CN201716078U - Signal processing module of liquid level transmitter - Google Patents
Signal processing module of liquid level transmitter Download PDFInfo
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- CN201716078U CN201716078U CN2010202693721U CN201020269372U CN201716078U CN 201716078 U CN201716078 U CN 201716078U CN 2010202693721 U CN2010202693721 U CN 2010202693721U CN 201020269372 U CN201020269372 U CN 201020269372U CN 201716078 U CN201716078 U CN 201716078U
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Abstract
The utility model relates to a measurement module, particularly to a signal processing module of a liquid level transmitter, which is used in a capacitance liquid level sensor for accurately measure capacitance value. Compared with the liquid level transmitter signal processing module in the prior art, the signal energizing circuit of the signal processing module provided by the utility model has the advantages that a special DDS chip as a signal source is adopted, so as to greatly improve signal frequency and amplitude stability; a band-pass filter is additionally arranged, so as to effectively filter out interference signals and improve system stability; a variable gain signal amplification circuit is additionally arranged, so that when measurement medium changes, the signal amplification times can be increased or decreased as required through the variable gain signal amplification circuit to meet the requirement for measurement accuracy; and negative voltage signals are converted into positive voltage signals by adopting an absolute value circuit instead of adopting the half-wave rectifying circuit in the liquid level transmitter signal processing in the prior art, so as to retain the negative voltage information in the original signal and improve measurement accuracy.
Description
Technical field
The utility model relates to a kind of measurement module, is used for the capacitive liquid level sensor specifically, is used for accurately measuring the liquid level transducer signal processing module of capacitance.
Background technology
The block diagram of the existing liquid level transducer signal processing module that is used for the capacitive liquid level sensor as shown in Figure 1, rectangular wave pumping signal circuit produces rectangular wave, being driven intensifier circuit strengthens, and send to fluid to be measured, by the rapier received signal and send signal amplification circuit to, after signal amplifies, be sent to half-wave rectifying circuit, be sent to integrating circuit again.Its shortcoming is as follows:
1. pumping signal adopts rectangular wave, in order to improve its driving force, the maximum level of rectangular wave has directly adopted system power supply, for example+5V, the amplitude of output drive signal is 0～+ 5V, dutycycle are 50% square wave signal, because the often fluctuation ratio of the power supply of system is bigger, therefore cause the drive level instability, thereby make that the change in voltage of feedback signal is bigger, also just influenced the precision of measuring thus;
2. existing liquid level transducer signal processing module lacks bandwidth-limited circuit, because the interference ratio of industry spot is bigger, if the signal of gathering is not carried out Filtering Processing, undesired signal will be received and amplify so, will make real signal by the serious interference of noise institute like this, the measuring accuracy that obviously also can reduce system also can reduce the stability of system;
3. the pumping signal of existing liquid level transducer signal processing module is built by mimic channel often, and along with variation of temperature, the frequency of signal and amplitude all significant change can take place, and also can influence measuring accuracy thus.
The utility model content
Technical problem to be solved in the utility model provides a kind of improved liquid level transducer signal processing module, realizes steady output and effective lifting of measuring accuracy to received signal of pumping signal.
The technical scheme that the utility model solves the problems of the technologies described above is as follows: a kind of liquid level transducer signal processing module, comprise signal generating circuit and signal receiving processing circuit, described signal generating circuit comprises interconnective sine wave exciting signal circuit and drives intensifier circuit that described signal receiving processing circuit comprises the elementary amplifying circuit of rapier, signal, bandwidth-limited circuit, variable gain signal amplification circuit, absolute value circuit, integrating circuit and the reverse ratio amplifying circuit that connects in turn;
In the described signal generating circuit, produce sine wave signal by the sine wave exciting signal circuit and amplify, and the rapier that sends in the signal receiving processing circuit by fluid to be measured receives through driving intensifier circuit;
In the described signal receiving processing circuit, rapier sends the signal that receives to signal elementary amplifying circuit and carries out elementary amplification, carry out filtering through amplifying signal by bandwidth-limited circuit, signal after the filtering carries out further gain amplifier by the variable gain signal amplification circuit, and voltage is sent to integrating circuit for negative signal after just getting by absolute value circuit, by integrating circuit is the direct current signal of amplitude stability with conversion of signals, and convert negative voltage signal to positive voltage signal by reverse ratio amplifying circuit, and signal sends the AD collector to and carries out signal analysis the most at last.
