公开(公告)号：EP1038379A4

公开(公告)日：2003-01-02

申请号：EP98960216

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

CPC classification number: H04L25/4927 ,  H04L25/03343

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：CA2398484C

公开(公告)日：2009-12-29

申请号：CA2398484

申请日：2001-02-01

Applicant: MOTOROLA INC

Inventor： MEHRABANZAD SEPEHR ,  KIM DAE-YOUNG

IPC: H04B1/38 ,  H04B3/23 ,  H04B14/04 ,  H04L5/14 ,  H04L25/49

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 the digital modem (26) transmitter is silenced (54) during generation of training signal by analog modem (12), with silencing of the digital modem's transmitter eliminating problems associated with echo during channel measurement at the digital modem. The above method thus eliminates echo duri ng channel estimation and removes any dependencies on the performance of the echo canceller normally used.

公开(公告)号：CA2397971C

公开(公告)日：2008-04-22

申请号：CA2397971

申请日：2001-02-01

Applicant: MOTOROLA INC

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

IPC: H04L12/12 ,  H04L29/08 ,  H04L1/00 ,  H04L25/03 ,  H04L27/02 ,  H04M11/00 ,  H04M11/06

Abstract: In a full duplex PCM modem system (10) having an analog (12) and digital (18) modem, a method and apparatus is provided for on-the-fly reconfiguring of analog (12) or digital (18) modem transmitter parameters without switching back to a retrain or startup mode. In one embodiment, the transmitter parameters for the analog modem (12) are modified to take into account channel impairments, in which modified precompensation parameters are sent from the digital modem (18) to the analog modem (12) without switching out of the data mode. In another embodiment, transmit power levels sensed at the analog modem (12) which are non-optimal are adjusted by new parameters sent from the digital modem (18) without having to switch back to the startup mode. In a further embodiment, transmitter parameters in the digital modem (18) are reconfigured to provide more an increased downstream data rate from the digital modem (18) upon sensing improvement in the quality of the downstream channel without switching back to the startup mode.

公开(公告)号：CA2399075C

公开(公告)日：2007-12-04

申请号：CA2399075

申请日：2001-02-01

Applicant: MOTOROLA INC

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

IPC: H04B1/38 ,  H04L25/38 ,  H04L5/16 ,  H04L7/02 ,  H04L25/49 ,  H04M11/06

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 of the fractional sampling phase so that the fractional sampling phase offset at the central office quantizer (22) is optimized.

公开(公告)号：CA2399513C

公开(公告)日：2005-04-19

申请号：CA2399513

申请日：2001-02-01

Applicant: MOTOROLA INC ,  3COM CORP

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

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 (100). If RBS is present, the slots affected by RBS are identifed. Next it is determined what data slots, if any, are affected by encoding (102). The PCM data frame is shifted to the RBS constraint and the encoding constraint do not coincide at any particular data slot (104). 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 (106). 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：CA2399076C

公开(公告)日：2004-10-12

申请号：CA2399076

申请日：2001-02-01

Applicant: MOTOROLA INC

Inventor： MAURER PATRICK ,  KIM DAE-YOUNG ,  MEHRABANZAD SEPEHR

IPC: H04L27/00 ,  H04B7/005 ,  H04B14/04 ,  H04L25/49 ,  H04M11/00 ,  H04B14/06 ,  H04L5/16 ,  H04L25/34 ,  H04B1/38

Abstract: In a PCM modem system in which equivalence classes are used to communicate information from a transmitter to a receiver, a method is provided to solve the problem of 180.degree. phase reversals in the communications channel which result in a garbled transmission. This is accomplished by re-mapping the equivalence classes into a form that can be differentially encoded and decoded such that equivalence class identity is not lost during a phase reversal of the channel. Referring to Figure 2, an incoming bit stream (10) is applied to a modulus converter ( 12) which is in turn coupled to a mapping block (14) which maps the output of the modulus converter to the type of structure shown in Figure 1 in which each equivalence class is provided with a label that includes a sign bit and magnitude bits.

公开(公告)号：CA2399543C

公开(公告)日：2004-08-17

申请号：CA2399543

申请日：2001-02-01

Applicant: 3COM CORP ,  MOTOROLA INC

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

IPC: H04L7/00 ,  H04L25/49

Abstract: A system and method for adjusting the phase of the analog signal produced by an analog modem (26) connected to a digital modem (20) over a telephone network (22). The digital portion of the telephone network is locked to the network clock, and the modems (20 and 26) have no control over the sampling timing or rate as the analog signal is sampled and quantized by a codec (23). If the analog signal is shifted in phase relative to the network clock.the codec (23) 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 (26) symbol frequency is locked (101) to the clock of the digital network (22) using loop-back timing. A phase estimate (103) is computed using the quantized samples of a known reference signal. Next, a phase offset (105) is calculated by comparing the phase estimate to an optimum phase value. Then the digital modem (20) sends the calculated phase offset information ( 107) to the analog modem (26). The analog modem (26) then delays its transmitted signal by the phase offset (109). After the phase of the analog modem's transmitter is adjusted, the analog signal reaches the codec (23) at the phase desired by the digital modem (20).

公开(公告)号：AU3324701A

公开(公告)日：2001-08-14

申请号：AU3324701

申请日：2001-02-01

Applicant: MOTOROLA INC

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

IPC: H04L29/08 ,  H04L1/00 ,  H04L25/03 ,  H04M11/00 ,  H04B1/38 ,  H04L5/16

Abstract: In a full duplex PCM modem system having an analog and digital modem, a method and apparatus is provided for on-the-fly reconfiguring of analog or digital modem transmitter parameters without switching back to a retrain or startup mode. In one embodiment, the transmitter parameters for the analog modem are modified to take into account channel impairments, in which modified precompensation parameters are sent from the digital modem to the analog modem without switching out of the data mode. In another embodiment, transmit power levels sensed at the analog modem which are non-optimal are adjusted by new parameters sent from the digital modem without having to switch back to the startup mode. In a further embodiment, transmitter parameters in the digital modem are reconfigured to provide more an increased downstream data rate from the digital modem upon sensing improvement in the quality of the downstream channel without switching to the startup mode.

公开(公告)号：AU3127901A

公开(公告)日：2001-08-14

申请号：AU3127901

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, a method and apparatus is provided for robust measuring of the communications channel in which the digital modem's transmitter is silenced during generation of training signals by the analog modem, with the silencing of the digital modem's transmitter eliminating problems associated with echo during channel measurement at the digital modem. The above method thus eliminates echo during channel estimation and removes any dependencies on the performance of the echo canceller normally used.

公开(公告)号：CA2398487A1

公开(公告)日：2001-08-09

申请号：CA2398487

申请日：2001-02-01

Applicant: MOTOROLA INC

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

IPC: H04L25/03 ,  H04B3/04 ,  H04B3/06 ,  H04B7/005 ,  H04L25/49 ,  H04B1/38 ,  H04B1/00 ,  H04B14/04 ,  H04B1/10

Abstract: A method and apparatus is provided for controlling the transmit power of an analog modem (12) when the transmit power does not match the desired transmi t power level, thus conforming to FCC regulations on transmit power and/or eliminating non-linearities associated with higher than required power level s and loss of signal-to-noise ratio and concomitant at loss of data rate if th e transmit power levels are less than that desired. The power level (26) at th e analog modem (12) is sensed to ascertain if it is not at the desired transmi t power level (28), with adjustment being provided by transmitting the desired change (30) in the transmit power level to the digital modem (18), whereupon mapping parameters (34, 36) are redefined by adjusting the number of equivalence classes, thus to adjust transmit power at analog modem (12).