CN108169566A - Online testing impedance circuit and method - Google Patents
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
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- H—ELECTRICITY
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- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
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Abstract
The embodiment of the present invention proposes a kind of online testing impedance circuit and method, is related to impedance detection field.The circuit includes signal input circuit, load circuit and impedance computation circuit.Signal input circuit is used to input composite audio signal.Load circuit is connected with signal input circuit, and load circuit includes the element incoming end and fixed value resistance of series connection.Impedance computation circuit includes first voltage detection unit, second voltage detection unit and impedance computation unit.First voltage detection unit includes the divider, the first LC wave filters, first switch capacitive filter and the first virtual value detecting circuit that are sequentially connected electrically；Second voltage detection unit includes the second amplifier, the 2nd LC wave filters, second switch capacitive filter and the second virtual value detecting circuit that are sequentially connected electrically.The online testing impedance circuit and method that the embodiment of the present invention is provided, can when element under test works detecting element impedance value, and then whether the working condition of monitoring element abnormal in real time.
Description
Technical Field
The invention relates to the field of impedance detection, in particular to an online impedance testing circuit and method.
Background
Generally, in a method for testing the impedance of a speaker, a voltage signal is applied to the speaker, a current flowing through the speaker is measured by a sampling resistor, and then the impedance is calculated. But this detection means is to detect the impedance curve of the loudspeaker at different frequencies. The method is off-line detection, and in a non-broadcast state, test audio needs to be added independently, and in a broadcast state, the test audio and the broadcast audio are overlapped and cannot be tested. If the broadcasting system is always in the state of playing background music and the like, impedance monitoring cannot be completed, and the damage condition of the loudspeaker cannot be found in time.
Disclosure of Invention
The invention aims to provide an online impedance test circuit and method, which can detect the impedance value of an element to be tested in real time when the element to be tested works, and further monitor whether the working state of the element to be tested is abnormal or not.
In order to achieve the above purpose, the embodiment of the present invention adopts the following technical solutions:
the embodiment of the invention provides an online impedance test circuit which comprises a signal input circuit, a load circuit and an impedance calculation circuit. The signal input circuit is used for inputting a composite audio signal, and the composite audio signal comprises a broadband broadcasting audio signal and a specific audio signal with a specific frequency. The load circuit is used for connecting an element needing impedance testing, is connected with the signal input circuit in series, and comprises a component connecting end and a constant value resistor which are connected in series. The impedance calculation circuit includes a first voltage detection unit, a second voltage detection unit, and an impedance calculation unit. The first voltage detection unit comprises a voltage divider, a first LC filter, a first switched capacitor filter and a first effective value detection circuit which are sequentially and electrically connected, the voltage divider is connected with the element access end in parallel, and the first effective value detection circuit is electrically connected with the impedance calculation unit; the second voltage detection unit comprises a second amplifier, a second LC filter, a second switched capacitor filter and a second effective value detection circuit which are sequentially and electrically connected, the second amplifier is connected with the constant value resistor in parallel, and the second effective value detection circuit is electrically connected with the impedance calculation unit; the impedance calculating unit is used for obtaining a current value of the load circuit according to the voltage value detected by the second voltage detecting unit and the impedance value of the constant value resistor, and is used for generating the impedance value of the element accessed by the element access end according to the voltage detected by the first voltage detecting unit and the current value of the load circuit.
Furthermore, the signal input circuit comprises a broadcast audio access end, a first filter and an adder which are electrically connected in sequence, wherein the broadcast audio access end is used for inputting broadband broadcast audio signals. The signal input circuit further comprises a specific audio access end which is electrically connected with the adder and used for inputting a specific audio signal with a specific frequency. The adder is used for adding the broadcast audio signal input by the broadcast audio access end and the specific audio signal input by the specific audio access end to obtain a composite audio signal. The signal input circuit further comprises a first amplifier, the first amplifier is electrically connected with the adder and is connected with the load circuit in series, and the first amplifier is used for receiving the composite audio signal obtained by adding the adder, amplifying the composite audio signal and then connecting the amplified composite audio signal to the load circuit.
Further, the first filter is a low pass filter.
Further, the low-pass filter is a 10KHz low-pass filter.
Further, the voltage of the broadcast audio signal input by the broadcast audio access terminal is greater than the voltage of the specific audio signal input by the specific audio access terminal.
Further, the impedance calculation unit comprises a processor and an indication subunit which are electrically connected in turn. The processor is electrically connected to the first effective value detection circuit and the second effective value detection circuit, and is configured to obtain a current value of the load circuit according to the voltage across the fixed value resistor and the impedance value of the fixed value resistor detected by the second voltage detection unit, and obtain an impedance value of an element connected to the element connection end according to the detected voltage across the element connection end and the current value of the load circuit, and send the impedance value of the element connected to the element connection end to the indication subunit. The indicating subunit is used for displaying different indicating information according to the received impedance value of the element accessed by the element access end.
