公开(公告)号：JPH01106515A

公开(公告)日：1989-04-24

申请号：JP26329287

申请日：1987-10-19

Applicant: ADVANTEST CORP

Inventor： YAMAGUCHI TAKAHIRO ,  NAKANISHI TORU ,  ARAKAWA NORIO ,  TAKANAGA YOSHIO

IPC: H03H17/02 ,  H03D7/00 ,  H03F99/00 ,  H03H17/00

Abstract: PURPOSE:To improve S/N at high speed with low cost by processing digitally a signal at all stages after an AD converter and applying mean (integration) processing to each frame for a time area. CONSTITUTION:The start of readout of a real memory 24 and the production of each local signal from a cosine wave generator 31 and a sinusoidal wave generator 32 are synchronized. That is, the real memory 24 is read by an address generated by the address generator 39 and the address production of the address generator 33 is reset at each start of readout and the address generators 33, 39 are synchronized. Thus, the momentary phase of a cosine local signal and a sine local signal in the trigger signal position of the waveform read from the real memory 24 is always made constant. Thus, the momentary phase of a complex waveform of each frame stored in each memory plane of the complex number memory is made constant and the complex number waveforms are in the coherent relation. The complex waveform of each frame stored in the corresponding address of the complex number memory 38 is averaged by an average means 41 to improve the S/N.

公开(公告)号：JPH0193914A

公开(公告)日：1989-04-12

申请号：JP25125087

申请日：1987-10-05

Applicant: ADVANTEST CORP

Inventor： YAMAGUCHI TAKAHIRO ,  NAKANISHI TORU ,  ARAKAWA NORIO ,  TAKANAGA YOSHIO

IPC: H03H17/08 ,  H03D7/00 ,  H03F99/00 ,  H03H17/02

Abstract: PURPOSE:To solve problems of restrictions on the dynamic range of a frequency converter and the drift of a DC amplifier by performing digital processing in all of means following an AD converter. CONSTITUTION:An input signal is converted to a digital signal by an AD converter 23 and has the frequency converted in first and second digital frequency converting means 24 and 25 by sine and cosine wave local signals and is converted to complex data by orthogonal modulation. Respective outputs of the first and second digital frequency converting means 24 and 25 pass first and second digital filters 28 and 29 to take out digital signals in preliminarily determined frequency bands, and they are resampled by first and second resampling means 31 and 32 and are successively stored in a complex memory 33. Thus, problems of restrictions on the dynamic range of the frequency converter and the drift of the DC amplifier are resolved.