公开(公告)号：CA2399513A1

公开(公告)日：2001-08-09

申请号：CA2399513

申请日：2001-02-01

Applicant: MOTOROLA INC ,  3COM CORP

Inventor： PILOZZI JOHN ,  PARIZHSKY VLADIMIR ,  MEHRABANZAD SEPEHR ,  KIM DAE-YOUNG ,  MAURER PATRICK ,  LIU JACK ,  AHMED S ARIF

IPC: H04J3/00 ,  H04B14/04 ,  H04J3/12 ,  H04L25/49 ,  H04M7/06 ,  H04L23/02 ,  H03M13/25

Abstract: A system and method for shifting the relative phases of a PCM data frame and a network RBS frame by one or more symbols is disclosed. The method includes determining whether or not RBS is present. If RBS is present, the slots affected by RBS are identified. Next it is determined what data slots, if any, are affected by encoding. The PCM data frame is shifted so the RBS constraint and the encoding constraint do not coincide at any particular data slot. For one particular PCM upstream modulation scheme, the digital modem adjusts the relative phases of the data-mode frame and network RBS frame such that a minimum number of trellis-modified symbols fall on network RBS affected slots. This information is transmitted to an analog modem. The amount of shift can be conveyed to an analog modem in the same data sequence used to send upstream constellation sets and mapping parameters during an initial training sequence. The present invention improves the performance of any PCM modem that employs a data frame structure in which not all symbols are subject to the same constraints, for example, due to trellis coding.

公开(公告)号：CA2399075A1

公开(公告)日：2001-08-09

申请号：CA2399075

申请日：2001-02-01

Applicant: MOTOROLA INC

Inventor： KIM DAE-YOUNG ,  MEHRABANZAD SEPEHR ,  PILOZZI JOHN ,  BROWN WILLIAM LESLIE

IPC: H04L25/38 ,  H04L5/16 ,  H04L7/02 ,  H04L25/49 ,  H04B1/38

Abstract: In a PCM modem system (fig.3), a method and apparatus for optimizing the fractional sampling phase offset in the upstream direction to maximize the upstream data rate utilizes a probing signal (fig. 4A) from the analog modem (12) generated during startup and having at least two distinct phases of a pure tone, with the probing signal (fig. 4A) being detected at the digital modem (14) where an optimum sampling phase value (72) is calculated. From th e calculated value (72), a signal representing the appropriate amount to delay the input data is transmitted back to the analog modem (12) for adjustment o f the fractional sampling phase so that the fractional sampling phase offset a t the central office quantizer (22) is optimized.

公开(公告)号：CA2398484A1

公开(公告)日：2001-08-09

申请号：CA2398484

申请日：2001-02-01

Applicant: MOTOROLA INC

Inventor： MEHRABANZAD SEPEHR ,  KIM DAE-YOUNG

IPC: H04B3/23 ,  H04L25/49 ,  H04B1/38

Abstract: In a full duplex PCM modem system (figure 2), a method and apparatus is provided for robust measuring of the communications channel (67) in which th e digital modem (26) transmitter is silenced (54) during generation of trainin g signal by analog modem (12), with silencing of the digital modem's transmitt er eliminating problems associated with echo during channel measurement at the digital modem. The above method thus eliminates echo during channel estimati on and removes any dependencies on the performance of the echo canceller normal ly used.

公开(公告)号：CZ9903542A3

公开(公告)日：2000-03-15

申请号：CZ354299

申请日：1998-04-03

Applicant: MOTOROLA INC

Inventor： EYUBOGLU VEDAT M ,  KIM DAE-YOUNG ,  TUNG CHIEN-CHENG

IPC: H04B14/04 ,  H04K1/10

公开(公告)号：AU1530199A

公开(公告)日：1999-07-19

申请号：AU1530199

申请日：1998-11-19

Applicant: MOTOROLA INC

Inventor： KIM DAE-YOUNG

IPC: H04L1/00 ,  H04B3/46 ,  H04B14/04 ,  H04J3/12 ,  H04L25/03 ,  H04L25/48 ,  H04L25/49 ,  H03D1/04 ,  H04B1/38 ,  H04L7/00

Abstract: A device and method for detecting digital impairments affecting an upstream pulse code modulation (PCM) channel in a digital communication network, involves; receiving, by a digital PCM modem interconnected to the digital communication network, a random sequence of digital values selected from a constellation of digital values transmitted over the upstream PCM channel of the digital communication network; establishing distributions of the received digital values, each distribution corresponding to one of a plurality of time intervals; and deriving from the distributions the types of robbed bit signaling and digital loss affecting the upstream PCM channel of the digital communication network for each time interval.

