Tektronix, Inc.

Sony/tektronix Corporation

Tektronix International Sales Gmbh

Sony/tektronik Corporation

Akira Nara

Osamu Hosoi

Hideaki Koyota

A modulation error is detected every symbol data to generate a trigger signal. The present invention focuses that there are limited patterns of shifts from one symbol data to the next one of the digital modulation signal. Measured values of amplitude, phase and/or frequency of symbol data are latched and then values at the next symbol timing are predicted from the latched measured values using said feature. The predicted and measured values are compared at the following symbol timing. If the difference (error) is over an acceptable range, a trigger signal is provided which allows acquiring a modulation error by symbol data.

Trigger generation for digital modulation signal analysis

A signal analyzer provides frequency domain data at different time and frequency resolution. First type frequency domain data is derived from time domain data of a signal under test by first type frames and displayed as a spectrogram. A selecting box is displayed on the spectrogram for selecting the first type frames. The signal analyzer produces second type frequency domain data by treating the time domain data corresponding to the first type frequency domain data included in the selected first type frames with the selecting box as one frame by FFT calculation. The resultant second type frequency domain data are displayed as a spectrum that has different time and frequency resolution from the spectrogram.

Signal analyzer and method for displaying frequency domain data

A first frequency analysis range and a second frequency analysis range narrower than the first one are set with an operation panel, etc. A first signal pathproduces first time domain data of a frequency converted signal under test by a first data production rate depending on the first frequency analysis range. A second signal pathproduces second time domain data of frequency converted signal under test by a second data production rate depending on the second frequency analysis range and slower than the first data production rate. A CPU receives the first and second time domain data in parallel and produces first and second frequency domain data by FFT wherein frequency shift amounts in the frequency conversions in the first and second signal paths are different depending on the difference between the center frequencies of the first and second frequency analysis ranges.

Signal analyzer and method for producing data therefore

A rectangle marker on a display of a signal analyzer simultaneously designates time and frequency intervals of data from a signal under test for analysis. The data of the signal under test is displayed as a graph having time and frequency axes. Sub-graphs show data designated by the rectangle marker as processed in the time domain, frequency domain and modulation domain. The resulting display provides an overview of the signal under test and simultaneously provides displays of measurements and analyzes for a designated portion of the data.

Display method for signal analyzer

While combining AD converters that one is wide band but narrow dynamic range and the other is narrow band but wide dynamic range, it allows settings to provide a common intermediate frequency signal to the AD converters. A first BPFprovides a first AD converterwith the output signal obtained by getting an intermediate frequency signal Sif through a first band in the second Nyquist zone of the first AD converter. A second BPFprovides a second AD converterwith the output signal obtained by getting the intermediate frequency signal Sif through a second band in the third Nyquist zone of the second AD converter. At this time, the second band is set in the center portion of the second Nyquist zone band, and the first band is set in the center portion of the band of the intermediate frequency signal.

Analog to digital conversion system

A signal analyzer repetitively memorizes waveform data of a signal under test to detect peaks P-Pof the waveform data. Waveform widths of the waveform data at a mask reference level, or a predetermined level down from the respective peaks, are evaluated as mask reference widths and then masks of the respective peaks are set using the mask reference level and mask reference widths. Hence the masks are automatically set, so a user can easily obtain time domain data and/or frequency domain data including characterizing portions in the signal under test.

Signal analyzer and method for signal analysis

A plurality of RF signals are generated with the RF signals synchronized with each other with high accuracy. Transmission data of the multiple channels are modulated, the modulated data of the channels are added to produce composite data and the composite data is stored in a data storage device. In the modulation process, the carrier frequencies are different from each other. The composite data comprises the data of the channels modulated in the frequency division multiplexing manner. The composite data is converted into an analog composite signal by a D/A converter and this analog signal is upconverted to an RF frequency by a frequency conversion circuit. A signal separation circuit produces two channel signals from the RF frequency signal. A signal output circuit generates the output signals having desired frequencies and signal levels.

Apparatus and method of generating a plurality of synchronized radio frequency signals

Time variation of phase noise characteristics is displayed for measurement. A peak power of a signal under test is detected to define the frequency as a reference frequency. An offset frequency from the reference frequency is repetitively changed and each time the phase noise power is integrated for a predetermined frequency width to evaluate an integration value. The integration values are divided by the predetermined frequency width. The divided values are further divided by the peak power to evaluate noise power ratios relative to the peak power. Then, relationship between the offset frequencies, noise characteristic values and time is displayed in a graph that shows the time variation of the phase noise characteristics.

