Adv Antest Corporation

Takeda Riken Kogyo Kabushiki Kaisha

Takeda Riken Kogyo Kubushikikaisha

Toshiharu Kasahara

Takahiro Yamaguchi

Hiroaki Takaoku

Takashi Kosuge

Takayoshi Fukui

Yoshiaki Miyamae

Osamu Aoyama

Hiromi Kosawa

Masayuki Ogawa

Kouichi Yamashita

Hitoshi Kitayoshi

Takayuki Ogami

A spectrum analyzer in which automatic setting of parameters such as band width is done by the analyzer without manual operator input and noise measurements are determined and displayed to the operator. This is accomplished by an input signal being supplied to a frequency mixer via an input variable attenuator. The frequency of the input signal is mixed with the frequency of a local signal from a frequency sweep generator. The mixed signal is then supplied to a band pass filter and the output of the filter is amplified by an amplifier. The frequency of the amplified output is mixed with the frequency of a local signal from a local oscillator by a frequency mixer. The intermediate frequency signal is taken out by a band pass filter and the output is detected by a detector. The detected output is converted into a digital signal by an A/D converter after passing through a low pass filter and the digital signal is stored in a buffer memory. A CPU sets an attenuation amount. The CPU also controls a frequency sweep generator by controlling a ramp voltage generator through a timing controller. The CPU sets a sweep frequency band, a band width RBW, a band width VBW, and a sampling period, as well as a display control of the data stored in the buffer memory on a display unit.

Measuring method by spectrum analyzer

A measuring device and method use a spectrum analyzer. The spectrum analyzer comprises a display screen controlled by a processor on which a spectrum of an input signal is displayed in a frequency region on a half portion of the display screen and a noise level at a frequency associated with the input signal is displayed in a time region on another half portion of the display screen.

A plurality of relatively prime excitation waveforms are generated and applied to an object to be measured. Data of the excitation waveforms and a response waveform from the object are extracted by one frame every n frames and subjected to Fourier transform, thereby computing an input auto spectral matrix and an input-output cross spectral matrix. A frequency response function of the object is calculated from averaged spectral matrices obtained by adding and averaging corresponding elements of the corresponding spectral matrices a predetermined number of times. Readout start addresses for multiple waveforms, each stored in one of a plurality of waveform memories and having continuity at both ends, are shifted relative to each other every n frames, thereby obtaining the plurality of relatively prime excitation waveforms.

Apparatus and method for measuring frequency response function

A method for testing and measuring distortion in electrical devices is provided. For signal processing and carrying devices, a signal generator generates a signal having known phase, amplitude and frequency, which is provided both to a device under test and a measuring unit. The measuring unit measures the amplitude, frequency and phase rotation of an output of the device under test and provides these measured values to a suppression signal generator. The suppression signal generator generates a suppression signal which is added to the output signal from the device under test for suppressing the fundamental wave of the output signal. This suppressed signal is then provided to the measuring unit, for comparison with the original output signal from the device under test for determining distortion factors. For testing signal reproducing devices, such as compact disc players and video tape recorders, such a device reproduces a series of signals, for which a series of corresponding suppression signals is generated by the suppression signal generator. Each suppression signal is added to the corresponding original signal and eliminates the fundamental wave in each signal in the series. The suppressed signals are then compared with the orginal corresponding signals for determining distortion factors of the signal reproducing device.

Distortion measuring system method utilizing signal suppression

A set value of a frequency setting register is accumulated upon each occurrence of a clock signal, and a waveform memory is read out by using the accumulated value as an address. In the waveform memory, amplitude data of one cycle of the waveform of a burst signal to be generated are stored at fixed phase intervals. The output read out of the waveform memory is converted into an analog signal. A wave-number counter counts the number of times the amplitude data of one cycle is read out of the waveform memory and, when having counted by a preset number of waves, yields a wave-number counting end signal. After the occurrence of the wave-number counting end signal, a phase counter counts clock signals, and, when the count value of the phase counter reaches a value corresponding to a preset end phase, the generation of the burst signal is stopped.

Burst signal generator

A frequency range of measurement is divided into a plurality of regions. For each region a test signal suitable for measurement of the region is generated independently, and the test signal is supplied to a device under test. The output of the device under test is converted by an AD converter into a digital signal, which is then subjected to fast Fourier transform. For each region the sensitivity of the AD converter is set for optimal conversion of the signal level at its input side by the converter, and then the fast Fourier transform is carried out. On the basis of the sensitivity set for one of the regions, the magnitude of the fast Fourier transform output in each of the other regions is corrected according to the sensitivities set for the other regions.

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Okegawa, Japan

Toshiharu Kasahara