Abstract: A system, apparatus and method for performing differential return loss measurements and other measurements as a function of frequency uses a digital storage oscilloscope (DSO) having spectral analysis functions. A waveform generator generates a differential test signal in the form of a series of pulses where each pulse includes spectral components associated with each of a plurality of frequencies of interest. A test fixture presents the differential test waveform to a load including at least one of a device under test (DUT), a short circuit, an open circuit and a balanced load. A signal acquisition device differentially measures the test waveform during each of the load conditions. The signal acquisition device computes an error correction parameter using measurements made during the short circuit, open circuit and balanced load conditions. The correction parameter tends to offset signal acquisition errors within measurements made during the DUT load condition.

Abstract: An acquisition apparatus for a test and measurement instrument includes an input to receive an input signal, a digitizer to digitize a selected signal, a bypass path to selectively couple the input to the digitizer, a frequency shift path to frequency shift the input signal and selectively couple the frequency-shifted input signal to the digitizer, the frequency shift path including a means for frequency shifting, an input switch to switch the input signal to one of the bypass path and the frequency shift path, and an output switch to provide the selected signal to the digitizer by selectively coupling an output of one of the frequency shift path and the bypass path to the digitizer.

Abstract: A method and apparatus for selectively providing bandwidth extension and channel matching for acquired signals under test (SUT). The method and apparatus includes a signal acquisition device for acquiring a signal under test (SUT) and generating therefrom a stream of acquired samples, where the signal acquisition device having associated with it a first bandwidth defining a nominal pass band. At least one digital filter imparts a gain equalization function to the acquired SUT samples within a spectral region including and extending beyond the nominal passband. A controller generates a display signal suitable for use by a display device, where the display signal representing waveform imagery associated with the gain equalized SUT.

Abstract: An enhancement filter for an oscilloscope is disclosed wherein the enhancement filter may be initially calibrated for one or more channels and/or for one or more attenuation settings such as 50 mV per division, 100 mV per division, and/or 200 mV per division, for example. In one embodiment, a desired filter response is selected to have a modified Gaussian type filter function having an at least approximately linear phase response, wherein the transfer function of the desired filter response comprises a step response that is be stored in the oscilloscope to be used as a part of calibration system of the oscilloscope.

Abstract: An apparatus and method for constraining an amplitude range parameter associated with the acquisition and display of a signal under test (SUT) acquires samples of the SUT that are constrained according to the amplitude range parameter to generate a stream of acquired samples representing a constrained SUT. A controller generates a display signal suitable for use by a display device that includes constrained SUT waveform imagery visually cooperating with amplitude segment delineators. The controller adapts the number of amplitude segment delineators in response to the amplitude range parameter.

Abstract: Apparatus for rapidly acquiring a large number of samples of a signal under test, stores the samples in a waveform memory without converting the samples to binary form. The signal under test is applied to an arrangement of comparators and exclusive-OR gates to provide a signal indicative of amplitude. The waveform memory is arranged in rows and columns. In one embodiment, the amplitude-indicative signal serves as a row address signal for the waveform memory, and a scanning control signal serves as a column address signal for the waveform memory. In another embodiment, an X-Y display is produced in which the column address signal is responsive to the amplitude of a second signal under test.

Abstract: A test and measurement instrument acquires a signal from a device under test, displays that signal as a source waveform, and makes measurements on that source waveform with regard to a predetermined property or event. The test and measurement instrument employs the method of the subject invention for placing these measurements into a waveform and directly correlating a position in the measurement waveform to the same area on the source waveform where they were measured. Specifically, the subject invention displays the correlation of points on a source waveform and a measurement waveform without requiring the use of a common horizontal time scale. In one embodiment of the invention, the measurement waveform is a histogram and a pointer to a given location in the histogram causes identification of corresponding areas in the source waveform.

Abstract: An apparatus and method for constraining temporal parameters associated with the acquisition and display of signals under test acquires samples of a signal under test (SUT) as corresponding sample records with each sample record having associated with it a duration parameter. Display grids cooperate with the resulting waveform imagery by either being locked to the waveform image or locked to a display frame. A controller allows a user to select a number of volts for each vertical grid segment and an amount of time for each horizontal grid segment. The duration parameter determines the length in seconds of the acquired waveform as displayed, which parameter may be changed by adjusting the timebase parameters of record length or sample rate. Therefore when displayed the number of grid lines change as the waveform is expanded or contracted (locked to waveform), or the units between grid lines change as the waveform is expanded or contracted (locked to display frame).

Abstract: A gate comparator control panel, in accordance with the subject invention, allows a user to define up to four different gate regions that may exist on any of the live waveforms, maths waveforms, or REF waveforms. A menu for each gate controls the position of each gate and selects the source for the signal that is to be gated. All gates must be the same width. A high level application copies the gated region of a waveform into a REF memory. For example, Gate 1 would go into REF 1, gate 2 into REF2 and so on. A user-settable tolerance value is used to determine if difference between the waveforms of the gates reaches a point at which a violation is indicated. A master gate position control causes all gates to move by the same amount, thus maintaining a constant distance between them. A master gate width control causes all gates to change width.

Abstract: A combined analog and DSP trigger system for a digital storage oscilloscope (DSO) enables the DSO to real-time trigger on events in an input analog signal based on traditional trigger events in the input analog signal and/or predetermined anomalous events detected in digitized samples of the input analog signal. A processor receives the digitized samples at the input of an acquisition memory to detect the anomalous events and provides an event detect signal to the trigger system. Predetermined amounts of the digitized samples around the events are acquired in an acquisition memory for further processing and display.