The beneficial effects of the utility model are: compare with the existing liquid level transducer signal processing module that is used for the capacitive liquid level sensor, increased bandpass filter, thereby the effective undesired signal of filtered signal has improved the stability of system; Increased the variable gain signal amplification circuit, when variation has taken place measuring media, can increase or reduce the enlargement factor of signal as required by the variable gain signal amplification circuit, to guarantee the requirement of measuring accuracy; Compare with the existing liquid level transducer signal processing module that is used for the capacitive liquid level sensor, no longer adopt half-wave rectifying circuit, and adopt absolute value circuit that the negative voltage signal of signal is become positive voltage signal, thus the negative voltage information in original signal kept, and then improved measuring accuracy.
On the basis of technique scheme, the utility model can also be done following improvement.
Further, described sine wave exciting signal circuit comprises the DDS chip, and described sine wave is produced by the DDS chip.
Adopt the beneficial effect of above-mentioned further scheme to be, adopt the DDS chip as signal source, improved the frequency of signal and stablizing of amplitude significantly, temperature is floated also smaller simultaneously.
Further, described variable gain signal amplification circuit comprises operational amplifier and signal gating switch chip, form feedback circuit between described operational amplifier and the signal gating switch chip, realize the enlargement factor of operational amplifier signal by the height storage battery of control signal gating switch chip pin.
Adopt the beneficial effect of above-mentioned further scheme to be, circuit is realized simple, and control is convenient, adopts operational amplifier and signal gating switch chip array mode to substitute the variable gain amplifier chip of realizing said function, and is with low cost.
Further, described signal gating switch chip is that MC14051 cake core or other can be realized the chip of said function.
Description of drawings
Fig. 1 is the existing logic diagram that is used for the liquid level transducer signal processing module of capacitive liquid level sensor;
Fig. 2 is the utility model liquid level transducer signal processing module logic diagram;
Fig. 3 is the elementary amplification circuit diagram of the signal in the utility model;
Fig. 4 is the bandwidth-limited circuit figure in the utility model;
Fig. 5 is the variable gain signal amplification circuit figure in the utility model;
Fig. 6 is the absolute value circuit figure in the utility model;
Fig. 7 is the integrating circuit figure in the utility model;
Fig. 8 is the anti-phase ratio amplifying circuit in the utility model.
Embodiment
Below in conjunction with accompanying drawing principle of the present utility model and feature are described, institute gives an actual example and only is used to explain the utility model, is not to be used to limit scope of the present utility model.
As shown in Figure 2, the utility model liquid level transducer signal processing module, comprise signal generating circuit and signal receiving processing circuit, signal generating circuit comprises interconnective sine wave exciting signal circuit 1 and drives intensifier circuit 2 that the signal receiving processing circuit comprises the elementary amplifying circuit 5 of rapier 4, signal, bandwidth-limited circuit 6, variable gain signal amplification circuit 7, absolute value circuit 8, integrating circuit 9 and the reverse ratio amplifying circuit 10 that connects successively.Wherein, sine wave exciting signal circuit 1 produces sine wave signal and sends to and drives intensifier circuit 2; Driving intensifier circuit 2 amplifies the sine wave signal that receives and sends rapier 4 to by fluid to be measured 3; Rapier 4 sends the signal that detects to connected signal elementary amplifying circuit 5; The elementary amplifying circuit 5 of signal carries out the signal that receives elementary amplification and sends bandwidth-limited circuit 6 to; Bandwidth-limited circuit 6 carries out filtering with the signal that receives, and after undesired signal filtering wherein, sends signal to variable gain signal amplification circuit 7; Variable gain signal amplification circuit 7 carries out gain amplifier with the signal that receives, and sends the signal behind the gain amplifier to absolute value circuit 8; Absolute value circuit 8 takes absolute value the signal that receives and sends integrating circuit 9 to; Integrating circuit 9 is a direct current signal with the conversion of signals that receives; Because the direct current signal after integrating circuit 9 conversion is a negative voltage signal, so, convert direct current signal to positive voltage signal by reverse ratio amplifying circuit 10, and send to AD collector 11 and carry out data analysis.
Include the DDS chip in the sine wave exciting signal circuit 1 in the utility model, sine wave signal is produced by the DDS chip, the sine wave signal that adopts the DDS chip to produce, its frequency and amplitude are all more stable, the influence that is subjected to the system power supply fluctuation is very little, and temperature is floated also smaller, and the DDS chip in the present embodiment has adopted the AD9834 chip of AD company to produce sine wave exciting signal.
