CN113126014B - Calibration system for realizing array parallelism of digital oscilloscope - Google Patents
Calibration system for realizing array parallelism of digital oscilloscope Download PDFInfo
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Abstract
The invention relates to a calibration system for realizing parallel array of a digital oscilloscope, which comprises a signal source group output module, a resistance measurement module, a switch topological structure and a control device; the signal source group output module is used for outputting four signals and reaches a case signal output end through a cable and the switch topological structure; the resistance measurement module is used for measuring resistance, calibrating the input resistance of the digital oscilloscope and achieving a chassis signal output end through a cable and the switch topological structure; and the control device is internally provided with parallel calibration software, so that each module and the calibrated oscilloscope are controlled, and the parallel calibration software is operated on a display to finish the parallel on-demand calibration of the digital oscilloscope array. The invention can realize the parallel calibration function of 25 channels of five digital oscilloscopes, the hardware has four basic signal output modules and resistance measurement functions, and the free switching of the signal source group and the oscilloscopes group is realized by switching the route switch.
Description
Technical Field
The invention relates to the technical field of oscilloscope calibration, in particular to a calibration system for realizing digital oscilloscope array parallelism.
Background
The digital oscilloscope is the most widely applied time domain measuring instrument, and in some large physical diagnosis platforms or large comprehensive test consoles, four acquisition channels of the digital oscilloscope cannot meet test requirements, so tens of hundreds of digital oscilloscopes are formed into a digital oscilloscope array test system through a local area network, direct or indirect multichannel accurate measurement of a plurality of electric parameters and physical parameters of a large-scale test device is completed, and reliable and necessary basis is provided for development, performance determination and experimental debugging of the device.
In terms of a metering standard device of the digital oscilloscope, from the aspect of project integrity, the current metering device can basically finish all-project metering of the digital oscilloscope within a certain bandwidth range (20 GHz), but adopts a single channel-by-channel mode, namely a serial and single-channel working mode. The metering device can be composed of a plurality of discrete devices with different signal output functions, and also can be composed of a single or a small number of comprehensive multifunctional calibration devices with higher integration level, wherein the latter is the first choice from the aspects of standard configuration cost, use convenience and metering development trend, the main products in foreign countries are multifunctional calibration devices such as 5820A, 9500 and the like of American Fulke company, and plug-in type or multifunctional integrated calibration devices such as TM504, CG5011 and the like of early-stage of American Taike company; the main products in China are NF4608A, NF4609A and the like of Jiangsu Nanfeng corporation, SO3, SO6, NH4602 (programmable) and the like of the national south China factory, and POC-2 (programmable) multifunctional calibrator developed by China metering institute Hua electric company.
At present, 9500 multifunctional calibrator produced by Fulke corporation in the United states is the multifunctional calibration equipment with highest index and the most complete functions in the world, is the multifunctional calibration equipment with higher integration level, can conveniently complete the calibration of digital oscilloscopes with the bandwidth below 6.4GHz by matching different active probes with a single equipment, and is the mainstream configuration of various large-scale metering structures at home and abroad in the aspect of pulse metering. However, 9500 is limited by the internal hardware structure, the main function signals of 5 signal output channels cannot be synchronously output in parallel, the metering process can only be performed in a single-channel one-by-one metering mode, which has become a bottleneck problem for further improving the metering efficiency of the multi-channel data acquisition equipment, and the calibration capability and efficiency of 9500 are very soft for hundreds of acquisition channels of digital oscilloscope arrays.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, provides a calibration system for realizing parallel array of a digital oscilloscope, and solves the defects of the prior calibration equipment.
The aim of the invention is achieved by the following technical scheme: a calibration system for realizing parallel array of digital oscilloscope comprises a signal source group output module, a resistance measurement module, a switch topological structure and a control device;
the signal source group output module is used for outputting a stable amplitude sine wave signal, a time scale signal, a fast edge signal and a direct current voltage signal, and reaches a case signal output end through a cable and the switch topological structure;
the resistance measurement module is used for measuring resistance, calibrating the input resistance of the digital oscilloscope and achieving a chassis signal output end through a cable and the switch topological structure;
and the control device is internally provided with parallel calibration software, so that each module and the calibrated digital oscilloscope are controlled, and the parallel calibration software is operated on a display to finish the parallel on-demand calibration of the digital oscilloscope array.
