Tektronix, Inc.

Thomas C Hill

Shigetsune Torin

John J Pickerd

Kan Tan

Nikhil M Deshpande

Kathryn A Engholm

Linley F Gumm

Kyle L Bernard

Alfred K Hillman, Jr

Xiaofen Chen

Robert T Flegal

Yi He

Marcus K DaSilva

Soraya J Matos

Leroy J Willmann

Eric J Dickes

R Eben Jenkins

Embodiments of the invention include a test and measurement instrument including a test signal input and a sampler coupled to the test signal input to generate a sampled test signal. The instrument also includes a noise reduction system that includes an additional oscillator coupled to the sampler and structured to generate a sampled oscillating signal, as well as a phase detector coupled to the sampled oscillating signal for measuring noise introduced by the sampler. The noise reduction system further includes a phase corrector coupled to the phase detector for removing the measured amount of noise from the sampled test signal. Methods of noise detection are also described.

Phase noise correction system for discrete time signal processing

A frequency mask trigger having frequency selective amplitude discrimination capability is provided for triggering when selected frequency components of an input signal fail to reach a desired power level. A frame of digital data representing an input signal is transformed into a frequency spectrum having at least one frequency bin, each frequency bin having a power amplitude value. Each power amplitude value is compared to an upper lower reference power levels and a lower reference power level. A trigger signal is generated when the power amplitude value in any frequency bin is above the lower reference power level and below the upper reference power level for a specified time duration.

Amplitude discrimination using the frequency mask trigger

An enhanced impulse response measurement for a pulsed frequency modulation (FM) radar signal provides a more accurate measurement of the amplitude of a secondary response relative to the amplitude of a main response. The pulsed FM radar signal is sampled to produce a time-domain sample record. The sample record is windowed to produce a windowed sample record. The windowed sample record is transformed into a frequency-domain spectrum. The spectrum is multiplied with the complex conjugate of a frequency-domain estimate of a transmitted pulsed FM radar signal to produce a de-spreaded pulse. The de-spreaded pulse is transformed into the time domain to produce a measurement of the impulse response having a main response and a secondary response. The amplitude of the secondary response is corrected to eliminate errors caused by the windowing.

Enhanced impulse response measurement of an FM radar transmitter pulse

A filter equalization technique for an analog signal path, such as in an instrument that simultaneously measures a signal over a band of frequencies, uses magnitude measurement data for high frequency bands for which phase-calibrated sources are not readily available. A sinusoidal signal source together with an accurate power meter is used to provide a stepped frequency input over a desired frequency band to the analog signal path with an accurate measured magnitude. The output of the analog signal path is digitized and the resulting frequency magnitudes are computed. Then the resulting power meter results are deducted from the frequency magnitudes measured each time by the instrument to determine the magnitude response of the analog signal path. Using a Hilbert transform the corresponding phase response is determined based on a minimum phase assumption over the desired frequency band. From the magnitude and phase responses an inverse or digital equalization filter may be designed for the analog signal path.

Filter equalization using magnitude measurement data

An acquisition apparatus for a test and measurement instrument including a splitter configured to split an input signal into a plurality of split signals, a plurality of oscillators, each oscillator configured to generate a periodic signal, a plurality of combiners, each combiner configured to combine an associated plurality of the periodic signals into an associated signal combination where at least one of the signal combinations is substantially non-periodic. The apparatus also includes a plurality of mixers, each mixer configured to mix an associated split signal and an associated signal combination into an associated mixed signal, a first digitizer configured to digitize an associated split signal, and a plurality of second digitizers, each second digitizer configured to digitize an associated mixed signal.

Bandwidth multiplication for a test and measurement instrument using non-periodic functions for mixing

A method of remotely estimating the functionality of a preamplifier mounted adjacent an antenna at the top of a mast or tower and coupled to a base station via a transmission medium, such as a coaxial cable, includes taking noise and/or signal power measurements at the base station via the coaxial cable for the amplifier when both powered and unpowered. The ratio of the respective noise and/or signal powers, after the receiver noise figure at the base station and the cable loss (estimated or measured) including any connection device loss are accounted for, provides an estimate of the functionality of the amplifier.

Remote estimation of amplifier functionality

A method of identifying a signal type uses parameters of the signal as a basis for automatic identification. A signal of interest is selected from a display of a spectral waveform for a specified frequency. An occupied bandwidth for the signal of interest is estimated and, if the occupied bandwidth is common to more than one known signal type, a complementary cumulative distribution function of peak power for the signal of interest is estimated. The signal type may be identified as a function of these parameters. Additionally the frequency of the signal of interest may be compared with a database of spectral assignments for known signal types to provide further information about the signal of interest.

Signal type identification

An improved calibration method for a vector network analyzer stores sparse calibration data, interpolates system error data from the sparse calibration data for each measurement by the vector network analyzer, and creates calibrated measurement data from the system error data and uncorrected measurement data at each measurement frequency. The sparse calibration data may be generated by measuring every Nth frequency step over a calibration frequency range greater than a specified measurement frequency range, or by measuring every frequency step over the calibration frequency range and compressing the resulting measurement data. The interpolation may be achieved by using a curve-fit algorithm, such as a parametric polynomial curve fitting algorithm.

Calibration for vector network analyzer

A frequency domain measurement device multi-phase modulates an RF frequency signal with a broadband signal, such as a pseudo random number, to produce an RF spread spectrum signal that encompasses a frequency range of interest. The RF spread spectrum signal is transmitted to a device under test, and a corresponding reflected signal from the device under test is correlated with the RF spread spectrum signal to produce information from which location of and distance to a fault in the device under test may be determined. A FIR filter is used as part of the correlation process to determine magnitude and phase versus frequency over the frequency range of interest for the device under test as well as location of and distance to the fault.

Frequency domain reflection measurement device

A differential amplifier is provided with means to control the collector-to-emitter voltage thereof proportionately with quiescent current therethrough to dynamically maintain thermal balance therebetween when the gain setting is changed.

Differential amplifier with dynamic thermal balancing

A phase lock circuit including a phase/frequency detector, a plurality of selectable filters, and a plurality of variable frequency signal generators connected in a loop to lock an output signal to an input signal. An out-of-frequency-range condition detector is provided to facilitate automatic selection of an appropriate in-range combination of filter and signal generator to cause lock to occur.

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Beaverton, OR, United States of America

Thomas C Hill