公开(公告)号：EP0766412A3

公开(公告)日：1998-12-09

申请号：EP96307072

申请日：1996-09-27

Applicant: PARADYNE CORP

Inventor： BETTS WILLIAM LEWIS ,  HAZEN RAMON B ,  SCOTT ROBERT EARL

IPC: H03H17/02 ,  H04B3/23 ,  H04B7/015 ,  H04B7/26

CPC classification number: H04B3/238

Abstract: A far-end modem (300) transmits a "pilot tone" during the time that a near-end modem (100) is training its echo canceller (650). Correspondingly, the near-end modem (100) is modified to notch or filter out this pilot tone from the received signal. The filtered received signal is then used by the near-end modem (100) to train its echo canceller (650).

公开(公告)号：WO9723086A3

公开(公告)日：1997-12-11

申请号：PCT/US9620051

申请日：1996-12-16

Applicant: PARADYNE CORP

Inventor： SCOTT ROBERT EARL

IPC: H04N1/00 ,  H04N1/333 ,  H04Q7/22 ,  H04N

CPC classification number: H04N1/33323 ,  H04N1/00281 ,  H04N2201/33357 ,  H04N2201/33364

Abstract: A Mobile Switching Center (MSC) includes a cellular modem pool (230) that comprises a number of pairs of modems in which the data terminal equipment (DTE) ports of each modem pair are cross-connected in a 'back-to-back' fashion. This allows the two modems of each pair to interchange data via their DTE ports and thereby isolate that portion of a cellular fax call over the cellular communications channel (200) from that portion of the cellular fax call through the PSTN. Fax information is transmitted over the PSTN-portion of the cellular fax call using a '1-D' fax compression scheme. However, fax information is transmitted over the cellular-portion of the cellular fax call using a '2-D' fax compression scheme and a data modulation as specified in AT & T Paradyne's 'Enhanced Throughput Cellular' (ETC) Protocol. The fax terminal equipment at the cellular end of the cellular fax call is configured to perform fax compression/decompression using the '2-D' fax compression scheme. The PSTN-side modem (300) of the cellular modem pool performs the translation between the '2-D' and '1-D' fax compression schemes transmitted on the cellular-side and PSTN-side, respectively.

公开(公告)号：EP0766411A3

公开(公告)日：1998-12-09

申请号：EP96307071

申请日：1996-09-27

Applicant: PARADYNE CORP

Inventor： BETTS WILLIAM LEWIS ,  HAZEN RAMON B ,  SCOTT ROBERT EARL

IPC: H03H17/02 ,  H04B3/23 ,  H04B7/015 ,  H04B7/26

CPC classification number: H04B3/238 ,  H04B3/237

Abstract: A processor (650) of a cellular modem (100) monitors for the presence of a residual echo signal during a full-duplex portion of a training sequence. In particular, the processor (650) monitors an equalizer error signal during a full-duplex training phase that follows the half-duplex training phase for the echo canceller. If the processor (650) detects a level of the error signal greater than a predefined threshold, it presumes the increase in the error signal is due to the presence of a residual echo signal and performs a predefined adjustment of the echo filter taps of the corresponding echo canceller of the cellular modem (100).