Abstract: A temperature stabilization scheme reduces the effects of temperature variations on the performance of an electronic system that is implemented on a circuit board. In the temperature stabilization scheme, the circuit has an isolated region that is coupled to a remainder ofthe circuit board by one or more electrical pathways. Associated with each of the electrical pathways is an incidental thermal conduction path between the isolated region and the remainder of the circuit board. A temperature sensitive component ofthe electrical system is coupled to a mounting site on the isolated region and interfaces with the remainder of the circuit board through the one or more electrical pathways. A series of heaters, thermally coupled to the isolated region provides a compensating thermal profile that opposes thermal instability caused by the incidental thermal conduction paths, where the opposition is over a portion of the isolated region that includes at least the mounting site of the temperature sensitive component.

Abstract: A precision positioner has a moveable stage coupled to an optical element, a frame, a first arm having at a first end a first coupling to the stage, and having a second end adapted to receive a first encoded translator referenced to the frame. The precision positioner also has a second arm having at a first end a second coupling to the stage and having a second end adapted to receive a second encoded translator referenced to the frame. In a first precision positioner, both the first and second couplings to the stage are one-axis rotary flexures. In a second precision positioner, the first coupling to the stage is a one-axis rotary flexure and the second coupling to the stage is a rigid non-flexure.

Abstract: A data decoding scheme operates on individual code symbols within an encoded data stream, enabling data to be recovered from the code symbols at a high rate. The decoding scheme, typically included within a receiver of a digital communication system or data network, does not rely on processing and storing multiple code symbols and is unencumbered by storage memory elements and decoding rate limitations associated with receiving and processing blocks of multiple code symbols. The decoding scheme generates bit sequences corresponding to each alternate data state of a received code symbol. Error vectors are generated as a result of comparing each of the generated bit sequences to the received code symbol. The data state of data represented by the code symbol within the encoded data stream is recovered from the code symbol by selecting the minimum of the generated error vectors.

Abstract: A tuning method for filters having multiple coupled resonators isolates the characteristics of each resonator, enabling a specified filter response to be achieved by adjusting the resonators according to response criteria. A target frequency response is defined for the filter and a target time domain response is computed based on the target frequency response. From the time domain response, a gating function is generated for each of the resonators. A stimulus signal is provided to the filter and the response to the stimulus signal is measured. The gating functions are then applied to isolate the characteristics of each resonator. Each resonator is adjusted according to response criteria chosen to achieve a specified filter response when the response criteria are satisfied.

Abstract: An optical source generates optical signals as a result of varying polarization states to achieve oscillation within an optical loop. The optical signals have narrow spectral width and the optical source is tuneable, so that optical components stimulated by the optical signals can be characterized over a predefined wavelength range with high wavelength resolution. The optical loop includes an optical gain element, a tuneable filter, and a polarization scrambler that provides a varying polarization transfer function. The optical gain element has sufficiently high gain within the passband of the tuneable filter and the polarization transfer function is sufficiently varied to attain oscillation within the optical loop, thereby generating the optical signals. The varying polarization transfer function of the polarization scrambler produces a corresponding variation in the polarization of the generated optical signals, which are coupled from the optical loop to an output.

Abstract: A capture scheme detects repetitive occurrences of finite-length bit patterns within an applied data signal to provide trigger events for equivalent time sampling of the data signal. The capture scheme enables acquisition of samples within designated bit patterns of the data signal, independent of whether the data signal is random in nature, since the designated finite-length bit patterns occur repetitively within the data signal. In an apparatus implementation of the capture scheme, a bit pattern detector detects a designated bit pattern within the applied data signal and generates trigger events responsive to the occurrences of the bit pattern. An equivalent time sampler receives the data signal and trigger events to acquire samples of the data signal within the designated bit pattern.

Abstract: A signal analyzer has an analysis scale and a display scale that are independently selectable. The signal analyzer receives a first representation of an applied signal and provides from the first representation at least two alternative representations. A first selective input enables a designated one of the alternative representations to be applied to a filter to reduce variance of the designated representation. The signal analyzer then converts the received one of the alternative representations having reduced variance to at least two alternative display scales. A second selective input enables a designated one of the alternative display scales to be displayed on a monitor, display screen or other output device of the measurement instrument or system.