Abstract: A real time digital storage oscilloscope acquires a long data record in an acquisition memory and processes the data of the long data record to search for predetermined events. Upon detection of such a predetermined event, circuitry generates an event detect signal, and data comprising an acquisition frame surrounding the event is applied to a waveform processing and display system. The long data record can be replayed in order to perform additional searches throughout the data record using different search criteria, thereby permitting multiple waveforms to be displayed simultaneously, each being captured as a result of a different user-defined event. A screen display may be programmed to display a different kind of event such as Runt signal, Overshoot, or Pulsewidth Violation in each waveform, or to display multiple occurrences of the same kind of event such as Runt signal in each waveform.

Abstract: An apparatus and method for constraining temporal parameters associated with the acquisition and display of signals under test.

Abstract: An apparatus and method for constraining amplitude range parameters associated with the acquisition and display of signals under test.

Abstract: A real time multi-channel digital storage oscilloscope acquires a relatively long data record for each channel in an acquisition memory and processes the data of the relatively long data record to search for predetermined events. Upon detection of such a predetermined event, circuitry generates an event detect signal, and data comprising an acquisition frame surrounding the event is applied to a waveform processing and display system. The relatively long data record can be replayed in order to perform additional searches throughout the data record using different search criteria, thereby permitting multiple waveforms to be displayed simultaneously, each being captured as a result of a different user-defined event. A screen display may be programmed to display a different kind of event such as Runt signal, Overshoot, or Pulsewidth Violation in each waveform, or to display multiple occurrences of the same kind of event such as Runt signal in each waveform.

Abstract: A system, apparatus and method for performing differential return loss measurements and other measurements as a function of frequency using a digital storage oscilloscope (DSO) including spectral analysis functions.

Abstract: A frequency domain analysis system incorporated into time domain measurement instrument has duration and resolution controls that respectively adjust the acquisition time intervals of a waveform record in seconds and adjusts the number of digital data samples over a specified duration. The duration of the acquisition waveform may be controlled using the duration control adjustment, a sample rate adjustment and a record length adjustment. The resolution controls concurrently adjusts the sample rate and the record length of the acquisition waveform while maintaining the duration constant. A movable and variable length frequency spectrum gate is applied to the digital data samples of the acquired waveform. A window filter is applied to the digital data samples within the gated region a spectrum analysis generator generates frequency domain values over the gates waveform record.

Abstract: A digital storage oscilloscope is capable of responding to its usual assortment of analog trigger signals and is also responsive in real time to an event detection signal provided by a processor unit having an input coupled for receiving a data stream from an A/D converter. The processor unit examines the streaming digital samples of a signal under test in real time for the occurrence of a predetermined event. Upon detection of one of the predetermined events, a frame of data surrounding the event is captured for waveform processing and display. Multiple waveforms can be displayed simultaneously, each being captured in response to a detection of a user-defined anomalous event. A screen display can be programmed to display a different kind of event such as Runt signal, Overshoot, or Pulsewidth Violation in each waveform, or to display multiple occurrences of the same kind of event such as Runt signal in each waveform.

Abstract: A real time digital storage oscilloscope acquires a long data record in an acquisition memory and processes the data of the long data record to search for predetermined events. Upon detection of such a predetermined event, circuitry generates an event detect signal, and data comprising an acquisition frame surrounding the event is applied to a waveform processing and display system. The long data record can be replayed in order to perform additional searches throughout the data record using different search criteria, thereby permitting multiple waveforms to be displayed simultaneously, each being captured as a result of a different user-defined event. A screen display may be programmed to display a different kind of event such as Runt signal, Overshoot, or Pulsewidth Violation in each waveform, or to display multiple occurrences of the same kind of event such as Runt signal in each waveform.

Abstract: A real time multi-channel digital storage oscilloscope acquires a relatively long data record for each channel in an acquisition memory and processes the data of the relatively long data record to search for predetermined events. Upon detection of such a predetermined event, circuitry generates an event detect signal, and data comprising an acquisition frame surrounding the event is applied to a waveform processing and display system. The relatively long data record can be replayed in order to perform additional searches throughout the data record using different search criteria, thereby permitting multiple waveforms to be displayed simultaneously, each being captured as a result of a different user-defined event. A screen display may be programmed to display a different kind of event such as Runt signal, Overshoot, or Pulsewidth Violation in each waveform, or to display multiple occurrences of the same kind of event such as Runt signal in each waveform.

Abstract: A “Streaming Distributed Oscilloscope” (SDO) architecture comprises at least one channel including a preamplifier module, a Digitizer Module, and an Acquisition Memory Module. An SDO couples all acquired samples of a waveform being monitored to all of its processing boards. Because multiple processor boards can access all of the sample data, an SDO can perform measurements on substantially all samples of a continuous data stream without dead time. An SDO is readily expandable in terms of memory length by simply adding more memory boards, and can be reconfigured by a user by virtue of its object-oriented architecture. An SDO waveform is defined by a trigger source and an acquisition memory. An SDO is capable of acquiring multiple waveforms based upon different triggers from the same data stream in the same channel. An SDO timebase for a given channel is defined by a decimator followed by an acquisition memory. Multiple timebases can co-exist in the same SDO channel.