公开(公告)号：CA2399543A1

公开(公告)日：2001-08-09

申请号：CA2399543

申请日：2001-02-01

Applicant: MOTOROLA INC ,  3COM CORP

Inventor： LIU JACK ,  AHMED S ARIF ,  PARIZHSKY VLADIMIR ,  KIM DAE-YOUNG ,  PILOZZI JOHN ,  MEHRABANZAD SEPEHR

IPC: H04L7/00 ,  H04L25/49

Abstract: A system and method for adjusting the phase of the analog signal produced by an analog modem connected to a digital modem over a telephone network. The digital portion of the telephone network is locked to the network clock, and the modems have no control over the sampling timing or rate as the analog signal is sampled and quantized by a codec. If the analog signal is shifted in phase relative to the network clock, then the codec may be sampling at unresolvable points on the analog signal, thereby causing errors and a decrease in the usable bandwidth for transmitting data. The analog modem symbol frequency is locked to the clock of the digital network using loop-back timing. A phase estimate is computed using the quantized samples of a known reference signal. Next, a "phase offset" is calculated by comparing the phase estimate to an optimum phase value. Then the digital modem sends the calculated phase offset information to the analog modem. The analog modem then delays its transmitted signal by the phase offset. After the phase of the analog modem's transmitter is adjusted, the analog signal reaches the codec at the phase desired by the digital modem.

公开(公告)号：CZ354299A3

公开(公告)日：2000-03-15

申请号：CZ354299

申请日：1998-04-03

Applicant: MOTOROLA INC

Inventor： EYUBOGLU VEDAT M ,  KIM DAE-YOUNG ,  TUNG CHIEN-CHENG

IPC: H04B14/04 ,  H04K1/10

公开(公告)号：AU1586899A

公开(公告)日：1999-07-19

申请号：AU1586899

申请日：1998-11-13

Applicant: MOTOROLA INC

Inventor： KIM DAE-YOUNG ,  HUMBLET PIERRE A

IPC: H04L27/04 ,  H04B14/04 ,  H04L25/03 ,  H04L25/49

Abstract: A transmitter in an analog pulse code modulation (PCM) modem (12) which transmits analog levels over an analog channel (18) to produce constellation points at a quantization device (26), wherein the constellation points correspond to groups of data bits to be transmitted to a digital PCM modem (28), the transmitter includes: a transmitter device which selects for each group of data bits to be transmitted a constellation point corresponding to the group of data bits and transmits over the analog channel a level that will produce at the input to the quantization device the selected constellation point; wherein the constellation points are chosen from a transmit constellation consisting of a plurality of non-uniformly spaced constellation points that have substantially equivalent, minimized error probability, constellation point to constellation point.

公开(公告)号：CA2317554A1

公开(公告)日：1999-07-08

申请号：CA2317554

申请日：1998-11-19

Applicant: MOTOROLA INC

Inventor： KIM DAE-YOUNG

IPC: H04L1/00 ,  H04B3/46 ,  H04B14/04 ,  H04J3/12 ,  H04L25/03 ,  H04L25/48 ,  H04L25/49 ,  H03D1/04 ,  H04L7/00 ,  H04B1/38

Abstract: A device an method for detecting digital impairments affecting an upstream pulse code modulation (PCM) channel in a digital communication network (36), involves: receiving, by a digital PCM modem (38) interconnected to the digital communication network (36), a random sequence of digital values selected from a constellation of digital values transmitted over the upstream PCM channel of the digital communication network (36); establishing distributions of the received digital values, each distribution corresponding to one of a plurality of time intervals; and deriving from the distributions the types of robbed bit signaling and digital loss affecting the upstream PCM channel of the digital communication network (36) for each time interval.

公开(公告)号：EP1295403A4

公开(公告)日：2004-05-19

申请号：EP00957811

申请日：2000-08-25

Applicant: MOTOROLA INC

Inventor： MEHRABANZAD SEPEHR ,  KIM DAE-YOUNG ,  PILOZZI JOHN

IPC: H04L29/08 ,  H04L5/14 ,  H04L25/49 ,  H04M11/00

CPC classification number: H04L5/1438 ,  H04L25/4927

Abstract: In order to achieve reliable and efficient communication over public switched telephone networks (PSTN), voice-band modems utilize sophisticated start-up procedures (310, 320, 33). This invention involves a start-up procedure that allows an analog modem (502) and a digital modem (530) to establish a dial-up connection that utilizes PCM modulation in both upstream and downstream directions for data transmission.