Further, the processor is a single chip microcomputer.
Further, the indicating subunit comprises at least one of a display screen, a light emitting tube, an audio alarm and a relay indicating contact.
Further, the first voltage detection unit further includes a first AD converter, and the first effective value detection circuit is electrically connected to the impedance calculation unit through the first AD converter. The second voltage detection unit further includes a second AD converter, and the second effective value detection circuit is electrically connected to the impedance calculation unit through the second AD converter.
The embodiment of the invention also provides an online impedance test method, which is applied to the online impedance test circuit, wherein the online impedance test circuit comprises a signal input circuit, a load circuit and an impedance calculation circuit, and the method comprises the following steps: the signal input circuit inputs a composite audio signal, wherein the composite audio signal comprises a broadband broadcast audio signal and a specific audio signal with a specific frequency; the load circuit is connected with an element needing impedance testing, the load circuit is connected with the signal input circuit in series, and the load circuit comprises a series-connected element connecting end and a constant-value resistor; the impedance calculation circuit comprises a first voltage detection unit, a second voltage detection unit and an impedance calculation unit; the first voltage detection unit comprises a voltage divider, a first LC filter, a first switched capacitor filter and a first effective value detection circuit which are sequentially and electrically connected, wherein the voltage divider is connected with the element access end in parallel, and the first effective value detection circuit is electrically connected with the impedance calculation unit and is used for detecting the voltage value of the specific audio signal generated at the two ends of the element access end; the second voltage detection unit comprises a second amplifier, a second LC filter, a second switched capacitor filter and a second effective value detection circuit which are sequentially and electrically connected, the second amplifier is electrically connected with the fixed value resistor, and the second effective value detection circuit is electrically connected with the impedance calculation unit and is used for collecting the voltage value of the specific audio signal generated at the two ends of the fixed value resistor; the impedance calculating unit obtains a current value of the specific audio signal generated in the load circuit according to the voltage value detected by the second voltage detecting unit and the impedance value of the constant value resistor, and generates an impedance value of an element accessed by the element access end according to the voltage value detected by the first voltage detecting unit and the current value of the specific audio signal generated in the load circuit.
Compared with the prior art, the online impedance test circuit and the online impedance test method provided by the embodiment of the invention have the advantages that the element is connected into the load circuit of the audio source containing the broadcast audio signal and the specific audio signal through the element connecting end, the voltage at the two ends of the element connecting end and the voltage at the two ends of the constant value resistor are respectively detected and obtained, the voltage value and the current value of the specific audio signal generated at the two ends of the element are obtained after processing, and then the impedance value of the element is obtained.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a schematic block diagram of an online impedance testing circuit provided by an embodiment of the present invention;
FIG. 2 is a schematic block diagram of a signal input circuit of an online impedance testing circuit according to an embodiment of the present invention;
FIG. 3 is a schematic block diagram of an impedance calculating unit of an online impedance testing circuit according to an embodiment of the present invention;
FIG. 4 is another schematic block diagram of an online impedance testing circuit provided by an embodiment of the present invention;
fig. 5 shows a schematic flow chart of an online impedance testing method according to an embodiment of the present invention.
In the figure: 10-an online impedance test circuit; 100-signal input circuit; 110-broadcast audio access; 120-a first filter; 130-an adder; 140-a first amplifier; 150-a specific audio access; 200-a load circuit; 210-element access; 220-constant value resistance; 300-impedance calculation circuit; 310-a first voltage detection unit; 311-a voltage divider; 312-a first LC filter; 313-a first switched-capacitor filter; 314-a first effective value detection circuit; 315-a first AD converter; 320-a second voltage detection unit; 321-a second amplifier; 322-a second LC filter; 323-a second switched capacitor filter; 324-a second significance detection circuit; 325 — a second AD converter; 330-impedance calculation unit; 331-a processor; 332-indicate subunits.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures. Meanwhile, in the description of the present invention, the terms "first", "second", and the like are used only for distinguishing the description, and are not to be construed as indicating or implying relative importance.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed" and "connected" are to be interpreted broadly, e.g., as being either fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Some embodiments of the invention are described in detail below with reference to the accompanying drawings. The embodiments described below and the features of the embodiments can be combined with each other without conflict.
Generally, in a method for testing the impedance of a speaker, a voltage signal is applied to the speaker, a current flowing through the speaker is measured by a sampling resistor, and then the impedance is calculated. But this detection means is to detect the impedance curve of the loudspeaker at different frequencies. The method is off-line detection, and in a non-broadcast state, test audio needs to be added separately, and in a broadcast state, the test audio and the broadcast audio are overlapped and cannot be tested. If the broadcasting system is always in the state of playing background music and the like, impedance monitoring cannot be completed, and the damage condition of the loudspeaker cannot be found in time. For example, in a ship broadcasting and alarm system, each cabin of a ship is configured with a corresponding speaker, when a control center is in normal broadcasting, emergency information is sent to each cabin through the speakers configured on the ship, and if a speaker of a certain cabin is damaged, the emergency information sent by the control center cannot be received.
