Abstract: A variable frequency synthesis apparatus and method use a phase prediction signal to enable integer division in the feedback path of a phase-lock-loop to provide an output signal at a rational frequency multiple of an applied reference signal. A fixed integer divide ratio is maintained within each period of the reference signal. The output signal provided by a variable frequency oscillator is frequency divided and is phase compared to the reference signal. The phase comparison produces a predictable, time-varying phase difference signal based on a known frequency difference between the output signal and the reference signal. The phase prediction signal cancels the predictable phase difference signal and isolates an phase error signal used to steer, or adjust, the frequency of the oscillator to precisely equal the rational frequency multiple of the applied reference signal when the phase error signal is minimized.

Abstract: A coaxial connector mounts directly to a planar substrate of a circuit module and is oriented perpendicularly to the substrate. A radially symmetric coaxial structure, maintained through a conductive bore in the substrate provides a good impedance match to a planar transmission line on the substrate. A flange of the coaxial connector provides the mating surface to the substrate. A nipple formed on the flange fits in the conductive bore, aligning the center conductor in the conductive bore and maintaining the coaxial structure. A bond connects the center conductor to a microstrip transmission line on the top of the substrate. In a first preferred embodiment of the present invention, a threaded flange receives a threaded coaxial bead to form the coaxial connector. In a second preferred embodiment a coaxial cable is soldered into a smooth flange to form a coaxial connector. In a third preferred embodiment a coaxial bead and a flange are integrated to form the coaxial connector.

Abstract: A detector array spectrometer simultaneously monitors wavelength, power, and signal-to-noise ratio of wavelength division multiplexed (WDM) channels in telecommunication networks. A spectrometer spatially separates signals from the WDM channels according to the channels' wavelengths. The separated signals are incident on an array of split-detectors that conforms to the spatial separation of the signals provided by the spectrometer. While the split-detectors are positioned to receive a signal from each WDM channel, a noise detector is positioned between adjacent split-detectors to measure noise. A common mode output from two halves of each split-detector indicates the power in a WDM channel, while a differential output from the halves indicates wavelength deviations in the WDM channels. The ratio of the common mode signal to the noise detector signal is used to monitor the signal-to-noise ratio of the WDM channel.

Abstract: In the present invention, a line driver circuit enables multiple timing signal generators to simultaneously deliver a timing signal to a load. The multiple or redundant timing signal generators each having a line driver circuit, provide an uninterrupted timing signal that is independent of failures of individual timing signal generators. The multiple timing signal generators share the task of providing the timing signal, i.e. power, to the load. In the event of a failure of one of the timing signal generators, the task of providing power to the load shifts to other of the multiple signal generators, maintaining an uninterrupted timing signal, undisturbed in amplitude, phase and pulse shape. The line driver of each timing signal generator has a drive capability to exceed that required for the timing signal. A voltage clamp regulates the amplitude of the timing signal when the timing signal generators are simultaneously functioning.

Abstract: A dumbbell shaped resonator efficiently couples IF signals from short transmission lines to an output transmission line at a radio frequency (RF) mixer's IF output port. The RF mixer uses short transmission lines and terminating resistors to match impedances within the mixer and to minimize the mixer's distortion. The RF mixer, including the dumbbell resonator, is constructed on a printed circuit board and has a low manufacturing cost. Alternatively, the output transmission line is center-tapped to provide a pair of IF signals having opposite phases.

Abstract: Transmit and receive programmable band select/transfer modules provide low cost means for selecting and translating spectral segments within sectors of a LMDS basestation. The modules are programmable to select spectral segments and translate the frequency of the selected segments to designated spectral positions in the sector's output signal. Each module shifts the frequency of an applied uwave signal to dispose a predetermined spectral segment about an IF frequency. The predetermined spectral segment is then selected using a fixed frequency filter at the IF frequency. The spectral segment has one of several bandwidths, selected by one of multiple fixed frequency filters in the modules. The module translates the frequency of the filtered spectral segment to dispose the selected spectral segment about an output frequency to provide the sector's output signal. An optional pilot signal or service channel may be summed with the filtered spectral segment prior to the frequency translation.