The signal source group output module comprises a direct current unit, a time scale unit, a stable amplitude sine wave unit and a fast edge pulse unit;
the direct current unit is controlled through the PXIe bus interface, achieves the function of five paths of parallel output direct current voltage signals, and provides direct current voltage signals for calibrating direct current bias and direct current gain of the digital oscilloscope;
the time scale unit realizes the function of outputting time scale signals in a single way and is used for calibrating the time reference of the digital oscilloscope;
the amplitude-stabilizing sine wave unit realizes the function of outputting amplitude-stabilizing sine waves in two paths in parallel and is used for calibrating the frequency bandwidth and the triggering sensitivity of the digital oscilloscope;
the fast edge pulse unit realizes the function of outputting fast edge signals in a single way and is used for calibrating the rising time of the digital oscilloscope.
All modules are integrated in a three-layer structure in a chassis, the signal source group output module is placed on the upper layer, the PXIe chassis is arranged on the middle layer, the direct current card, the radio frequency switch card, the resistance measurement module and the control device are inserted in the chassis, and the power supply module is placed on the lower layer, so that the power supply module has the characteristics of small volume, light weight, high integration level and convenience in carrying
And the routing circuit of the signal source group is free to connect the sine wave signal, the time scale signal, the fast edge signal, the direct current voltage signal and the resistance measuring unit with all channels of the calibrated digital oscilloscope in three stages by utilizing 15 radio frequency switches in total of 3 radio frequency switch cards according to the principle of division-total-division.
The free connection of the sine wave signal, the time scale signal, the fast edge signal, the direct current voltage signal and the resistance measuring unit and each channel of the calibrated oscilloscope is realized by three stages, and the free connection comprises the following steps:
the fast edge signal, the time mark signal and the two paths of sine signals are respectively output to the second-stage radio frequency switch through split switching of the first-stage radio frequency switch; the second-stage radio frequency switch gathers various signals split by the first-stage radio frequency switch on one switch, so that each second-stage radio frequency switch can output the sine wave signal, the time mark signal, the fast edge signal, the direct current voltage signal and the resistance measurement signal; and the third-stage radio frequency switch sequentially and correspondingly inputs the collected signals to all channels of the oscillograph, so that each oscillograph channel has the input functions of the sine wave signal, the time mark signal, the fast edge signal, the direct-current voltage signal and the resistance measurement signal, and the calibration of the digital oscillograph array is completed.
And correcting the influence of the direct-current voltage signal caused by environmental change by adopting a real-time correction method, and correcting the influence of the switch cable on the stable-amplitude sine wave signal attenuation and resistance measurement accuracy by adopting a pre-correction method.
The method for correcting the influence of the direct current voltage signal caused by environmental change by adopting the real-time correction method comprises the following steps:
according to the on-demand calibration requirement of the oscilloscope array, the DC gain and DC bias are realized for the calibration project using the DC voltage signal, statistics is carried out on the DC voltage signals used by all oscilloscope models in the digital oscilloscope array, the DC voltage point to be calibrated is determined, and a corresponding calibration point database is created;
before calibrating the oscilloscope array each time, connecting a direct-current voltage signal output end of a calibration system to a voltage measurement end of a digital meter module of the calibration system through a 50 omega load, and performing self-calibration hardware connection; according to the model of the oscilloscope to be calibrated, a corresponding calibration point database file is called, parallel self-calibration software is opened to control a power supply board and a switch route of a switch topological structure to measure the voltage of a direct-current voltage signal output end, a calibration formula is used for compensating the direct-current voltage signal, the compensated signal is measured again, and the correction value is stored in the calibration point database until the signal meets the index requirement of the direct-current voltage signal;
and opening parallel self-calibration software to call a correction value database file, and correcting direct-current gain and direct-current bias items of the oscilloscope by using correction values of direct-current voltage signals in the database file to realize real-time correction and on-demand calibration.
