Tektronix, Inc.

Gordon W Shank

Daniel G Knierim

Eric P Etheridge

Lloyd R Bristol

David H Eby

Jeffrey A Kleck

Henry G Fox

Kevin A Robertson

Earl P Eason

To increase the percentage of time that an input signal is actively monitored, a digital oscilloscope has an acquisition system (100) that includes an analog-to-digital converter (15), an acquisition memory (40), an acquisition rasterizer (50), and a raster acquisition memory (60). The rasterizer contains circuitry (52) for concurrently rasterizing and combining the results of several acquisitions together and with a stored composite raster image to produce a new composite raster image, while additional acquisition records are being created and stored in the acquisition memory. A display system 200 takes the composite raster images after they contain the results of many acquisitions and overlays these single-bit raster images on a multi-bit raster image that is then decremented to produce a simulated persistence effect. The number of new pixels turned on as a result of each acquisition can be counted during the combining process and used to stop acquisitions, signal the operator, or specially treat that particular acquisition when the number of new pixels created by a particular acquisition exceeds a predetermined value. Acquisition circuitry for multiple channels can be used on one channel to further increase the percentage of time that the signal is monitored.

Digital oscilloscope architecture for signal monitoring with enhanced

To increase the percentage of time that an input signal is actively monitored, a digital oscilloscope has an acquisition system (100) that includes an analog-to-digital converter (15), an acquisition memory (40), an acquisition rasterizer (50), and a raster acquisition memory (60). The rasterizer contains circuitry (52) for concurrently rasterizing and combining the results of several acquisitions together and with a stored composite raster image to produce a new composite raster image, while additional acquisition records are being created and stored in the acquisition memory. A display system (200) takes the composite raster images after they contain the results of many acquisitions and overlays these single-bit raster images on a multi-bit raster image that is then decremented to produce a simulated persistence effect. The number of new pixels turned on as a result of each acquisition can be counted during the combining process and used to stop acquisitions, signal the operator, or specially treat that particular acquisition when the number of new pixels created by a particular acquisition exceeds a predetermined value. Acquisition circuitry for multiple channels can be used on one channel to further increase the percentage of time that the signal is monitored.

A zero dead time acquisition system for a digital storage oscilloscope (DSO) has an input buffer that stores an initial value from an acquisition memory for each sample interval of an input analog signal. The input analog signal is oversampled and digitized so that there are multiple digitized samples of the analog signal for each sample interval. At the beginning of a sample interval the initial value from the input buffer is transferred to an accumulation register, the output of which is compared with the multiple samples of the analog signal during the sample interval. If any of the multiple samples falls outside the limit determined by the value in the accumulation register, in a save on delta mode a latch is set to generate an error signal that terminates further acquisition cycles. In an envelope mode the comparison result causes the value in the accumulation register to be replaced with the sample value that fell outside the limit to establish a new limit, either maximum or minimum. At the end of the sample interval the value in the accumulation register is transferred to the acquisition memory while a new initial value is transferred to the accumulation register. In this manner both envelope and save on delta modes are implemented directly in the acquisition memory without requiring digital processing time so that the hold-off time after the acquisition cycle may be reduced to zero, producing 'zero dead time.'

Zero dead time acquisition for a digital storage oscilloscope

An apparatus and method for digitizing a repetitive waveform using an analog oscilloscope uses a successive approximation technique. For each sample point on the repetitive waveform a digitizing level is compared with the repetitive waveform at that sample point, and the digitizing level is adjusted until it essentially equals the magnitude of the repetitive waveform at that point. The particular sample point is determined by comparing a delay level with a ramp signal that starts from an initial fixed trigger point on the repetitive waveform. Each point is digitized in this manner in one of three modes. The first mode samples the same point on successive iterations of the waveform until that point is digitized, and then the next point is digitized. The second mode samples each point once per iteration of the waveform by stepping the delay level n times during each iteration, and adjusting the digitizing level individually for each sample point until the digitization is complete. The third mode generates a fast ramp having n cycles per iteration of the waveform so that the delay level stays the same, but each sample point is sampled once each waveform iteration. Otherwise it is essentially the same as mode two. In like manner maxima and minima for segments of the waveform may be determined using a window interval rather than a sample pulse.

