Asymmetric acquisition and disjoint time trigger in test and measurement instrument

Abstract

A test and measurement instrument includes two or more channels to allow the test and measurement instrument to be connected to a device under test (DUT), each channel including an analog-to-digital converter (ADC) and one or more trigger engines, each trigger engine determining one or more trigger conditions, a display to allow the test and measurement instrument to display data from the ADC, a user interface, and a controller. And one or more processors configured to execute the code to cause the one or more processors to collect data from the two or more channels at a different time than other of the two or more channels in response to the one or more trigger conditions. A test and measurement instrument, similar to the foregoing, in addition to one or more channels with an ADC, has at least one channel with an auxiliary input and a threshold detector instead of an ADC.

Description

[0001] Cross-references to related applications This disclosure is a non-provisional application filed on August 28, 2024, entitled “ASYMMETRIC ACQUISITIONS AND DISJOINTED TIME TRIGGER IN ATEST AND MEASUREMENT INSTRUMENT”, U.S. Provisional Application No. 63 / 688,259, and claims the benefit of that provisional application, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0002] This disclosure relates to test and measurement instruments, and more specifically, to acquisition and triggering techniques in test and measurement instruments such as oscilloscopes. Background Technology

[0003] In traditional oscilloscopes, all input channels are sampled at the same rate in a time-synchronized manner based on trigger conditions. Although trigger conditions may occur on a single channel or across multiple channels, all channels are sampled at the same time and at the same sampling rate for a given coherent dataset. Many existing oscilloscopes have a trigger engine responsible for determining the time slice to be acquired.

[0004] Test and measurement instruments such as oscilloscopes currently lack the ability to allow users to configure the instrument to use more resources to acquire the channel of interest while sampling other channels at a lower sampling or acquisition rate. Current oscilloscopes may use auxiliary inputs as a trigger or part of a trigger, but do not display the waveform. Users can manually move the auxiliary input to an analog channel to view the waveform, but this cannot be done without manual intervention. Attached Figure Description

[0005] Figure 1 An embodiment of a test and measurement device with asymmetric acquisition is shown.

[0006] Figure 2 An embodiment of a channel in a test and measurement device is shown.

[0007] Figure 3 An example of a process for acquiring and inspecting waveforms using non-overlapping time triggers is shown.

[0008] Figure 4 This demonstrates a rotatable 3D rendering with asymmetric acquisition. Detailed Implementation

[0009] The embodiments described herein include test and measurement instruments and methods for acquiring data from different channels in a configurable manner, independent of other channels. These channels can acquire data independently by acquiring data at different times, at different sampling rates, or any combination thereof in response to different triggering conditions. The independently acquired data can then be combined to form a coherent dataset spanning time, rate, and events.

[0010] As an example, a process can acquire individual channels or a subset of all channels based on a triggering condition, including a time reference, observed on that channel or subset of channels. For example, channel 1 acquisition could be based on the rising edge of channel 1, and channel 2 acquisition could be based on the rising edge of channel 2. This can also be done for any triggering type, such as rising edge, falling edge, pulse width, specific positioning modes in serial transmission, etc. The discussion here refers to the result as coherent acquisition, where a portion of the acquisition is the measurement time alignment between the individual channel captures. In this example, conventional alignment acquisition has a substantially zero incremental time for all channels.

[0011] This discussion refers to data acquisition as "asymmetric acquisition" because acquisition occurs with some degree of asymmetry, such as different trigger times, different trigger types, different sampling rates, or combinations thereof. As used herein, the term "disjoint-time triggering" refers to acquisitions where the triggering conditions occur at different times relative to each channel. Triggers may occur simultaneously, even if they are different triggers on different channels, but multiple channels are triggered independently.

[0012] Figure 1 This is a block diagram of a multi-channel test and measurement instrument 10. The test and measurement instrument 10 includes a section for interacting with the device under test (DUT), referred to herein as an input / output section 20, and a display and control section 40. The input / output section 40 of the instrument 10 includes multiple channels, such as 30, labeled as channel 1, channel 2, through channel n. The instrument can include any number of channels.

[0013] As described in more detail below, instrument 10 may include a general-purpose timing controller 24, a general-purpose trigger controller 22, and a general-purpose storage controller 26. Figure 1 In this context, these components appear to be located within the input / output section 20 of instrument 10, but they can be physically located anywhere within instrument 10.

