Abstract: A picture quality assessment method based upon spatial location with or without subsampling within the picture divides the video picture into a plurality of arbitrarily sized, geometric segments. A segment weighting map is generated that provides one value for “safe picture” segments of the video picture and another value for the other segments. Optionally one or more of the segments may be subsampled to reduce processing time for realtime applications. The video picture on a segment basis is compared with a corresponding test video picture using a picture quality assessment algorithm to generate a quality error value for each segment. The quality error values are weighted according to the segment weighting map, and on an error display the weighted quality error values are displayed.

Abstract: A flat panel liquid crystal display (10) has an addressing structure (12) that uses an ionizable gaseous medium captured within channels (2) in a first electrode structure (42). An electro-optical material (44) structure positioned between the first electrode structure and a second electrode structure (40) has thickness that is determined by spacers (104, 110, and 126) that are formed on second electrode structure at points directly opposite support structures (66) between the channels. Such spacers provide support for the second electrode structure and do not intrude into the active area (70) of the display. The spacers are preferably formed of a polyimide resin layer using a photoetch process. Particulate spacers (110) can also be entrained in a black surround material (110) before it is applied to achieve spacers confined to inactive regions. Alternately, spacers (126) can be formed of the black surround material using a two-step photoetching process.

Abstract: The present invention relates to a method for checking a data exchange between participants in a call established on a communication medium in compliance with a protocol. In order to identify the various stages in a call process conforming to the protocol and to break said protocol once the checking procedure has started, the invention suggests that the data exchange be captured by-means of a protocol monitor (PM) connected to a communication medium (CM) and based on the finite state automaton principle. The test automaton contains the same states and state variables as the protocol automaton designed to define the communication protocol, apart from the fact that the test automaton is allocated a plurality of values within the same range of corresponding state variable values in the protocol automaton.

Abstract: A cooling system for a test and measurement instrument including a variable-speed fan, useful with different instruments having different configurations, employs a plurality of sensors disposed at predetermined locations within an enclosure of the instrument, and is software programmable with predetermined parameters of each particular configuration of each particular instrument. At least one of the sensors measures the temperature of a component that dissipates power at a substantially constant rate, and at least one of the sensors does not include a heat source to provide heat for measurement.

Abstract: An ultra high frequency current probe is fabricated in the form of a surface mount device, designed to be a part of the circuit providing the current being observed.

Abstract: Unusual waveforms are defined in terms of how many “new” pixels are affected by the process of rasterizing them. New pixels can be those not yet affected by the rasterization of any waveform in the current set of acquisitions, or to be those that have had higher values in their raster memory location but have now been decayed to below a defined value. Once detected, such waveforms can be re-rasterized with extra intensity or into a different color by using a reserved range of values of those storable in the raster memory. Alternatively, the special region of values can be used as a counter/timer to maintain the pixels associated with unusual waveforms at a brightest intensity value, or in the color equivalent, for an extended period of time. User input can be used to affect the definition of “new” pixels and to control the special persistence given to unusual waveforms. Unusual waveforms can also be saved in long term memory.

Abstract: An apparatus for video clock and framing signal extraction by transport stream snooping parses MPEG2 Transport Packet headers from a transmission transport stream and partially decodes the headers to identify those corresponding to a specified packet identification (PID). From the specified headers a program clock is decoded and compared with a recovered program clock generated by a local clock oscillator and a local clock counter. The comparison is used to finely tune the recovered program clock frequency. Also from the heads video framing information is decoded, and such framing information and the recovered program clock are used to generate a video reference signal.

Abstract: An improved FIR filter based upon squaring is used to self-determine a filter constant equal to the sum-of-squares of the filter coefficients. An input signal is forced to zero for T samples, where T is the number of accumulator cells in an accumulator stage, and at the end of such zero samples the output from the filter is latched as the filter constant for use in filtering the normal input signal. The FIR filter may also be placed in a co-processor mode, using a FIFO register between the input of the FIR filter and a processor bus. A CPU on the bus initiates the co-processor mode and loads data into the FIFO. When the FIFO has data the data is read out and input to the FIR filter. The output of the FIR filter is placed on the processor bus. To determine the values of the filter coefficients loaded in the FIR filter, the data loaded by the CPU is an impulse signal having T−1 zero samples before and after an impulse sample, the output for each sample representing one of the filter coefficients.

Abstract: A correction method for an electronic instrument accessory probe utilizes an error correction equation wherein at least one term contains an exponent less than unity. One simple such equation is: S=Cs2+Bs+A+b|s|x (where 0<x<1), but additional terms may be added, either with integer exponents greater than 2, or with other fractional exponents less than one. In the most simple embodiment, there are only four coefficients and the only term with a fractional exponent has an exponent of ½ (i.e., x=0.5). A second set of coefficients may be needed for the correction of negative values.

Abstract: A compressed video and audio transport stream multiplexer pre-builds a multiplex pattern in microprocessor local memory using a microprocessor with a DMA controller. The transport stream headers, a null packet, program specific information tables and packetized elementary stream buffers accessed by an assembly buffer that has DMA control blocks, two blocks per transport stream packet. The DMA control blocks are built and loaded into the assembly buffer based upon the number of packets required for the packetized elementary streams and program specific information according to the multiplex pattern. Packetized elementary stream data is received from respective sources and loaded into the packetized elementary stream buffers, and then output according to the DMA control blocks in the assembly buffer to form the transport stream.

