CN113126014A - Calibration system for realizing array parallelism of digital oscilloscope - Google Patents
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Abstract
The invention relates to a calibration system for realizing the array parallelism of a digital oscilloscope, which comprises a signal source group output module, a resistance measurement module, a switch topological structure and a control device, wherein the signal source group output module is connected with the resistance measurement module; the signal source group output module is used for outputting four signals and reaching a signal output end of the case through a cable and the switch topological structure; the resistance measurement module is used for measuring resistance, calibrating input resistance of the digital oscilloscope and reaching a signal output end of the case through the cable and the switch topological structure; parallel calibration software is arranged in the control device, so that each module and the calibrated oscilloscope are controlled, and the parallel calibration software is operated on the display to complete parallel on-demand calibration of the digital oscilloscope array. The invention can realize the parallel calibration function of 25 oscilloscope channels in total of five digital oscilloscopes, the hardware has four basic signal output modules and resistance measurement functions, and the free switching between a signal source group and an oscilloscope 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 a most widely applied time domain measuring instrument, and in some large physical diagnosis platforms or large comprehensive test control platforms, four acquisition channels of the digital oscilloscope usually cannot meet the test requirements, so that tens of hundreds of digital oscilloscopes form a digital oscilloscope array test system through a local area network, direct or indirect multichannel accurate measurement of numerous electrical parameters and physical parameters of a large test device is completed, and reliable and necessary bases are provided for development, performance determination and experimental debugging of the device.
In the aspect of a metering standard device of a digital oscilloscope, from the aspect of project integrity, the conventional metering device can basically complete the whole project metering of the digital oscilloscope within a certain bandwidth range (20GHz), but all the conventional metering devices adopt a single channel-by-channel mode, namely a serial and single-path working mode. The metering device can be composed of a plurality of discrete devices with different signal output functions, or can be composed of a single or a small number of comprehensive multifunctional calibration devices with higher integration level, the latter is the first choice from the viewpoints of standard configuration cost, use convenience and metering development trend, and the main foreign products comprise multifunctional calibrators such as 5820A and 9500 of the FULKE company in America, and plug-in type or multifunctional integrated calibration devices such as TM504 and CG5011 of the TAKE company in America in the early period; the domestic main products comprise NF4608A, NF4609A and the like of Jiangsu Nanfeng company, SO3, SO6, NH4602 (programmable) and the like of China Naghua factories, and POC-2 (programmable) multifunctional calibrator developed by China metropolis Hua electric company.
At present, a 9500 multifunctional calibrator produced by the FULKE company in America is multifunctional calibration equipment with the highest index and the most complete functions in the world at present, is multifunctional calibration equipment with higher integration level, can conveniently finish the calibration of a digital oscilloscope with the bandwidth of below 6.4GHz by matching a single device with different active probes, 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 its 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 by one-by-one metering of single channels, which has become a bottleneck problem of further improving the metering efficiency of multi-channel data acquisition equipment, and the calibration capability and efficiency of 9500 appear to be weak for digital oscilloscope arrays with hundreds to thousands of acquisition channels.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, provides a calibration system for realizing the array parallelism of a digital oscilloscope, and solves the defects of the prior calibration equipment.
The purpose of the invention is realized by the following technical scheme: a calibration system for realizing the array parallelism of a 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 constant-amplitude sine wave signal, a time scale signal, a fast edge signal and a direct-current voltage signal and reaching a case signal output end through a cable and the switch topological structure;
the resistance measurement module is used for measuring resistance, calibrating input resistance of the digital oscilloscope and reaching a signal output end of the case through the cable and the switch topological structure;
parallel calibration software is arranged in the control device, so that each module and the calibrated digital oscilloscope are controlled, and the parallel calibration software is operated on the display to complete parallel on-demand calibration of the digital oscilloscope array.