[0014] The control section 40 of instrument 10 includes a set of input controllers 48 through which a user can control the instrument. The input controllers 48 may include a graphical user interface (GUI) 50 or a programming interface (PI) 52. Other input controllers 48 may include various knobs and switches, either on or off instrument 100, as is conventionally known.

[0015] One or more main or central processing units 44 may be configured to execute instructions from memory 46 and to perform any methods and / or associated steps indicated by those instructions, such as receiving and storing signals acquired from input / output section 20, or performing any test and measurement functions of instrument 10. The instrument may store the acquired signals as waveforms in memory 46, one or more acquisition memories associated with the channel, or other various other memories that may be located throughout instrument 10.

[0016] One or more processors 44 can control the output display 42 to display waveforms, measurements, and other data to the user. The output display 42 may include, for example, an LCD or any other display monitor. If the display includes a touchscreen, the display may also be part of the input controller.

[0017] Although Figure 1 The diagram illustrates components of a test and measurement instrument 10 as integrated within it; however, those skilled in the art will understand that any of these components may be located external to the test and measurement instrument 10 and may be coupled to the test and measurement instrument 10 in any conventional manner, such as wired and / or wireless communication media and / or mechanisms. In some embodiments, a remote computer may be connected to the instrument 10 to operate the instrument.

[0018] Furthermore, while the general-purpose trigger controller 22, general-purpose timing controller 24, and general-purpose storage controller 26 may include shared components between channels, each channel may include a trigger module or engine. The trigger engine in each channel can provide each channel with triggering and acquisition capabilities independent of other channels. Figure 2 The channel (e.g., from) is shown Figure 1 A more detailed representation of an embodiment of (30).

[0019] Figure 2 The four-channel configuration is shown; it should be understood that... Figure 2 An example is shown, and the instrument can have more or fewer channels. The instrument will have one or more channels that can acquire data from the DUT independently of the other channels. Data enters the channel from the DUT and may undergo signal conditioning, such as amplification at amplifier / receiver 60. Analog-to-digital converter (ADC) 62 then samples the signal and converts it into digital data. When trigger engine 64 detects a trigger event in the data stream from ADC 62, it then instructs data storage device 66 to store the data. It should be noted that channels can share these components, such as amplifiers, ADCs, and storage devices.

[0020] The trigger engine may include some type of processing element, such as a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), or other processing element, which can receive programming or otherwise controlled by a source. Figure 1 The instrument 10 is controlled by one or more central processing units 44. The one or more processors 44 of the instrument 10 may include processing elements located within the trigger engine. The one or more central processing units can also control the trigger engine even when the trigger engine does not have any processing elements. However, in implementation, the trigger engine receives signals to control acquisition independently of acquisitions performed on other channels.

[0021] In some embodiments, each channel includes a complete copy of the triggering capability on each acquisition circuit, meaning each channel.

[0022] Test and measurement instruments with independent channels mean that channels can acquire data independently in multiple ways. This allows one or more processors to acquire data in response to triggering conditions on at least one of two or more channels that differ from the other channels.

[0023] In one embodiment, a channel may respond to the same triggering condition occurring at different times on each of two or more channels. In this embodiment, the instrument may be triggered using a single trigger, but different triggering engines begin acquisition at different times. In another embodiment, a channel may acquire data in response to a triggering condition on at least one of two or more channels that is different from the other two or more channels. This corresponds to the rising edge example above, which causes acquisition to occur on the rising edges of channel 1 and channel 2.

[0024] In one embodiment, the instrument can use this capability to analyze the transmission effects of a signal. The condition could be that the RF energy in a specific frequency band on each channel exceeds a threshold. For example, wireless communication signals can be transmitted and received, where both the source and destination signals are sampled by an oscilloscope. Path characteristics, such as frequency response, path delay, multipath interference, etc., can be more easily visualized, where the source and destination signals overlap or stack at a reference point (e.g., the start of a burst). Wireless environments are inherently dynamic and sometimes highly dynamic as the transmitter or receiver moves. Automatically aligning source and receiver data allows the user to focus on signal effects.

[0025] This will allow users to analyze received signals as a function of transmission time, which is used as a reference to the transmitter. For example, variations in the characteristics of the received waveform of a radar signal can be visualized by rendering the sampled waveform as a function of transmission time, which may typically correspond to the distance to the target.

[0026] In wired communication, the signal under discussion is effectively confined within a waveguide. Similarly, the transmission effects of wires or circuit board traces can be analyzed as a function of time delay, which may correspond to the length of the wire or trace.