The correcting the influence of the switch cable on the stable amplitude sine wave signal attenuation and the resistance measurement accuracy by adopting the pre-correction method comprises the following steps:
the method for correcting the stable amplitude sine wave power comprises the following steps: the method comprises the steps of obtaining stable amplitude sine wave power of an output end of a stable amplitude sine wave unit under different frequencies and voltage amplitudes by using a power meter, obtaining the attenuation of a switch topological structure and a cable by using a network analyzer, and comparing the obtained attenuation with the amplitude and power of a reference point to obtain a final amplitude signal output by the stable amplitude sine wave unit after correction under different frequencies;
and determining amplitude values of calibration points of the amplitude-stabilized sine wave according to the calibration and point selection requirements of the digital oscilloscope, calibrating signal output ends of two paths of amplitude-stabilized sine wave units which are output in parallel one by one through a power meter, and sequentially obtaining output power of the amplitude-stabilized sine wave units.
The correction method of the DC resistance measurement accuracy comprises the following steps: selecting standard resistors with known indexes and resistance values, and measuring the resistance values of the standard resistors after passing through the cable and switch topological structure by using a resistor measuring board card; comparing the reading of the board card with the standard resistance value to obtain an interface end resistance measurement correction value after passing through a switch topological structure; because the correction value is determined, the influence quantity is pre-corrected in a programming mode, and the direct current resistance measurement function is ensured to meet the requirements of technical indexes.
The invention has the following advantages: a calibration system for realizing parallel array of digital oscilloscopes can realize parallel calibration function of 25 channels of five oscilloscopes in total, hardware has four basic signal output modules and resistance measurement functions, and free switching of a signal source group and an oscilloscopes group is realized through a switching route switch. Because the number of the direct current gain and the direct current offset calibration points is relatively large, the metering efficiency can be greatly improved by adopting a five-path parallel calibration mode aiming at the direct current signal, and the calibration system has the advantages of small volume, light weight, high integration level, convenience in carrying out, on-site movement, strong metering guarantee pertinence, high metering efficiency and the like.
Drawings
FIG. 1 is a flow chart of a time base calibration procedure;
FIG. 2 is a flow chart of a rise time calibration procedure;
FIG. 3 is a schematic diagram of a switch routing structure according to the present invention;
FIG. 4 is a schematic diagram of DC voltage signal attenuation;
FIG. 5 is a flow chart of the real-time correction of DC voltage signals;
FIG. 6 is a diagram showing the calibration result of DC voltage signals of each channel of the digital oscilloscope unit 1;
FIG. 7 is a schematic diagram of a steady amplitude sine wave signal attenuation;
FIG. 8 is a schematic diagram of a constant amplitude sine wave signal correction;
FIG. 9 is a schematic diagram of the verification result of the amplitude-stabilized sine wave signals of each channel of the digital oscilloscope unit 1;
FIG. 10 is a flow chart of an overall calibration method.
Detailed Description
For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Accordingly, the following detailed description of the embodiments of the present application, provided in connection with the accompanying drawings, is not intended to limit the scope of the application, as claimed, but is merely representative of selected embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present application without making any inventive effort, are intended to be within the scope of the present application. The invention is further described below with reference to the accompanying drawings.
The invention relates to a digital oscilloscope array parallel calibration system based on a switch topological structure, which particularly comprises a power supply, direct-current voltage, a time scale, a stable amplitude sine wave, a fast edge pulse four basic signal output module, a resistance measurement module, a switch topological structure, parallel calibration software, a display, a control system and the like, wherein the power supply, the direct-current voltage, the time scale, the stable amplitude sine wave and the fast edge pulse are arranged in a chassis. The four basic signals and the resistance measurement modules reach the signal output end of the chassis through a cable and switch topological structure and are connected with the calibrated digital oscilloscope, the control system controls each module and the calibrated digital oscilloscope, and parallel calibration software is operated on a display to finish the parallel on-demand calibration of the digital oscilloscope array.
