Computer graphics processing and selective visual display system – Display driving control circuitry – Controlling the condition of display elements
Reexamination Certificate
1998-01-12
2003-02-18
Luu, Sy D. (Department: 2174)
Computer graphics processing and selective visual display system
Display driving control circuitry
Controlling the condition of display elements
C345S440000, C345S950000, C702S068000
Reexamination Certificate
active
06522345
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to signal measurement systems and, more particularly, to simultaneously invoking automated measurements in a signal measurement system.
2. Related Art
Conventional signal measurement systems such as digital oscilloscopes sample, record and display time-varying analog signals. Samples of an input signal are taken and quantized, and the resultant digital representations are stored in a waveform memory under the control of a sampling clock. The acquired data may be subsequently read out as locations in memory are sequentially addressed by a clock signal to provide digital data which can be converted to a time-varying output signal for a waveform display. The sampling clock may be operated at one of several selectable rates depending upon the frequency content of the input signal. The selection of the portion of the analog input signal which is sampled and stored is determined by appropriate triggering circuitry to enable the operator to display the desired portion of the waveform.
There are many types of display elements which can be presented in signal measurement systems in general and test and measurement instruments in particular. For example, in addition to the waveforms representing the signals currently received at the channel inputs, waveforms referred to as function waveforms may also be displayed. Function waveforms are waveforms created by processing one or more signal waveforms. Such processing may include, for example, performing arithmetic manipulations on a signal waveform or combining multiple input signal waveforms in some predetermined manner. The resulting function waveforms are stored in a display memory for subsequent retrieval and display. In addition, memory waveforms may also be displayed. Memory waveforms are waveforms which have been previously captured and stored in a memory device of the signal measurement system. In addition to the above waveforms, other display elements such as marker indicators, trigger indicators, etc., are typically displayed.
A primary function provided by signal measurement systems in the analysis of signals is to enable an operator to perform an automated measurement of a desired signal parameter. Automated measurements allow an operator to quickly and accurately determine values of key attributes of acquired signals without the use of manual calculations. Automated measurements are also a useful and productive technique for characterizing electrical signals using common, well-understood quantities such as peak-to-peak voltage, rise time and frequency. In addition, automated measurements are often used to verify that a given circuit or hardware component as satisfies established performance specifications.
To invoke an automated measurement of a signal waveform displayed in a conventional signal measurement system, a number of operator actions are typically required to be performed. These include the performance of one or more actions to select a desired measurement, followed by additional actions to identify a waveform on which to perform the measurement, referred to herein as the source waveform. In addition to associating the selected measurement with a selected waveform, additional information often needs to be specified. This information may include, for example, the portion or extent of the source waveform over which the selected measurement is to be applied. This extent most often corresponds to a certain time period of the source waveform.
Conventional techniques for invoking oscilloscope measurements often involve the use of push-button keys on the instrument's front panel. A measurement is selected by depressing a dedicated key with the associated measurement's name printed on or above it. A source waveform is subsequently identified, either by pressing a key associated with a particular channel, or by turning a knob that scrolls through a list of possible sources.
In another conventional approach, the desired measurement is selected by pressing a multifunction ‘softkey’ having a currently-assigned function of invoking a given measurement. Typically, the softkey is located near a textual or graphical display whereat the key's current function is displayed. With this approach, the current function of the softkey must first be assigned through the activation of a ‘menu’ or ‘setup’ key. The menu/setup key may be a fixed function key located on the front panel, or may itself be a softkey having a currently-assigned function of assigning functions to one or more other softkeys. In such conventional systems, source waveform selection is typically accomplished with still additional softkey operations. In other conventional instruments, a hybrid solution is employed. For example, in one conventional approach, measurement selection is accomplished with fixed functions keys while source waveform selection is performed using softkeys.
As noted, in addition to selecting the measurement and source waveform, oftentimes a specific region of the source waveform must be selected by the user. Typically, this is achieved by the operator selecting a desired horizontal extent of the source waveform for measurement. For example, an individual pulse among a series of pulses may need to be selected to measure the period of the signal. Conventional signal measurement systems employ several different methods to select a specific waveform extent or region. In one conventional approach, measurements are applied to the first cycle of the displayed waveform beginning with the left-most pulse. In these systems, the horizontal position controls must be adjusted by the user so that the pulse of interest appears at the left-most position on the waveform display prior to invoking the measurement on the waveform.
In other conventional approaches, a set of marker indicators (visual lines with adjustable vertical and horizontal positions) must be activated and positioned such that the markers bound the region of the source waveform to be measured. Yet another technique is to eliminate the need for region selection by adjusting both horizontal scale and position and, perhaps, the trigger specification, such that only the pulse of interest appears on the waveform display.
There are a number of drawbacks to these latter conventional approaches. First, these conventional techniques require multiple key presses and/or knob turns to be implemented in a specified sequence in order to properly invoke a measurement. Not only is such an arrangement difficult to understand and operate, considerable time is consumed performing the requisite steps to obtain a desired measurement. This is particularly problematic when a number of measurements are to be performed on different regions of many waveforms. Moreover, the it requirement to select a region or horizontal extent often places additional sequencing constraints on the overall invocation process. Common to many implementations of conventional systems is the requirement that the identification of the waveform region must be performed prior to selection of the measurement. Thus, these conventional approaches require both the source waveform and waveform region to be identified prior to the selection of the automated measurement. This is often counter-intuitive to the typical user who most often wants to choose the measurement first, then apply the measurement to a certain extent of a certain displayed waveform.
A further drawback to the above conventional approaches is the limited indications provided to the user with instructions and feedback. For example, certain measurements are only applicable to certain types of waveforms. Conventional systems typically provide no indications to notify a user whenever an attempted application of a particular measurement to a particular waveform is incorrect. As a result, the user may navigate through a significant series of softkey layers to select the source waveform, manipulate various knobs to identify the region to measure, and then again navigate among a number of so
Agilent Technologie,s Inc.
Luu Sy D.
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