CN114047369B - Digital oscilloscope and digital channel correction method for digital oscilloscope - Google Patents
Digital oscilloscope and digital channel correction method for digital oscilloscope Download PDFInfo
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Abstract
The application discloses a digital channel correction method for a digital oscilloscope and the digital oscilloscope, wherein the method comprises the steps of firstly, performing zero level correction on a comparator of each digital channel to obtain zero level flip voltage of the digital channel; then acquiring respective analog trigger compensation time of each digital channel when the digital channel is at an analog channel trigger source; then obtaining the digital trigger compensation time of each digital channel when the digital channel is used as a trigger source; and finally, acquiring the mixed trigger compensation time of each digital channel when the analog channel and the digital channel are in mixed trigger, and acquiring the mixed trigger correction parameters when the analog channel and the digital channel are in mixed trigger according to the mixed trigger compensation time. Because the mixed trigger compensation time is obtained according to the time of the first trigger signal of each digital channel during the mixed trigger, the waveform displayed by the digital oscilloscope is only deflected to one direction, and the purpose of stabilizing the waveform is further achieved.
Description
Technical Field
The invention relates to the technical field of electronic instruments, in particular to a digital oscilloscope and a digital channel correction method for the digital oscilloscope.
Background
The digital oscilloscope is an indispensable tool for designing, manufacturing and maintaining electronic equipment, the digital oscilloscope is mainly used at present, the digital oscilloscope is increasingly popularized due to functions of waveform triggering, storing, displaying, measuring, analyzing and the like, and the digital oscilloscope is considered as eyes of engineers as the scientific and market demands are rapidly developed, and the digital oscilloscope is used as a necessary tool for meeting measurement challenges of the engineers. Particularly, in the development process of electronic circuits, an oscilloscope is required to be frequently used for debugging and measuring, the measurement precision is higher and higher, and the performance requirement on the oscilloscope is higher and higher. The trigger system of the digital oscilloscope can stably display repeated periodic signals and can display signals with specific characteristics, and the precision and the flexibility of the trigger system determine whether the digital oscilloscope can accurately display and analyze the measurement signals. The trigger system of the digital oscilloscope comprises two parts of trigger establishment and time measurement. The trigger establishing part comprises four parts of a high-speed comparator, trigger source selection, trigger condition judgment and trigger pulse formation, and is mainly realized by a high-speed analog comparator and a high-speed logic gate circuit. The time measurement is mainly used for measuring the time interval delta t between the sampling point and the trigger point and is realized through a time measurement chip. Inaccuracies in the measurement results of the time measurement chip can cause individual displayed waveforms to shift relative to the trigger point. The random component of the time measurement chip error causes this offset to change on each trigger event, resulting in display waveform trigger jitter. When the oscilloscope is used, the stability of the waveform directly influences the user experience, and the stable waveform is beneficial to the user to observe abnormal signals. How to optimize the trigger system of the oscilloscope is an important subject in the research and development field of the oscilloscope.
Disclosure of Invention
The invention mainly solves the technical problem that the waveform jitter is generated by the deviation of individual display waveforms displayed by an oscilloscope relative to a trigger point.
According to a first aspect, there is provided in one embodiment a method for digital channel correction for a digital oscilloscope, comprising:
performing zero level correction on a comparator of each digital channel to obtain a zero level turnover voltage of the digital channel;
taking an analog channel as a trigger source, correcting the trigger time of the digital channel according to the trigger time of the analog channel to obtain the analog trigger compensation time of each digital channel when the analog channel is triggered, and then obtaining the analog trigger correction parameter of the digital oscilloscope when the analog channel is taken as the trigger source according to the analog trigger compensation time;
taking a digital channel as a trigger source, correcting the digital channel to obtain respective digital trigger compensation time of each digital channel when the digital channel is triggered, and then obtaining digital trigger correction parameters of the digital oscilloscope when the digital channel is taken as the trigger source according to the digital trigger compensation time;
correcting the digital channel by taking the analog channel and the digital channel as a trigger source simultaneously to acquire respective mixed trigger compensation time of each digital channel when the analog channel and the digital channel are in mixed trigger, and acquiring mixed trigger correction parameters of the digital oscilloscope when the analog channel and the digital channel are in mixed trigger according to the mixed trigger compensation time; wherein the hybrid trigger compensation time for each of the digital channels is obtained in accordance with a time at which a first trigger signal for the respective digital channel occurs.