Abstract: A lossy capacitive circuit element, or DC scrubber, is printed on a circuit substrate and absorptively filters high frequency signals in circuit modules. A top conductor of the DC scrubber is separated from a ground conductor by a layer of high dielectric material. A resistive layer, positioned either above or below the top conductor absorbs high frequency signals applied to the top conductor while the dielectric layer shunts the signals to the ground conductor. Alternatively, a pair of DC scrubbers are stacked vertically to configure the lossy capacitive structures in parallel. Signal isolation provided by the DC scrubber and the stacked DC scrubber enables inexpensive DC interfaces to be used in the circuit modules.

Abstract: A signal distribution structure, or polyline, provides isolation between signal paths in high frequency systems, such as RF or microwave communication systems. The polyline has an inner conductor surrounded by a lossy insulator and a conductive shield. The conductive shield isolates the inner conductor from high frequency signals in the system while the lossy insulator attenuates high frequency signals present on the inner conductor. Low frequency signals on the inner conductor are relatively unattenuated by the polyline. Alternatively, an open polyline is formed in which the conductive shield is absent. The polyline and the open polyline are printed on a ceramic substrate or other type of carrier using known thick-film processing techniques.

Abstract: In the present invention, an easily assembled, reliable bending neck is formed for use with invasive medical devices. The bending neck comprises a series of pivotally hinged segments, each having a central lumen. The segments are positioned end-to-end, while the lumens collectively provide a shaft to accommodate delicate interconnections to a head assembly attached to the bending neck. Separate from the lumen are channels formed in each segment. The channels, combined from each segment, run the length of the bending neck and are aligned to accommodate cables used to articulate the bending neck. The separation of the lumen from the channels isolates the delicate interconnections from the motion of the cables as the bending neck is articulated.The cables and the separated lumen and channels form a bending neck having high reliability, that is easy to assemble, for use with invasive medical devices.

Abstract: An error correction method reduces transmission measurement errors and improves measurement accuracy of vector network analyzers. A reflection measurement made using a thruline standard connected between a source port and load port of a transmission/reflection (T/R) test set characterizes the impedance match of the load port while a reflection calibration characterizes the source port. The source port characterization and the load port characterization are then processed to correct a transmission tracking error in subsequent transmission measurements made on a device under test (DUT), without impacting the measurement speed of the VNA. A reflection measurement made with the DUT connected between the source and load port provides a measurement of the DUT's input reflection coefficient, including the effect of the impedance mismatch of the load port. This reflection measurement and the source port characterization are processed to correct a DUT input mismatch error.

Abstract: A relative intensity noise (RIN) standard provides a reference optical noise signal used to characterize the relative frequency response and calibrate the absolute level of an optical receiver. The RIN standard includes an optical filter, illuminated by a high power optical noise source, or alternatively, the RIN standard includes a coherent laser signal combined with amplified spontaneous emission from a variety of gain media. The RIN standard is characterized and marked with a specific RIN value and is readily transported between measurement sites, providing a portable standard for optical receiver calibration. The reference optical noise signal is applied to the optical receiver to characterize the receiver's transfer function. Once the transfer function of the optical receiver is characterized and the receiver is calibrated using the RIN standard, optical noise figure and other performance parameters of high bandwidth optical components are readily measured.

Abstract: In the present invention, an intraoperative ultrasound transducer probe, or intraoperative probe, has a housing, to which, interchangeable accessories may be attached. The interchangeable accessories adapt the intraoperative probe's shape to provide access to a patient's body parts in confined spaces in intraoperative environments. In one embodiment of the present invention a first interchangeable accessory has an extension handle that may be attached to the intraoperative probe to enable an operator to reach into surgical incisions and view the patient's body parts. In an alternate embodiment of the present invention a second interchangeable accessory has a finger cuff for attaching the intraoperative probe to an operator's finger. The finger cuff may be used in place of the extension handle, providing access to a patient's body parts in confined spaces, such as the posterior side of the heart for epicardial imaging during open heart surgery.

Abstract: Multiple electroluminescent (EL) emitters are constructed from layers deposited on a substrate and incorporated with a broadband sensor to form a colorimeter. The EL emitters produce light covering spectral segments determined by a filter layer and an active layer wherein the spectral segments sufficiently cover the visible spectrum to enable a wide range of colors to be accurately measured. The colorimeter is mounted in a desktop color printer to measure the color content of printed images and to calibrate the printer.