Because the voltage magnitude of the sine wave signal that the DDS chip is produced is lower, for example for the AD9834 chip, the peak value of the sine wave signal of its generation is 300 mV to the maximum, obviously driving force is not enough, therefore need strengthen its driving force by driving intensifier circuit 2, drive intensifier circuit 2 and be that by amplifier sine wave signal to be amplified to peak-to-peak value earlier be 9V, further improve by the driving force of follower again sine wave signal.Signal after the intensifier circuit 2 of overdriving just mails to rapier 4 by fluid to be measured 3, receives by rapier 4.
From the circuit angle, fluid to be measured 3 and rapier 4 have been formed a variable capacitance jointly, and the variation of the liquid level of fluid to be measured 3 will directly cause the variation of the capacitance of variable capacitance, thereby can realize judgement to liquid level by the capacitance of measuring this variable capacitance.
As shown in Figure 3, circuit diagram for the elementary amplifying circuit 5 of the signal in the utility model, wherein variable capacitance Cx is aforementioned middle fluid to be measured 3 and the rapier 4 common variable capacitances of forming, because the variation of the capacitance of variable capacitance Cx will cause the variation of the electric signal in the circuit, therefore by the elementary amplifying circuit 5 of this signal with and subsequent each functional circuit to the filtering of signal in the circuit, operations such as amplification both can obtain very desirable liquid level information, specifically, in Fig. 3, variable capacitance Cx is connected in the negative input of operational amplifier U5C, coupling capacitance Cs is connected between the negative input and output terminal of operational amplifier U5C, input voltage U
iBe pumping signal, the voltage of output is U
o, by the principle of operational amplifier as can be known:
Wherein, coupling capacitance Cs capacitance is fixed, and works as U
iDuring for the fixing pumping signal of voltage, tested variable capacitance Cx value and output voltage U
o, linear, therefore pass through output voltage U
oMeasurements and calculations just can obtain liquid level to be determined.
Bandwidth-limited circuit 6, adopt as shown in Figure 4 the second order multichannel feedback bandwidth-limited circuit that infinitely gains, wherein the Q value of selected described bandpass filter is 10, the logical frequency of band is that 40K(should be with that to lead to frequency identical with exciting signal frequency), thus the undesired signal as far as possible in the filtering received signal.
As shown in Figure 5, circuit diagram for variable gain signal amplification circuit in the utility model, this circuit mainly is made up of operational amplifier and signal gating switch chip, wherein the signal gating switch chip is the MC14051 cake core, the MC14051 cake core is equivalent to hilted broadsword eight throw switches, which passage of switch connection, 3 bit address sign indicating number A by input, B, C decides, here the C pin is fixed as low level, so A by control MC14051 cake core, two pins of B, can realize different signal gating passages, also just make the difference of feedback circuit of amplifier thus, and then can realize 1 times, 2 times, the gain amplifier of 3 times and 4 times.For example, when the pin of A and B all was high level, then the 13rd pin of MC14051 cake core and the 3rd pin were connected, and so for operational amplifier U1, the circuit of its feedback is 10 K, and its Amplifier Gain is 1 times.When Q6 was low level for high level Q7, then the 14th and the 3rd pin was connected, and feedback resistance is 20 K thus, so gain amplifier is 2 times.The level of A, B pin and the relation of output gain are as shown in the table:
| The A pin | The B pin | Gain |
| 0 | 0 | 1 |
| 1 | 0 | 2 |
| 0 | 1 | 3 |
| 1 | 1 | 4 |
Another advantage of this variable-gain amplification circuit circuit is with low cost, satisfy in precision on the basis of system requirements, the mode that adopts signal gating switch chip and operational amplifier to make up realizes the method for adjustment of the gain of signal, rather than adopt variable gain amplifier chip, can realize thus reducing cost.Selection about the gating switch chip can not only be confined to the MC14051 cake core, other can realize same confession all replaceable MC14051 cake core of chip realize the gain adjustment of signal.
Adopt this variable gain signal amplification circuit, when variation has taken place in measuring media, become oil by water as measuring media, its capacitance will great changes will take place, by the variable gain signal amplification circuit can be suitable enlargement factor is increased, with the assurance measuring accuracy, otherwise can suitably reduce the circuit enlargement factor by the variable gain signal amplification circuit, saturated to prevent gain amplifier.