Based on the actual problem that the impedance of the loudspeaker cannot be tested during the normal operation of the loudspeaker in the prior art, the embodiment of the invention provides a solution that: connecting an element which is formed by connecting all loudspeakers in parallel as a whole into an audio source containing broadcast audio signals and specific audio signals, detecting the voltage without the broadcast audio signals at two ends of the element formed by connecting all the loudspeakers in parallel and the current without the broadcast audio signals at two ends of the element, obtaining the impedance value of the element, monitoring the impedance value in real time, and when the impedance value of the element is changed, indicating that one loudspeaker in the loudspeakers is damaged. Referring to fig. 1, fig. 1 shows a schematic structural diagram of an online impedance testing circuit 10 according to an embodiment of the present invention, in the embodiment, the online impedance testing circuit 10 includes a signal input circuit 100, a load circuit 200, and an impedance calculating circuit 300.
The signal input circuit 100 is used to input a composite audio signal as an audio source for the load circuit 200. The composite audio signal includes a broadband broadcast audio signal and a specific audio signal with a specific frequency, and the broadcast audio signal is used as a medium for transmitting broadcast information, and the frequency range of the broadcast audio signal is 20Hz to 12KHz, but when the online impedance test circuit 10 provided by the embodiment of the present invention performs an impedance test, the voltage generated by the broadcast audio signal loaded at two ends of the device to be tested and the current generated by the broadcast audio signal passing through the device to be tested are filtered, and the impedance value of the device to be tested is calculated by using the voltage and the current generated by the specific audio signal with the specific frequency. Therefore, the frequency of the specific audio signal can be selected to be greater than the maximum frequency of the broadcast audio, such as 13KHz, 14KHz, 18KHz, etc. Preferably, as an implementation manner, in an online impedance testing circuit 10 provided by the embodiment of the present invention, the frequency of the specific audio signal may be selected to be a value in a range of 19KHz to 20KHz, such as 19.1KHz, 19.3KHz or 19.7 KHz.
It should be noted that, since the voltage of the broadcast audio signal is larger, and is generally a standard level of 70V or 100V or 120V, and the voltage of the specific audio signal is larger according to the test effect and power, the test effect is better when the voltage is larger, and the power consumption is larger, the voltage used may be 1V, and therefore, the voltage of the specific audio signal contained in the voltage loaded in the load circuit 200 is often much larger than the voltage of the specific audio signal.
The load circuit 200 is used for connecting an element needing to test the impedance value, and is connected with the signal input circuit 100 in series, so that the signal input circuit 100 is used as an audio source of the load circuit 200, a voltage is formed at two ends of the connected element needing to test the impedance value, a current is formed in a loop of the load circuit 200, and the impedance value of the element is calculated. As an implementation manner, in the online impedance testing circuit 10 provided in the embodiment of the present invention, the load circuit 200 includes an element access end 210 and a constant resistor 220, which are electrically connected to each other, where the element access end 210 is used to access an element with an impedance value to be tested, so as to measure a voltage across the element; the fixed resistor 220 is used for detecting the voltage at two ends of the fixed resistor 220 after being connected in series with the element to be tested accessed by the element access end 210, so as to obtain the current passing through two ends of the fixed resistor 220, and further obtain the current passing through the element to be tested.
The impedance calculating circuit 300 is configured to obtain an impedance value of the device under test by obtaining a voltage applied across the device under test connected at the device connecting terminal 210 and a current passing through the device under test.
The impedance calculating circuit 300 includes a first voltage detecting unit 310, a second voltage detecting unit 320, and an impedance calculating unit 330.
The first voltage detection unit 310 is used for acquiring a voltage value loaded by the element access end 210. The first voltage detection unit 310 includes a voltage divider 311, a first LC filter 312, a first switched capacitor filter 313, and a first effective value detection circuit 314, which are electrically connected in sequence. The voltage divider 311 is connected in parallel with the element access terminal 210, and since the voltage applied to the load circuit 200 tends to be high, the voltage divider 311 is used to adjust the voltage applied to the element access terminal 210, so as to adjust the voltage applied to the first LC filter 312 to an appropriate value, thereby preventing the first LC filter 312 from being damaged due to overvoltage operation caused by an excessively high voltage.