The signal source group output module comprises a direct current unit, a time scale unit, an amplitude-stabilized sine wave unit and a fast edge pulse unit;
the direct current unit is controlled through a PXIe bus interface, the function of outputting direct current voltage signals in parallel in five paths is realized, and the direct current voltage signals are provided for calibrating direct current bias and direct current gain of the digital oscilloscope;
the time scale unit realizes the function of outputting a time scale signal in a single path and is used for calibrating the time reference of the digital oscilloscope;
the amplitude-stabilized sine wave unit realizes the function of outputting two paths of amplitude-stabilized sine waves in parallel and is used for calibrating the frequency bandwidth and the trigger sensitivity of the digital oscilloscope;
the fast edge pulse unit realizes the function of outputting a fast edge signal in a single path and is used for calibrating the rising time of the digital oscilloscope.
All modules are integrated in a three-layer structure in a case, the signal source group output module is arranged on the upper layer, the PXIe cage is arranged on the middle layer, a direct current card, a radio frequency switch card, a resistance measurement module and a control device are inserted into the cage, and a power supply module is arranged on the lower layer
And (3) utilizing 15 radio frequency switches of 3 radio frequency switch cards according to a division-total-division principle to realize 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 unit and each channel of the calibrated digital oscilloscope in three stages.
The freely connecting the sine wave signal, the time scale signal, the fast edge signal, the direct current voltage signal and the resistance measuring unit with each channel of the calibrated oscilloscope by three stages comprises the following steps:
the fast edge signal, the time scale signal and the two paths of sine signals are respectively output to a second-stage radio frequency switch by splitting and switching a first-stage radio frequency switch; the second-stage radio frequency switches collect various signals split by the first-stage radio frequency switches to one switch, so that each second-stage radio frequency switch can output the sine wave signal, the time scale 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 each channel of the oscilloscope, so that each oscilloscope channel has the input functions of the sine wave signal, the time scale signal, the fast edge signal, the direct current voltage signal and the resistance measurement unit, and the calibration of the digital oscilloscope 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 switching cable on the attenuation of the constant-amplitude sine wave signal and the resistance measurement accuracy by adopting a pre-correction method.
The method for correcting the influence of the direct-current voltage signal caused by the environmental change by adopting the real-time correction comprises the following steps:
according to the requirement of the oscilloscope array for calibration according to the requirement, realizing direct current gain and direct current bias on the calibration item using the direct current voltage signal, counting the direct current voltage signals used by all oscilloscope models in the digital oscilloscope array, determining a direct current voltage point to be calibrated, and establishing a corresponding calibration point database;
before the oscilloscope array is calibrated each time, connecting a direct-current voltage signal output end of a calibration system to a voltage measuring 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, calling a corresponding calibration point database file, opening a parallel self-calibration software to control a power supply board card and a switch route of a switch topological structure to measure the voltage of a direct-current voltage signal output end, compensating the direct-current voltage signal through a calibration formula, re-measuring the compensated signal, and storing the correction value into a calibration point database after the signal meets the index requirement of the direct-current voltage signal;
and opening a parallel self-calibration software calling correction value database file, and correcting direct current gain and direct current offset items of the 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.
The method for correcting the influence of the switching cable on the attenuation of the constant-amplitude sine wave signal and the resistance measurement accuracy by adopting the pre-correction method comprises the following steps:
the method for correcting the power of the constant-amplitude sine wave comprises the following steps: acquiring the power of the output end of the constant-amplitude sine wave unit under different frequencies and voltage amplitudes by using a power meter, acquiring the attenuation of a switch topological structure and a cable by using a network analyzer, and comparing the attenuation with the amplitude and the power of a reference point to obtain a final amplitude signal output by the constant-amplitude sine wave unit after correction under different frequencies;
and determining the amplitude of a stable-amplitude sine wave calibration point according to the calibration point selection requirement of the digital oscilloscope, and respectively calibrating the signal output ends of the two paths of the stable-amplitude sine wave units which are output in parallel one by one through a power meter to sequentially obtain the output power of the stable-amplitude sine wave units.