For sinusoidal signal being become the direct current signal that the AD collector can be gathered, so the signal of the negative semiaxis of sinusoidal signal need be removed, in order to keep the signal of negative semiaxis, thereby can improve measuring accuracy, therefore adopted absolute value circuit.As shown in Figure 6, be absolute value circuit of the present utility model.By circuit shown in Figure 6 as can be known:
Work as U
i0 o'clock, U
O1＜0, diode Q2 ends, so U
P1=U
N2=U
I, make I
R1=I
R2=0, so U
o=U
I
Work as U
i＜0 o'clock, U
O10, so diode Q2 conducting is U
P1=U
N2=U
P2=0, be virtual earth, therefore
So
This circuit has been realized accurate full-wave rectification.
As shown in Figure 7, be the circuit diagram of integrating circuit in the utility model.The running of the integration by integrating circuit can make the change equalization of signal, reduces the influence of noise signal simultaneously.Signal becomes the direct current signal of amplitude stability through after the processing of integrating circuit, and the size and the measured capacitance values of this signal amplitude are linear.Output voltage U in the integrating circuit shown in Figure 7
oWith input voltage U
iThe pass be:
As shown in Figure 8, be the anti-phase ratio amplifying circuit in the utility model.Because the signal of integrating circuit output is a negative voltage signal, just can carry out AD and gather so need to be converted to positive voltage, having adopted gain in the present embodiment is 1 anti-phase ratio amplifying circuit, among Fig. 8, resistance R
10Resistance equal resistance R
11Resistance, so output voltage U
oWith input voltage U
iThe pass be:
So far obtain the output voltage U among Fig. 8
oPromptly finished whole Signal Processing, with the output voltage U among Fig. 8
oSend to the AD collector and can realize measurement liquid level information.
The above only is preferred embodiment of the present utility model, and is in order to restriction the utility model, not all within spirit of the present utility model and principle, any modification of being done, is equal to replacement, improvement etc., all should be included within the protection domain of the present utility model.
Claims (4)
1. liquid level transducer signal processing module, comprise signal generating circuit and signal receiving processing circuit, it is characterized in that, described signal generating circuit comprises interconnective sine wave exciting signal circuit and drives intensifier circuit that described signal receiving processing circuit comprises the elementary amplifying circuit of rapier, signal, bandwidth-limited circuit, variable gain signal amplification circuit, absolute value circuit, integrating circuit and the reverse ratio amplifying circuit that connects in turn;
In the described signal generating circuit, produce sine wave signal by the sine wave exciting signal circuit and amplify, and the rapier that sends in the signal receiving processing circuit by fluid to be measured receives through driving intensifier circuit;
In the described signal receiving processing circuit, rapier sends the signal that receives to signal elementary amplifying circuit and carries out elementary amplification, carry out filtering through amplifying signal by bandwidth-limited circuit, signal after the filtering carries out further gain amplifier by the variable gain signal amplification circuit, and voltage is sent to integrating circuit for negative signal after just getting by absolute value circuit, is direct current signal by integrating circuit with conversion of signals, and convert negative voltage signal to positive voltage signal by reverse ratio amplifying circuit, and signal sends the AD collector to and carries out signal analysis the most at last.
2. liquid level transducer signal processing module according to claim 1 is characterized in that: described sine wave exciting signal circuit comprises the DDS chip, and described sine wave is produced by the DDS chip.
3. liquid level transducer signal processing module according to claim 1, it is characterized in that: described variable gain signal amplification circuit comprises operational amplifier and signal gating switch chip, form feedback circuit between described operational amplifier and the signal gating switch chip, realize the enlargement factor of operational amplifier signal by the height storage battery of control signal gating switch chip pin.