Abstract: Absolute delay of a FTD is characterized by applying a stimulus signal to a first port of the FTD. A second port of the FTD is coupled to a delay element having a known delay and a reflective termination. A drive signal is applied to a third port of the FTD. A time domain reflection response to the stimulus signal is obtained and a signal peak within the response that corresponds to a return signal from the reflective termination is identified. Absolute delay of the frequency translation device is then extracted based on the known delay of the delay element and a time that corresponds to the occurrence of the identified signal peak. Delay versus frequency is characterized by isolating a segment of the obtained time domain reflection response that corresponds to a return signal from the reflective termination. Inverse frequency transforming the isolated segment of the time domain reflection response provides delay characteristics of the FTD versus frequency.

Abstract: A method automatically scales a sampled representation of a waveform applied to a sampling system, regardless of the nature of the waveform. The method, implemented within a digital oscilloscope or other type of sampling system, achieves amplitude auto-scaling from samples of the applied waveform acquired when the sampling system is un-triggered. The method then determines the nature of the applied waveform based on the number of acquired samples within an intermediate amplitude band and the number of amplitude transitions across the amplitude band. Records are then taken with the sampling system triggered and the occurrence of alternative designated events, based on the nature of the waveform, is detected within the records. Time offset and time gain are adjusted based on a first occurrence and a second occurrence of the designated event.

Abstract: A tuning method for filters having multiple coupled resonators isolates the characteristics of each resonator, enabling a specified filter response to be achieved by adjusting the resonators according to response criteria. A target frequency response is defined for the filter and a target time domain response is computed based on the target frequency response. From the time domain response, a gating function is generated for each of the resonators. A stimulus signal is provided to the filter and the response to the stimulus signal is measured. The gating functions are then applied to isolate the characteristics of each resonator. Each resonator is adjusted according to response criteria chosen to achieve a specified filter response when the response criteria are satisfied.

Abstract: A mode selection method for signal analyzers having alternative swept and Fast Fourier Transform (FFT) modes of operation enables tradeoffs between measurement speed and dynamic range to be optimized in selecting between the alternative operating modes. The method includes setting the signal analyzer to either a manual state or an automatic state according to a first input to a user interface. When the manual state is set, the analyzer is operated in either the swept operating mode or the FFT operating mode according to a second input to the user interface. When the automatic measurement state is set, a third input to the user interface determines whether measurement speed or dynamic range is optimized. Measurement speed is optimized according to a first optimization scheme and dynamic range is optimized according to a second optimization scheme.

Abstract: A measurement scheme characterizes chromatic dispersion of an optical system having physically separated access points. A modulation signal at a local access point of the optical system and a reference signal at a remote access point of the optical system are generated and the signals are synchronized via timing signals derived from global positioning satellites (GPS). The modulation signal modulates optical test signals having predetermined optical wavelengths and the modulated optical test signals are applied to the local access point of the optical system. Modulated optical test signals are transmitted through the optical system from the local access point to the remote access point where the signals are demodulated. The time delay of the demodulated signal relative to the reference signal is measured at the remote access point by a phase comparison of the demodulated signal and the reference signal or alternatively by measuring the relative time delay directly.

Abstract: A compressible conductive interface provides electrical continuity between a first group of contacts and a second group of contacts in the presence of a compression force applied between the groups of contacts. An insulating housing in the compressible conductive interface has one or more channels and a matrix of apertures. Compressible bars in the compressible conductive interface each have a pair of opposing sides, a base and a nose and are positioned in the channels so that the nose of the compressible bar is at a bottom of the channel into which the compressible bar is positioned. A series of conductive elements, each having a conductive frame and a conductive slider, are also included in the compressible conductive interface. Each conductive element of the compressible conductive interface has a neutral state and a loaded state.

Abstract: A scale control method provides fine scale control in a measurement instrument and also provides scale control spanning wide adjustment ranges. The method detects the presence of the user input to a control sensor and establishes an acceleration factor for the input based on a rate at which events are generated by the control sensor. The acceleration factor modifies a defined scale step size that has a correspondence to the events generated by the control sensor. The defined scale step size, as modified by the acceleration factor, is added to a prior scale to establish a present scale. The present scale and prior scale are used to select a detent value from a series of detent values and to determine if a detent is applicable. When a detent is applicable, the present scale is set to the selected detent value and control of the scale parameters is then determined by this detent value.