The correction method for the direct current resistance measurement accuracy comprises the following steps: selecting a standard resistor with known indexes and resistance values, and measuring the resistance value of the standard resistor after passing through a cable and switch topological structure by using a resistor measuring board card; comparing the reading of the board card with the resistance of a standard resistor to obtain a resistance measurement correction value of an interface end 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 the parallelism of a digital oscilloscope array can realize the parallel calibration function of 25 oscilloscope channels in total of five oscilloscopes, hardware has four basic signal output modules and a resistance measurement function, and free switching of a signal source group and an oscilloscope group is realized by switching a route switch. Because the number of calibration points of the direct current gain and the direct current offset is more, 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 and field movement, strong pertinence of metering guarantee, high metering efficiency and the like.
Drawings
FIG. 1 is a flowchart of a time base calibration procedure;
FIG. 2 is a flowchart 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 real-time correction of DC voltage signals;
fig. 6 is a schematic diagram of a calibration result of the dc voltage signal of each channel of the digital oscilloscope unit 1;
FIG. 7 is a schematic diagram of attenuation of a constant amplitude sine wave signal;
FIG. 8 is a schematic diagram of a constant-amplitude sine wave signal correction;
fig. 9 is a schematic diagram of a result of verifying a constant-amplitude sine wave signal of each channel of the digital oscilloscope unit 1;
FIG. 10 is a flowchart of an overall calibration method.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, 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 obvious that the described embodiments are only a part of the embodiments of the present application, and not all the embodiments. The components of embodiments of the present application, generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the detailed description of the embodiments of the present application provided below in connection with the appended drawings is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present application without making any creative effort, shall fall within the protection 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 specifically comprises a power supply, four basic signal output modules of direct-current voltage, time scale, amplitude-stabilized sine wave and fast edge pulse, a resistance measurement module, a switch topological structure, parallel calibration software, a display, a control system and the like which are arranged in a case. The four basic signal and resistance measurement modules reach the signal output end of the case through a cable and a switch topological structure and are connected with the calibrated digital oscilloscope, the control system controls each module and the calibrated digital oscilloscope, and the parallel calibration software is operated on the display to complete the parallel on-demand calibration of the digital oscilloscope array.
The inner part of the case comprises a three-layer structure, and a stable-amplitude sine wave, time scale and fast-edge pulse signal output module is arranged on the upper layer; a PXIe cage is arranged in the middle, and a direct current card, a switch card, a resistance measurement module and a controller are inserted in the cage; a power supply module is arranged on 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 PXIe cage adopts a PXI and PXIe mixed bus backboard, is compatible with standard PXI and PXIe modules, and integrates and controls five direct current cards, five radio frequency switch cards, one meter card and one zero slot controller system. The zero-slot controller controls the board card in the PXIe cage, controls and communicates the external fixed-amplitude sine wave module, the time scale module and the fast edge pulse module by using a USB (universal serial bus) and a serial port, controls the calibrated digital oscilloscope by using a network port, and provides a hardware platform for compiling parallel calibration software. The power supply module supplies power for a PXIe cage and a constant-amplitude sine wave and fast-edge pulse module, and has 3.3V, 5V, 12V and 15V voltage output ends, the maximum total power is 750W, the voltage regulation rate is less than or equal to 0.1 percent, and the load regulation rate is less than or equal to 3 percent. The signal output end is a double-end SMA stainless steel seat, one end of which is connected with a microwave switch card in the case, and the other end of which is fixed on the back of the case. The arrangement structure is a 5 x 5 matrix, each column corresponds to 5 oscilloscopes to be calibrated, and each row corresponds to 5 channels of the oscilloscopes. The heat radiation fan is used for controlling the temperature inside the case, and 2 groups of 4 fans are arranged at two ends of the cage, so that the heat radiation efficiency inside the cage 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-stabilized sine wave module has two parallel output functions of amplitude-stabilized sine waves, the controller controls through the USB for calibrating the frequency bandwidth and trigger sensitivity items of the digital oscilloscope, and the frequency range is as follows: 900 kHz-1.1 GHz, amplitude range is: 5mVp-p to 5 Vp-p. The time scale module has the function of outputting a time scale signal in a single path, and the controller controls the time scale module through a serial port and is used for calibrating a time base project of the digital oscilloscope, wherein the time scale module comprises the following steps: 1 mus-1 s, maximum allowable error: 2.5X 10-7. When the time base calibration of the digital oscilloscope is carried out, parallel calibration software is operated to read calibration points in an on-demand calibration database, a time scale module is controlled to send out corresponding periodic signals, then the signals are input into corresponding digital oscilloscope calibration channels through a switch routing structure in the control chart 3, and display readings on the digital oscilloscope are read to finish the calibration;
