Abstract: A control circuit produces a control voltage for a tunable delay line in response to the magnitude of digital input data. The magnitude of the control voltage output corresponding to any digital input magnitude is independently adjustable to compensate for any nonlinear response of the delay to control voltage input such that the time delay produced by the delay line is substantially a linear function of the digital input to the control voltage source.

Abstract: A method for locking scales to a waveform display uses reference points from the waveform to determine starting scale points. Based upon the starting scale points and the characteristics of the waveform the scales are calculated. Any changes in gain in the waveform are applied to the scales so that the scales change in direct proportion to the waveform. The field/line numbers of a television video signal are tracked and displayed on the waveform display to identify that portion of the waveform relative to a picture frame which is being displayed.

Abstract: A voltage controlled, triggered oscillator includes a NAND gate and a set of series connected triggerable delay circuits, the output of the NAND gate being fed back to one of its inputs through the delay circuits. A trigger signal is applied to another input of the NAND gate and to triggering inputs of the delay circuits. When the trigger signal is asserted, each delay circuit produces an output signal of state which tracks the state of its input signal but with a predetermined delay so that the NAND gate output oscillates with a frequency determined by the delay times of the delay circuits and the propagation time of the NAND gate. When the trigger signal is deasserted the NAND gate output is terminated and each delay circuit drives its output signal high regardless of the state of its input signal so that the oscillator may be rapidly retriggered.

Abstract: A digitizer system includes M digitizers, each producing a separate waveform data sequence representing a succession of instantaneous magnitudes of an input signal at sample times determined by a periodic clock signal. Transmission of the clock signal to each digitizer is delayed by a corresponding adjustable delay time so as to control the relative sample timing of the digitizers. To adjust sample timing, a sine wave signal is applied as the input signal to each digitizer such that the M digitizers produce M separate waveform data sequences in response to said input signal and the M data sequences are interleaved and windowed to form a single waveform data sequence. A first sequence of complex numbers representing a discrete Fourier transform of the single waveform data sequence is generated and then a second sequence of M complex numbers is formed from elements corresponding to relative magnitude peaks of the first sequence.

Abstract: A measurement instrument has a plurality of operation levels with different respective sets of operational functions associated therewith. Each operational function has at least two independently selectable characteristics related thereto. When an operation level of the instrument is selected, the instrument displays the characteristics related to each operational function associated with the selected operation level, and the operator is able to select one characteristic related to the or each operational function associated with the operation level. The characteristics related to at least one of the operational functions may each have a single value, e.g. relating to a mode of operation of the instrument. If one of the characteristics has a range of values, a value of that characteristic may be selected within the range.

Abstract: An oscilloscope having a displayed trigger indicator is provided in which triggering level, slope, and source information on displayed directly on the viewing screen adjacent corresponding waveforms. In a preferred embodiment, a vertical bar represents the triggering level range, and a marker or dot is superimposed thereon to indicate the trigger level. Slope polarity is also indicated, as is triggering source. These indicators permit the triggering point to be quickly selected and set while viewing them in relationship to corresponding waveforms, and are always on screen for convenient reference and waveform photography.

Abstract: A method for determining the carrier frequency of a pulsed signal based upon nominal parameters for the pulsed signal input by an operator selects an algorithm based upon a duty factor calculated from the nominal parameters. For large duty factors a conventional maximum peak detection algorithm is used to identify a spectral line having the greatest amplitude as the carrier frequency. For smaller duty factors the first nulls on each side of the main lobe of the frequency spectrum for the pulsed signal are determined and used to calculate a carrier frequency. The spectral line having the maximum peak value within a window about the calculated carrier frequency is identified as the carrier frequency.

Abstract: A method for positioning cursors at a specific point on a displayed waveform uses a cursor to determine the maximum and minimum points on the waveform about a transition portion. For each position of the cursor between the maximum and minimum points an intersection between the cursor and the waveform is computed as a percentage of the difference between the maximum and minimum points. The cursor is then positioned at a point on the transition portion where the percentage is a desired value for the specific point.

Abstract: An apparatus for displaying the display outputs of a plurality of simultaneously active computer processes in corresponding windows on a single screen includes a microcomputer, a display screen and display system software. The software represents a plurality of virtual terminals, one corresponding to each active process, for emulating the operation of real terminals communicating with the processes. Each virtual terminal maintains a display list comprising a set of instructions defining a display on a screen according to the output from the corresponding process. The software also includes a screen process for maintaining a subrectangle list comprising a set of instructions for allocating window portions of the screen to the displays defined by the separate display lists. A display list processor is provided for creating the windows on the screen according to the display and subrectangle lists.

Abstract: A method for automatically finding color bars within a television video signal checks for a black burst at the end of a horizontal video line to determine the appropriate color bar standard for testing. Then a reference color burst, such as the yellow color burst, is searched for in the appropriate location within the horizontal line. Related color burst locations are demodulated to produce related color angles which are checked for relationship with the reference color burst. Also the luminance amplitudes for each color burst are compared to each other to determine whether a correct amplitude relationship is present. Each horizontal line of a picture frame is tested until either the color bars are found or all the horizontal lines have been tested. The found color bars are displayed in an appropriate format together with the line number within the picture frame, or a message indicating no color bars is displayed.