Abstract: A circuit board grounding scheme has a series of slots that are self-aligning with a series of conductive standoffs. Each standoff has a tapered head supported by a neck and a base that is coupled to a conductive member. A narrow portion of the tapered head of each standoff penetrates a corresponding one of the slots in the circuit board, aligning the circuit board with the standoffs. Once aligned with the standoffs, the circuit board rests on the bases of the standoffs in a neutral position. The circuit board is then biased toward the necks of the standoffs, becoming wedged in a non-uniform gap that is formed between a wide end of the tapered head and the base of each standoff. One or more ground areas on the circuit board contacts the wide end of the tapered head or the base of the standoff. The standoffs are coupled to the conductive member using fasteners, or the standoffs are compression fit into the conductive member. Alternatively, the standoffs are formed to be continuous with the conductive member.

Abstract: A display mounting system for electronic instruments includes an elastomeric mount having a continuous frame that secures an electrically conductive, optically transmissive plate in alignment with a viewing surface of the display. A compressible ridge protruding from an internal surface of the frame is interposed between the plate and the viewing surface and disposed about the perimeter of the plate, forming an environmental seal between a rear surface of the plate and the viewing surface of the display. A first series of tabs distributed along a front edge of the frame adjacent to the internal surface engage the front surface of the plate while a second series of tabs distributed along a rear edge of the frame adjacent to the internal surface and opposite from the front edge engage a back surface of the display.

Abstract: An internally triggered equivalent-time sampling system characterizes high-speed data signals having a predetermined nominal data rate by using an internal oscillator that runs independent of a synchronous trigger signal. The sampling system acquires samples of the data signal at a strobe rate, set by the oscillator, which is lower than the nominal data rate of the data signal. The samples, the strobe rate, and the nominal data rate are communicated to a quality optimizer which compensates for static rate deviations between the nominal data rate and the actual data rate of the data signal to establish timing correspondence between the acquired samples. The timing correspondence establishes the time placement of the acquired samples when characterizing the data signal on a display or other output device. When the oscillator has high timing stability relative to the data signal, jitter and other attributes of the data signal are accurately characterized.

Abstract: An optical monochromator has high signal selectivity and low insertion loss, and is well-suited for characterizing a variety of optical signals, including closely-spaced optical channels within DWDM systems. The optical monochromator includes a bulk-optic polarization beam splitter that separates orthogonal polarization states of an applied optical signal into separate optical beams. Low insertion loss is achieved by reconciling the polarization states of the separate optical beams to an optimum polarization state that minimizes insertion loss when the optical beams are applied to a dispersive element. High signal selectivity is achieved using a multipass configuration and by illuminating large areas of the dispersive element, since large beam diameters are accommodated by the bulk-optic polarization beam splitter.

Abstract: A variable optical delay element that is physically compact introduces time delays to an applied optical signal. The variable optical delay element includes a pair of substantially parallel members, each having a linear reflective surface facing the reflective surface of the other member. An input lens secured to a first end of the first linear member collimates an optical beam launched by an input fiber while an output lens secured to a second member focuses the collimated optical beam onto an optical output fiber. A first actuator adjusts the offset relationship between the members in a direction parallel to the pair of members to designate the number of reflections of the collimated optical beam by the reflective surfaces before being received by the output lens. A second actuator adjusts the distance separating the linear reflectors. The optical signal is delayed by a predefined time interval by adjusting the offset positions of the members and the distance separating the members.

Abstract: A polarization scrambling device randomly varies the polarization states of multiple applied optical signals. The scrambling device includes a polarization scrambler coupled to a wavelength-dependent polarization randomizer having cascaded birefringent elements in which the axes of polarization of the cascaded elements are rotationally offset. The scrambling device causes random variations in the relative and the absolute polarization states of the applied optical signals. The birefringence, lengths, and number of cascaded birefringent elements are chosen to assure that the polarization states of optical signals at the different wavelengths are sufficiently randomized, even when the applied optical signals are closely spaced in frequency.