sends pwm signal and drives ultrasonic probe two to launch ultrasound wave through transformer drive circuit two, ultrasound wave runs into ultrasonic echo that determinand back reflection returns to be reflected back by the reception of described ultrasonic probe one, and convert it into ultrasonic echo signal, ultrasonic echo signal is through amplifying, filtering, after shaping circuit two processes, become the signal that central processing unit can catch sampling to be received by central processing unit, the real velocity of sound that central processing unit is recorded by ultrasonic probe one and the travel-time between ultrasonic probe two bottom surface and determinand calculate the distance of determinand.
Further,
Described central processing unit leaves RS485 communication interface, and connect host computer by RS485 communication interface, the described range data recorded by central processing unit sends host computer to;
Described central processing unit is linking number analog conversion circuit also, and the described range data that central processing unit records also can convert the signal of the 4-20mA of industrial occasions to by D/A converting circuit.
Further,
Described central processing unit is connected with display device, the range data recorded is exported by display device and shows, and described display device is also for carrying out optimum configurations;
Described central processing unit also leaves relay output interface, and described relay output interface is used for local control or warning.
Further,
Described central processing unit comprises central processing unit one and central processing unit two, and described central processing unit one and central processing unit two are respectively used to control and process ultrasonic probe one and ultrasonic probe two;
Communication connection is adopted between described central processing unit one and central processing unit two.
The present invention also provides the another kind of ultrasonic sensor adopting the above-mentioned ultrasonic ranging method based on the actual measurement velocity of sound, comprises ultrasonic probe and central processing unit, it is characterized in that,
Described central processing unit connects a gear train, and gear train connects a reverberation;
The reverberation be connected with gear train moves to immediately below ultrasonic probe, for measuring real velocity of sound after being used for the drive singal that central processor sends in the reception by described gear train; Described gear train also for after measurement real velocity of sound, receives the withdrawal signal that central processing unit sends, emitting substance is shifted out ultrasonic probe measurement range;
Described central processing unit connection transformer driving circuit and amplification, filtering, shaping circuit, described ultrasonic probe is arranged between transformer drive circuit and amplification, filtering, shaping circuit;
Described transformer drive circuit, for driving, ultrasonic probe is first backward is positioned at reverberation immediately below ultrasonic probe or determinand launches ultrasound wave, ultrasound wave runs into reverberation or determinand reflects, the ultrasonic echo be reflected back is received by described ultrasonic probe, and converting it into ultrasonic echo signal, ultrasonic echo signal is received by central processing unit after the process of amplification, filtering, shaping circuit.
Further, described gear train is electric transmissio mechanism;
Described electric transmissio mechanism comprises motor, electric machine controller and the detent mechanism be arranged on transmission shaft, and electric machine controller is connected with central processing unit signal, controls electric machine controller go drive motor to perform corresponding actions by central processing unit.
The ultrasonic sensor adopting the above-mentioned ultrasonic ranging method based on the actual measurement velocity of sound to realize range finding in the present invention also comprises: supersonic level sensor, ultrasonic range finder, ultrasonic distance-measuring sensor, ultrasonic level gage, ultrasonic level/level-sensing device etc.
The present invention has following beneficial effect:
1, the method for going the compensation velocity of sound with measuring tempeature of abandoning tradition of the present invention, adopt the mode directly measuring the velocity of sound, therefore can overcome in ultrasonic ranging because being subject to the impact in air themperature, pressure, humidity, air quality etc., and the measuring accuracy error caused and instability, greatly can improve the ability of measuring accuracy and anti-external environmental interference.
In the method for 2, ultrasonic ranging of the present invention, acoustic velocity measutement uses direct metering system completely, and measure the velocity of sound and measure that determinand adopts be timesharing or independent measure, therefore compared with documents CN204214517U, there is the measuring accuracy that this is higher, the interference performance of environment resistant interference performance and anti-spurious echo.
Accompanying drawing explanation
In order to be illustrated more clearly in the technical scheme of the embodiment of the present invention, be briefly described to the accompanying drawing used required in embodiment below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.
