Tektronix, Inc.

Kyle L Bernard

Nikhil M Deshpande

Xiaofen Chen

Edward C Gee

Man-Kit Yau

Thomas L Kuntz

Linley F Gumm

Thomas C Hill

David H Eby

Steven W Stanton

Soraya J Matos

Craig D Bryant

Koichi Sega

Robert E Tracy

Leroy J Willmann

Julian B Sessions

A method and apparatus for continuous RF signal visualization with high resolution acquires RF signal data within a specified frequency bandwidth seamlessly to produce digitized time domain data. The digitized time domain data is processed in both the frequency and time domains to form high resolution spectral and time traces which are stored. To match human visualization abilities, the high resolution traces are combined to form low resolution traces which are displayed. With the spectral traces, spectrum bitmaps may be generated and stored so that the spectrum bitmap for any displayed spectral trace may be recalled and displayed. The high resolution traces for any specified low resolution trace may be recalled for display. Finally multiple trigger event types may be generated and displayed with the displayed traces.

Continuous RF signal visualization with high resolution

An automated spectrum monitoring system may include a measurement device having a signal information display configured to visually present signal information pertaining to a signal, a real-time trigger detector configured to detect a trigger corresponding to the signal, and a mapping application configured to determine a geographic location of a source of the signal and visually present an indication of the geographic location.

Device for automated signal capture and location based on real-time analysis of signal characteristics

A system and method for performing wide-band spectral analysis of transient signals using a real-time spectrum analyzer (RTSA). A frequency window is selected for RTSA acquisition, the frequency window being narrower in bandwidth than the frequency spectrum of interest. An RTSA is successively tuned to a plurality of different frequencies within the frequency spectrum of interest, where such successive tuning is controlled based on a characteristic of the signal. The RF signal is received, and, for each of the plurality of different frequencies, power data is acquired for the signal in a band centered on the frequency and having a bandwidth equal to that of the frequency window. A representation of the frequency spectrum of interest is then constructed from the power data acquired during the successive tunings of the RTSA.

Wide-bandwidth spectrum analysis of transient signals using a real-time spectrum analyzer

An autocorrelation trigger comprising a correlator detector for producing a correlation coefficient by correlating a signal with a time-delayed version of the signal and generating a trigger in real-time when the correlation coefficient corresponds to a predetermined condition is provided. A method of producing trigger based upon an autocorrelation measurement is also provided. The autocorrelation trigger may be used to produce a trigger based upon the degree to which the autocorrelation relates to an autocorrelation model, such as, the degree of randomness in a signal.

RF autocorrelation signal trigger generator

An RF/IF signature trigger for acquiring received RF signal data is generated by correlating the received RF signal data in the form of a time domain RF/IF signal, a detected RF/IF signal and/or a frequency domain RF/IF signal with a reference signal defined by a signal signature record representing desired/undesired RF/IF signal patterns, detected RF pulse shapes, special RF markers used specifically for triggering signal acquisitions, particular signal patterns of interest and the like. The resulting correlation factor continuously calculated in real time is compared with a variable correlation threshold such that when the correlation factor reaches the variable correlation threshold, either positive or negative, the RF/IF signature trigger is generated to acquire the received RF signal data for analysis.

Real-time RF/IF signature trigger

A realtime power mask trigger generator for an instrument that acquires data in response to a trigger signal integrates power amplitudes over a defined bandwidth within a frequency spectrum for an input signal to produce an average signal power, and compares the average signal power with a specified reference power level for the defined bandwidth. Violation of the reference power level by the average signal power generates the trigger signal for acquiring data from the input signal about the trigger event by the instrument. The frequency spectrum may be divided into more than one defined frequency bandwidth, and each defined frequency bandwidth may have its own specified reference power level. The defined frequency bandwidths and associated reference power levels define a realtime power mask trigger.

Realtime power mask trigger

A measurement instrument is provided with an FFT module providing a frequency domain output; and a power calculator connected to the frequency domain output to measure power statistics for a test signal of arbitrary length. In some embodiments, a spectrum integration module is provided to calculate the power contained within a frequency band. In an embodiment, a filter/averaging module is provided to compute signal power statistics over an arbitrary time period. Accumulators may be provided to store data related to maximum power, minimum power, average power, or peak to average power. A CCDF module may be provided in some embodiments to calculate CCDF related measurements. Also provided are methods of making power statistic measurements.