The inside of the case comprises a three-layer structure, and a stable amplitude sine wave, a time scale and a fast edge pulse signal output module are arranged on the upper layer; the middle is a PXIe cage, and a direct current card, a switch card, a resistance measurement module and a controller are inserted into the cage; a power supply module is arranged at the lower layer; the left side and the right side are provided with a cooling fan and a handle; the front is a display; the back is a calibration output end, a direct current signal self-calibration end and a network port end.
Furthermore, the PXI cage adopts a PXI and PXI mixed bus backboard, is compatible with standard PXI and PXI modules, and integrates and controls five direct current cards, five radio frequency switch cards, a digital meter card and a zero-slot controller system. The zero slot controller controls the PXIe cage inner board card, controls and communicates the external amplitude-stabilizing sine wave module, the time scale module and the fast edge pulse module by using the USB and the serial port, controls the calibrated digital oscilloscope by using the network port, and simultaneously provides a hardware platform for writing parallel calibration software. The power supply module supplies power for the PXIe cage, the stable-amplitude sine wave and fast-edge pulse module, and has voltage output ends of 3.3V, 5V, 12V and 15V, the maximum total power is 750W, the voltage regulation rate is less than or equal to 0.1%, and the load regulation rate is less than or equal to 3%. The signal output end is a double-head SMA stainless steel seat, one end of the signal output end is connected with a microwave switch card in the case, and the other end of the signal output end is fixed on the back of the case. The array structure is a matrix of 5 multiplied by 5, each column corresponds to 5 oscilloscopes to be calibrated, and each row corresponds to 5 channels of the oscilloscopes. The cooling fans are used for controlling the temperature inside the case, 2 groups of 4 fans are arranged at two ends of the case, so that the cooling efficiency inside the case is ensured, and the temperature difference between the air inside and outside the case is controlled below 10 ℃.
Further, as shown in fig. 1, the amplitude-stabilizing sine wave module has two paths of parallel output amplitude-stabilizing sine wave functions, and the controller is controlled by the USB, and is used for calibrating the frequency bandwidth and the triggering sensitivity items of the digital oscilloscope, and the frequency range is as follows: 900 kHz-1.1 GHz, the amplitude range is: 5mVp-p to 5Vp-p. The time scale module has a function of outputting time scale signals in a single way, and the controller is controlled through a serial port and used for calibrating time base items of the digital oscilloscope, and the time scale module has a period of: 1 mu s-1 s, maximum allowable error: 2.5X10 -7 . When time-based calibration of the digital oscilloscope is carried out, parallel calibration software is operated to read calibration points in a calibration database according to needs, a time scale module is controlled to send out corresponding periodic signals, then the signals are input into corresponding digital oscilloscope calibration channels through controlling a switch routing structure in FIG. 3, and display readings on the digital oscilloscope are read to finish calibration;
as shown in fig. 2, the fast-edge pulse module has a function of outputting a fast-edge signal in a single way, and the controller is controlled through a serial port and used for calibrating a rising time item of the digital oscilloscope, and the amplitude range is as follows: 6 mV-3V, rise time: not greater than 120ps; overshoot: not more than 20%. When the ascending time item calibration is carried out, firstly, running concurrency calibration software reads calibration amplitude points in a calibration on-demand database, controls a fast edge module to sequentially send out fast edge signals, then inputs the signals into corresponding digital oscilloscope calibration channels through controlling a switch routing structure in FIG. 3, and reads display readings on the digital oscilloscope to complete the calibration;
the resistance measurement module is controlled through the PXI bus interface, has a resistance measurement function, calibrates the input resistance of the digital oscilloscope, and has the maximum allowable error: 0.3%. The direct current module is controlled through the PXIe bus interface, has the function of outputting direct current voltage signals in five paths in parallel, and provides direct current voltage signals for calibrating direct current bias and direct current gain items of the digital oscilloscope, and the direct current voltage range is as follows: measuring range of 0V-200V, 600mV, error limit: (+/-) (0.020% reading +50μV).