as shown in fig. 2, the fast edge pulse module has a function of outputting a fast edge signal in a single path, and the controller performs control through a serial port, and is used for calibrating a rise time item of the digital oscilloscope, wherein the range of the amplitude is as follows: 6 mV-3V, rise time: not greater than 120 ps; overshoot: not more than 20%. When the rise time item is calibrated, firstly, running parallel calibration software to read a calibration amplitude point in a calibration on-demand database, controlling a fast edge module to sequentially send a fast edge signal, then controlling a switch routing structure in fig. 1 to input the signal into a corresponding digital oscilloscope calibration channel, and reading a display reading on the digital oscilloscope to finish calibration;
the resistance measurement module is controlled through a PXI bus interface, has a resistance measurement function, calibrates the input resistance of the digital oscilloscope, and has the maximum allowable error: plus or minus 0.3 percent. The direct current module is controlled through a PXIe bus interface, has a 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, wherein the direct current voltage range is as follows: 0V-200V, 600mV range, error limit: + (0.020% reading +50 μ V).
As shown in fig. 3, the routing circuit of the signal source group is designed according to the principle of division-total-division, and free connection between 5 signals and each channel of the calibrated oscilloscope is realized in three stages by using 15 radio frequency switches of five radio frequency switch cards. 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 measurement 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 collects various signals split by the first-stage switch to one switch, namely each second-stage radio frequency switch has an output function of five signals; and the third-stage radio frequency switch sequentially corresponds the collected signals to each channel of the oscilloscope, so that each oscilloscope channel has the input function of five signals, and the oscilloscope is calibrated.
As shown in fig. 4, the influence of the environmental change on the dc small-voltage signal can be corrected by using the real-time correction method.
The direct current voltage signal is sent by the direct current integrated circuit board, passes through the switch topological structure and each passageway of cable to oscilloscope unit, because the influence of switch topological structure and cable resistance, the signal can appear attenuating. When the input resistance of the oscilloscope is 1M omega, the influence quantity is small and can be ignored, and when the input resistance of the oscilloscope is 50 omega 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 50 Ω, the direct-current voltage passes through the switch topology structure and the signal attenuation rule behind the cable, and the attenuation signal is corrected, so that the direct-current voltage signal at the signal output end of the calibration device is finally ensured to meet the technical index requirement.
The direct current voltage is freely switched from the direct current power supply board card to the switch topological structure through the cable 1, and then is transmitted to each channel of the oscilloscope unit through the cable 2 from the switch topological structure. Therefore, the dc voltage signal attenuation mainly includes three parts, which are two-section cable attenuation and switch attenuation, respectively. In the experimental process, it is found that the small voltage signal (such as 3mV) has a large influence along with the environmental change signal, and the requirement of the experimental field environment cannot be completely met by directly adopting a pre-correction mode, but the attenuation amount of the small voltage signal is determined 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 idea of the real-time correction method is: the calibration device outputs a plurality of direct current voltage signals to the calibrated oscilloscope through the switch topological structure and the cable, before calibration is carried out, the voltage measurement reaching the port of the oscilloscope is carried out by utilizing the high-accuracy voltage measurement function of the digital meter module of the calibration device, the value is taken as an accurate direct current voltage value, and the method has the advantage of considering the difference caused by cable replacement every time. The calibration device can realize the parallel calibration of five oscilloscopes with different models by switching the switch routing structure, and self-calibration real-time correction needs to be respectively carried out on different magnitude points of each model due to the difference of calibration points of the oscilloscopes with different models. Aiming at different channels of the same oscilloscope model, according to the design principle of the switch topological structure, the switch topological structure passed by each channel of each oscilloscope unit is completely the same and only related to the current environment, so that the single channel is calibrated in real time each time.