Time arbitrary signal power statistics measurement device and method

A method of creation/editing masks/waveforms for an instrument invokes a mask editor from an application running on the instrument. A context or signal waveform displayed in the application is transferred as a reference to a mask editor graphic display together with an unrelated current mask, which may be a previously existing mask or a default mask. The current mask is edited with respect to the reference to define a new mask, such as by changing the positions of points, adding points or deleting points that define the current mask. Then the mask editor is exited and the application recalled, with the new mask being applied to the context in the application.

In-context creation and editing of masks and waveforms

A modulation analyzer includes a smoothing processor which processes the coordinates of symbol landing points to generate a curve that optimally fits the landing points under a selected criterion.

Enhanced constellation display for VSB television signals

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 measurement receiver demodulator has a first processing channel for producing a filtered signal sample output where the signal samples are processed through a transmission system receiver filter and a second processing channel producing an unfiltered signal sample output where the signal samples are not processed through the transmission system receiver filter. The first processing channel down converts digitally modulated IF signal samples and filters the down converted signal samples using a combined transmission system receiver filter and front end hardware compensation filter. A synchronizer produces timing phase and rate offset parameters that are applied to a resampling filter to synchronize the filtered signal samples to symbol instances of the symbol modulation. The filtered, time-aligned signal samples are scaled using a derived scaling factor. A pilot offset level, if present, is estimated and removed. The resultant signal samples are processed through an equalizer to produce filtered, time-aligned, scaled equalized signal samples that are output as filtered signal samples. The second processing channel receives the down converted signal samples and uses compensation and equalization filter coefficients, timing parameters, and the scaling from the first processing channel in compensation, resampling and equalization filters and a scaler to produce compensated, time-aligned, scaled equalized signal samples that are output as unfiltered signal samples.

Measurement receiver demodulator

A frequency spectrum measurement apparatus sweeps a desired frequency range using multiple scan lines. A controller provides a non-contiguous sequence of input values to a frequency synthesizer operating as a local oscillator for generating a non-contiguous frequency output signal over the desired frequency range with each value offsetting a current frequency output signal from a previous frequency output signal. A mixer receives an input signal and the variable frequency synthesizer signal for generating an intermediate frequency signal that is filtered through a bandpass filter. The power of the intermediate frequency signal output of the bandpass filter is measured and displayed. The frequency spectrum measurement apparatus is usable in measuring out of channel emissions of a terrestrial RF broadcast digital television signal.

Frequency spectrum measurement apparatus

A measurement acquisition and display system generates graphical displays of Cumulative Distribution Function (CDF) peak-to-average power ratio measurements of a digitally modulated RF signal and an ideal digitally modulated RF signal, such as an 8-VSB digital television signal. A variable target operating point or planning factor value is enterable into the system that defines an operating point on the ideal CDF of peak-to-average power ratio display. The corresponding operating point on the RF signal CDF of peak-to-average power ratio display is determined and numerically displayed along with a numerical display of the difference between the ideal and real operating points. Alarm limit variables may be set for generating an alarm signal when the RF signal peak-to-average power ratio exceeds the alarm limits. The measurement acquisition and display system further generates a graphical display of channel frequency spectrum of the digitally modulated RF signal.

Measurement acquisition and display apparatus

An in-service hum and low frequency distortion measurement technique for in-service cable television channels having a video modulated carrier frequency obtains peak samples of the horizontal sync signal to effectively filter out the vertical interval frequency. The data record formed by the peak samples is filtered and input to a fast Fourier transform to obtain magnitude values for the fundamental and first harmonic frequency components corresponding to a powerline. From these magnitude values hum and low frequency distortion is computed as a percentage relative to the amplitude of the carrier frequency. The same procedure may be used with an input CW signal in an out-of-service measurement for hum only, the difference between the in-service and out-of-service measurements determining the low frequency distortion due to the video signal.

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Tigard, OR, United States of America

Kyle L Bernard