Analog oscilloscope digitizer

An oscilloscope automatically measures an interval between first and second triggering events in a repetitive input signal. The oscilloscope includes A and B sweep circuits for generating event triggered 'A' and 'B' sweep ramps, respectively. The oscilloscope also includes two comparators. One comparator generates an 'A' indicating signal when the A sweep ramp reaches the level of a first adjustable reference signal. The other comparator generates a 'B' indicating signal when the B sweep ramp reaches the level of a second adjustable reference signal. The oscilloscope initially sets both sweep circuits to repetitively trigger on the first event and sets the first reference signal to a constant level. While monitoring relative timing of the A and B indicating signals, the oscilloscope iteratively adjusts the second reference signal to a 'first pass' level for which the A and B indicating signals are repetitively generated at substantially similar times. Thereafter, the B sweep ramp is set to repetitively trigger on the second triggering event while the A sweep ramp continues to repetitively trigger on the first triggering event. The oscilloscope then iteratively adjusts the second reference signal to a 'second pass' level at which the A and B indicating signals are again generated at substantially similar times. The difference between the first and second pass levels is proportional to, and therefore a measure of, the interval between the first and second trigger events.

Time interval measurement system for analog oscilloscope

A method of measuring automatically the peak-to-peak amplitude of electrical input signal utilizes both trigger circuits of a dual trigger oscilloscope. The steps of the method include adjusting automatically the trigger level of the first trigger circuit until the first trigger level is equal to the maximum peak of the input signal while adjusting automatically the trigger level of the second trigger circuit until that level is equal to the minimum peak of the signal. The second level is then subtracted from the first level to calculate the amplitude. To minimize the time involved, the method distinguishes between signals faster than and slower than a preselected frequency and calculates more rapidly the amplitude for faster signals. Time is also minimized by adjusting hysteresis levels and voltage level settling times as the trigger levels are increased and decreased in search of the peak signal values.

Automatic peak-to-peak amplitude measurement system

A method for automatically expanding and displaying a narrow pulse on an oscilloscope screen. The time sweep signal of the oscilloscope is first set to contain a predetermined number of input signal cycles. The speed of the time sweep is increased by an internal controller a number of settings to expand the signal cycle by a factor sufficient to place less than a single signal cycle within the sweep signal and an expanded singal pulse of greater than a specified duty factor outside the sweep signal. The dual trigger generators of the scope are set to trigger on opposite slopes of the pulse. If both trigger generators trigger, then the pulse is within the specified duty factor and the controller directs it to be displayed on the oscilloscope screen in its expanded form. The specified duty factor can be made exact by adjusting the duration of the sweep signal to match the duration of the duty factor once the period of the signal cycle is determined.

Automatic pulse display

A delayed sweep oscilloscope having a word recognizer displays multi-digit parameters representing an event count necessary to initiate a delayed sweep, and a word to be recognized on oscilloscope data input lines. The numbers are modified digit-by-digit by rotating a first control knob to move a cursor on the screen to select a digit to be altered and then by rotating a second control knob to alter the selected digit. The control knobs are mounted on the oscilloscope front panel and when not used to modify these parameters, the control knobs may be used to control other oscilloscope functions.

Method and apparatus for adjusting displayed oscilloscope parameters

An oscilloscope displays a menu consisting of set of field codes and one configuration code set grouped with each field code. Each field code represents an oscilloscope operating parameter while each configuration code represents an alternative oscilloscope operating mode associated with the operating parameter. A configuration cursor is displayed underlining one configuration code in each field thereby indicating the current operating configuration of the oscilloscope. The configuration of the oscilloscope may be changed by first rotating a first control knob, mounted on the oscilloscope front panel, to locate a field selection cursor under a selected field code and then by rotating a second control knob to move the associated configuration cursor under the desired configuration code. The configuration of each field may be altered by selective operation of the two control knobs in this manner. The menu is displayed only when the oscilloscope configuration is to be changed and the two control knobs are used for other oscilloscope control purposes when the menu is not displayed.

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Portland, OR, United States of America

Gordon W Shank