Firstly, according to the requirement of the oscilloscope array for on-demand calibration, counting the direct current gain and direct current offset of a calibration item using a direct current signal, and direct current signal points used by all oscilloscope models in the oscilloscope array, determining a direct current voltage point to be calibrated, and establishing a corresponding calibration point database;
secondly, before the oscilloscope array is calibrated on site each time, connecting a direct-current signal output end of the calibration device to a voltage measuring end of a digital meter module of the calibration device through a 50 omega load, and performing self-calibration hardware connection; calling a corresponding calibration point database file according to the model of the oscilloscope to be calibrated; opening self-calibration software, controlling a power supply board 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 a 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 offset 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 CH 1-CH 4 dc signals of the oscilloscope unit 1 are verified, the black solid line represents the relative error of each amplitude of the dc signal after applying the correction value, and the red dotted line represents the maximum allowable error curve, and it can be seen from the graph that, when the load is 50 Ω, the error of each point is within the maximum allowable error range within the range of ± magnitude (3 mV-3V).
As shown in fig. 7 and 8, the influence of the switching cable on the attenuation of the constant-amplitude sine wave signal and the resistance measurement accuracy can be corrected by using the pre-correction method.
After being sent out by the constant-amplitude sine wave module, the constant-amplitude 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 topological structure of the cable and the switch, so that the index of the constant-amplitude sine wave signal reaching the oscilloscope unit is influenced, and the attenuation of the signal with the same amplitude and different frequencies is different. Therefore, the method has important significance for researching the signal attenuation rule of the constant-amplitude sine wave module of the oscilloscope array calibrating device and adjusting the output signal size of the constant-amplitude sine wave module so that the input signal of the oscilloscope unit meets the technical index requirement.
The cable and the switch topological structure are considered as a whole, and the attenuation of signals between the signal output end of the amplitude-stabilized sine wave module and the two ends of the input end of the oscilloscope unit is kept stable in the actual calibration process, so that the attenuation can be measured by a network analyzer in advance, and the signal output amplitude of the amplitude-stabilized sine wave module is pre-compensated. The calibration idea is as follows: the power meter is used for obtaining the power of the stable-amplitude sine wave at the output end of the stable-amplitude sine wave module under different frequencies and voltage amplitudes, the network analyzer is used for obtaining the attenuation of the switch topological structure and the cable, and the attenuation is compared with the amplitude and the power of the reference point, so that the corrected final output amplitude of the signal of the stable-amplitude sine wave module under different frequencies is obtained.
In the oscilloscope array calibrating device, two paths of stable-amplitude sine wave signals which are output in parallel are respectively compensated and corrected. Determining the amplitude of a stable-amplitude sine wave calibration point according to the requirement of oscilloscope calibration point selection, respectively calibrating the signal output ends of two paths of parallel-output stable-amplitude sine wave modules by using a power meter one by one, and sequentially obtaining the output power of the stable-amplitude sine wave modules, wherein the data are shown in the following table 1 and table 2;
TABLE 1 first path of constant amplitude sine wave signal output power
TABLE 2 second path of constant amplitude sine wave signal output power
The attenuation of the cable and the switch topological structure is calibrated by using a network analyzer, one end of the attenuation is connected with the output end of the constant-amplitude sine wave module, the other end of the attenuation is connected with the input end of the oscilloscope unit, and because the characteristics of the cable and the switch topological structure of five channels of each oscilloscope unit are consistent, each oscilloscope unit only selects one channel for calibration, and the calibration result is shown in the following table 3.
TABLE 3 oscilloscope Unit switches and Cable Signal attenuation
Through tables 1-3, the magnitude of the signal output amplitude of the two parallel amplitude-stabilizing sine wave modules can be determined by using the following calculation formulas.