4. liquid level transducer signal processing module according to claim 3 is characterized in that: described signal gating switch chip is the MC14051 cake core.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010202693721U CN201716078U (en) | 2010-07-23 | 2010-07-23 | Signal processing module of liquid level transmitter |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010202693721U CN201716078U (en) | 2010-07-23 | 2010-07-23 | Signal processing module of liquid level transmitter |
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| CN201716078U true CN201716078U (en) | 2011-01-19 |
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| CN2010202693721U Expired - Fee Related CN201716078U (en) | 2010-07-23 | 2010-07-23 | Signal processing module of liquid level transmitter |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104034956A (en) * | 2014-05-30 | 2014-09-10 | 杭州电子科技大学 | Positive/negative voltage measuring circuit |
| DE102013107120A1 (en) * | 2013-07-05 | 2015-01-08 | Endress + Hauser Gmbh + Co. Kg | Signal generator for a measuring device and measuring device for automation technology |
| CN104713615A (en) * | 2015-03-23 | 2015-06-17 | 杭州电子科技大学 | Circuit of drainage pipe network liquid level measurement device |
| CN103256964B (en) * | 2013-04-16 | 2015-12-02 | 周德海 | A kind of capacitance liquid level measurement mechanism |
| CN106289450A (en) * | 2016-07-27 | 2017-01-04 | 上海航天设备制造总厂 | Point type electric capacity Low Temperature Liquid bit changer |
| CN106289451A (en) * | 2016-07-27 | 2017-01-04 | 上海航天设备制造总厂 | Merogenesis condenser type Low Temperature Liquid bit changer |
| CN106371150A (en) * | 2016-08-31 | 2017-02-01 | 上海太弘威视安防设备有限公司 | Hazardous liquid detecting instrument based on DDS |
| CN109921796A (en) * | 2017-12-13 | 2019-06-21 | 林项武 | A kind of circuit that the electric signal of mechanical periodicity is converted to direct current signal level |
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2010
- 2010-07-23 CN CN2010202693721U patent/CN201716078U/en not_active Expired - Fee Related
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103256964B (en) * | 2013-04-16 | 2015-12-02 | 周德海 | A kind of capacitance liquid level measurement mechanism |
| US10061344B2 (en) | 2013-07-05 | 2018-08-28 | Endress + Hauser Gmbh + Co. Kg | Signal generator for a measuring apparatus and measuring apparatus for automation technology |
| DE102013107120A1 (en) * | 2013-07-05 | 2015-01-08 | Endress + Hauser Gmbh + Co. Kg | Signal generator for a measuring device and measuring device for automation technology |
| CN104034956B (en) * | 2014-05-30 | 2017-02-15 | 杭州电子科技大学 | Positive/negative voltage measuring circuit |
| CN104034956A (en) * | 2014-05-30 | 2014-09-10 | 杭州电子科技大学 | Positive/negative voltage measuring circuit |
| CN104713615A (en) * | 2015-03-23 | 2015-06-17 | 杭州电子科技大学 | Circuit of drainage pipe network liquid level measurement device |
| CN104713615B (en) * | 2015-03-23 | 2017-12-26 | 杭州电子科技大学 | A kind of circuit of drainage pipeline networks liquid level detection device |
| CN106289450A (en) * | 2016-07-27 | 2017-01-04 | 上海航天设备制造总厂 | Point type electric capacity Low Temperature Liquid bit changer |
| CN106289451A (en) * | 2016-07-27 | 2017-01-04 | 上海航天设备制造总厂 | Merogenesis condenser type Low Temperature Liquid bit changer |
| CN106289450B (en) * | 2016-07-27 | 2019-01-18 | 上海航天设备制造总厂 | Point type capacitor low temperature liquid-level converter |
| CN106289451B (en) * | 2016-07-27 | 2019-01-18 | 上海航天设备制造总厂 | Merogenesis condenser type low temperature liquid-level converter |
| CN106371150A (en) * | 2016-08-31 | 2017-02-01 | 上海太弘威视安防设备有限公司 | Hazardous liquid detecting instrument based on DDS |
| CN109921796A (en) * | 2017-12-13 | 2019-06-21 | 林项武 | A kind of circuit that the electric signal of mechanical periodicity is converted to direct current signal level |
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Legal Events
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| ASS | Succession or assignment of patent right |
Owner name: BEIJING COLLIHIGH SENSOR TECHNOLOGY CO., LTD. Free format text: FORMER OWNER: BEIJING COLLIHIGH SENSOR TECHNOLOGY CENTER Effective date: 20120309 |
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| C41 | Transfer of patent application or patent right or utility model | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20120309 Address after: 100085 Beijing, Haidian District on the road to information on the ground floor, building 1-1, No. 8, building A Patentee after: Beijing Collihigh Sensor Technology Co., Ltd. Address before: 100085 Beijing, Haidian District on the road to information on the ground floor, building 1-1, No. 8, building A Patentee before: Beijing Collihigh Sensor Technology Center |
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| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20110119 Termination date: 20130723 |