As shown in fig. 3, the routing circuit of the signal source group is designed according to the principle based on the division-total-division, and five radio frequency switch cards are utilized to totally use 15 radio frequency switches to realize the free connection of 5 signals and all channels of the calibrated oscilloscope in three stages. The first-stage radio frequency switch splits the fast edge signal, the time scale signal, the two paths of sine signals and the digital meter measuring function, namely, the output function of the six-channel signal is realized by switching the first-stage radio frequency switch; the second-stage radio frequency switch gathers various signals split by the first-stage switch to one switch, namely, each second-stage radio frequency switch has the output function of five signals; and the third-stage radio frequency switch sequentially corresponds the collected signals to all channels of the oscilloscope, so that each oscilloscope channel has five signal input functions, and the calibration of the oscilloscope is completed.
As shown in fig. 4, the influence of the environmental change on the direct current small voltage signal can be corrected by adopting a real-time correction method.
The direct-current voltage signal is sent by the direct-current board card, and the signal is attenuated due to the influence of the switch topological structure and the cable resistance through each channel from the switch topological structure and the cable to the oscilloscope unit. When the input resistance of the oscilloscope is 1MΩ, the influence amount is small and can be ignored, and when the input resistance of the oscilloscope is 50 Ω and the direct current voltage is a small voltage signal, the influence of the attenuation on the signal is more obvious. Therefore, when the load resistance is 50Ω, the direct-current voltage is corrected by the switching topology structure and the signal attenuation rule after the cable, and finally, the direct-current voltage signal at the signal output end of the calibrating device is ensured to meet the technical index requirement.
The direct-current voltage is freely switched from the direct-current power supply board card through the cable 1 to the switch topological structure, and then from the switch topological structure to each channel of the oscilloscope unit through the cable 2. Thus, the dc voltage signal attenuation mainly comprises three parts, two cable attenuations and switch attenuations, respectively. In the experimental process, the small voltage signal (such as 3 mV) has larger influence along with the environmental change signal, and the requirement of the experimental field environment can not be completely met directly by a pre-correction mode, but the attenuation of the small voltage signal is more definite under the current environmental condition, namely the system error is dominant, so that the accuracy of the direct current voltage signal can be improved by adopting a real-time correction mode.
As shown in fig. 5, the concept of the real-time correction method is as follows: the calibrating device outputs multipath direct-current voltage signals to the calibrated oscilloscope through the switch topological structure and the cable, and before calibration is carried out, the high-accuracy voltage measuring function of the meter module of the calibrating device is utilized to measure the voltage reaching the port of the oscilloscope, and the value is used as an accurate direct-current voltage value. The calibrating device can realize parallel calibration of five oscilloscopes of different types through switching of a switch routing structure, and self-calibration real-time correction is needed to be carried out respectively aiming at different magnitude points of each model due to the difference of the calibrating points of the oscilloscopes of different types. Aiming at different channels of the same oscilloscope model, according to the design principle of a switch topological structure, the switch topological structure of each channel of each oscilloscope unit is completely the same and is only relevant to the current environment, so that a single channel is calibrated in real time each time.
Firstly, according to the on-demand calibration requirement of an oscilloscope array, counting the DC signal points used by all oscilloscope models in the oscilloscope array by using the DC gain and DC bias of a calibration project of the DC signal, determining the DC voltage points to be calibrated, and creating a corresponding calibration point database;
secondly, before the on-site calibration of the oscilloscope array is carried out each time, connecting a direct current signal output end of a calibrating device to a voltage measuring end of a calibrating device meter module through a 50 omega load, and carrying out self-calibration hardware connection; according to the model of the oscilloscope to be calibrated, a corresponding calibration point database file is called; opening self-calibration software, controlling a power panel card and a corresponding switch route, measuring the voltage of a signal output end, compensating a direct current signal by using a calibration formula, measuring the signal again after compensation, determining that the signal meets the technical index requirement of the direct current signal, and storing the correction value to a database;
and finally, opening digital oscilloscope array calibration software, calling a correction value database file, and calibrating oscilloscope direct current gain and direct current bias items by using the correction value of the direct current signal in the database file to realize real-time correction and on-demand calibration.
As shown in fig. 6, the results of the verification of the CH 1-CH 4 dc signals of the oscilloscope unit 1 are shown, the black solid line represents the relative error of each amplitude of the dc signal after the correction value is adopted, and the red dotted line represents the maximum allowable error curve, and as can be seen from the figure, when 50Ω is loaded, the errors of each point are all within the maximum allowable error range within the range of the amplitude± (3 mV-3V).