Since the composite audio signal input by the signal input circuit 100 includes a broadband broadcast audio signal and a specific audio signal with a specific frequency, the frequency of the broadcast audio signal is selected within a certain interval range, and the frequency selected by the specific audio signal is greater than that of the broadcast audio signal, at this time, the voltage processed by the voltage divider 311 may be filtered according to the frequency by using the first LC filter 312. The filtering manner of the first LC filter 312 is as follows: selecting the frequency of the specific audio signal as a target frequency, and carrying out preliminary filtering on the broadcast audio signal contained in the voltage to greatly reduce the broadcast audio signal contained in the voltage and enable the amplitude of the broadcast audio and the specific audio to be close to 1: 1. After the first LC filter 312 performs the preliminary filtering, the obtained voltage is further filtered by the first switched capacitor filter 313, so that the broadcast audio signal contained in the voltage is further attenuated, and the specific audio signal is relatively amplified, so that the high-selectivity frequency selection circuit formed by the first LC filter 312 and the first switched capacitor filter 313 makes the broadcast audio signal contained in the finally obtained voltage less than 1% of the specific audio signal.
After being filtered by the first switched capacitor filter 313, most of the obtained voltages include a specific audio signal with a specific frequency, that is, the obtained voltage is an ac signal, so that a first dc voltage value corresponding to the ac voltage obtained by the first switched capacitor filter 313 is determined by the first effective value detection circuit 314 electrically connected to the first switched capacitor filter 313, and the first dc voltage value is an effective voltage value representing the specific audio signal loaded on both ends of the element connected to the element connection end 210. Meanwhile, first effective value detector circuit 314 obtains a first effective voltage value, and then sends the first effective voltage value to impedance calculator unit 330 electrically connected to first effective value detector circuit 314.
The second voltage detecting unit 320 is configured to collect voltage values loaded at two ends of the constant value resistor 220, and further calculate the voltage values with the impedance value of the constant value resistor 220 to obtain a current value passing through the load circuit 200. The second voltage detection unit 320 includes a second amplifier 321, a second LC filter 322, a second switched capacitor filter 323, and a second effective value detection circuit 324, which are electrically connected in this order. The second amplifier 321 is connected in parallel to the fixed resistor 220 to obtain a voltage applied across the fixed resistor 220, and the second LC filter 322, the second switched capacitor filter 323, and the second effective value detector circuit 324 perform the same functions as the first LC filter 312, the first switched capacitor filter 313, and the first effective value detector circuit 314, respectively, to obtain a second dc voltage value representing an effective voltage value of the specific audio signal applied to the fixed resistor 220. Meanwhile, the second effective value detection circuit 324 obtains the second effective voltage value, and then sends the second effective voltage value to the impedance calculation unit 330 electrically connected to the second effective value detection circuit 324.
The impedance calculating unit 330 performs calculation according to the received second voltage effective value and by combining the impedance value of the fixed value resistor 220 and the parameters such as the amplification factor of the second amplifier 321, so as to obtain the current value passing through the fixed value resistor 220, and since the element connected to the element connection end 210 is connected in series with the fixed value resistor 220, the current value passing through the fixed value resistor 220 at this time also represents the current value passing through the element. Therefore, the impedance calculating unit 330 is further configured to perform calculation according to the received first voltage effective value and in combination with the calculated current value, and obtain the impedance value of the element.
Based on the above design, the online impedance testing circuit 10 provided in the embodiment of the present invention accesses an element into the load circuit 200 including a power supply for broadcasting an audio signal and a specific audio signal through the element access end 210, and after respectively detecting and obtaining the voltage at the two ends of the element access end 210 and the voltage at the two ends of the fixed value resistor 220, the voltage generated by the specific audio signal at the two ends of the element and the current of the specific audio signal passing through the element are obtained after processing, so as to obtain the impedance value of the element.
In the above design, the voltage value and the current value used in the impedance value calculation of the to-be-tested element are obtained by filtering in the impedance calculation circuit 300, and if there is a frequency overlapping portion between the broadband broadcast audio signal and the specific audio signal with a specific frequency, the accuracy of the impedance value representing the to-be-tested element obtained by the impedance calculation circuit 300 is also affected to a certain extent. Therefore, a solution provided by the embodiment of the present invention is: the frequency of the incoming broadcast audio signal is filtered in the signal input circuit 100 so that the broadcast audio signal does not overlap the frequency of the specific audio signal when it is incoming. Referring to fig. 2, fig. 2 shows a schematic structural diagram of a signal input circuit 100 of an online impedance testing circuit 10 according to an embodiment of the present invention, in which the signal input circuit 100 includes a broadcast audio incoming end 110, a first filter 120, and an adder 130, which are electrically connected in sequence.
The broadcast audio incoming terminal 110 is used to input a broadband broadcast audio signal. At this time, since the frequency of the broadcast audio signal varies within a frequency range, the first filter 120 of the broadcast audio incoming terminal 110 filters a broadband broadcast audio signal input from the broadcast audio incoming terminal 110, so that the frequency of the broadcast audio signal is within a certain range and has no overlapping portion with the frequency of the specific audio signal. As an implementation manner, in the online impedance testing circuit 10 provided in the embodiment of the present invention, the first filter 120 is a 10KHz low-pass filter, that is, only a portion of the broadcast audio signal input by the broadcast audio input terminal 110 with a frequency less than or equal to 10KHz can pass through, that is, the frequency of the broadcast audio signal filtered by the first filter 120 is less than or equal to 10KHz, and the broadcast audio signal is sent to the adder 130.