Wherein V represents the amplitude value of the corrected stable-amplitude sine wave, mV; v0Representing the amplitude value of the sine wave with the stable amplitude of the reference point, mV; p represents the power of the sine wave with stable amplitude, dBm, calculated through compensation and correction; p0Representing the power of the constant amplitude sine wave, dBm, through the reference point.
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. An Agilent E9304A power meter is selected as a standard to measure the power of the constant-amplitude sine wave signal at the output end of the calibration device. The oscilloscope units 1, 3 and 4 adopt a first fixed-amplitude sine wave output module, and the oscilloscope units 2 and 5 adopt a second fixed-amplitude 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 the CH 1-CH 5 channels of the oscilloscope unit 1, the flatness error measured by the power meter is within the range of frequency 50 MHz-1 GHz and amplitude 5 mV-5V, the red dotted line represents the corresponding maximum allowable error, and as can be seen from the figure, each flatness error is (-0.5) dB, and the requirements of the technical protocol are met.
As shown in fig. 10, the overall calibration method of the calibration device of the present invention comprises: in the preparation stage, firstly, self-calibration is performed on the direct current output signal of the calibration device (influences of a signal switch array, a long cable and the like are corrected), and then, 25 output channels of the calibration device are sequentially connected to 5 digital oscilloscope units to be calibrated of the digital oscilloscope array. And (3) according to the position of the unit to be calibrated in the array, pressing a diagram to perform corresponding check, because the IP address of each unit in the array is fixed, searching and returning the IP address of the unit to be calibrated by a program in a database, after the checking device and each unit are normally communicated, reading information such as the model, the number and the like of the unit to be calibrated by the program, inputting the information into the database together with information such as a user, temperature and humidity, date and the like, then reading the calibration parameters of each calibration unit from the database by the program, and executing a parallel calibration program.
The foregoing is illustrative of the preferred embodiments of this invention, and it is to be understood that the invention is not limited to the precise form disclosed herein and that various other combinations, modifications, and environments may be resorted to, falling within the scope of the concept as disclosed herein, either as described above or as apparent to those skilled in the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (8)
1. A calibration system for realizing the parallelism of a digital oscilloscope array is characterized in that: the device comprises a signal source group output module, a resistance measuring module, a switch topological structure and a control device;
the signal source group output module is used for outputting a constant-amplitude sine wave signal, a time scale signal, a fast edge signal and a direct-current voltage signal and reaching a case signal output end through a cable and the switch topological structure;
the resistance measurement module is used for measuring resistance, calibrating input resistance of the digital oscilloscope and reaching a signal output end of the case through the cable and the switch topological structure;
parallel self-calibration software is arranged in the control device, so that each module and the calibrated oscilloscope are controlled, and the parallel calibration software is operated on the display to complete the parallel on-demand calibration of the digital oscilloscope array.
2. The system for realizing the calibration of the digital oscilloscope arrays according to claim 1, wherein: the signal source group output module comprises a direct current unit, a time scale unit, an amplitude-stabilized sine wave unit and a fast edge pulse unit;
the direct current unit is controlled through a PXIe bus interface, the function of outputting direct current voltage signals in parallel in five paths is realized, and the direct current voltage signals are provided for calibrating direct current bias and direct current gain of the digital oscilloscope;
the time scale unit realizes the function of outputting a time scale signal in a single path and is used for calibrating the time reference of the digital oscilloscope;
the amplitude-stabilized sine wave unit realizes the function of outputting two paths of amplitude-stabilized sine waves in parallel and is used for calibrating the frequency bandwidth and the trigger sensitivity of the digital oscilloscope;
the fast edge pulse unit realizes the function of outputting a fast edge signal in a single path and is used for calibrating the rising time of the digital oscilloscope.
3. The system for realizing the calibration of the digital oscilloscope arrays according to claim 1, wherein: all modules are integrated in a three-layer structure in a case, the signal source group output module is arranged on the upper layer, the PXIe cage is arranged on the middle layer, a direct current card, a radio frequency switch card, a resistance measurement module and a control device are inserted into the cage, and a power supply module is arranged on the lower layer.