Abstract: An instrumentation receiver suitable for receiving a digitally modulated radio frequency input signal having a pilot signal at the RF frequency and symbol data generated at a symbol frequency generates a digitally modulated intermediate frequency signal having the pilot signal at the intermediate frequency equal to an integer multiple of the digital data's symbol frequency where the integer multiple is equal to or greater than one. A reference signal having a frequency equal to an integer multiple of the symbol frequency where the integer multiple is equal to or greater than one mixes with the IF signal to generate a control signal for controlling a local oscillator that generates a local oscillator signal for mixing with the digitally modulated RF input signal for locking the pilot signal to the reference signal.

Abstract: An adaptive equalizer for use in a digital transmission receiver includes Q-channel regeneration. A equalization filter produces complex valued equalized signal samples representative of a digital transmission signal. A slicer produces ideal real component values of the equalized signal samples. A Q-regeneration filter produces ideal imaginary component values of the equalized signal samples from the ideal real component values. The ideal real and imaginary component values are combined with the component values of the equalized signal samples to produce a complex valued error signal. The error signal is fed back to scale update values for updating coefficient values of the equalization filter. Delays in the equalizer provide storage to synchronize various equalizer signal and component values with the Q-regeneration filter output.

Abstract: An apparatus and method for inverting a color display on a dark background to produce a display on a substantially white background suitable for printing, includes the element of maintaining the same apparent relative intensities in both the LCD display on a dark background and the hardcopy displayed on a light background. The apparatus includes a memory including a first palette for the LCD display, a second palette for the hardcopy display, and a look-up table. A controller accesses the first and second palettes and look-up table for converting display data from LCD data to color-inverted printer data.

Abstract: High precision image alignment detection uses an iterative part pixel shift detection algorithm to accurately determine the displacement of a received image with respect to a reference image. An alignment pattern is inserted into the original image and a portion of the alignment pattern, such as a single line, also is stored as a reference image. Using cross-correlation the received image is compared with the reference image to locate the alignment pattern, and selected portions of the received image alignment pattern are then used in conjunction with the reference image to determine the total pixel shift of the received image. An integer pixel shift is determined by cross-correlation of the received alignment pattern with the reference image. Using the integer pixel shift to identify a starting point, data is extracted from the received alignment pattern about a specific feature and a part pixel shift is measured.

Abstract: An output amplifier for a strobed sampling circuit has first and second operational amplifiers coupled to receive the sampled output from the sampling circuit. The operational amplifiers each have a RC circuit having a high ohmic value resistor that is coupled from its inverting input terminal to its output terminal. The non-inverting input terminals receive biasing voltages that are coupled to the sampling circuit. The gating strobes to the sampling circuit produces a DC current through the feedback resistor as a result of strobe pulses being integrated by the RC circuit. Respective electronic switches are coupled in parallel with the RC circuits of the operational amplifiers and are closed at a predetermined time interval after each strobe pulse to discharge the stored charge on the capacitors prior to the next strobe pulse. The output signals from the operational amplifiers are summed in a summing amplifier.

Abstract: A new oscilloscope design improves the processing of acquired voltage-versus-time data through the efficient high speed acquisition and rasterization of such data into a form that includes multiple-bits-per-pixel intensity information. The multi-bit-per-pixel variable intensity rasterizer is optimized for maximum throughput and most efficient use of memory bandwidth. In the presence of faltering trigger rates, rasterization interruption provides a high probability of capturing the data associated with the slow triggers. Circuitry is provided to compensate for acquisition time and amplitude non-linearities. Many-bits-per-pixel intensity information is mapped into a fewer-bits-per-pixel format by a controllable transfer function that provides multiple viewing capabilities for the operator. Another mode of operation emphasizes infrequent events over commonly occurring ones using variations in brightness or color.

Abstract: A circuit for detecting and automatically responding to ground faults. A passive protection PTC resistor is coupled in series with an active protection switch, the active protection switch being controlled by a control circuit to open the switch when excess current is detected to be flowing in the common path of one of the channels. Floating and grounded versions are described.

Abstract: A trigger delay compensation arrangement for use in a digital storage oscilloscope, includes a trigger circuit for receiving a TRIGGER OUT signal generated from a logic analyzer in response to a logic analyzer trigger event signal, for starting a post trigger counter. It also includes a data entry circuitry for entering data input by a user, the data being representative of a delay between a reception of the logic analyzer trigger event signal and the generation of the TRIGGER OUT signal by the logic analyzer. A post trigger counter stops an acquisition of signal data upon expiration of a count of the post trigger counter. A controller, coupled to the data entry circuitry and to the post trigger counter receives the delay representative data, and adjusts the count of the post trigger counter in a direction to compensate for the delay.

Abstract: An apparatus and method useful in a test and measurement instrument for selecting a particular television field for display, determines the television system standard from the input signal, uses the standard selection to determine the time for one field, and multiplies the field rate by an operator-supplied number of fields to calculate the required holdoff time. The subject invention relieves the operator from turning the holdoff control multiple times, and also relieves the operator from having to calculate the time delays for any of one to seven fields of holdoff (in the case of a PAL signal).

Abstract: A measurement acquisition and display system generates graphical displays of Cumulative Distribution Function (CDF) peak-to-average power ratio measurements of a digitally modulated RF signal and an ideal digitally modulated RF signal, such as an 8-VSB digital television signal. A variable target operating point or planning factor value is enterable into the system that defines an operating point on the ideal CDF of peak-to-average power ratio display. The corresponding operating point on the RF signal CDF of peak-to-average power ratio display is determined and numerically displayed along with a numerical display of the difference between the ideal and real operating points. Alarm limit variables may be set for generating an alarm signal when the RF signal peak-to-average power ratio exceeds the alarm limits. The measurement acquisition and display system further generates a graphical display of channel frequency spectrum of the digitally modulated RF signal.