The signal input circuit 100 further includes a specific audio input terminal 150, and the specific audio input terminal 150 is electrically connected to the adder 130, and is configured to input a specific audio signal of a specific frequency and transmit the specific audio signal to the adder 130. Wherein the frequency of the specific audio signal is different from the frequency of the broadcast audio signal filtered by the first filter 120. Meanwhile, as an embodiment, the frequency of the specific audio signal is greater than that of the broadcast audio signal, and the voltage of the specific audio signal is less than that of the broadcast audio signal.
The adder 130 obtains the broadcast audio signal input from the broadcast audio input terminal 110 and the specific audio signal input from the specific audio input terminal 150, and adds the two signals to obtain a composite audio signal. Since the frequencies of the broadcast audio signal and the specific audio signal are different from each other, the adder 130 adds the broadcast audio signal and the specific audio signal to obtain a composite audio signal.
The signal input circuit 100 further includes a first amplifier 140, wherein the first amplifier 140 is electrically connected to the adder 130 and is connected in series to the load circuit 200, and is configured to receive the composite audio signal added by the adder 130, and appropriately amplify the composite audio signal according to the user's requirement, and then connect the amplified composite audio signal to the load circuit 200 as an audio source of the load circuit 200. At this time, the audio sources in the load circuit 200 include both a broadband broadcast audio signal and a specific audio signal of a specific frequency.
Based on the above design, in the online impedance testing circuit 10 provided in the embodiment of the present invention, the first filter 120 filters the broadcast audio signal input from the broadcast audio input terminal 110, so that there is no overlapping portion between the frequency of the broadcast audio signal received by the impedance calculating circuit 300 and the frequency of the specific audio signal, and further the testing performance of the online impedance testing circuit 10 is increased, so that the impedance value of the testing result is more reliable.
After obtaining the voltage applied across the device under test and the voltage applied across the fixed resistor 220, the knowledge of the user about the change in the impedance value of the device under test can be obtained in a variety of ways. One implementation manner provided by the embodiment of the present invention is as follows: the processor 331 calculates the impedance value of the dut in real time and represents the change of the impedance value of the dut by indicating the different states displayed by the subunit 332. Referring to fig. 3, fig. 3 shows a schematic structural diagram of an impedance calculating unit 330 of the online impedance testing circuit 10 according to an embodiment of the present invention, in which the impedance calculating unit 330 includes a processor 331 and an indicating subunit 332 electrically connected in sequence.
The processor 331 is electrically connected to the first effective value detection circuit 314 and the second effective value detection circuit 324, respectively, and is configured to obtain a current value passing through the fixed value resistor 220 according to the voltage across the fixed value resistor 220 and the impedance value of the fixed value resistor 220 detected by the second voltage detection unit 320, at this time, since the first voltage detection unit 310 and the second voltage detection unit 320 both have filtered the broadcast audio signal in the composite audio signal, the obtained current passing through the fixed value resistor represents the current value of the specific audio signal passing through the fixed value resistor 220, and since the fixed value resistor 220 is connected in series with the element connection terminal 210, the obtained current value represents the current value of the specific audio signal generated on the load circuit 200. The processor 331 is further configured to obtain an impedance value of the component connected to the component connection end 210 according to ohm's law and according to the detected voltage value loaded across the component connection end 210 and the current value of the load circuit 200, and send the impedance value to the indication subunit 332.
As an implementation manner, in the online impedance testing circuit 10 provided in the embodiment of the present invention, the processor 331 is a single chip.
After receiving the impedance value of the component connected to the characterization component connection end 210 and sent by the processor 331, the indication subunit 332 displays different indication information according to the difference of the received impedance value.
In one embodiment, the indicating subunit 332 includes at least one of a display screen, a light emitting tube, an audio alarm and a relay indicating contact in the online impedance testing circuit 10 according to the embodiment of the present invention. When the indication subunit 332 includes a display screen, the received impedance value information may be displayed, so that the user can know the impedance value of the element connected at this time; when the indicating subunit 332 includes light emitting tubes, the magnitude of the impedance value can be represented by displaying different luminances according to the relationship between the magnitude of the preset impedance value and the luminance, or the magnitude of the impedance value can be represented by lighting different numbers of light emitting tubes according to the relationship between the magnitude of the preset impedance value and the number of the light emitting tubes; when the indicating subunit 332 includes an audio alarm, it is possible to set a range of impedance values, and when the impedance value changes in this range, it indicates that the impedance value of the component connected to the component connection terminal 210 fluctuates in a normal range, and the audio alarm does not send an alarm signal, and when the change of the impedance value exceeds this set range, the audio alarm sends an alarm message to prompt the user that the impedance value of the component connected to the component connection terminal 210 is abnormal, or when the impedance value exceeds a certain range, the audio alarm pushes a relay to make a contact perform a closing or opening action to notify the peripheral control circuit.
