Agilent Technologies, Inc.

Motorola Corporation

Hewlett-packard Company

James R Stimple

Kenneth R Wildnauer

Timothy P Craig

Barry G Broome

Paul M Erickson

Joseph Newhall West

Paul Emerson Bussard

Mark D Zinser

Jeffrey Elmer Pape

John D Knight

Steven D Warwick

Dennis Derickson

Eugene Rudkevich

Jady Palko

Zoltana D Azary

A measurement system includes a clock recovery system and a measurement module coupled to the clock recovery system. The clock recovery system has an associated response characteristic. The clock recovery system receives an input signal and recovers a clock signal from the input signal. The measurement module is coupled to the clock recovery system and measures a phase error signal received from the clock recovery system, time-referenced to a trigger signal that is applied to the measurement module, where the phase error signal represents the phase difference between the input signal and the recovered clock signal. A processor applies the associated response characteristic to the measured phase error signal to determine the phase of the input signal.

Clock recovery system with triggered phase error measurement

An optical phase standard includes a coupler dividing an applied optical signal between a measurement interferometer and a frequency reference branch. Resulting signals at the outputs of the measurement interferometer and the frequency reference branch are sampled. The samples acquired at the output of the frequency reference branch are mapped to optical frequencies that are traceable to a frequency standard provided by an absorption cell. This mapping determines the optical frequencies at which the samples acquired are at the output of the measurement interferometer. From the acquired samples at the output of the measurement interferometer, phase characteristics of a device under test (DUT) are extracted. Aspects of the optical phase standard are alternatively implemented according to an optical phase standardization method.

Optical phase standard

An optical frequency discriminator includes an interferometer cascaded with an absorption cell that provide a composite signal. A receiver samples a composite signal and maps to the sample positions of the acquired samples, corresponding optical frequencies of an applied optical signal.

Optical frequency discriminator

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.

Polarization randomized optical source having short coherence length

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.

Multi-wavelength polarization scrambling device

A double-pass scanning monochromator for use in an optical spectrum analyzer includes an input optical fiber for emitting an input light beam, a diffraction grating for diffracting the input light beam to produce a spatially dispersed light beam, a slit for passing a selected portion of the dispersed light beam, a motor for rotating the diffraction grating, a shaft angle encoder for sensing grating position, and an output optical fiber. The light that passes through the slit is directed to the diffraction grating and is recombined by the diffraction grating to produce an output light beam. The light beam to be analyzed is incident on the diffraction grating during first and second passes. A polarization rotation device rotates the polarization components of the light beam by 90.degree. between the first and second passes so that the output of the monochromator is independent of the polarization of the input light beam. The output optical fiber is translated by a micropositioning assembly in a plane perpendicular to the output light beam during rotation of the diffraction grating to automatically track the output light beam and to provide optical chopping.

Diffraction grating position sensing and control for a scanning

A double pass scanning monochromator for use in an optical spectrum analyzer includes an input optical fiber for emitting an input light beam, a diffraction grating for diffracting the input light beam to produce a spatially dispersed light beam, a slit for passing a selected portion of the dispersed light beam, a motor for rotating the diffraction grating, a shaft angle encoder for sensing grating position, and an output optical fiber. The light that passes through the slit is directed to the diffraction grating and is recombined by the diffraction grating to produce an output light beam. The light beam to be analyzed is incident on the diffraction grating during first and second passes. A polarization rotation device rotates the polarization components of the light beam by 90.degree. between the first and second passes so that the output of the monochromator is independent of the polarization of the input light beam. The output optical fiber is translated by a micropositioning assembly in a plane perpendicular to the output light beam during rotation of the diffraction grating to automatically track the output light beam and to provide optical chopping.

Optical spectrum analyzer having double-pass monochromator

An optical spectrum analyzer is provided with a user selectable sensitivity. Required operating parameters are set in response to user selection of sensitivity to permit measurement of an input light beam at the selected sensitivity. Setting the required parameters includes setting a required gain of a video channel to permit measurement of a specified maximum light signal and to provide the selected sensitivity, setting a required video bandwidth of the video channel to provide the selected sensitivity at the required gain of the video channel and setting a sweep rate to provide the selected sensitivity at the required video bandwidth. When the normal bandwidth of the video channel is not adequate to provide the selected sensitivity, the electrical signal is passed through a digital filter having a filter coefficient set to provide the required video bandwidth. A peak detector is incorporated in the video channel to accurately measure signal amplitudes in a fast scanning condition.

Optical spectrum analyzer having adjustable sensitivity

A plurality of horizontally directive antenna sectors are arranged in a configuration to receive signals from remote transmitters over a given angle in the horizontal plane. A scanning system is operative in one of several modes to sequentially couple each sector to a receiver. In its first mode, each sector is sequentially scanned with the peak signal level therefrom being compared to a reference level. If the signal level on any sector exceeds the reference level the scanner activates to its second mode wherein scanning of all sectors continues for a predetermined interval after which the system advances to a selective scanning mode wherein scan is limited to that sector with the largest stored signal level relative to the reference level, and to those sectors adjacent said sector for a predetermined time interval. At the end of this interval, scanning is inhibited and the receiver is coupled to that sector which exhibited the strongest relative signal level during the scanning sequences. In this listen mode, if the signal level from the sector falls to a minimum level or a coded squelch is undetected for a given period, the system reverts to the first scanning mode. The system periodically updates the reference levels to account for changes in background noise or the presence of an interfering signal.

Sectored antenna receiving system

Each of a plurality of antenna sectors is sequentially coupled to a receiver via an antenna switch. The switch is operated by control logic circuitry which monitors the peak signal levels of the signals received by each sector. Unique circuitry is implemented which prevents the control logic from responding to spurious transient signals processed by the receiver's tuned circuits following each instance of antenna switching.

Antenna sampling system

The pre-limited IF signal from an FM receiver is coupled to a pair of linear amplifiers in a cascade configuration. The outputs from the amplifiers are detected and passed to piecewise linear amplifiers. Each piecewise linear amplifier is designed to exhibit a gain characteristic which is dependent on the level of signals applied at its input. A summing circuit sums the piecewise linear amplified signals in predetermined proportion to thereby produce a DC signal which is linearly related to the receiver's quieting level.

High dynamic range detector for indicating the quieting level of an FM

A plurality of horizontally directive antenna sectors are arranged in configuration to receive signals from remote transmitters over a given angle in the horizontal plane. A scanning system is operative in one of several modes to sequentially couple each sector to a receiver. In its first mode, each sector is sequentially scanned with the output signal level therefrom being compared to a reference level. If the signal level on any sector exceeds the reference level the scanner activates to its second mode wherein scanning continues for a predetermined interval. At the end of the interval, scanning is inhibited and the receiver is coupled to that sector which produced the strongest signal level during the second mode scanning cycle. In the inhibit scan mode, if the signal level from the sector falls to a minimum level for a given time period the system reverts to the first scanning mode.

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Santa Rosa, CA, United States of America

James R Stimple