As shown in fig. 7 and 8, the influence of the switching cable on the attenuation of the stable sine wave signal and the accuracy of resistance measurement can be corrected by adopting a pre-correction method.
After the amplitude-stabilized sine wave signal is sent out by the amplitude-stabilized sine wave module, the amplitude-stabilized sine wave signal reaches the digital oscilloscope unit for calibration through the cable and the switch topological structure. In the process, the signal amplitude is attenuated due to the influence of the cable and the switch topological structure, so that the stable amplitude sine wave signal index reaching the oscilloscope unit is influenced, and the attenuation of signals with the same amplitude and different frequencies is different. Therefore, the method and the device for researching the signal attenuation rule of the amplitude-stabilized sine wave module of the oscilloscope array calibration device have important significance in adjusting the output signal of the amplitude-stabilized sine wave module and enabling the input signal of the oscilloscope unit to meet the technical index requirement.
The cable and the switch topological structure are regarded as a whole, and because the signal attenuation from the signal output end of the amplitude-stabilized sine wave module to the two ends of the input end of the oscilloscope unit is kept stable in the actual calibration process, the attenuation can be measured in advance through the network analyzer, and the signal output amplitude of the amplitude-stabilized sine wave module is pre-compensated. The calibration thought is as follows: the method comprises the steps of obtaining stable amplitude sine wave power of an output end of a stable amplitude sine wave module under different frequencies and voltage amplitudes by using a power meter, obtaining the attenuation of a switch topological structure and a cable by using a network analyzer, and comparing the obtained signal with the amplitude and power of a reference point to obtain corrected stable amplitude sine wave module signals under different frequencies, and finally outputting the amplitude.
In the oscilloscope array calibration device, two paths of stable amplitude sine wave signals which are output in parallel are respectively compensated and corrected. Determining amplitude values of calibration points of the amplitude-stabilized sine wave according to the calibration and point selection requirements of the oscilloscopes, calibrating signal output ends of two paths of amplitude-stabilized sine wave modules which are output in parallel one by using a power meter, and sequentially obtaining output power of the amplitude-stabilized sine wave modules, wherein the data are shown in the following tables 1 and 2;
TABLE 1 first path constant amplitude sine wave signal output power
Table 2, second-path amplitude-stabilized sine wave signal output power
The attenuation of the cable and the switch topological structure is calibrated by using the network analyzer, one end of the attenuation is connected with the output end of the amplitude-stabilizing sine wave module, the other end of the attenuation is connected with the input end of the oscilloscope unit, and as the characteristics of the five channel cables and the switch topological structure of each oscilloscope unit are consistent, only one channel is selected for calibration by each oscilloscope unit, and the calibration result is shown in the following table 3.
TABLE 3 oscilloscope cell switches and cable signal attenuation
Through tables 1-3, the magnitude of the signal output amplitude of the two-path parallel amplitude-stabilizing sine wave module can be determined by using the following calculation formula.
Wherein V represents the amplitude of the corrected stable amplitude sine wave, mV; v (V) 0 Representing the amplitude of a stable sine wave of a reference point, and mV; p represents the stable amplitude sine wave power calculated through compensation and correction; p (P) 0 Represents the steady amplitude sine wave power through the reference point, dBm.
And verifying the function of outputting the stable-amplitude sine wave signal by the system, wherein the verification index is the flatness of the stable-amplitude sine wave signal. And (3) measuring the stable amplitude sine wave signal power of the output end of the calibrating device by using an Agilent E9304A power meter as a standard. The oscilloscope units 1, 3 and 4 adopt a first amplitude-stabilizing sine wave output module, and the oscilloscope units 2 and 5 adopt a second amplitude-stabilizing sine wave output module. The oscilloscope unit 1 is taken as an example for verification, and other oscilloscope units are similar.