Fig. 1 is the structural representation of the embodiment of the present invention 1;
Fig. 2 is the measurement procedure schematic diagram of the embodiment of the present invention 1;
Fig. 3 is the structural representation of the embodiment of the present invention 2;
Fig. 4 is the measurement procedure schematic diagram of the embodiment of the present invention 2.
Embodiment
Below in conjunction with accompanying drawing and specific embodiment, the invention will be further described:
Following examples 1 and embodiment 2 are the specific embodiment that method of the present invention is applied to level gauging, are specially a kind of supersonic level sensor.
Embodiment 1:
As shown in Figure 1 and Figure 2:
A kind of supersonic level sensor comprises ultrasonic probe one (holes probe) 11 and ultrasonic probe 2 12 (range finding probe); Ultrasonic probe 1 is for measuring real velocity of sound; Ultrasonic probe 2 12 is for measuring the distance of liquid level to be measured.
Central processing unit is connection transformer driving circuit one and amplification respectively, filtering, shaping circuit one, central processing unit sends pwm signal and drives ultrasonic probe 1 to launch ultrasound wave through transformer drive circuit one, ultrasound wave fires back after running into the reverberation 2 (described reverberation can be a baffle plate) being arranged on known fixed distance, the ultrasonic echo be reflected back is received by described ultrasonic probe 1, and convert it into ultrasonic echo signal, ultrasonic echo signal is through amplifying, filtering, after shaping circuit one processes, become the signal that central processing unit can catch sampling to be received by central processing unit, real velocity of sound is at that time drawn by central processing unit internal calculation,
Central processing unit also distinguishes connection transformer driving circuit two and amplification, filtering, shaping circuit two, central processing unit sends pwm signal and drives ultrasonic probe 2 12 to launch ultrasound wave through transformer drive circuit two, ultrasound wave runs into liquid level back reflection to be measured and returns, the ultrasonic echo be reflected back is received by described ultrasonic probe 2 12, and convert it into ultrasonic echo signal, ultrasonic echo signal, after amplification, filtering, shaping circuit two process, becomes the signal that central processing unit can catch sampling and is received by central processing unit.
The real velocity of sound that central processing unit is recorded by ultrasonic probe 1 and the travel-time of ultrasound wave between ultrasonic probe 2 12 and determinand calculate the distance of liquid level to be measured.
Described central processing unit leaves RS485 communication interface, and connect host computer by RS485 communication interface, the distance recorded by central processing unit sends host computer to.
Described central processing unit linking number analog conversion circuit, the distance that central processing unit records also can convert the signal of the 4-20mA of industrial occasions to by D/A converting circuit.
Described central processing unit is connected with display device by external display interface, and exported by display device by the distance L ' recorded and show, described display device is also for carrying out optimum configurations.
Described central processing unit also leaves relay output interface, and described relay output interface can be used for local control or warning.
The method that supersonic level sensor in the present embodiment measures liquid level is as follows:
A, known fixed distance L is set, utilizes ultrasonic probe one to measure real velocity of sound V at that time
real;
A1. the known fixed distance L place immediately below ultrasonic probe one arranges a reverberation;
A2. sent by central processing unit and transmit, transmitting sends ultrasound wave through the transformer drive circuit one rear drive ultrasonic probe one that boosts, and time when ultrasonic probe one sends ultrasound wave is t1;
The ultrasound wave that ultrasonic probe one sends out is reflected back after the reverberation running into fixed range L place, the ultrasonic echo be reflected back is by the reception of described ultrasonic probe one, and convert it into ultrasonic echo signal, ultrasonic echo signal is returned to central processing unit through amplification, filtering, shaping circuit one and triggers sampling after processing, the time that ultrasonic probe one receives ultrasonic echo is t2;
Central processing unit calculates the t during this period of time that ultrasonic probe one sends ultrasound wave and receives ultrasonic echo, described t=t2-t1;
A3. central processing unit is according to formula: V
real=s/t=2L/ (t2-t1), calculates real velocity of sound V at that time
real, and the velocity of sound recorded is stored in central processing unit;
B, utilize the real velocity of sound V recorded in steps A
realmeasure the distance L ' of ultrasonic probe two bottom surface and determinand;
B1. sent by central processing unit and transmit, transmitting sends ultrasound wave through the transformer drive circuit two rear drive ultrasonic probe two that boosts, and time when ultrasonic probe two sends ultrasound wave is t1 ';
The ultrasound wave that ultrasonic probe two sends is reflected back after running into determinand, the ultrasonic echo be reflected back is by the reception of described ultrasonic probe two, and convert it into ultrasonic echo signal, ultrasonic echo signal is returned to central processing unit through amplification, filtering, shaping circuit two and triggers sampling after processing, the time that ultrasonic probe two receives ultrasonic echo is t2 ';
Central processing unit calculates the t ' during this period of time that ultrasonic probe two sends ultrasound wave and receives ultrasonic echo, described t '=t2 '-t1 ';
B2. central processing unit obtains real velocity of sound V
real, and according to formula: L '=V
real× (1/2t ')=1/2V
real(t2 '-t1 '), calculate the distance L ' of ultrasonic probe two bottom surface and liquid level to be measured.