In an embodiment, the zero-level correcting the comparator of each digital channel to obtain the zero-level flip voltage of the digital channel includes:
when the digital oscilloscope has no external signal input, inputting a voltage calibration signal to the negative input end of the comparator of each digital channel; adjusting the voltage of the voltage calibration signal, and recording the voltage value of the voltage calibration signal when the output end of the comparator of each digital channel outputs a first electric signal and a second electric signal;
acquiring a zero level flip level value of each digital channel according to the voltage value of the voltage calibration signal when the output end of the comparator of each digital channel outputs the first electric signal and the second electric signal;
the zero level inversion level value of the digital channel is an average value of the voltage calibration signal when the output end of each comparator outputs the first electric signal and the voltage value of the voltage calibration signal when the output end of each comparator outputs the second electric signal.
In an embodiment, the calibrating the digital channels by using the analog channels as trigger sources to obtain the analog trigger compensation time of each digital channel at the time of triggering the analog channels includes:
inputting an analog trigger calibration signal with known signal parameters to the digital oscilloscope;
inputting the analog trigger calibration signal into the analog channel and the digital channel simultaneously;
taking one digital channel in the digital oscilloscope as a reference calibration channel, taking the trigger time of the analog channel as a reference, and aligning the trigger time of the reference calibration channel with the trigger time of the analog channel;
and acquiring the delay time of the trigger time of each digital channel and the reference calibration channel when the digital channels have different time base values, and taking the delay time as the analog trigger compensation time of the digital channel when the digital channels have different time base values.
In an embodiment, the calibrating the digital channels by using the digital channels as trigger sources to obtain respective digital trigger compensation times of each digital channel at the time of triggering the digital channels includes:
inputting a digital trigger calibration signal with known signal parameters to the digital oscilloscope;
inputting the digital trigger calibration signal into the digital channel;
and taking the triggering time of the reference calibration channel as a reference, acquiring the delay time of each digital channel relative to the triggering time of the reference calibration channel when the digital channel has different base values, and taking the delay time as the digital triggering compensation time of the digital channel when the digital channel has different base values.
In one embodiment, the time base value is not less than 50 ms.
In an embodiment, the calibrating the digital channel by using the analog channel and the digital channel as a trigger source simultaneously to obtain the respective hybrid trigger compensation time of each digital channel when the analog channel and the digital channel are hybrid triggered includes:
inputting a mixed trigger calibration signal with known signal parameters to the digital oscilloscope;
inputting the mixed trigger calibration signal into the analog channel and the digital channel simultaneously;
and taking the triggering time of the reference calibration channel as a reference, acquiring the delay time of the triggering time of each digital channel and the reference calibration channel when the digital channels are at different base values, and acquiring the mixed triggering compensation time of the digital channels when the digital channels are at different base values according to the acquired delay time.
In an embodiment, the obtaining the hybrid trigger compensation time of the digital channel at different time base values according to the obtained delay time includes:
when the delay time is between-200 ps and 200ps, setting the mixed trigger compensation time of the digital channel to be 0 second;
when the delay time is a positive value larger than 1.5ns, setting the mixed trigger compensation time of the digital channel to be 0 second;
and when the delay time is a negative value and the absolute value of the delay time is more than 1.5ns, taking the delay time as the mixed trigger compensation time of the digital channel.
In an embodiment, the acquiring, according to the mixed trigger compensation time, a mixed trigger correction parameter of the digital oscilloscope when the analog channel and the digital channel are mixed and triggered includes:
and recording the mixed trigger compensation time of each digital channel at different time bases to serve as the mixed trigger correction parameter of the digital channel at different time bases.
According to a second aspect, an embodiment provides a digital oscilloscope, which includes a control processor, digital channels and analog channels, wherein the control processor executes to implement the digital channel correction method according to the first aspect, so as to obtain trigger correction parameters of each of the digital channels at the time of analog channel triggering, digital channel triggering and mixed triggering respectively.
According to the digital channel correction method of the embodiment, firstly, zero level correction is carried out on the comparator of each digital channel to obtain zero level turnover voltage of the digital channel; then acquiring respective analog trigger compensation time of each digital channel when the digital channel is at an analog channel trigger source; then obtaining the digital trigger compensation time of each digital channel when the digital channel is used as a trigger source; and finally, acquiring the mixed trigger compensation time of each digital channel when the analog channel and the digital channel are in mixed trigger, and acquiring the mixed trigger correction parameters when the analog channel and the digital channel are in mixed trigger according to the mixed trigger compensation time. Because the mixed trigger compensation time is obtained according to the time of the first trigger signal of each digital channel during the mixed trigger, the waveform displayed by the digital oscilloscope is only deflected to one direction, and the purpose of stabilizing the waveform is further achieved.
