Abstract: 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. In a first example, the filter characteristics are applied by performing an FFT on display spectrum data, which has had its frequency axis replaced by a corresponding time axis, 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.

Abstract: 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.

Abstract: A frequency converter is provided for combining multiple inputs into a single frequency conversion path. A first frequency conversion stage 50 has first and second frequency conversion paths 501 and 502 that receive first and second input signals to produce first and second IF signals respectively. A combiner 19 sums up the first and second IF signals to provide it as one signal to the next frequency conversion stages 60 and 70. Oscillation frequencies of local oscillators 141 and 142 in the paths 501 and 502 are controlled to have a frequency difference FD between them so that the center frequencies of the first and second IF signals have the frequency difference FD between them. The output of the combiner 19 includes components of multi-channels but processed by the same circuits.

Abstract: 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 analyses for a designated portion of the data.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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 14 for FFT processing time domain data in real time, a FIFO memory 22 for delaying the time domain data before the FFT process, and a double port memory 24 for storing FFT processed frequency data from the FFT processor 14 and delayed time domain data read out from the FIFO memory 22. The delay time of the FIFO memory 22 is set up according to the process time of the FFT processor 14 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.

Abstract: 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.

Abstract: The present invention provides a wide band IQ splitting apparatus suitable for using in a spectrum analyzer. A quadrature oscillator 30 generates a pair of quadrature signals. An amplitude and phase adjuster 32 receives the quadrature signals and adjusts the balances of the amplitude and the phase between them. An analog splitter 20 mixes an analog IF signal with the pair of quadrature signals for splitting the analog IF signal into analog I and Q signals. First and second analog to digital converters 22 and 24 convert the analog I and Q signals into digital I and Q signals, respectively. A control and processing circuit detects the imbalances of the amplitude and phase between the digital I and Q signals for controlling the amplitude and phase adjuster 32. The amplitude and phase adjuster 32 is previously calibrated. For this first calibration, the analog splitter 20 receives a first calibration signal instead of the analog IF signal.