Repeating said steps A like this and step B, realizes the distance L ' of Real-Time Monitoring determinand.
The alarming value preset in the data recorded in real time and central processing unit is compared by central processing unit, if exceed default alarming value will send signal to warning device by central processing unit, realizes the Real-Time Monitoring to thing distance to be measured.
The data repeating to record can also be kept in internal memory by central processing unit, and within a period of time of setting, intelligent algorithm filtering process is carried out to the data recorded, reduce the interference that the flowing because of determinand surface wave or propagation medium causes, make the more stable more realistic value of data.
Two ultrasonic probes are adopted in the present embodiment, and one reverberation 2 is set at known fixed distance L place, ultrasonic probe 11 is used for measuring real velocity of sound in real time by known fixed distance L, ultrasonic probe 12 carries out ultrasonic distance accurately by the real velocity of sound recorded and measures, therefore can not be subject to environmental impact when ultrasound wave carries out level gauging, thus substantially increase repeatability and the precision of measurement.
Embodiment 2:
As shown in Figure 3, Figure 4:
A kind of supersonic level sensor comprises ultrasonic probe 1 ' and central processing unit:
Central processing unit connects a gear train 3 ', and gear train 3 ' connects a reverberation 2 ' (described reverberation can be a baffle plate);
The reverberation 2 ' be connected with gear train 3 ', for after central processor sends in the reception drive singal, moves to immediately below ultrasonic probe 1 ', for measuring real velocity of sound by described gear train 3 '; Described gear train 3 ' also for after measurement real velocity of sound, receives the withdrawal signal that central processing unit sends, emitting substance 2 ' is shifted out ultrasonic probe measurement range;
Described central processing unit connection transformer driving circuit and amplification, filtering, shaping circuit, described ultrasonic probe is arranged between transformer drive circuit and amplification, filtering, shaping circuit;
Described transformer drive circuit, send for central processor in the reception that pwm signal rear drive ultrasonic probe 1 ' is first backward is positioned at reverberation 2 ' immediately below ultrasonic probe 1 ' or determinand launches ultrasound wave, ultrasound wave runs into reverberation 2 ' or determinand reflects, the ultrasonic echo be reflected back is received by described ultrasonic probe, and converting it into ultrasonic echo signal, ultrasonic echo signal is received by central processing unit after the process of amplification, filtering, shaping circuit.
The real velocity of sound that central processing unit is recorded by ultrasonic probe and the travel-time of ultrasound wave between ultrasonic probe and determinand calculate the distance of liquid level to be measured.
Gear train 3 ' in the present embodiment is electric transmissio mechanism;
Described electric transmissio mechanism comprises motor, electric machine controller and the detent mechanism be arranged on transmission shaft, and electric machine controller is connected with central processing unit signal, controls electric machine controller go drive motor to perform corresponding actions by central processing unit.
Described central processing unit leaves RS485 communication interface, and connect host computer by RS485 communication interface, the distance recorded by central processing unit sends host computer to.
Described central processing unit linking number analog conversion circuit, the distance that central processing unit records also can convert the signal of the 4-20mA of industrial occasions to by D/A converting circuit.
Described central processing unit is connected with display device by external display interface, and exported by display device by the distance L ' recorded and show, described display device is also for carrying out optimum configurations.
Described central processing unit also leaves relay output interface, and described relay output interface can be used for local control or warning.