Drawings
FIG. 1 is a flow chart illustrating a digital channel calibration method according to an embodiment;
FIG. 2 is a schematic diagram showing the connection of a comparator in the digital oscilloscope according to one embodiment;
FIG. 3 is a schematic diagram of the circuit connections of the comparator in the digital oscilloscope according to one embodiment;
FIG. 4 is a schematic diagram of an embodiment of digital channel calibration triggered by an analog channel;
FIG. 5 is a schematic diagram of an embodiment of digital channel calibration triggered by a digital channel;
FIG. 6 is a schematic diagram illustrating an inversion of the digital channels after alignment in one embodiment;
FIG. 7 is a schematic illustration of the delay formation in one embodiment;
fig. 8 is a schematic diagram of the waveform jitter formation in one embodiment.
Detailed Description
The present invention will be described in further detail with reference to the following detailed description and accompanying drawings. Wherein like elements in different embodiments are numbered with like associated elements. In the following description, numerous details are set forth in order to provide a better understanding of the present application. However, those skilled in the art will readily recognize that some of the features may be omitted or replaced with other elements, materials, methods in different instances. In some instances, certain operations related to the present application have not been shown or described in detail in order to avoid obscuring the core of the present application from excessive description, and it is not necessary for those skilled in the art to describe these operations in detail, so that they may be fully understood from the description in the specification and the general knowledge in the art.
Furthermore, the features, operations, or characteristics described in the specification may be combined in any suitable manner to form various embodiments. Also, the various steps or actions in the method descriptions may be transposed or transposed in order, as will be apparent to one of ordinary skill in the art. Thus, the various sequences in the specification and drawings are for the purpose of describing certain embodiments only and are not intended to imply a required sequence unless otherwise indicated where such sequence must be followed.
The numbering of the components as such, e.g., "first", "second", etc., is used herein only to distinguish the objects as described, and does not have any sequential or technical meaning. The term "connected" and "coupled" when used in this application, unless otherwise indicated, includes both direct and indirect connections (couplings).
High-end oscilloscopes often support mixed triggering, which supports both analog channel triggering and digital channel triggering. In actual measurement, the analog channel and the digital channel are often required to be opened simultaneously, so that the trigger source can select the analog channel or the digital channel, which is called hybrid trigger. Suppose that the analog channel parameter of an oscilloscope is 8bit resolution 4 channel 1G sample rate and the digital channel parameter is 16 channel 500M sample rate. The analog channel triggering means that an external signal is input through an analog channel and is quantized into an 8-bit digital signal by an ADC (analog to digital converter), and the sampled signal is used for subsequent triggering processing; and the digital channel triggering means that an external signal is input through a digital channel, is quantized into a 1-bit signal through a comparator, and the sampled signal is used for subsequent triggering processing. The digital oscilloscope is an accurate test and measurement instrument, the stability of the waveform directly influences the user experience when in use, and the stable waveform is beneficial to the user to observe abnormal signals.
In the digital channel correction method disclosed in the embodiment of the application, firstly, zero level correction is performed on a comparator of each digital channel to obtain zero level flip voltage of the digital channel; then acquiring respective analog trigger compensation time of each digital channel when the digital channel is at an analog channel trigger source; then obtaining the digital trigger compensation time of each digital channel when the digital channel is used as a trigger source; and finally, acquiring the mixed trigger compensation time of each digital channel when the analog channel and the digital channel are in mixed trigger, and acquiring the mixed trigger correction parameters when the analog channel and the digital channel are in mixed trigger according to the mixed trigger compensation time. Because the mixed trigger compensation time is obtained according to the time of the first trigger signal of each digital channel during the mixed trigger, the waveform displayed by the digital oscilloscope is only deflected to one direction, and the purpose of stabilizing the waveform is further achieved.
Example one
Referring to fig. 1, a flow chart of an embodiment of a digital channel calibration method is shown, the digital channel calibration method includes:
And performing zero level correction on the comparator of each digital channel to obtain a zero level reversal voltage of each digital channel. When the digital oscilloscope has no external signal input, inputting a voltage calibration signal to the negative input end of the comparator of each digital channel, adjusting the voltage of the voltage calibration signal, and recording the voltage value of the voltage calibration signal when the output end of the comparator of each digital channel outputs a first electric signal and a second electric signal. And acquiring a zero level flip level value of the digital channel according to the voltage value of the voltage calibration signal when the output end of the comparator of each digital channel outputs the first electric signal and the second electric signal. The zero level inversion level value of the digital channel is an average value of the voltage calibration signal when the output end of each comparator outputs the first electric signal and the voltage value of the voltage calibration signal when the output end of each comparator outputs the second electric signal.