Based on the above design, in the online impedance testing circuit 10 provided in the embodiment of the present invention, after the impedance value of the component connected to the component connection end 210 is obtained through calculation by using the processor 331 such as the single chip microcomputer, different indication information is displayed by the indication subunit 332 to represent whether the impedance value of the component changes, so that a user can find the change of the impedance value of the component in time, and check and repair the component in time.
In the above design, since the first effective value and the second effective value of the voltage directly sent to the processor 331 by the first effective value detection circuit 314 and the second effective value detection circuit 324 are both analog signals, the processor 331 needs to convert the first effective value and the second effective value of the voltage into digital signals before performing calculation processing, and therefore, the online impedance test circuit 10 has a high requirement on the processor 331, i.e., must include an AD signal conversion function, and further increases the cost of the entire online impedance test circuit 10. Based on this, a solution provided by the embodiment of the present invention is: the signal received by the processor 331 is a digital signal by being electrically connected to the processor 331 through the first and second AD converters 315 and 325, respectively, with the first and second effective value detection circuits 314 and 324. Referring to fig. 4, fig. 4 shows another schematic structural diagram of an online impedance testing circuit 10 according to an embodiment of the present invention, in the embodiment, the first voltage detecting unit 310 further includes a first AD converter 315, the first effective value detecting circuit 314 is electrically connected to the impedance calculating unit 330 through the first AD converter 315, the first AD converter 315 converts an analog signal of a first effective voltage value at two ends of the device under test, which is accessed by the characterization device access end 210 and sent by the first effective value detecting circuit 314, into a digital signal, and then sends the digital signal to the impedance calculating unit 330, so that the impedance calculating unit 330 can directly use the first effective voltage value.
Meanwhile, the second voltage detection unit 320 further includes a second AD converter 325, the second effective value detection circuit 324 is electrically connected to the impedance calculation unit 330 through the second AD converter 325, and the second AD converter 325 converts the analog signal representing the second effective voltage value at both ends of the fixed value resistor 220, which is sent from the second effective value detection circuit 324, into a digital signal and then sends the digital signal to the impedance calculation unit 330, so that the impedance calculation unit 330 can directly use the second effective voltage value.
Based on the above design, according to the online impedance testing circuit 10 provided in the embodiment of the present invention, the first voltage detecting unit 310 and the second voltage detecting unit 320 are respectively connected to the first AD converter 315 and the second AD converter 325, so that the voltage values received by the impedance calculating unit 330 are all digital signals capable of being directly processed, thereby reducing the functional requirements of the impedance calculating unit 330 and reducing the cost of the online impedance testing circuit 10.
The embodiment of the present invention further provides an online impedance testing method, which is applied to the online impedance testing circuit 10, where the online impedance testing circuit 10 includes a signal input circuit 100, a load circuit 200, and an impedance calculating circuit 300, the impedance calculating circuit 300 includes a first voltage detecting unit 310, a second voltage detecting unit 320, and an impedance calculating unit 330, where the first voltage detecting unit 310 includes a voltage divider 311, a first LC filter 312, a first switched capacitor filter 313, and a first effective value detecting circuit 314 that are electrically connected in sequence, the voltage divider 311 is connected in parallel with the element access end 210, the first effective value detecting circuit 314 is electrically connected with the impedance calculating unit 330, the second voltage detecting unit 320 includes a second amplifier 321, a second LC filter 322, a second switched capacitor filter 323, and a second effective value detecting circuit 324 that are electrically connected in sequence, the second amplifier 321 is electrically connected with the fixed resistor 220, the second effective value detection circuit 324 is electrically connected to the impedance calculation unit 330. Referring to fig. 5, fig. 5 is a schematic flowchart illustrating an online impedance testing method according to an embodiment of the present invention, in which the online impedance testing method includes the following steps:
s100, the signal input circuit inputs a composite audio signal.
In the present embodiment, the signal input circuit 100 inputs a composite audio signal including a broadcast audio signal of a wide frequency band and a specific audio signal of a specific frequency.
And S200, connecting a load circuit to an element needing impedance testing.
In this embodiment, the load circuit 200 is connected in series with the signal input circuit 100, the load circuit 200 includes a component access end 210 and a constant value resistor 220 connected in series, the impedance value of the constant value resistor 220 is a determined value, and the component access end 210 is used for accessing a component to be impedance tested.
S300, the first voltage detection unit detects the voltage value of the specific audio signal generated at two ends of the element access end.