Display for measuring phase noise characteristics

A data processing method is provided to enable a calculation based signal analyzer, such as an FFT based spectrum analyzer, to produce results corresponding to a swept spectrum analyzer employing a video bandwidth (VBW) filter. Once a spectrum is produced the frequency axis is replace by a corresponding time axis, so that a time domain filter, such as a video bandwidth (VBW) filter can be applied. The filter characteristics are applied by performing an FFT to produce frequency domain data, multiplying by the frequency response to produce a filtered version, performing an inverse FFT and replacing the time axis with the original frequency axis to produce a filtered version of the display spectrum data.

Data processing method for spectrum analyzer

An up-converterfrequency-up-converts an analog signal Sm. A down-converterfrequency-down-converts analog signal Sm. A signal selection blockselects one of the frequency-up-converted signal Sfu and frequency-down-converted signal Sfd. The signal Se selected by the signal selection blockis provided to the primary winding of a transformer. A signal induced in the secondary winding of the transformeris provided to an A/D converterto produce a digital signal Dm. For example, if the analog signal Sm has DC or a low frequency close to DC, the signal Sfu is selected as the signal Se. If the analog signal Sm does no have DC nor a low frequency close to DC, the signal Sfd is selected as the signal Se.

Analog to digital conversion apparatus

A wideband signal analyzer has a plurality of frequency conversion paths for simultaneously processing different contiguous frequency bands of an input signal. Each frequency conversion path provides time domain data for input to a digital signal processor. The digital signal processor interpolates each group of time domain data to produce interpolated time domain data having a number of data points that satisfies a Nyquist condition for a combined bandwidth of the frequency conversion paths. A calibration signal set to a border frequency between a pair of frequency conversion channels is used to calibrate the gains and phase differences between the frequency conversion paths so that the digital signal processor identifies corresponding time domain data between the interpolated time domain data groups. A suite of frequency domain data is calculated by the digital signal processor from the interpolated time domain data groups and stored for subsequent display.

Wideband signal analyzer

A frequency down converter that maintains accuracy even if the frequency pass band is wide uses a reference frequency band within the frequency pass band, the reference frequency band being resistant to degradation by aging or temperature variation. The ideal characteristics of the reference frequency band are previously stored. The frequency down converter has a calibration signal source that inputs a calibration signal to the frequency down converter to measure the characteristics of the reference frequency band and to store differences from the ideal characteristics. The calibration signal is input to obtain the characteristic data of other frequency bands within the frequency pass band, and the characteristic data are revised by the above differences. Then compensation coefficients to compensate the revised characteristic data into the ideal characteristics are calculated. The frequency down converter uses the compensation coefficients to compensate the frequency domain data, which maintains the accuracy over the wide frequency pass band.

Method of measuring and calibrating frequency down converter

This invention relates to a real time signal analyzer that can produce time domain data and frequency domain data at the substantial same time and in real time, securing the simultaneousness between them, and can analyze them with changing the setting of the center frequency and the signal analysis span arbitrarily in low cost configuration. The apparatus has frequency conversion means and for shifting the frequency of input time domain data according to a selectable center frequency data and for decimating them according to a selectable decimation coefficient, a FFT processor for FFT processing the output data of the frequency conversion means in real time, a delay means for delaying the output data of the frequency conversion means for a predetermined time, a frequency domain data memory means for storing the FFT processed frequency domain data from the FFT processor, a time domain data memory means for storing the delayed time domain data read out from the delay means, and feedback means and for feeding the data read out from the time domain data memory means back to the frequency conversion means instead of the input time domain data.

Real time signal analyzer

This invention relates to a new type real time signal analyzer that has both merits of a conventional real time FFT analyzer and a conventional vector signal analyzer and clears both demerits of them. This apparatus has a FFT processor for FFT processing time domain data in real time, a FIFO memory for delaying the time domain data before the FFT process, and a double port memory for storing FFT processed frequency data from the FFT processor and delayed time domain data read out from the FIFO memory . The delay time of the FIFO memory is set up according to the process time of the FFT processor that allows to secure time correspondence between the delayed time domain data and the frequency domain data. Therefore it respectively provides the data of the time domain and the frequency domain in real time at the same time that are synchronized each other.

Real-time signal analyzer

A wide band signal analyzer includes a frequency converter for converting a signal under test to an intermediate frequency signal. A narrow band signal processor receives the intermediate frequency signal and produces a first digital signal representing a first frequency band of the intermediate frequency signal and a wide band signal processor receives the intermediate frequency signal and produces a second digital signal representing a second frequency band of the intermediate frequency signal. A transfer rate decelerator decelerates the transfer rate of the second digital signal, and a digital processor processes selectively the first digital signal or the output signal of the transfer rate decelerator. A memory stores the processed output of the digital processor.

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Tokyo, Japan

Akira Nara