Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Electrical signal parameter measurement system
Reexamination Certificate
1999-04-20
2003-05-27
Barlow, John (Department: 2863)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Electrical signal parameter measurement system
C345S440100
Reexamination Certificate
active
06571185
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to automatic setup of an oscilloscope or similar instrument, and more particularly to such a setup function that is continually responsive to the type of input signal and which provides user choices that anticipate the user's needs based on characteristics of the input signal. Multiple signal views are associated into a set of signal views, each member of said set being operatively connected for easy access for other members of the set.
CROSS-REFERENCE TO RELATED APPLICATIONS
[not applicable]
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT
[not applicable]
BACKGROUND OF THE INVENTION
Prior art oscilloscopes with automatic setup functions were sometimes limited in usefulness by the difficulty of getting from one appropriate view to another. A new paradigm of oscilloscope operator interface control is needed, a paradigm that provides instant connectivity and transport between different signal views within a set of related views.
Oscilloscopes have for some time been able to automatically determine vertical gain, vertical position, trigger level and horizontal time scale settings in response to simple signal inputs, such as a sine wave or square wave. However, the effectiveness of these automatic settings was sometimes compromised by the need to make assumptions about the nature of the input signal.
Oscilloscopes typically power-up to a “factory” or “power-up” setup. Doing so serves several functions. This will typically be a frequently used setup, and therefore has some chance of being at or close to a suitable setup for what the user presently wants to do. Even if it is not, it provides a stable starting point for further work. Having a stable starting point that the user becomes familiar with, enables a user to make rapid and minimal adjustments to get to the desired setting for the present task, assuming that no known saved setting is a closer starting point. If the oscilloscope is shared with other users, it is often desirable for the present user who finds the scope already turned on to initially go to the factory setting to make sure that the instrument is not in some strange mode left by the last user. This assumes that the power-up setup is among the stored setups available to recall, otherwise the same result will require turning the power off and on again. It is also useful to have an oscilloscope power-up to a known state for use in remote-programmed or remote-controlled situations. This allows the remote controlling program or operator to only send changes from the initial state, as opposed to having to send a command for every possible controllable parameter in order to ensure that the final state of the instrument is known.
Originally, the automatic function was limited to initial setup, and it ended its routine once that setup was achieved and the user took over. More recently, however, the automatic function on some oscilloscopes continued controlling the setup during operation, although such a mode is usually optional and may be shut off by the user. Within parts of the industry, this feature is known as “auto-ranging” or “continuous setup”, so as to be distinguishable from the “auto-setup” in which the setup parameter control terminated after the initial setup. An auto ranging oscilloscope responds to simple changes in a simple input by modifying its horizontal sweep setting, its vertical gain setting, or, in some cases, even its trigger level settings, in response to the changed inputs.
U.S. Pat. No. 5,155,431 to Holcomb for “Very Fast Autoscale Topology for Digitizing Oscilloscopes”, hereby incorporated by reference, describes an oscilloscope that can quickly achieve an appropriate setup by finding the signal maximum and signal minimum through the utilization of peak detection circuitry. U.S. Pat. No. 5,397,981 to Wiggers for “Digital Storage Oscilloscope with Automatic Timebase”, hereby incorporated by reference, describes an oscilloscope that can adjust its timebase during operation to keep a constant number of cycles on the screen, even in the presence of a change in frequency of the input signal. Additionally, and apparently for the same type of application, the time axis of the display of this oscilloscope may be labeled in degrees per division instead of time per division.
Some oscilloscopes of the prior art have had the capability of making one or more automated measurements on a simple input signal, such as a sine wave or square wave. These measurements, which had to be selected by an operator, could include frequency (or period), duty cycle, peak-to-peak amplitude, or rise and fall times. For example, U.S. Pat. No. 4,362,394 to Menlove for “Time Interval Measurement Arrangement”, hereby incorporated by reference, describes a method and apparatus to make accurate measurements on a complex repetitive waveform.
U.S. Pat. No. 4,779,044 to Skolnick et al. for “Voltage, Current and Frequency Measuring of Non-standard Waveforms”, hereby incorporated by reference, describes one way that the period of a regular binary signal can measured by sensing transitions and using a counter to determine the interval between them.
U.S. Pat. No. 4,271,391 to Kmetz for “Digital Voltmeter with Electro-Optical Indication of the Waveform”, hereby incorporated by reference, discloses a digital voltmeter that displays a waveform at maximum available vertical amplitude and also displays that voltage level as a numerical value.
U.S. Pat. No. 4,716,345 to Shank et al. for “Automatic Pulse Display”, hereby incorporated by reference, describes a method for using two trigger detection circuits to trigger at the same level on opposite slopes of a pulse waveform. This provides a way to calculate the duty cycle of the waveform and position it on the screen. This oscilloscope can automatically expand and display an otherwise narrow pulse in the signal input to make the positive portion fill most of the display. This is convenient when a pulse type signal has a very low duty cycle (percentage of total period of the signal wherein the signal is in its “high” state.)
U.S. Pat. No. 5,637,994 to Carder for “Waveform Measurement”, hereby incorporated by reference, discloses a way to measure the features of a waveform with indeterminate, i.e., variable, arrival times. The time between separate threshold crossings is measured as one of the threshold points is moved. This allows a point-by-point reconstruction of a repetitive waveform occurring at variable intervals.
U.S. Pat. No. 4,985,844 to Foley, et al. for “Statistical Waveform Profiler Employing Counter/Timer”, hereby incorporated by reference, describes an oscilloscope system that repetitively performs pulse width measurements, and to enable this feature the system automatically determines suitable resolution and offset settings. U.S. Pat. No. 5,155,431 to Holcomb for “Very Fast Autoscale Topology For Digitizing Oscilloscopes”, hereby incorporated by reference, describes an oscilloscope with dedicated peak detector hardware that operates in conjunction with a trigger counter to rapidly set the vertical scale and offset and the horizontal sweep rate.
Histograms provide a powerful tool for waveform analysis and instrument control. U.S. Pat. No. 4,985,844 to Foley et al. for “Statistical Waveform Profiler Employing Counter/Timer”, hereby incorporated by reference, describes a histogram-based counting arrangement that makes measurements on repetitive input signals and uses the results as the basis for the generating a histogram. Histograms can also provide a basis for automated measurements, although more slowly than with some of the specialized approaches described elsewhere herein.
U.S. Pat. No. 5,495,168 to deVries for “Method of Signal Analysis Employing Histograms to Establish Stable, Scaled Displays in Oscilloscopes”, hereby incorporated by reference, describes an oscilloscope system that uses both amplitude histograms and time histograms. The amplitude histogram method is used first to determine the minimum and maximum amplitude levels of the signal
Azinger Frederick A.
Gauland Michael A.
Saxe Charles L.
Siegel Roy I.
Sullivan Steven K.
Barlow John
Gray Francis I.
Griffith Boulden G.
Lenihan Thomas F.
Pretlow Demetrius
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