In the present embodiment, the first voltage detection unit 310 includes a voltage divider 311, a first LC filter 312, a first switched capacitor filter 313, and a first effective value detection circuit 314, which are electrically connected in this order, the voltage divider 311 being connected in parallel with the element access terminal 210, the first effective value detection circuit 314 being electrically connected to the impedance calculation unit 330. The voltage divider 311 adjusts the voltage applied across the component input 210 to the operating voltage of the first LC filter 312 and the first switched capacitor filter 313. Since the voltage applied to the device access 210 includes both the broadband broadcast audio signal and the specific audio signal with the specific frequency, the frequency selective circuit composed of the first LC filter 312 and the first switched capacitor filter 313 filters the broadband broadcast audio signal in the voltage with the adjusted voltage, retains the voltage generated by the specific audio signal with the specific frequency at the device access 210, and converts the voltage into the first effective voltage value of the dc voltage through the first effective value detection circuit 314, and sends the first effective voltage value to the impedance calculation unit 330, wherein the first effective voltage value represents the voltage value generated by the specific audio signal at the device access 210.
S400, the second voltage detection unit detects the voltage value of the specific audio signal generated at two ends of the constant value resistor.
In the present embodiment, the second voltage detection unit 320 includes a second amplifier 321, a second LC filter 322, a second switched capacitor filter 323, and a second effective value detection circuit 324, which are electrically connected in sequence, the second amplifier 321 is electrically connected to the fixed resistor 220, and the second effective value detection circuit 324 is electrically connected to the impedance calculation unit 330. Since the impedance value of the fixed resistor 220 is generally small, the voltage generated by the composite audio signal at the two ends of the fixed resistor 220 is also small, after the second amplifier 321 adjusts the voltage at the two ends of the fixed resistor 220 to the proper working voltage of the second LC filter 322 and the second switched capacitor filter 323, the high-selectivity frequency selection circuit formed by the second LC filter 322 and the second switched capacitor filter 323 filters the broadcast audio signal, retains the voltage generated by the specific audio signal with a specific frequency at the two ends of the fixed resistor 220, and converts the voltage into a second voltage effective value of the dc voltage through the second effective value detection circuit 324, and sends the second voltage effective value to the impedance calculation unit 330, wherein the second voltage effective value represents the voltage value generated by the specific audio signal at the two ends of the fixed resistor 220.
S500, the impedance calculating unit obtains a current value of the specific audio signal generated in the load circuit according to the voltage value detected by the second voltage detecting unit and the impedance value of the constant value resistor, and generates an impedance value of the element connected to the element connecting end according to the voltage value detected by the first voltage detecting unit and the current value of the specific audio signal generated in the load circuit.
In the present embodiment, the impedance calculating unit 330 obtains the current value of the specific audio signal generated in the load circuit 200 after receiving the voltage value detected by the second voltage detecting unit 320, i.e. the effective value of the second voltage, and according to the impedance value of the fixed value resistor 220; meanwhile, according to the voltage value detected by the first voltage detecting unit 310, that is, after the first voltage effective value, the impedance value of the to-be-tested element connected to the element connecting terminal 210 is generated by combining the calculated current value generated by the specific audio signal in the load circuit 200.
To sum up, compared with the prior art, the online impedance testing circuit 10 and the method provided in the embodiments of the present invention access an element into the load circuit 200 including a power supply for broadcasting an audio signal and a specific audio signal through the element access end 210, and respectively detect and obtain the voltage at the two ends of the element access end 210 and the voltage at the two ends of the fixed value resistor 220, and then obtain the voltage generated by the specific audio signal at the two ends of the element and the current of the specific audio signal through the element after processing, so as to obtain the impedance value of the element, the online impedance testing circuit 10 provided in the embodiments of the present invention can detect the impedance value of the element to be tested in real time when the element to be tested is in operation, so as to monitor whether the operating state of the element is abnormal in real time; meanwhile, the broadcast audio signals introduced from the broadcast audio access terminal 110 are filtered by the first filter, so that the frequency of the broadcast audio signals received by the impedance calculation circuit 300 does not overlap with the frequency of the specific audio signals, and the test performance of the online impedance test circuit 10 is further improved, so that the impedance value of the test result is more reliable; meanwhile, after the impedance value of the element accessed by the element access end 210 is obtained by calculation through the processor 331 such as a single chip microcomputer, different indication information is displayed through the indication subunit 332 to represent whether the impedance value of the element changes, so that a user can find the change of the impedance value of the element in time and check and repair the element in time; the first voltage detection unit 310 and the second voltage detection unit 320 are respectively connected to the first AD converter 315 and the second AD converter 325, so that the voltage values received by the impedance calculation unit 330 are all digital signals capable of being directly processed, the functional requirements of the impedance calculation unit 330 are reduced, and the cost of the online impedance test circuit 10 is reduced.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Claims (10)
1. An online impedance test circuit is characterized by comprising a signal input circuit, a load circuit and an impedance calculation circuit;
the signal input circuit is used for inputting a composite audio signal, and the composite audio signal comprises a broadband broadcast audio signal and a specific audio signal with a specific frequency;
the load circuit is used for connecting an element needing impedance testing, the load circuit is connected with the signal input circuit in series, and the load circuit comprises a component connecting end and a constant value resistor which are connected in series;
the impedance calculation circuit comprises a first voltage detection unit, a second voltage detection unit and an impedance calculation unit; wherein,
the first voltage detection unit comprises a voltage divider, a first LC filter, a first switch capacitor filter and a first effective value detection circuit which are sequentially and electrically connected, the voltage divider is connected with the element access end in parallel, and the first effective value detection circuit is electrically connected with the impedance calculation unit;
the second voltage detection unit comprises a second amplifier, a second LC filter, a second switched capacitor filter and a second effective value detection circuit which are sequentially and electrically connected, the second amplifier is connected with the constant value resistor in parallel, and the second effective value detection circuit is electrically connected with the impedance calculation unit;
the impedance calculating unit is used for obtaining a current value of the load circuit according to the voltage value detected by the second voltage detecting unit and the impedance value of the constant value resistor, and is used for generating the impedance value of the element accessed by the element access end according to the voltage detected by the first voltage detecting unit and the current value of the load circuit.