Referring to fig. 2 for performing zero level correction on the comparator, fig. 2 is a schematic connection diagram of the comparator in the digital oscilloscope in an embodiment, the programmable logic device 21 is configured to input a voltage calibration signal to the DAC22, the DAC22 inputs the voltage calibration signal to a negative input terminal of the comparator, the programmable logic device 21 is further configured to record a first electrical signal or a second electrical signal output by an output terminal of the comparator, and the programmable logic device 21 is further configured to adjust a voltage of the voltage calibration signal, so that a signal output by the output terminal of the comparator changes, and record a voltage value of the voltage calibration signal when the signal output by the output terminal of the comparator changes. Referring to fig. 3, which is a schematic diagram illustrating the circuit connections of the comparator in the digital oscilloscope in an embodiment, the digital oscilloscope has four analog channels and sixteen digital channels, and one DAC is used to control the reference levels of the comparator in the eight digital channels, as shown in fig. 3, DAC1 controls channels 1 to 8, and DAC2 controls channels 9 to 16. The specific steps of the zero level correction method for the comparator include:
1) the external input of the digital oscilloscope is cut off, and at the moment, a digital channel of the digital oscilloscope is pulled down to the ground through resistors R1-R16, which is equivalent to inputting a voltage signal of 0V;
2) the output reference voltage of the DAC is adjusted to be 0V by the programmable logic device, and at the moment, the voltage of the positive input end of the comparator is different due to the problems of PCB wiring voltage division, contact resistance voltage division and the like;
3) the programmable logic device reads vout 1-vout 16 output by the output end of the comparator, and judges according to bit that 1 represents that the voltage of the positive input end of the comparator is higher than the DAC output reference voltage, and 0 represents that the voltage of the positive input end of the comparator is lower than the DAC output reference voltage;
4) the programmable logic device continuously adjusts the voltage of the voltage calibration signal input to the DAC, so that vout 1-vout 16 output by the output end of the comparator are all 1, at this time, the DAC1 corresponds to a code word code _ high1, the DAC2 corresponds to a code word code _ high2, and the two code words are recorded;
5) the programmable logic device continuously adjusts the voltage of the voltage calibration signal input into the DAC, so that vout 1-vout 16 output by the output end of the comparator are all 0, at this time, the DAC1 corresponds to a code word code _ low1, the DAC2 corresponds to a code word code _ low2, and the two code words are recorded;
6) the value of the final zero level flip level of DAC1 is:
level1=(code_high1+code_low1)/2；
wherein level1 is the value of the final zero level flip level of DAC1, code _ low1 is the value when the comparator outputs are all 0, and code _ high1 is the value when the comparator outputs are all 1.
By analogy, the final zero level flip level of DAC2 has the value:
level2=(code_high2+code_low2)/2；
wherein level2 is the value of the final zero level flip level of DAC2, code _ low2 is the value when the comparator outputs are all 0, and code _ high2 is the value when the comparator outputs are all 1.
When zero level correction is performed on the comparator according to the method in the prior art, all channels are not inverted in steps 3) and 4), but more than half of the channels are inverted to consider that the voltage calibration signal is effective for all channels, which may cause that the contact resistance of the undetected channels possibly generated due to cold welding or other reasons is very large, so that the inverted level is abnormal, and the abnormal channel cannot be found in time without traversing all the channels during correction.
And step 120, acquiring a simulation trigger correction parameter.
The analog channels are used as trigger sources, the trigger time of the digital channels is corrected according to the trigger time of the analog channels to obtain the analog trigger compensation time of each digital channel when the analog channels are triggered, and then the analog trigger correction parameters of the digital oscilloscope when the analog channels are used as the trigger sources are obtained according to the analog trigger compensation time. The method for acquiring the analog trigger compensation time comprises the following steps:
firstly, inputting an analog trigger calibration signal with known signal parameters into a digital oscilloscope; then, inputting the analog trigger calibration signal into the analog channel and the digital channel simultaneously; taking a digital channel in the digital oscilloscope as a reference calibration channel, taking the trigger time of the analog channel as a reference, and aligning the trigger time of the reference calibration channel with the trigger time of the analog channel; and simultaneously acquiring the delay time of the trigger time of each digital channel and the reference calibration channel when the digital channels have different time base values, and taking the delay time as the analog trigger compensation time of the digital channels when the digital channels have different time base values.
