Adv Antest Corporation

Hitoshi Takahashi

Masao Nagano

A digital signal modulation analysis device is to shorten the time for modulation analysis, and at the same time to structure a measurement device that is small in scale and inexpensive. A digital signal modulation analysis device includes a frequency convertor which converts a signal from a device under test to a first intermediate frequency signal, a sampling part which converts the first intermediate frequency signal to a second intermediate-frequency signal whose frequency is lower than that of the first intermediate frequency to store the second intermediate frequency signal in a memory, a Hilbert converter which converts an incoming signal into orthogonal component signals through a quadrant-modulate detection process, an initial synchronization part which determines a carrier center frequency, a symbol-demodulation/parameter-estimation part which determines optimal parameters to minimize a modulation error and demodulates all symbol data to determine reference data for the all symbol data, and a modulation-precision calculation component which calculates modulation-precision data and modulation-error data for each symbol.

Digital signal modulation analysis device

An FM input signal V(t) is A/D converted, then an in-phase component I and a quadrature component Q are obtained. Then, an instantaneous phase .theta.=tan.sup.-1 (Q/I) of the V(t) is obtained and also an instantaneous frequency of the modulated signal f.sub.a (t)=(1/2.pi.)d.theta./dt is obtained. Alternately, f.sub.a (t)=(IdQ/dt-QdI/dt)/{2.pi.(I.sup.2 +Q.sup.2)} is directly obtained from I and Q. A positive peak P+ and a negative peak P- of the obtained f.sub.a (t) is detected to display the average value of these as a frequency deviation.

Method and apparatus for measuring FM frequency deviation

A digital signal modulation analysis device is to shorten the time for modulation analysis, and at the same time to structure a measurement device that is small in scale and inexpensive. A digital signal modulation analysis device includes a frequency converter which converts a signal from a device under test to a first intermediate frequency signal, a sampling part which converts the first intermediate frequency signal to a second intermediate-frequency signal whose frequency is lower than that of the first intermediate frequency to store the second intermediate frequency signal in a memory, a Hilbert converter which converts an incoming signal into orthogonal component signals through a quadrant-modulate detection process, an initial synchronization part which determines a carrier center frequency, a symbol-demodulation/parameter-estimation part which determines optimal parameters to minimize a modulation error and demodulates all symbol data to determine reference data for the all symbol data, and a modulation-precision calculation component which calculates modulation-precision data and modulation-error data for each symbol.

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Gyoda, Japan

Hitoshi Takahashi