Abstract: A method for determining the period of a periodic signal, possibly including noise, includes the step of calculating a signal representing the difference between the periodic signal, and the periodic signal delayed by a time T. The variance of the difference representative signal is then computed. The steps of computing a difference signal, and determining the variance of the difference signal is repeated for different times T. The period of the periodic signal is determined to be the time T producing the minimum variance. Apparatus implementing this method includes a source of the periodic signal. A difference circuit computes a signal representing the difference between the periodic signal, and the periodic signal delayed by a time T, and a variance circuit computes a signal representing the variance of the difference representative signal. A control circuit varies the time T. A minimum selector selects the time T producing the minimum variance as the period of the periodic signal.

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 providing a probing interface for a circuit under test exhibits a relatively narrow profile and a vertical orientation so that it does not block access to connectors in adjacent slots. The vertical orientation is made possible by the use of a circuit material comprising alternate sections of flexible material and rigid material. Advantageously, the signal lines between the circuit card under test and its motherboard are direct and relatively short, and the probing connection points are isolated from the direct signal lines by a plurality of isolation resistors. The probing adapter includes the capability of monitoring the bus of the system under test and disassembling monitored AGP codes.

Abstract: A channel member for a PALC panel includes a transparent plate having a planar surface and first and second electrodes on the planar surface of the transparent plate. The first electrode has a width in the range 35-90 .mu.m and a height in the range 0.5-30 .mu.m and the second electrode has a width in the range 30-70 .mu.m and a height in the range 0.5-30 .mu.m. A rib is attached to the first electrode and has a width in the range 15-40 .mu.m, a height in the range 80-200 .mu.m and a ratio of height to width of at least about 5:1.

Abstract: A system for phase-locking a clock to a digital audio signal embedded within a digital video signal uses an audio extractor, frequency dividers, and an adjusted bandwidth loop filter to prevent phase jitter associated with the digital audio signal preventing the functionality of the phase-lock loop or having unacceptable effects on the generated audio sample frequency signal. Extracted audio samples are divided down and input to a phase detector. The signal is then filtered using a series of loop filters, one of which has an adjusted bandwidth to reject phase jitter. A clock then outputs the generated synthesized audio sample frequency using the output from the series of loop filters, and the synthesized frequency signal is looped back through a second frequency divider to the phase detector.

Abstract: An electronic instrument includes a housing having opposed end surfaces each including a handle mount. A bail handle with an elongated middle portion has extending arms connected at opposite ends, and the arms have free ends for connection at the handle mounts. The handle pivots between a first stable position and a second stable position about a pivot axis passing through the handle mounts. A pair of detent mechanisms each have a first portion connected to the housing, and a second portion connected to the handle, and each detent mechanism includes a spring which urges the first and second portions toward each other along the pivot axis.

Abstract: A channel structure for a PALC display panel comprises a channel member defining at least one channel, a cathode having an upper surface exposed in the channel, and an anode having an upper surface exposed in the channel. The upper surface of the anode is of substantially uniform composition and has a conductivity perpendicular to its upper surface of at least about 10.sup.-4 ohm.sup.-1 cm.sup.-1.

Abstract: An improved time domain reflectometer (TDR) includes a capacitor coupled in series between a transmission medium under test and the TDR receiver input. A switch, operating under microprocessor control, selectively couples and uncouples the capacitor to a voltage reference, such as ground. During the generation of interrogating pulses from the TDR and the acquisition of data from the transmission medium under test, the capacitor is uncoupled from the voltage reference and acts as a DC blocking capacitor. During periods of non-TDR activity, the capacitor is coupled to voltage reference and acts as a load for low frequency interference appearing on the transmission medium. The capacitor-switch operation blocks low frequency interference signals from the receiver input of the TDR.

Abstract: An interleaved digital peak detector has multiple acquisition pipes with each pipe receiving a common input signal. Each acquisition pipe receives a common sample clock signal that is delayed through an analog delay circuit for selectively delaying the sample time of each analog-to-digital converter in the pipe. Each pipe has peak detector that receives the digitalized output from the analog-to-digital converter and accumulates maximum and minimum peak values. A programmable decimator receives the sample clock signal and a decimation value for establishing an acquisition clock by decimating the sample clock signal as a function of the decimation value to trigger a latch circuit for storing the accumulated maximum and minimum values from the peak detector.