The step is to correct the digital channel by taking the analog channel as a trigger source, and aims to align the digital channel when the analog channel is taken as the trigger source. In an embodiment, first, it is defined that the waveform is biased to a negative value toward the left and biased to a positive value toward the right, please refer to fig. 4, which is a schematic diagram of a digital channel calibration principle triggered by an analog channel in an embodiment, wherein cx1 represents the analog channel, ch1 to ch16 represent the digital channel, and there are various situations in delay of the digital channel when triggered by the analog channel. The step of obtaining the analog trigger compensation time includes,
1. the trigger parameters are configured, and the analog channels and the digital channels input the same analog trigger calibration signal and can be distributed to all the channels by one mother signal. In one embodiment, the analog trigger calibration signal is a square wave signal with the frequency of 10Hz, the amplitude is set according to the gear of an analog channel, the digital oscilloscope selects rising edge trigger according to the principle of being convenient to watch, and the trigger level is 0V;
2. triggering by an analog channel, wherein the rising edge of a square wave of a simulation triggering calibration signal is positioned in the middle of a digital oscilloscope, the rising edge of the digital channel is not aligned with the middle of the oscilloscope due to the problems of probe routing, PCB routing delay and the like, and the delay values of ch 1-ch 16 are recorded at the moment and are respectively expressed as follows:
delay1，delay2，……，delay15，delay16；
and taking the 50ms time base as an upper limit, traversing the minimum storage depth and all time base combinations below 50ms, and recording the delay values of all combinations of all digital channels, wherein the delay of the 1ns time base is expressed as:
1ns=delay1，delay2，……，delay15，delay16；
the delay of a 2ns time base is expressed as:
2ns= delay1，delay2，……，delay15，delay16；
and the other time bases are analogized in turn.
3. All delay records are recorded as a file _ delay 1;
the software of the oscilloscope compensates the delay values at each time base by the values recorded in the file _ delay1 file.
The reason why the 50ms time base is adopted as the upper limit is that the delay of the digital channel is not very large, the delay cannot be seen by naked eyes under the 50ms time base, and each time base is not required to be traversed, so that the correction efficiency is improved.
And correcting the digital channels by taking the digital channels as trigger sources to acquire the digital trigger compensation time of each digital channel when the digital channels are triggered, and acquiring digital trigger correction parameters of the digital oscilloscope when the digital channels are taken as the trigger sources according to the digital trigger compensation time. The method for acquiring the digital trigger compensation time comprises the following steps:
firstly, inputting a digital trigger calibration signal with known signal parameters into a digital oscilloscope; then inputting the digital trigger calibration signal into a digital channel; then, the triggering time of the calibrated reference calibration channel is used as a reference in step 120, and the delay time of each digital channel relative to the triggering time of the reference calibration channel when the digital channel has different base values is obtained and used as the digital triggering compensation time of the digital channel when the digital channel has different base values.
The digital channel is corrected by taking the digital channel as a trigger source, so that the digital channel is aligned when the digital channel is taken as the trigger source. Referring to fig. 5, which is a schematic diagram illustrating a digital channel calibration principle triggered by a digital channel in an embodiment, after step 120, triggers between an analog channel and a digital channel are aligned, in this step, the digital channel is calibrated by using the digital channel as a trigger source, and various delays occur in the remaining digital channels when the digital channel is triggered. The method for acquiring the digital trigger compensation time comprises the following steps:
(1) configuring trigger parameters, inputting the same digital trigger calibration signals into an analog channel and a digital channel, distributing the digital trigger calibration signals to all the channels by a mother signal, setting the digital trigger calibration signals to be square waves with the frequency of 10Hz and the amplitude according to the gear setting of the analog channel, and taking the amplitude as a principle of being convenient to watch, selecting rising edge trigger by a digital oscilloscope, and setting the trigger level to be 0V;
(2) the digital channel ch1 is used as a trigger, the analog channel is not concerned at the moment, then the rising edge of the square wave of the digital trigger calibration signal is positioned in the middle of the oscilloscope, the rising edge of the digital channel is not aligned to the middle of the oscilloscope due to the problems of probe routing, PCB routing delay and the like, and the delay values of ch 1-ch 16 are recorded at the moment and are respectively expressed as:
delay1，delay2，……，delay15，delay16；
and with the 50ms time base as an upper limit, traversing the minimum storage depth and all time base combinations below 50ms, and recording the delay values of all combinations of all digital channels.
The delay of a 1ns time base is expressed as:
1ns=delay1，delay2，……，delay15，delay16；
the delay of a 2ns time base is expressed as:
2ns= delay1，delay2，……，delay15，delay16；
and so on for other time bases.