2. The circuit of claim 1, wherein the signal input circuit comprises a broadcast audio input terminal, a first filter, and an adder electrically connected in sequence, the broadcast audio input terminal is used for inputting a broadband broadcast audio signal;
the signal input circuit further comprises a specific audio access end which is electrically connected with the adder and used for inputting a specific audio signal with a specific frequency;
the adder is used for adding the broadcast audio signal input by the broadcast audio access end and the specific audio signal input by the specific audio access end to obtain a composite audio signal;
the signal input circuit further comprises a first amplifier, the first amplifier is electrically connected with the adder and is connected with the load circuit in series, and the first amplifier is used for receiving the composite audio signal obtained by adding the adder, amplifying the composite audio signal and then connecting the amplified composite audio signal to the load circuit.
3. The circuit of claim 2, wherein the first filter is a low pass filter.
4. The circuit of claim 3, wherein the low pass filter is a 10KHz low pass filter.
5. The circuit of claim 2, wherein the voltage of the broadcast audio signal input by the broadcast audio access is greater than the voltage of the particular audio signal input by the particular audio access.
6. The circuit of claim 1, wherein the impedance calculation unit comprises a processor and an indication subunit electrically connected in sequence;
the processor is electrically connected with the first effective value detection circuit and the second effective value detection circuit respectively, and is used for obtaining the current value of the load circuit according to the voltage at the two ends of the constant value resistor and the impedance value of the constant value resistor detected by the second voltage detection unit, obtaining the impedance value of the element accessed by the element access end according to the detected voltage value at the two ends of the element access end and the current value of the load circuit, and sending the impedance value of the element accessed by the element access end to the indication subunit;
the indicating subunit is used for displaying different indicating information according to the received impedance value of the element accessed by the element access end.
7. The circuit of claim 6, wherein the processor is a single-chip microcomputer.
8. The circuit of claim 6, wherein the indicating subunit comprises at least one of a display screen, a light emitting tube, and an audio alarm, relay indicating contacts.
9. The circuit according to any one of claims 1 to 8, wherein the first voltage detection unit further includes a first AD converter, the first effective value detection circuit being electrically connected to the impedance calculation unit through the first AD converter;
the second voltage detection unit further includes a second AD converter, and the second effective value detection circuit is electrically connected to the impedance calculation unit through the second AD converter.
10. An online impedance testing method is applied to an online impedance testing circuit, the online impedance testing circuit comprises a signal input circuit, a load circuit and an impedance calculating circuit, and the method comprises the following steps:
the signal input circuit inputs a composite audio signal, wherein the composite audio signal comprises a broadband broadcast audio signal and a specific audio signal with a specific frequency;
the load circuit is connected with an element needing impedance testing, the load circuit is connected with the signal input circuit in series, and the load circuit comprises a series-connected element connecting end and a constant-value resistor;
the impedance calculation circuit comprises a first voltage detection unit, a second voltage detection unit and an impedance calculation unit; wherein,
the first voltage detection unit detects a voltage value generated by the specific audio signal at two ends of the element access end, the first voltage detection unit comprises a voltage divider, a first LC filter, a first switch capacitor filter and a first effective value detection circuit which are sequentially and electrically connected, the voltage divider is connected with the element access end in parallel, and the first effective value detection circuit is electrically connected with the impedance calculation unit;
the second voltage detection unit detects a voltage value generated by the specific audio signal at two ends of the constant value resistor, the second voltage detection unit comprises a second amplifier, a second LC filter, a second switched capacitor filter and a second effective value detection circuit which are sequentially and electrically connected, the second amplifier is electrically connected with the constant value resistor, and the second effective value detection circuit is electrically connected with the impedance calculation unit;
the impedance calculating unit obtains a current value of the specific audio signal generated in the load circuit according to the voltage value detected by the second voltage detecting unit and the impedance value of the constant value resistor, and generates an impedance value of an element accessed by the element access end according to the voltage value detected by the first voltage detecting unit and the current value of the specific audio signal generated in the load circuit.
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