Abstract: A plasma addressed liquid crystal display panel includes a channel substrate, a cover sheet sealed to the channel substrate and extending over the channels in the channel substrate, helium in the sealed volume defined by the channel substrate and the cover sheet at a partial pressure within the range from about 50 mB to about 350 mB, and a body of a storage material that reversibly absorbs and releases hydrogen, the hydrogen being present at a partial pressure in the sealed volume within the range from about 0.02 mB to about 36 mB.

Abstract: A video error/distortion checker generates a difference signal from an input repetitive digital signal and a reference data signal corresponding to the input repetitive digital signal. The difference signal is compared with maximum and minimum threshold values to generate an error signal when the difference signal exceeds either threshold value. The difference signal also is used to generate a running range value that is compared with a total range value to produce the error signal when during one iteration of the repetitive digital signal the difference signal exceeds a specified range defined by the total range value. The error signal is suitably displayed, either visually or alphanumerically or both, so that an operator may recognize the type, severity and location of errors in the repetitive digital signal.

Abstract: An anode in a channel of a PALC display panel is composed of an electrically conductive core and a protective coating made of a material that is electrically conductive and is non-reactive with hydrogen.

Abstract: An adaptive cursor for interpreting displays of grouped data words highlights all of the bits of a segment associated with the bit position of the cursor. The grouped data words are extracted as an ancillary block from a serial digital input signal block. The format for the grouped data words is stored in a programmable read only memory (PROM). A microprocessor accesses the PROM according to the bit position of the cursor to determine the bits that make up the segment, and causes the segment to be highlighted. The microprocessor also decodes the segment to provide a corresponding alphanumeric display.

Abstract: An apparatus for acquiring waveform data from a metallic transmission cable under test includes a transmitter for generating interrogating pulses for examining a segment or segment lengths of the transmission cable under test. A variable gain receiver receives a return signal from the segment or segment lengths of the cable and generates at least two gain segment acquisitions of waveform data representative of the signal from each segment or segment lengths with each gain segment acquisition of waveform data being generated with a different receiver gain. A controller operating under program control initiates the generation of interrogating pulses, establishes the receiver gain for each gain segment acquisition of waveform data, and controls the gain segment acquisitions of waveform data over the segment or segment lengths. An event table is created containing event characterization data for each gain segment.

Abstract: A method for rasterization of a set of voltage-versus-time data-address pairs into horizontal and vertical locations of a multi-bit raster display memory of a digital oscilloscope or similar electronic data acquisition instrument is disclosed. It provides a new way of controlling digital intensity, by allowing the operator and/or a function based on the instrument's trigger rate to set the number of intensity units available for brightening the pixels affected by the rasterization of each acquisition data pair. If a vector has more pixels than there are units of intensity available, the number of pixels that are to be brightened is limited but spread out over the vector's length by an algorithm that includes at least some degree of randomization. If there are more units of intensity available than there are pixels to put them in, the extra ones can either be distributed into each pixel or randomly added along the vector or ignored.

Abstract: A PALC panel is filled with LC material by creating a partial vacuum in the LC space and a peripheral receiving space inward of an attachment bead which secures the lower substrate assembly to the upper substrate assembly and introducing sufficient LC material into the receiving space to fill the LC space. The receiving space is then sealed. The volume of the receiving space is substantially greater than the volume of the LC space.

Abstract: An improved pulse generator circuit includes a pulse shaper circuit for generating interrogating bipolar pulse having reduced or no energy at zero frequency for use in a measurement test instrument for characterizing a transmission medium, such a twisted pair and coaxial transmission cables.

Abstract: A logic analyzer uses a single tapped delay line and a single array of sampling cells for high speed digital signal acquisition, by controlling both edges of a substantially 50% duty cycle clock signal to drive a delay line buffer chain. The chain operates continuously; there being no need for interruptions for precharge intervals. Thus, the need for a second delay line buffer chain is eliminated.

Abstract: A method by which a microprocessor based handheld multi-meter, or other handheld electronic instrument, can communicate with a computer or other microprocessor based device through the measurement input jacks of the handheld multi-meter. A handheld meter, thus equipped, can receive control or calibration data from, and provide test or calibration data to, a host computer or microprocessor based accessory or other instrument. To enable this capability, the handheld meter employs dual-signal, single-axis jacks, for example split banana jacks, for one or more of its signal and ground receptacles. The handheld meter and the computer, or another microprocessor based instrument or accessory device that the meter is to communicate with, are equipped with mutually compatible software and appropriate hardware to support single signal path communication.

Abstract: A dynamically controlled timing signal generator includes a source of a controlled current, a timing signal generating circuit coupled to the controlled current source for generating the timing signal, and a feedback circuit coupled to the controlled current source for controlling the controlled current source to produce a desired controlled current.