(3) All delay records are recorded as a file _ delay 2;
the software of the oscilloscope compensates the delay values at each time base by the values recorded in the file _ delay2 file.
The reason why the 50ms time base is adopted as the upper limit is that the delay of the digital channel is not very large, the delay cannot be seen by naked eyes under the 50ms time base, and each time base is not required to be traversed, so that the correction efficiency is improved.
Correcting the digital channel by taking the analog channel and the digital channel as a trigger source simultaneously to acquire respective mixed trigger compensation time of each digital channel when the analog channel and the digital channel are mixed and triggered, and acquiring mixed trigger correction parameters of the digital oscilloscope when the analog channel and the digital channel are mixed and triggered according to the mixed trigger compensation time; the hybrid trigger compensation time for each digital channel is obtained from the time at which the first trigger signal for the respective digital channel occurs. The method for acquiring the hybrid trigger compensation time comprises the following steps:
firstly, inputting a mixed trigger calibration signal with known signal parameters into a digital oscilloscope; then, inputting the mixed trigger calibration signal into an analog channel and a digital channel simultaneously; and then, taking the trigger time of the reference calibration channel as a reference, acquiring the delay time of the trigger time of each digital channel and the reference calibration channel at different time base values, and acquiring the mixed trigger compensation time of the digital channel at different time base values according to the acquired delay time.
In the step, the digital channel and the analog channel are used as trigger sources to correct the digital channel, and the digital channel and the analog channel are subjected to positive value synchronization, so that the waveform is deflected in one direction only during mixed triggering, and the waveform is more stable. After the steps 120 and 130, the waveform trigger centers of the digital oscilloscope are already aligned, please refer to fig. 6, which is a schematic diagram illustrating the inversion of each digital channel aligned in one embodiment, and based on the correction result shown in fig. 6, the waveforms can be biased in the same direction by performing the correction value synchronization, specifically including:
a) configuring trigger parameters, inputting the same mixed trigger calibration signal into an analog channel and a digital channel, distributing the mixed trigger calibration signal to all the channels by a mother signal, setting the amplitude of the mixed trigger calibration signal according to the gear setting of the analog channel so as to be convenient for viewing as a principle, and selecting rising edge trigger by an oscilloscope to trigger the level to be 0V;
b) taking the digital channel ch1 as a trigger, and not considering the analog channel at this time, the rising edge of the square wave of the mixed trigger calibration signal is located in the middle of the oscilloscope, the rising edge of the digital channel is not aligned with the middle of the oscilloscope due to the problems of reference level difference of the comparator and the like, and at this time, the delay values of ch 1-ch 16 are recorded, and are expressed as:
delay1，delay2，……，delay15，delay16；
and traversing the minimum storage depth and all time base combinations below 50ms by taking the 50ms time base as an upper limit, recording delay values of all combinations of all digital channels, and judging one channel by one channel at the moment.
Assuming that the channel delay is between [ -200ps,200ps ] then the channel is considered aligned with the oscilloscope neutral position, forcing the channel delay value to be recorded as 0 ns;
taking the waveform to be aligned to the right as an example, if the delay value of the channel is a negative value and the absolute value is greater than 1.5ns, recording the delay value;
if the delay value of the channel is positive and greater than 1.5ns, recording the delay as 0 ns;
the delay of a 1ns time base is expressed as:
1ns=delay1，delay2，……，delay15，delay16；
the delay of a 2ns time base is expressed as:
2ns= delay1，delay2，……，delay15，delay16；
and so on for other time bases.
c) All delay records are recorded as one file as file _ delay 3;
software acquires file _ delay3 to compensate delay values under each time base;
the reason why the 50ms time base is adopted as the upper limit is that the delay of the digital channel is not very large, the delay cannot be seen by naked eyes under the 50ms time base, and each time base is not required to be traversed, so that the correction efficiency is improved.
It is an important point of the present invention that the displayed waveform is biased in only one direction in step 140.
Recording the mixed trigger compensation time of each digital channel under different time bases to be used as the mixed trigger correction parameter of the digital channel under different time bases, namely acquiring file _ delay3, file _ delay3 and file _ delay3 to be used as the trigger correction parameter of each digital channel of the digital oscilloscope when the analog channel is triggered, when the digital channel is triggered and when the mixed trigger is triggered respectively.