Abstract: In the present invention a monolithic step attenuator has internal frequency compensation provided by a field effect transistor, or FET, fabricated to have a well defined drain-to-source capacitance. The drain-to-source capacitance of the FET cancels the effect of parasitic impedances, providing a constant frequency response for the monolithic step attenuator within a defined frequency range. In a first embodiment of the present invention, internal frequency compensation is provided by a FET connected in a shunt arm of a Tee resistor network forming the monolithic step attenuator. In a second embodiment of the present invention, internal frequency compensation is provided by a pair of FETs, each FET connected in one of two shunt arms of a Pi resistor network forming the monolithic step attenuator. In a third embodiment of the present invention, a multicell step attenuator is formed by connecting multiple monolithic step attenuators having internal frequency compensation in series.

Abstract: An amplitude control system uses a pair of parallel integrators to rapidly adjust the amplitude of a test signal between two precisely determined power levels in an RF signal generator. The amplitude control system initializes a first power level by switching a first integrator into a feedback signal path to establish a first drive voltage, corresponding to the first power level. A second power level is initialized by switching a second integrator into the feedback signal path to establish a second drive voltage, corresponding to the second power level. The amplitude control system then alternately switches each of the integrators into the feedback signal path to alternately apply the first and second drive voltages to a level modulator, which rapidly adjusts the amplitude of the test signal to each of the two initialized power levels.

Abstract: In the present invention, a control system uses acoustic data produced by an ultrasound system to assess whether the acoustic environment presented to the ultrasound system's transducer is an imaging environment, such as patient's body, or a nonimaging environment, such as air. Various operating parameters of the ultrasound system may be controlled based on the assessment. In the nonimaging environment, the control system reduces the amplitude of a drive signal applied to the transducer, substantially reducing power dissipation in the transducer. The control system detects a transition to the imaging environment and returns the drive signal to the amplitude used in the previous imaging environment. If the nonimaging environment persists for greater than a predetermined time period, the control system initiates a standby mode which substantially reduces power consumption by the ultrasound system. The control system is readily integrated into the imaging stream of an ultrasound system.

Abstract: A cable management system organizes transducer cables connecting multiple transducer probes to a mobile ultrasound imaging system. The transducer cables and the cable management system form a cable array. Each transducer cable within the cable array is held by a retaining clip and rides in a common slot assembly. The retaining clips are suspended in the slot assembly by retaining rings. The cable management system slidably mounts multiple transducer cables on the mobile ultrasound imaging system, avoiding entanglement with casters of the mobile ultrasound imaging system and with other transducer cables in the cable array.

Abstract: A large dynamic range infrared receiver with a variable input resistance for use in optical communication systems is described. The variable resistance provides this infrared receiver with three ranges of sensitivity depending on the power of the optical signal incident on the receiver. At low optical power, the variable resistance is high, providing the infrared receiver with high sensitivity. For intermediate optical power the variable resistance is reduced, providing the infrared receiver with medium sensitivity. At high optical power levels, the variable resistance switches to a low value, reducing the infrared receiver's sensitivity and limiting the voltage across the variable resistance.

Abstract: A rotatable finger probe provides rotation of an image plane about an image axis in interoperative and intra cavity ultrasound imaging applications. A finger clip attaches the rotatable finger probe to a physician's finger and by movement of the finger, the imaging axis is aimed at a patient's body part to be imaged. Once the image axis is aimed at the patient's body part, rotation of the image plane by the rotatable finger probe is activated remotely.

Abstract: A peripheral optical element efficiently collects light emitted by a light emitting diode (LED) to produce a high luminous intensity of emitted light within a limited viewing angle relative to an optical axis. An LED is positioned in the center of the peripheral optical element, the element comprising a base, a refractive and reflective surface, and an exiting surface. In one preferred embodiment of the present invention, the peripheral optical element is radially symmetric to form a ring element. In an alternative embodiment of the present invention an array of multiple peripheral optical elements is mounted in a frame to accommodate multiple LEDs, forming a light panel for power signaling applications.