Anritsu Corporation

Ken Mochizuki

Seiya Suzuki

Takashi Aoki

Takashi Murakami

Masaharu Uchino

Osamu Sugiyama

Kazuhiko Ishibe

Tadanori Nishikobara

Kosuke Sasaki

Naosuke Tsuchiya

A frequency synthesizeroutputs a periodic signal r(t) at a frequency detuned by a predetermined frequency &#x394;f [Hz] from a frequency of 1/integer of a frequency of a reference clock signal f0 synchronized with a signal to be measured ws. A first sampler unitsamples the signal to be measured ws at a timing of the trigger signal CLK. A second sampler unitsamples an I signal I(t) at the timing of the trigger signal CLK. A phase shifteroutputs a Q signal Q(t) obtained by shifting a phase of the reference clock signal f0 by 90&#xb0;. A third sampler unitsamples the Q signal at the timing of the trigger signal CLK. A correction value calculation unitcalculates a correction value &#x394;t(n) based on sampling data I(n) and Q(n) and a set value t(n) of a sampling time.

Sampling circuit, sampling method, sampling oscilloscope, and waveform display method

In an emphasis optimization device, a calculating unit calculates an inverse characteristic of an amplitude characteristic based on the amplitude characteristic of a transmission path, and an inverse Fourier transform unit performs an inverse Fourier transform on the inverse characteristic to obtain an impulse response. An extracting unit extracts, from the obtained impulse response, an impulse response corresponding to the number of taps necessary for emphasis to be added to a digital signal to be transmitted on the transmission path. An emphasis amount calculating unit converts the extracted impulse response into a value of the emphasis to calculate an emphasis amount.

Optimization method of optimally setting emphasis and optimization device for optimally setting emphasis

An apparatus for rapidly measuring jitter transfer characteristics is provided. A modulation signal generator generates a modulation signal M including a plurality of sinusoidal components having known amplitudes mto mand different frequencies fto f, and outputs the modulation signal M to a jitter generator. A clock signal C phase-modulated by the modulation signal M is input to a data signal generator, a data signal D synchronized with the clock signal C is provided to a measurement object, a data signal D' output from the measurement object is input to a clock recovery unit to recover a clock signal component C&#x2032;, and the clock signal component C&#x2032; is phase-detected by a phase detector. A signal amplitude detector detects the amplitudes of the plurality of sinusoidal components included in the modulation signal M from an output signal M&#x2032; of the phase detector, and an operation processor calculates a ratio of the detected amplitudes and the known amplitudes for each of the sinusoidal components, respectively.

Apparatus for measuring jitter transfer characteristic

It is an object of the invention to correctly display the waveform of a demodulation signal with a single apparatus. A jitter demodulator which demodulates a jitter component of a digital signal input from the outside, a jitter amount detector which detects the amplitude value of a demodulation signal output from the jitter demodulator, an interpolator which measures a period of the demodulation signal output from the jitter demodulator and interpolates the demodulation signal processing with a rate corresponding to the measured period, a display unit, and a display control section which displays on the display unit the value detected by the jitter amount detector and a waveform of the demodulation signal interpolated by the interpolator are provided in a single housing.

Jitter measuring apparatus

In order to stably measure an input interval time of a pulse signal with high precision, a time interval measuring apparatus includes a reference signal generator, a phase shifter, first and second A/D converters, an error correction unit, an instantaneous phase calculation unit, and an interval time calculation unit. The phase shifter divides a reference signal of a sine wave having a predetermined frequency from the reference signal generator into a first analog signal and a second analog signal having phases shifted to each other. The first and second A/D converters perform sampling of the first analog signal and the second analog signal from the phase shifter, respectively, at an input timing of a pulse signal to be measured, and output a first and second digital sample values. The error correction unit corrects direct current offset errors generated in, respectively, the first and second digital sample values output from the first and second A/D converters, a phase error with respect to 90&#xb0;, and an amplitude error. The instantaneous phase calculation unit calculates an instantaneous phase of the reference signal based on the corrected first and second digital sample values. The interval time calculation unit determines an input interval time of the pulse signal based on a variation of instantaneous phases.

Time interval measuring apparatus and jitter measuring apparatus using the same

A wander generator has a random number signal generator unit, a filter unit, a clock generator unit, a modulator unit, and a setting unit. The random number generator unit sequentially generates random number signals comprised of a plurality of bits at a constant speed in accordance with a predetermined algorithm. The filter unit receives a random number signal sequence generated by the random number signal generator unit for filtering. The clock generator unit generates a clock signal. The modulator unit modulates the frequency of clock signal generated by the clock generator unit with a signal output from the filter unit. The setting unit applies the filter unit with a signal for setting each amplitude value of a spectrum of a signal sequence output from the filter unit.

Wander generator, and digital line tester and phase noise transfer characteristic analyzer using the same

An orthogonal signal generating unit converts a signal to be measured into two orthogonal signals which are two signals whose phases are orthogonal to one another. An instantaneous phase calculating unit calculates an instantaneous phase based on the two orthogonal signals within a range between a lower limit phase value set in advance and an upper limit phase value set in advance. A differential value detecting unit detects a differential value of the instantaneous phase. A differential value correcting unit corrects the differential value, and outputs a corrected differential value when the differential value of the instantaneous phase is over the range dependent on the lower limit phase value and the upper limit phase value. An offset component eliminating unit eliminates an offset component included in the corrected differential value from the corrected differential value output from the differential value correcting unit, and outputs a differential value from which the offset component has been eliminated. An integration unit determines a jitter amount of the signal to be measured by integrating the differential value which is output from the offset component eliminating unit, and from which the offset component has been eliminated.

Jitter measurement device and jitter measurement method

Wonder generator, digital line tester comprising the same, and phase noise transfer characteristic analyzer

An MTIE test signal generating apparatus generates a predetermined MTIE test signal. An MTIE measuring unit includes a low-pass measuring filter having a predetermined high-cut characteristic. A cycle-amplitude setting portion sets a cycle corresponding to an observation time of each of desired plural specific points for a predetermined MTIE characteristic and an amplitude corresponding to a difference in the MTIE value between adjacent specific points. Plural signal generating portions generate plural signals each having the cycle and the amplitude having repetitive waveforms and then outputting to each of the desired plural specific points. A holding time setting portion sets a holding time for holding the upper and lower limit values of the repetitive waveforms over the predetermined time so that a signal cycle having at least the shortest cycle of the plural signals is longer than a predetermined time corresponding to the predetermined high-cut characteristic of the low-pass measuring filter.

Growing community of inventors

Atsugi, Japan

Ken Mochizuki