公开(公告)号：DE19680107C2

公开(公告)日：2000-06-21

申请号：DE19680107

申请日：1996-01-23

Applicant: ADVANTEST CORP

Inventor： TAKAOKU HIROAKI ,  FUKUI TAKAYOSHI

IPC: G01R23/173 ,  H03L7/18 ,  G01R23/16 ,  H03B23/00

Abstract: A spectrum analyzer having an improved local oscillator for use in a digital step sweep is capable of minimizing a dynamic spurious response which is inverse proportional to a unit step time in the step sweep. The local oscillator includes a random clock delay which provides a random clock to a direct digital synthesizer to incorporate random timings in a time length of the unit step time for sweeping the local oscillator. In another aspect, the local oscillator includes a sweep step number control which maximizes the number of steps in the step sweep to ultimately decrease the dynamic spurious response.

公开(公告)号：DE19680107T1

公开(公告)日：1997-04-17

申请号：DE19680107

申请日：1996-01-23

Applicant: ADVANTEST CORP

Inventor： TAKAOKU HIROAKI ,  FUKUI TAKAYOSHI

IPC: G01R23/173 ,  H03L7/18 ,  G01R23/16 ,  H03B23/00

Abstract: A spectrum analyzer having an improved local oscillator for use in a digital step sweep is capable of minimizing a dynamic spurious response which is inverse proportional to a unit step time in the step sweep. The local oscillator includes a random clock delay which provides a random clock to a direct digital synthesizer to incorporate random timings in a time length of the unit step time for sweeping the local oscillator. In another aspect, the local oscillator includes a sweep step number control which maximizes the number of steps in the step sweep to ultimately decrease the dynamic spurious response.

公开(公告)号：DE19635890C2

公开(公告)日：2001-10-18

申请号：DE19635890

申请日：1996-09-04

Applicant: ADVANTEST CORP

Inventor： FUKUI TAKAYOSHI ,  YAMASHITA KOUICHI ,  YAMAGUCHI TAKAHIRO ,  AOYAMA OSAMU ,  KOSUGE TAKASHI ,  MIYAMAE YOSHIAKI ,  KASAHARA TOSHIHARU ,  TAKAOKU HIROAKI

IPC: G01R23/16 ,  G01R29/26 ,  G01R23/20

公开(公告)号：DE19635890A1

公开(公告)日：1997-03-13

申请号：DE19635890

申请日：1996-09-04

Applicant: ADVANTEST CORP

Inventor： FUKUI TAKAYOSHI ,  YAMASHITA KOUICHI ,  YAMAGUCHI TAKAHIRO ,  AOYAMA OSAMU ,  KOSUGE TAKASHI ,  MIYAMAE YOSHIAKI ,  KASAHARA TOSHIHARU ,  TAKAOKU HIROAKI

IPC: G01R23/16 ,  G01R29/26 ,  G01R23/20

Abstract: The passband of two filters (19,24) is adjusted automatically so that a relationship between a waveform to be displayed (35) and a noise level or dynamic range is fulfilled. The bandwidth of a low-pass filter (27) for the output from a demodulator is set to one-tenth of the passband. A frequency span is fixed at three times the frequency interval. The frequency at which the highest peak level of the input signal occurs is found and selected as the central frequency of the display.