[0027] In embodiments where each channel has full trigger capability, the software and individual processors (e.g., FPGA images on existing hardware) can be modified to trigger independently under conditions (e.g., edges) on each channel, and then collected and aligned for display. Figure 3 An example of this type of acquisition is shown.

[0028] exist Figure 3 In the diagram, solid lines represent signals acquired on one channel near the transmitter, and dashed lines represent signals acquired on different channels near the receiver. These signals are contained within conductors. The diagram above illustrates how triggering would occur without disjoint timing triggering. Triggering is configured for a specific data pattern. Due to signal transmission time, the captured waveforms are not aligned on the display, making comparison difficult. Triangle pointer 70 marks a reference point in the signal pattern for the source signal, and triangle pointer 72 marks a reference point in the signal pattern for the receiver waveform.

[0029] In the diagram below, the two channels trigger the same pattern in the data, regardless of the transmission time. The two triangular pointers 70 and 72 are now aligned as trigger references. This allows the user to probe more points and always obtain a clear comparison of two or more waveforms. The offset is automatically determined, shifting the focus from the delay of the probed signal to changes in the shape of the probed signal, which are typically caused by transmission line losses.

[0030] The examples here change the inherent assumption in the UI of conventional test and measurement instruments that the displayed waveforms are captured in the exact same way at exactly the same time. The point of the "asymmetric acquisition" or "non-intersecting time acquisition" mode is to deliberately not capture waveforms at the same time.

[0031] Another advantage of triggering at different times is that it allows capturing the changes (increments) between those times as axes on a graph. The time difference between non-intersecting time acquisitions is itself a measurable and plottable value. For example, as a wireless receiver approaches a transmitter, the transmission delay and the characteristics of the received waveform change. An oscilloscope can represent this in a 3D projection, showing the received waveform as a function of transmission time or effective distance.

[0032] Figure 4An example of this type of projection is shown. The two axes are amplitude on the vertical axis and time on the horizontal axis. The third axis could be transmission time. In this figure, assuming there is a probe on the transmitter and a probe on the receiver, the third axis, moving in and out of the page, visualizes the changes in the signal as a function of transmission time. This image can be continuously updated as the two DUTs operate and the conditions around the DUTs change.

[0033] This graph can be displayed on the user interface screen of test and measurement instruments, allowing users to manipulate the perspective, for example, to better understand signal distortion as a function of transmission distance or time. The instrument can also use color or grayscale to identify different transmission time acquisitions in two-dimensional or three-dimensional projections, for example... Figure 4 The one shown in the image.

[0034] It can also be used to capture distortion along the conductor. The ability to use disjoint time triggering makes testing much easier to set up. Users can set up the oscilloscope once to trigger the source and destination on different channels at separate times, and then easily pass it through different DUTs at different conductor lengths without reconfiguring the oscilloscope for different times of flight. In this case, the time of flight is not of interest, but it does provide an ease-of-use factor where the user does not care about the timing of the channels.

[0035] In some embodiments, useful information can be revealed by cross-correlation of two signals acquired multiple times. Potentially, advanced filters including learning filters can be used, and the oscilloscope can trigger anomalous differences or correlations, where the term "difference" indicates negative correlation and "correlation" implies positive correlation, where the difference or correlation exceeds a threshold from other differences or correlations. The advantage of independent triggering is that it can be used to eliminate time differences between sampling points, a factor that hinders analysis, especially when the time difference varies.

[0036] In some hardware designs, high-performance processing, such as fast frame rate or fast Acq (acquisition), requires significant resource usage during acquisition. Oscilloscopes or instruments can explicitly allow the user to configure the instrument to acquire one or more channels of interest with maximum resource "intensity" while simultaneously sampling other channels at lower sampling or acquisition rates. This allows for higher fidelity results, such as a higher "live time" for the channels of interest, while still monitoring other signals, perhaps simply to provide a reference frame.

[0037] Common current oscilloscope configurations use an "auxiliary" or "aux" input as a trigger or part of a trigger, but do not display the waveform. In some use cases, the user manually moves the signal from the auxiliary input to one of the analog inputs to allow the user to view the auxiliary signal (aux signal). According to some embodiments of this disclosure, the instrument can present the state of the "aux trig" signal as another type of asymmetric acquisition, where the "aux trig" signal has only two states and may not be sampled at the same sampling rate as other channels.

[0038] In summary, the embodiments of this disclosure improve two general areas of operation for test and measurement instruments. First, the embodiments make full use of limited hardware resources to maximize the collection and presentation of useful information to the user. Second, the embodiments improve user efficiency by helping the user understand complex datasets, which is achieved by aligning events occurring at different and potentially unpredictable times to obtain a faster path to understanding the captured information.