As shown in FIG. 9, the solid line represents CH 1-CH 5 channels of the oscilloscope unit 1, the flatness error measured by the power meter is utilized within the range of 50 MHz-1 GHz and the range of 5 mV-5V, and the red dotted line represents the corresponding maximum allowable error, and as can be seen in the figure, each flatness error is between (-0.5) dB, thereby meeting the requirements of the technical protocol.
As shown in fig. 10, the overall calibration method of the calibration device of the present invention is: in the preparation stage, firstly, self-calibration is carried out on a direct-current output signal of the calibrating device (the influence of a signal switch array, a long cable and the like is corrected), and then 25 output channels of the calibrating device are sequentially connected to 5 digital oscilloscope units to be calibrated of a digital oscilloscope array. And correspondingly checking according to the position of the unit to be calibrated in the array by pressing the map, searching and returning the IP address of the unit to be calibrated by the program into the database due to the fixed IP address of each unit of the array, inputting the model, the number and other information of the unit to be calibrated together with the information of the user, the temperature, the humidity, the date and the like into the database by the program after the inspection device and each unit are normally communicated, reading the calibration parameters of each calibration unit from the database by the program, and executing the parallel calibration program.
The foregoing is merely a preferred embodiment of the invention, and it is to be understood that the invention is not limited to the form disclosed herein but is not to be construed as excluding other embodiments, but is capable of numerous other combinations, modifications and environments and is capable of modifications within the scope of the inventive concept, either as taught or as a matter of routine skill or knowledge in the relevant art. And that modifications and variations which do not depart from the spirit and scope of the invention are intended to be within the scope of the appended claims.
Claims (5)
1. A calibration system for implementing digital oscilloscope array parallelism, characterized in that: the device comprises a signal source group output module, a resistance measurement module, a switch topological structure and a control device;
the signal source group output module is used for outputting a stable amplitude sine wave signal, a time scale signal, a fast edge signal and a direct current voltage signal, and reaches a case signal output end through a cable and the switch topological structure;
the resistance measurement module is used for measuring resistance, calibrating the input resistance of the digital oscilloscope and achieving a chassis signal output end through a cable and the switch topological structure;
the control device is internally provided with parallel self-calibration software, so that each module and the calibrated oscilloscope are controlled, and the parallel calibration software is operated on a display to finish the parallel on-demand calibration of the digital oscilloscope array;
all modules are integrated in a three-layer structure in a chassis, the signal source group output module is placed on the upper layer, the middle layer is a PXIe chassis, a direct current card, a radio frequency switch card, a resistance measurement module and a control device are inserted in the chassis, the power supply module is placed on the lower layer, the switch topology structure comprises 5 radio frequency switch cards, the PXIe chassis adopts a PXI and PXIe mixed bus backboard, the resistance measurement module controls through a PXI bus interface, the direct current card sends out direct current voltage signals, and the direct current voltage signals are transmitted to each channel of an oscilloscope unit through the switch topology structure and a cable;
according to the principle of division-total-division, the routing circuit of the signal source group utilizes 15 radio frequency switches in total of 5 radio frequency switch cards to realize the free connection of the sine wave signal, the time mark signal, the fast edge signal, the direct current voltage signal and the resistance measurement signal with all channels of the calibrated oscilloscope in three stages;
the free connection of the sine wave signal, the time scale signal, the fast edge signal, the direct current voltage signal and the resistance measurement signal and all channels of the calibrated oscilloscope is realized by three stages, and the free connection comprises the following steps:
the fast edge signal, the time scale signal, the two paths of sine signals and the resistance measurement signal are respectively output to the second-stage radio frequency switch through split switching of the first-stage radio frequency switch;
the second-stage radio frequency switch gathers various signals split by the first-stage radio frequency switch on one switch, so that each second-stage radio frequency switch can output the sine wave signal, the time mark signal, the fast edge signal, the direct current voltage signal and the resistance measurement signal; the direct-current voltage signal has a five-path parallel output function, so that the metering efficiency of the direct-current gain and direct-current bias calibration project of the digital oscilloscope is greatly improved;
and the third-stage radio frequency switch sequentially and correspondingly inputs the collected signals to all channels of the oscillograph, so that each oscillograph channel has the input functions of the sine wave signal, the time mark signal, the fast edge signal, the direct-current voltage signal and the resistance measurement signal, and the calibration of the oscillograph is completed.