Abstract: An apparatus for controlling the pressure exerted on a probe in an integrated circuit testing station is disclosed. The apparatus is mounted to a support structure within the station directly above the probe. The testing station further includes a motorized lift system for moving an integrated circuit upward against the probe for testing. The invention uses a pressure pad positioned directly above the probe which is attached to the support structure using a resilient member. Associated with the pad is an electrical contact system connected to the lift system. As the lift system moves the circuit upward, it contacts the probe which pushes against the pad. Movement of the probe and circuit against the pad permits secure engagement of the probe with the circuit. As the circuit continues to move upward, the pad is urged upward, causing the electrical contact system to deactivate the lift system before damage to the probe occurs.

Abstract: A probe body for a measurement system comprises a probe-tip terminal for connection by way of a probe tip to a test point, a cable port for connection by way of at least one cable to a measurement instrument, probe circuitry, a function generator, and a switch. In a first state of the switch, the input terminal of the probe circuitry is connected to the probe-tip terminal and in a second state of the switch the input terminal of the probe circuitry is connected to the function generator. When the switch is in the second state, the function generator may be used to impress a signal having a predetermined waveform on the probe circuitry.

Abstract: A disk operating system converts virtual storage space locations of one or more processes into real disk or core memory storage space locations of a computer system. Real and virtual storage space are divided into equal sized pages. Real storage pages are grouped into variable sized segments and a separate segment page table is provided for each real storage segment, each entry therein characterizing the nature and location of a page. A separate process map list is provided for each process, each entry therein mapping an area of contiguous virtual storage pages onto a segment page table. Before a process executes a program, the operating system uses the associated process map list, along with the segment page tables mapped by the list, to create a process page table which directly maps virtual storage pages of a process into real storage pages.

Abstract: A cathode-ray tube has at least two mounting members that are angularly spaced about the axis of the CRT, and a support structure for receiving the CRT has mounting members for engagement with the mounting members of the CRT, whereby the CRT and the support structure have at least first and second pairs of mutually interengageable mounting members. The first pair of mounting members comprises a first cylindrical post and a circular hole for receiving the first post and the second pair of mounting members comprises a second cylindrical post and a slot having a width substantially equal to the diameter of the second post.

Abstract: A substrate structure having contact pads is mounted to a circuit board which has pads of conductive material exposed at one main face of the board and has registration features which are in predetermined positions relative to the contact pads of the circuit board. The substrate structure is provided with leads which are electrically connected to the contact pads of the substrate structure and project from the substrate structure in cantilever fashion. A registration element has a plate portion and also has registration features which are distributed about the plate portion and are engageable with the registration features of the circuit board, and when so engaged, maintain the registration element against movement parallel to the general plane of the circuit board. The substrate structure is attached to the plate portion of the registration element so that the leads are in predetermined position relative to the registration features of the registration element.

Abstract: A switchable color filter comprising a pair of twisted nematic liquid crystal devices (126 and 128) and a light polarizing system (108) which includes three color selective polarizing filters (102, 104, and 106) is incorporated as an optical subassembly in a field sequential color display system (100) to provide output states of white light and light of three different colors to form an image in full color and high brightness with strong color contrast.

Abstract: A pulse generator utilizes a pair of current sources acting through a pair of Schottky diode switches to provide load currents in opposite directions through a load resistor to produce an output voltage across the load resistor of magnitude proportional to the difference between the load current magnitudes. The pulse generator output voltage is abruptly driven to zero potential by applying balanced, rapid slewing voltage pulses to the Schottky diode switches, causing the switches to simultaneously divert the load currents from the load resistor. The balanced voltage pulses are developed at the terminals of a step-recovery diode by switching the step-recovery diode from forward to reverse bias state.

Abstract: A stereo signal separation system for separating the L+R and L-R components of a BTSC stereo signal mixes the BTSC signal with a multiple of the pilot frequency. To recover the L+R component the mixer output is combined with the input BTSC signal, and to recover to L-R component the mixer output is combined with a second mixer output shifted ninety degrees. The combined output is low pass filtered to recover the desired component.

Abstract: A strain relief system for flexible circuits has a tapered cover laminate affixed to either side of the flexible circuit to form a cover laminate/flexible circuit assembly, with the widest portion of the cover laminate being at the point of maximum bending stress of the flexible circuit to provide a stiffer assembly at that point. A rigid stiffener having a bending radius also is affixed to either side of the cover laminate/flexible circuit assembly at the point of maximum bending stress to provide strain relief, the bending radii being laterally offset from each other so that bending in opposite directions occurs at different locations of the flexible circuit. The result is a gentle, low stress bend in the flexible circuit when subjected to regular bending.

Abstract: A frame buffer memory has a random access memory (RAM) for storing pixel data words, each word containing pixel data corresponding to a separate set of a plurality pixels along a horizontal raster line of a screen display. Each word is separately addressed.The RAM is organized into tiles, with each tile comprising an array of pixel data word rows and columns corresponding to a separate rectangular subset of horizontally and vertically contiguous display pixels. The RAM is addressed by sequentially applying row and column addresses. A first subset of the column address determines which pixel word row within each tile is addressed, while and a second subset of the column address determines which pixel word column within each tile is addressed. All other bits of the row and column addresses determine which tile is addressed.