[0039] The aspects of this disclosure can operate on specially created hardware, firmware, digital signal processors, or specially programmed general-purpose computers including processors that operate according to programmed instructions. As used herein, the terms controller or processor are intended to include microprocessors, microcomputers, application-specific integrated circuits (ASICs), and special-purpose hardware controllers. One or more aspects of this disclosure can be embodied in computer-usable data and computer-executable instructions, for example, in one or more program modules executed by one or more computers (including monitoring modules) or other devices. Typically, program modules include routines, programs, objects, components, data structures, etc., which perform specific tasks or implement specific abstract data types when executed by a processor in a computer or other device. Computer-executable instructions can be stored on non-transitory computer-readable media, such as hard disks, optical disks, removable storage media, solid-state storage, random access memory (RAM), etc. As those skilled in the art will understand, the functionality of a program module can be combined or distributed in various aspects as desired. Furthermore, this functionality can be wholly or partially embodied in firmware or hardware equivalents such as integrated circuits, FPGAs, etc. Specific data structures can be used to more efficiently implement one or more aspects of this disclosure, and such data structures are contemplated within the scope of the computer-executable instructions and computer-usable data described herein.

[0040] In some cases, the disclosed aspects may be implemented in hardware, firmware, software, or any combination thereof. The disclosed aspects may also be implemented as instructions carried or stored on one or more non-transitory computer-readable media, which may be read and executed by one or more processors. Such instructions may be referred to as a computer program product. As discussed herein, a computer-readable medium means any medium accessible by a computing device. By way of example and not limitation, a computer-readable medium may include computer storage media and communication media.

[0041] Computer storage media refers to any medium that can be used to store computer-readable information. By way of example and not limitation, computer storage media may include RAM, ROM, electrically erasable programmable read-only memory (EEPROM), flash memory or other storage technologies, optical disc read-only memory (CD-ROM), digital video disc (DVD) or other optical disc storage devices, magnetic tape cassettes, magnetic tape, disk storage devices or other magnetic storage devices, and any other volatile or non-volatile, removable or non-removable media implemented in any technology. Computer storage media excludes signals themselves and temporary forms of signal transmission.

[0042] A communication medium is any medium that can be used for computer-readable information communication. By way of example and not limitation, a communication medium may include coaxial cable, fiber optic cable, air, or any other medium suitable for communication of electrical, optical, radio frequency (RF), infrared, acoustic, or other types of signals.

[0043] Example The following provides illustrative examples of the disclosed techniques. Embodiments of these techniques may include one or more of the examples below, as well as any combination thereof.

[0044] Example 1 is a test and measurement instrument comprising: two or more channels for allowing the test and measurement instrument to connect to a device under test (DUT), each channel including an analog-to-digital converter (ADC) and one or more trigger engines, each trigger engine determining one or more trigger conditions; a display allowing the test and measurement instrument to display data from the ADC; a user interface; and one or more processors configured to execute code such that the one or more processors, in response to one or more trigger conditions, acquire data from the two or more channels at a time different from that of the other channels in the two or more channels.

[0045] Example 2 is a test and measurement instrument of Example 1, wherein one or more processors include a central processing unit and processors for each of two or more channels.

[0046] Example 3 is a test and measurement instrument of Example 2, wherein one or more trigger engines include one trigger engine for each channel, and each trigger engine has one or more processors.

[0047] Example 4 is a test and measurement instrument of any of Examples 1 to 3, wherein one or more processors include one or more central processing units, and one or more trigger engines are controlled by one or more central processing units.

[0048] Example 5 is a test and measurement instrument of any of Examples 1 to 4, where the ADC is shared between two or more channels.

[0049] Example 6 is a test and measurement instrument of any of Examples 1 to 5, wherein the code that causes one or more processors to acquire data from two or more channels includes code that causes one or more processors to acquire data in response to a trigger condition on at least one of the two or more channels that is different from the other channels of the two or more channels.

[0050] Example 7 is a test and measurement instrument of any of Examples 1 through 6, wherein the code that causes one or more processors to acquire data includes code that causes one or more processors to acquire data based on the same triggering condition occurring at different times on each of two or more channels.

[0051] Example 8 is a test and measurement instrument of any of Examples 1 to 7, wherein the code causing one or more processors to acquire data includes code causing one or more processors to acquire data on each of the two or more channels in response to an independent triggering condition for each of the two or more channels, and the one or more processors are further configured to: align the data of each of the two or more channels in time to produce aligned data; and display the aligned data of all two or more channels on a display.