The method that supersonic level sensor in the present embodiment measures liquid level is as follows:
Steps A, known fixed distance is set, utilizes ultrasonographic head to measure real velocity of sound V at that time
real
A1. on central processing unit, a gear train 3 ' is connected, the connected reverberation 2 ' of gear train 3 ', send signal to gear train 3 ' by central processing unit, baffle plate 2 ' is moved to the known fixed distance L place immediately below ultrasonic probe 1 ' by drive transmission device 3 ';
A2. sent by central processing unit and transmit, transmit through transformer drive circuit boosting rear drive ultrasonic probe 1 ' to reverberation transmission ultrasound wave, time during ultrasonic probe 1 ' transmission ultrasound wave is t1;
The ultrasound wave that ultrasonic probe 1 ' sends out is reflected back after the reverberation 2 ' running into fixed range L place, the ultrasonic echo be reflected back is received by described ultrasonic probe 1 ', and convert it into ultrasonic echo signal, ultrasonic echo signal is returned to central processing unit and triggers sampling after amplification, filtering, shaping circuit process, and the time that ultrasonic probe 1 ' receives ultrasonic echo is t2;
Central processing unit calculate ultrasonic probe 1 ' send ultrasound wave and receive ultrasonic echo t during this period of time, described t=t2-t1;
A3. central processing unit is according to formula: V
real=s/t=2L/ (t2-t1), calculates real velocity of sound V at that time
real, and the velocity of sound recorded is stored in central processing unit;
Step B0: send signal to gear train 3 ' by central processing unit, drive transmission device 3 ' is regained, and described reverberation 2 ' is shifted out hyperacoustic measurement range;
B, the real velocity of sound that records in steps A is utilized to measure the distance L ' of determinand
B1. provide PMW by central processing unit to transmit, transmit through sending ultrasound wave through transformer drive circuit boosting rear drive ultrasonic probe 1 ' to determinand, time during ultrasonic probe 1 ' transmission ultrasound wave is t1 ';
The ultrasound wave that ultrasonic probe 1 ' sends is reflected back after running into determinand, the ultrasonic echo be reflected back is received by described ultrasonic probe 1 ', and convert it into ultrasonic echo signal, ultrasonic echo signal is returned to central processing unit and triggers sampling after amplification, filtering, shaping circuit process, and the time that ultrasonic probe 1 ' receives ultrasonic echo is t2 ';
Central processing unit calculates the t ' during this period of time that ultrasonic probe 1 ' sends ultrasound wave and receives ultrasonic echo, described t '=t2 '-t1 ';
B2. central processing unit obtains real velocity of sound V
real, and according to formula: L '=V
real× (1/2t ')=1/2V
real(t2 '-t1 '), calculate the distance L ' of ultrasonic probe bottom surface and liquid level to be measured.
Repeating said steps A like this and step B, realizes the distance L ' of Real-Time Monitoring determinand.
The alarming value preset in the data recorded in real time and central processing unit is compared by central processing unit, if exceed default alarming value will send signal to warning device by central processing unit, realizes the Real-Time Monitoring to thing distance to be measured.
The data repeating to record can also be kept in internal memory by central processing unit, and within a period of time of setting, intelligent algorithm filtering process is carried out to the data recorded, reduce the interference that the flowing because of determinand surface wave or propagation medium causes, make the more stable more realistic value of data.
The present embodiment connects a gear train 3 ' on the central processing unit of supersonic level sensor, by the mode of time-sharing multiplex, periodic control reverberation 2 ' moves to fixed range position, ultrasonic probe 1 ' below, then the velocity of sound is recorded, when reverberation 2 ' shifts out ultrasonic probe measurement range, again the velocity of sound that the last time measures is used as next time level gauging time the velocity of sound used.Therefore, the level gauging of each short time is all first adopt the mobile reverberation 2 ' of gear train 3 ' to carry out velocity of sound sampling, and the velocity of sound then by gathering carries out normal level gauging.So make ultrasonic measurement not by the impact of external environment, substantially increase repeatability and the precision of measurement.
Above-described embodiment further illustrates of the present invention, instead of limit the scope of the invention.Do not depart from whole technical scope of the present invention, can various amendment and change be carried out.