In an embodiment of the present application, a digital oscilloscope is further disclosed, which includes a control processor, a digital channel, and an analog channel, where the control processor executes a program to implement the digital channel correction method described above, so as to obtain a trigger correction parameter of each digital channel when the analog channel is triggered, when the digital channel is triggered, and when the digital channel is triggered in a mixed manner.
Step 140 in the present embodiment is for compensating the waveform jitter, and please refer to fig. 8, which is a schematic diagram illustrating the principle of waveform jitter formation in an embodiment, after step 120 and step 130, the trigger point is aligned with the trigger center; in step 110, the output voltages of the DACs are not completely equal to each channel, the digital signal is discrete, if a thermal noise causes the reference level to be higher or lower, and when the reference level just crosses a sampling point, the displayed waveform is sometimes left and sometimes right, which is called jitter, and the jitter is left or right with the trigger center as the origin. As shown in fig. 8, delay1 and delay 2; after the correction in step 110, the threshold level of the comparator is already within a reasonable range, and at this time, the waveform only needs to be corrected in one direction; when a sampling point is 2ns at a sampling rate of 500M, the jitter is ± 2ns, and if the waveforms of all digital channels are only biased to the right, only the delay value in fig. 8 needs to be recorded; when delay2 occurs, the software compensates the waveform to the right; when delay1 occurs, the waveform is held stationary; when the waveform is just aligned to the middle, the waveform is kept still; the process is the correction process in step 140, and as a result, the original jitter of-2 ns to +2ns is finally changed into the jitter of 0 to +2ns, so that the waveform stability is improved.
All the compensation is realized in real time by software through waveform compensation, and all the physical delays exist without any change. From another perspective, this compensation procedure fools the user's eyes, but this does not violate the principle of measurement accuracy, but rather makes the waveform easier to observe and more stable.
The application discloses a digital channel correction method, which comprises the steps of firstly, carrying out zero level correction on a comparator of each digital channel to obtain zero level turnover voltage of the digital channel; then acquiring respective analog trigger compensation time of each digital channel when the digital channel is at an analog channel trigger source; then obtaining the digital trigger compensation time of each digital channel when the digital channel is used as a trigger source; and finally, acquiring the mixed trigger compensation time of each digital channel when the analog channel and the digital channel are in mixed trigger, and acquiring the mixed trigger correction parameters when the analog channel and the digital channel are in mixed trigger according to the mixed trigger compensation time. Because the mixed trigger compensation time is obtained according to the time of the first trigger signal of each digital channel during the mixed trigger, the waveform displayed by the digital oscilloscope is only deflected to one direction, and the purpose of stabilizing the waveform is further achieved.
Those skilled in the art will appreciate that all or part of the functions of the various methods in the above embodiments may be implemented by hardware, or may be implemented by computer programs. When all or part of the functions of the above embodiments are implemented by a computer program, the program may be stored in a computer-readable storage medium, and the storage medium may include: a read only memory, a random access memory, a magnetic disk, an optical disk, a hard disk, etc., and the program is executed by a computer to realize the above functions. For example, the program may be stored in a memory of the device, and when the program in the memory is executed by the processor, all or part of the functions described above may be implemented. In addition, when all or part of the functions in the above embodiments are implemented by a computer program, the program may be stored in a storage medium such as a server, another computer, a magnetic disk, an optical disk, a flash disk, or a removable hard disk, and may be downloaded or copied to a memory of a local device, or may be version-updated in a system of the local device, and when the program in the memory is executed by a processor, all or part of the functions in the above embodiments may be implemented.
The present invention has been described in terms of specific examples, which are provided to aid understanding of the invention and are not intended to be limiting. For a person skilled in the art to which the invention pertains, several simple deductions, modifications or substitutions may be made according to the idea of the invention.
Claims (10)
1. A digital channel correction method for a digital oscilloscope, comprising:
performing zero level correction on a comparator of each digital channel to obtain a zero level turnover voltage of the digital channel;
taking an analog channel as a trigger source, correcting the trigger time of the digital channel according to the trigger time of the analog channel to obtain the analog trigger compensation time of each digital channel when the analog channel is triggered, and then obtaining the analog trigger correction parameter of the digital oscilloscope when the analog channel is taken as the trigger source according to the analog trigger compensation time;
taking a digital channel as a trigger source, correcting the digital channel to obtain respective digital trigger compensation time of each digital channel when the digital channel is triggered, and then obtaining digital trigger correction parameters of the digital oscilloscope when the digital channel is taken as the trigger source according to the digital trigger compensation time;
correcting the digital channel by taking the analog channel and the digital channel as a trigger source simultaneously to acquire respective mixed trigger compensation time of each digital channel when the analog channel and the digital channel are in mixed trigger, and acquiring mixed trigger correction parameters of the digital oscilloscope when the analog channel and the digital channel are in mixed trigger according to the mixed trigger compensation time; wherein the hybrid trigger compensation time for each of the digital channels is obtained in accordance with a time at which a first trigger signal for the respective digital channel occurs.