[0052] Example 9 is a test and measurement instrument of any of Examples 1 through 8, wherein one or more processors are further configured to execute code to: track the time difference between the times of data acquisition on different channels of two or more channels; and plot the time difference on a display.

[0053] Example 10 is a test and measurement instrument of any of Examples 1 through 9, wherein the code that causes one or more processors to display the time difference causes one or more processors to display the time difference using a rotatable 3D graph.

[0054] Example 11 is a test and measurement instrument of any one of Examples 1 to 10, wherein one or more processors are further configured to execute code that causes one or more processors to: detect one of the correlations or differences between two signals on different channels of two or more channels within a time period; and identify differences that exceed a threshold difference during that time period.

[0055] Example 12 is a test and measurement instrument comprising: one or more channels allowing the instrument to connect to a device under test (DUT), including an analog-to-digital converter (ADC) and a trigger engine, each trigger engine defining one or more trigger conditions; one or more channels allowing the instrument to connect to the DUT, including an auxiliary input with a threshold detector and a trigger engine, each trigger engine defining one or more trigger conditions; a display allowing the instrument to display data from the ADC; a user interface; and one or more processors configured to execute code to cause the one or more processors to: acquire data from the one or more channels having the ADC; and sample the auxiliary input independent of the one or more channels having the ADC.

[0056] Example 13 is a method comprising: determining one or more trigger conditions; and, in response to one or more trigger conditions, acquiring data from two or more channels connected to the device under test (DUT) at a time different from that of the other channels in two or more channels.

[0057] Example 14 is a method of Example 13, wherein data acquisition includes acquiring data in response to a trigger condition on at least one of two or more channels that is different from the other two or more channels.

[0058] Example 15 is a method of either Example 13 or 14, wherein data acquisition includes acquiring data based on the same triggering condition occurring at different times on each of two or more channels.

[0059] Example 16 is a method of any one of Examples 13 to 15, wherein data acquisition further includes: acquiring data on each of the two or more channels in response to an independent triggering condition for each of the two or more channels; aligning the data of each of the two or more channels based on the independent triggering condition for each of the two or more channels to produce aligned data with an alignment time difference and aligned channels; and displaying the alignment data of all two or more channels on a display on a test and measurement instrument.

[0060] Example 17 is a method of Example 16, wherein displaying the time difference of alignment includes displaying the time difference of alignment using a 3D graph that indicates the time difference of alignment on the display by one of waveform plotting position, grayscale gradient, or color.

[0061] Example 18 is a method of any of Examples 13 to 17, and further includes: tracking the time difference between the times of data acquisition on different channels of two or more channels; and plotting the time difference on a display.

[0062] Example 19 is a method of any of Examples 13 to 18, further comprising: detecting the difference between two signals on different channels of two or more channels within a time period; and identifying differences exceeding a threshold during that time period.

[0063] Example 20 is the method of Example 16, and also includes generating another further trigger condition to observe the difference on the aligned channel and display the result when the difference threshold is exceeded.

[0064] The previously described versions of the disclosed subject matter have many advantages, which have been described or are obvious to those skilled in the art. Nevertheless, these advantages or features are not required in all versions of the disclosed apparatus, system, or method.

[0065] All features disclosed in the specification, including the claims, abstract, and drawings, and all steps in any disclosed method or process, may be combined in any combination except for combinations in which at least some of such features and / or steps are mutually exclusive. Unless otherwise expressly stated, each feature disclosed in the specification (including the claims, abstract, and drawings) may be replaced by an alternative feature for the same, equivalent, or similar purpose.

[0066] Furthermore, this written description refers to specific features. It should be understood that the disclosure in this specification includes all possible combinations of those specific features. Where a specific feature is disclosed in the context of a particular aspect or example, that feature may also be used, to the extent possible, in the context of other aspects and examples.

[0067] Furthermore, when a method having two or more defined steps or operations is mentioned in this application, the defined steps or operations may be performed in any order or simultaneously, unless the context precludes those possibilities.

[0068] Although specific examples of the invention have been shown and described for illustrative purposes, it should be understood that various modifications may be made without departing from the spirit and scope of the invention. Therefore, the invention should not be limited except for the appended claims.

