公开(公告)号：EP0118762A3

公开(公告)日：1988-06-08

申请号：EP84101289

申请日：1984-02-08

申请人： HITACHI, LTD.

发明人： Kobayashi, Masaharu Hitachi-Hachimanyama ,  Noguchi, Takaharu ,  Nishimura, Keizo ,  Tanaka, Hiromichi ,  Nishida, Masami ,  Arai, Takao

IPC分类号： H03K13/02

CPC分类号： H04B14/04 ,  H03M1/0631

摘要： A digital-to-analog converter device for PCM signals at different sampling frequencies (f s1 , f s2 . f s3 ) comprises a signal converter (6a) which expands the frequency distance between a PCM signal band and a side band by converting the sampling frequencies associated with the PCM signals to be reproduced into higher fequencies (2f s1 , 2f s2 ; f s3 ') ' With this signal converter, a single low-pass filter (4a) can be simplfied, having a gradual ramp cut-off characteristic for removal of the side band wherein a pass band cut-off frequency and a stop band cut-off frequency can be adapted for low pass filtering of the PCM signals at different sampling frequencies.

公开(公告)号：EP0077075B1

公开(公告)日：1986-07-16

申请号：EP82109467.9

申请日：1982-10-13

申请人： Hitachi, Ltd.

发明人： Tanaka, Hiromichi ,  Kimura, Hiroyuki ,  Noda, Tsutomu ,  Arai, Takao ,  Kobayashi, Masaharu ,  Inoue, Shigeki

IPC分类号： G11B5/09 ,  G11B19/28 ,  G01R29/027

CPC分类号： G11B19/28 ,  G01R29/0273 ,  G11B20/10 ,  Y10S388/912 ,  Y10S388/916

公开(公告)号：EP0118762A2

公开(公告)日：1984-09-19

申请号：EP84101289.1

申请日：1984-02-08

申请人： HITACHI, LTD.

发明人： Kobayashi, Masaharu Hitachi-Hachimanyama ,  Noguchi, Takaharu ,  Nishimura, Keizo ,  Tanaka, Hiromichi ,  Nishida, Masami ,  Arai, Takao

IPC分类号： H03K13/02

CPC分类号： H04B14/04 ,  H03M1/0631

摘要： A digital-to-analog converter device for PCM signals at different sampling frequencies (f s1 , f s2 . f s3 ) comprises a signal converter (6a) which expands the frequency distance between a PCM signal band and a side band by converting the sampling frequencies associated with the PCM signals to be reproduced into higher fequencies (2f s1 , 2f s2 ; f s3 ') ' With this signal converter, a single low-pass filter (4a) can be simplfied, having a gradual ramp cut-off characteristic for removal of the side band wherein a pass band cut-off frequency and a stop band cut-off frequency can be adapted for low pass filtering of the PCM signals at different sampling frequencies.

公开(公告)号：EP0077075A1

公开(公告)日：1983-04-20

申请号：EP82109467.9

申请日：1982-10-13

申请人： Hitachi, Ltd.

发明人： Tanaka, Hiromichi ,  Kimura, Hiroyuki ,  Noda, Tsutomu ,  Arai, Takao ,  Kobayashi, Masaharu ,  Inoue, Shigeki

IPC分类号： G11B5/09 ,  G11B19/28 ,  G01R29/027

CPC分类号： G11B19/28 ,  G01R29/0273 ,  G11B20/10 ,  Y10S388/912 ,  Y10S388/916

摘要： In a pulse width detector circuit, a high-level pulse width and a low-level pulse width of a digital signal derived by slicing an analog signal reproduced from a disc (1) at a predetermined level are independently measured (29, 30) and maximum or minimum values thereof in a predetermined time interval are stored, and an average value, sum or difference of the maximum or minimum high-level pulse width and the maximum or minimum low-level pulse width is calculated (37) to detect a correct pulse width of original data recorded on the disc.