2. The method of claim 1, wherein the zero-level correcting the comparator of each digital channel to obtain the zero-level flip voltage of the digital channel comprises:
when the digital oscilloscope has no external signal input, inputting a voltage calibration signal to the negative input end of the comparator of each digital channel; adjusting the voltage of the voltage calibration signal, and recording the voltage value of the voltage calibration signal when the output end of the comparator of each digital channel outputs a first electric signal and a second electric signal;
acquiring a zero level flip level value of each digital channel according to the voltage value of the voltage calibration signal when the output end of the comparator of each digital channel outputs the first electric signal and the second electric signal;
the zero level inversion level value of the digital channel is an average value of the voltage calibration signal when the output end of each comparator outputs the first electric signal and the voltage value of the voltage calibration signal when the output end of each comparator outputs the second electric signal.
3. The method of claim 2, wherein the taking the analog channel as a trigger source, and correcting the trigger time of the digital channel according to the trigger time of the analog channel to obtain the analog trigger compensation time of each of the digital channels when the analog channel triggers, comprises:
inputting an analog trigger calibration signal with known signal parameters to the digital oscilloscope;
inputting the analog trigger calibration signal into the analog channel and the digital channel simultaneously;
taking one digital channel in the digital oscilloscope as a reference calibration channel, taking the trigger time of the analog channel as a reference, and aligning the trigger time of the reference calibration channel with the trigger time of the analog channel;
and acquiring the delay time of the trigger time of each digital channel and the reference calibration channel when the digital channels have different time base values, and taking the delay time as the analog trigger compensation time of the digital channel when the digital channels have different time base values.
4. The method of claim 3, wherein the using digital channels as trigger sources to correct the digital channels to obtain the digital trigger compensation time of each digital channel at the time of triggering the digital channel comprises:
inputting a digital trigger calibration signal with known signal parameters to the digital oscilloscope;
inputting the digital trigger calibration signal into the digital channel;
and taking the triggering time of the reference calibration channel as a reference, acquiring the delay time of each digital channel relative to the triggering time of the reference calibration channel when the digital channel has different base values, and taking the delay time as the digital triggering compensation time of the digital channel when the digital channel has different base values.
5. The method of claim 4, wherein the time base value is not less than 50 ms.
6. The method of claim 4, wherein said calibrating said digital channels using said analog channels and said digital channels simultaneously as a trigger source to obtain respective hybrid trigger compensation times for each of said digital channels at a hybrid trigger of said analog channels and said digital channels comprises:
inputting a mixed trigger calibration signal with known signal parameters to the digital oscilloscope;
inputting the mixed trigger calibration signal into the analog channel and the digital channel simultaneously;
and taking the triggering time of the reference calibration channel as a reference, acquiring the delay time of the triggering time of each digital channel and the reference calibration channel when the digital channels are at different base values, and acquiring the mixed triggering compensation time of the digital channels when the digital channels are at different base values according to the acquired delay time.
7. The method as claimed in claim 6, wherein said obtaining the hybrid trigger compensation time of the digital channel at different time base values according to the obtained delay time comprises:
when the delay time is between-200 ps and 200ps, setting the mixed trigger compensation time of the digital channel to be 0 second;
when the delay time is a positive value larger than 1.5ns, setting the mixed trigger compensation time of the digital channel to be 0 second;
and when the delay time is a negative value and the absolute value of the delay time is more than 1.5ns, taking the delay time as the mixed trigger compensation time of the digital channel.
8. The method of claim 7, wherein the obtaining the mixed trigger correction parameter of the digital oscilloscope at the mixed trigger of the analog channel and the digital channel according to the mixed trigger compensation time comprises:
and recording the mixed trigger compensation time of each digital channel at different time bases to serve as the mixed trigger correction parameter of the digital channel at different time bases.
9. A computer-readable storage medium, characterized in that the medium has stored thereon a program which is executable by a processor to implement the method according to any one of claims 1-8.
10. A digital oscilloscope comprising a control processor, digital channels and analog channels, wherein said control processor is programmed to implement the digital channel correction method according to any one of claims 1 to 8 to obtain trigger correction parameters for each of said digital channels at analog channel trigger, digital channel trigger and mixed trigger, respectively.
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