Claims

1. A test and measurement instrument comprising: two or more channels that allow the test and measurement instrument to connect to a device under test (DUT), each channel including an analog-to-digital converter (ADC) and one or more trigger engines, each trigger engine determining one or more trigger conditions; a display that allows the test and measurement instrument to display data from the ADCs; a user interface; and one or more processors configured to execute code to cause the one or more processors to acquire data from the two or more channels at different times from other channels of the two or more channels in response to the one or more trigger conditions.

2. The test and measurement instrument as claimed in claim 1, wherein the one or more processors include a central processor and a processor for each of the two or more channels.

3. The test and measurement instrument as claimed in claim 2, wherein the one or more trigger engines include one trigger engine for each channel, each trigger engine having one of the one or more processors.

4. The test and measurement instrument as claimed in claim 1, wherein the one or more processors include one or more central processors and the one or more trigger engines are controlled by the one or more central processors.

5. The test and measurement instrument as claimed in claim 1, wherein the ADCs are shared among the two or more channels.

6. The test and measurement instrument as claimed in claim 1, wherein the code that causes the one or more processors to acquire data from the two or more channels includes code that causes the one or more processors to acquire data in response to a different trigger condition on at least one of the two or more channels from other channels of the two or more channels.

7. The test and measurement instrument as claimed in claim 1, wherein the code that causes the one or more processors to acquire data includes code that causes the one or more processors to acquire data based on a same trigger condition occurring on each of the two or more channels at different times.

8. The test and measurement instrument as claimed in claim 1, wherein the code that causes the one or more processors to acquire data includes code that causes the one or more processors to acquire data on each of the two or more channels in response to independent trigger conditions for each of the two or more channels, and the one or more processors are further configured to: align data for each of the two or more channels in time to produce aligned data; and display the aligned data for all of the two or more channels on the display.

9. The test and measurement instrument as claimed in claim 1, wherein the one or more processors are further configured to execute code to: track time differences between data acquisition return times on different channels of the two or more channels; and plot the time differences on the display. ​ 10. The test and measurement instrument as claimed in claim 1, wherein the code that causes the one or more processors to display the time difference causes the one or more processors to display the time difference using a rotatable three-dimensional plot.

11. The test and measurement instrument as claimed in claim 1, wherein the one or more processors are further configured to execute code that causes the one or more processors to: detect one of a correlation or a difference between two signals on different ones of the two or more channels over a time period; and identify differences that exceed a threshold difference during the time period.

12. A test and measurement instrument comprising: one or more channels that allow the instrument to connect to a device under test (DUT), including analog-to-digital converters (ADCs) and trigger engines, each trigger engine determining one or more trigger conditions; one or more channels that allow the instrument to connect to a device under test (DUT), including auxiliary inputs with threshold detectors and trigger engines, each trigger engine determining one or more trigger conditions; a display that allows the instrument to display data from the ADCs; a user interface; and one or more processors configured to execute code to cause the one or more processors to: acquire data from the one or more channels with the ADCs; and sample the auxiliary inputs independent of the one or more channels with the ADCs.

13. A method comprising: determining one or more trigger conditions; and acquiring data from two or more channels connected to a device under test (DUT) at different times from other ones of the two or more channels in response to the one or more trigger conditions.

14. The method as claimed in claim 13, wherein acquiring data includes acquiring data in response to a trigger condition on at least one of the two or more channels that is different from other ones of the two or more channels.

15. The method as claimed in claim 13, wherein acquiring data includes acquiring data based on a same trigger condition occurring on each of the two or more channels at different times.

16. The method as claimed in claim 13, acquiring data further comprising: acquiring data on each of the two or more channels in response to independent trigger conditions for each of the two or more channels; aligning the data for each of the two or more channels based on the independent trigger conditions for each of the two or more channels to produce aligned data with aligned time differences and aligned channels; and displaying the aligned data for all of the two or more channels on a display on a test and measurement instrument.

17. The method as claimed in claim 16, wherein displaying the aligned time differences includes displaying the aligned time differences using a three-dimensional plot that indicates the aligned time differences on the display by one of waveform plot position, gray scale gradient, or color.

18. The method as claimed in claim 13, further comprising: tracking time differences between times of data acquisition on different ones of the two or more channels; and plotting the time differences on a display.

19. The method as claimed in claim 13, further comprising: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ detecting a difference between two signals on different channels of two or more channels over a time period; and identifying the difference that exceeds a threshold difference during the time period.

20. The method as claimed in claim 16, further comprising generating another further trigger condition to observe the difference on the aligned channels and displaying the result when the difference threshold is exceeded.

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