4. The system of claim 3, wherein the system comprises: and (3) according to a division-total-division principle, utilizing 5 radio frequency switch cards to totally realize 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 with each channel of the calibrated oscilloscope in three stages by utilizing 15 radio frequency switches.
5. The system of claim 4, wherein the system comprises: the freely connecting the sine wave signal, the time scale signal, the fast edge signal, the direct current voltage signal and the resistance measurement signal with each channel of the calibrated oscilloscope by three stages comprises the following steps:
the fast edge signal, the time scale signal, the two paths of sinusoidal signals and the resistance measuring unit are respectively output to a second-stage radio frequency switch by splitting and switching a first-stage radio frequency switch;
the second-stage radio frequency switches gather various signals split by the first-stage radio frequency switches to one switch, and each second-stage radio frequency switch can output the sine wave signal, the time scale signal, the fast edge signal, the direct-current voltage signal and the resistance measuring unit; the direct-current voltage signal has a five-path parallel output function, so that the metering efficiency of a direct-current gain and direct-current offset calibration project of the digital oscilloscope is greatly improved;
and the third-stage radio frequency switch sequentially and correspondingly inputs the collected signals to each channel of the oscilloscope, so that each oscilloscope channel has the input functions of the sine wave signal, the time scale signal, the fast edge signal, the direct current voltage signal and the resistance measuring unit, and the oscilloscope is calibrated.
6. A calibration system for implementing parallelism of a digital oscilloscope array according to any one of claims 1 to 5, 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 switching cable on the attenuation of the constant-amplitude sine wave signal and the resistance measurement accuracy by adopting a pre-correction method.
7. The system of claim 6, wherein the system comprises: the method for correcting the influence of the direct-current voltage signal caused by the environmental change by adopting the real-time correction comprises the following steps:
according to the requirement of the oscilloscope array for calibration according to the requirement, realizing direct current gain and direct current offset for the calibration item using the direct current voltage signal, counting the direct current voltage signals used by all digital oscilloscope models in the digital oscilloscope array, determining a direct current voltage point to be calibrated, and establishing a corresponding calibration point database;
before the oscilloscope array is calibrated each time, connecting a direct-current voltage signal output end of a calibration system to a voltage measuring 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, calling a corresponding calibration point database file, opening a parallel self-calibration software to control a power supply board card and a switch route of a switch topological structure to measure the voltage of a direct-current voltage signal output end, compensating the direct-current voltage signal through a calibration formula, re-measuring the compensated signal, and storing the correction value into a calibration point database after the signal meets the index requirement of the direct-current voltage signal;
and opening a parallel self-calibration software to call a correction value database file, and calibrating the direct current gain and direct current offset 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.
8. The system of claim 6, wherein the system comprises: the method for correcting the influence of the switching cable on the attenuation of the constant-amplitude sine wave signal and the resistance measurement accuracy by adopting the pre-correction method comprises the following steps:
the method for correcting the power of the constant-amplitude sine wave comprises the following steps: acquiring the power of the stable sine wave at the output end of the stable sine wave unit under different frequencies and voltage amplitudes by using a power meter, comparing the attenuation of a switch topological structure and a cable acquired by a network analyzer with the amplitude and the power of a reference point, determining the amplitude of a stable sine wave calibration point according to the calibration point selection requirement of a digital oscilloscope after acquiring the final amplitude signal output by the stable sine wave unit under different frequencies and correcting the signal output ends of the two paths of stable sine wave units which are output in parallel one by one through the power meter, and sequentially acquiring the output power of the stable sine wave units;
the correction method for the direct current resistance measurement accuracy comprises the following steps: selecting a standard resistor with known indexes and resistance values, and measuring the resistance value of the standard resistor after passing through a cable and switch topological structure by using a resistor measuring board card; comparing the reading of the board card with the resistance of a standard resistor to obtain a resistance measurement correction value of an interface end 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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