2. A calibration system for implementing digital oscilloscope array parallelism according to claim 1, wherein: the signal source group output module comprises a direct current unit, a time scale unit, a stable amplitude sine wave unit and a fast edge pulse unit;
the direct current unit is controlled through the PXIe bus interface, achieves the function of five paths of parallel output direct current voltage signals, and provides direct current voltage signals for calibrating direct current bias and direct current gain of the digital oscilloscope;
the time scale unit realizes the function of outputting time scale signals in a single way and is used for calibrating the time reference of the digital oscilloscope;
the amplitude-stabilizing sine wave unit realizes the function of outputting amplitude-stabilizing sine waves in two paths in parallel and is used for calibrating the frequency bandwidth and the triggering sensitivity of the digital oscilloscope;
the fast edge pulse unit realizes the function of outputting fast edge signals in a single way and is used for calibrating the rising time of the digital oscilloscope.
3. A calibration system for implementing digital oscilloscope array parallelism according to claim 1 or 2, wherein: and correcting the influence of the direct-current voltage signal caused by environmental change by adopting a real-time correction method, and correcting the influence of the switch cable on the stable-amplitude sine wave signal attenuation and resistance measurement accuracy by adopting a pre-correction method.
4. A calibration system for implementing digital oscilloscope array parallelism according to claim 3, wherein: the method for correcting the influence of the direct current voltage signal caused by environmental change by adopting the real-time correction method comprises the following steps:
according to the on-demand calibration requirement of the oscilloscope array, the DC gain and DC bias are realized for the calibration project using the DC voltage signal, statistics is carried out on the DC voltage signals used by all digital oscilloscope models in the digital oscilloscope array, the DC voltage point to be calibrated is determined, and a corresponding calibration point database is created;
before calibrating the oscilloscope array each time, connecting a direct-current voltage signal output end of a calibration system to a voltage measurement end of a digital meter module of the calibration system through a 50 omega load, and performing self-calibration hardware connection; according to the model of the oscilloscope to be calibrated, a corresponding calibration point database file is called, parallel self-calibration software is opened to control a power supply board and a switch route of a switch topological structure to measure the voltage of a direct-current voltage signal output end, a calibration formula is used for compensating the direct-current voltage signal, the compensated signal is measured again, and the correction value is stored in the calibration point database until the signal meets the index requirement of the direct-current voltage signal;
and opening parallel self-calibration software to call a correction value database file, and calibrating direct-current gain and direct-current bias items of the digital oscilloscope by using the correction value of the direct-current voltage signal in the database file to realize real-time correction and on-demand calibration.
5. A calibration system for implementing digital oscilloscope array parallelism according to claim 3, wherein: the correcting the influence of the switch cable on the stable amplitude sine wave signal attenuation and the resistance measurement accuracy by adopting the pre-correction method comprises the following steps:
the method for correcting the stable amplitude sine wave power comprises the following steps: the method comprises the steps of obtaining stable amplitude sine wave power of output ends of a stable amplitude sine wave unit under different frequencies and voltage amplitudes by using a power meter, comparing the amplitude and the power of a reference point after obtaining a switch topological structure and the attenuation of a cable by using a network analyzer, obtaining final amplitude signals output by the stable amplitude sine wave unit after correction under different frequencies, determining stable amplitude sine wave calibration point amplitude according to digital oscilloscope calibration point selection requirements, calibrating signal output ends of two paths of stable amplitude sine wave units which are output in parallel one by using the power meter, and sequentially obtaining output power of the stable amplitude sine wave unit;
the correction method of the DC resistance measurement accuracy comprises the following steps: selecting standard resistors with known indexes and resistance values, and measuring the resistance values of the standard resistors after passing through the cable and switch topological structure by using a resistor measuring board card; comparing the reading of the board card with the standard resistance value to obtain an interface end resistance measurement correction value after passing through a switch topological structure; because the correction value is determined, the influence quantity is pre-corrected in a programming mode, and the direct current resistance measurement function is ensured to meet the requirements of technical indexes.
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