Abstract: A pulse amplitude modulated (PAM) mapper includes a constellation matrix memory which stores indications of a plurality of different constellations. The constellations are stored as masks of one hundred twenty-eight bits where a bit set to one indicates that the constellation includes the PCM code represented by the corresponding .mu.-law code.

Abstract: A mapper for a PAM encoder is provided and includes apparatus for generating desired code levels, and a constellation matrix memory which stores indications of a plurality of different N-dimensional constellations. The plurality of different constellations are used individually or together to support a plurality of different modem data (bit) rates. In order to maximize performance in the presence of robbed bit signalling, multidimensional constellations having different numbers of points are used together in the coding of a single group of bits.

Abstract: A pulse amplitude modulated (PAM) mapper includes a constellation matrix memory which stores indications of a plurality of different constellations, wherein at least one of the different stored constellations is of different dimension than another of the stored constellations. The constellations are used individually or together to support a plurality of different modem data rates. In a preferred embodiment, the mapper also includes a logic block, a constellation controller, a PAM code generation block, and an output register. The logic block receives incoming bits and groups the bits as a function of the desired or agreed upon bit rate as indicated by the constellation controller, and provides a plurality of each group of bits to the PAM code generation block, and one or more sign bits to the output register. The PAM code generation block uses the provided bits to choose at least one point from one of the constellations, and uses each chosen constellation point to generate a PAM code (typically .mu.

Abstract: A two-level or three-level probing signal is generated by a transmitter for transmission over a channel and for detection and analysis by a receiver. The two-level probing signal is a signal having a first PCM .mu.-law level over a first frame, and a second PCM .mu.-law level over a second frame. The two-level probing signal when combined with detection and analysis is generally sufficient for determining the presence and order of RB-signaling and PAD attenuation, and the extent of PAD attenuation may also be determined. The three-level probing signal is similar to the two-level probing signal but includes a third .mu.-law level over a third frame. A preferred two-level probing signal is a signal having a PCM .mu.-law level of .+-.975 for a first frame, and a signal having a PCM .mu.-law level of .+-.1023 for a second frame (or vice versa), although other sets of signals such as .+-.1087 and .+-.879 can be utilized. One preferred three-level probing signal is a signal having a PCM .mu.-law level of .+-.

Abstract: A spectral and power shaping mapper for high data rate signaling modem is provided. Based on data rates and other criteria, groups of incoming bits are grouped together, with a first subgroup of bits being used to generate two sign vectors, a second subgroup of bits being used in conjunction with an appended bit to generate two magnitude manipulation vectors, and a third subgroup of bits being used in a modulus converter to generate a plurality of quotients (r.sub.k). The quotients and magnitude manipulation vectors are used to select two or more sequences of constellation points from a multidimensional constellation. The sequences of selected points are combined with the sign vectors to generate four sequences of octets for a shaping selector. The shaping selector, preferably in the form of a convolutional encoder state machine uses criteria such as lowest cost paths and/or lowest average power in order to select which sequence of octets to output.

Abstract: A pulse amplitude modulated (PAM) mapper includes a constellation matrix memory which stores indications of a plurality of different constellations, wherein at least one of the different stored constellations is of different dimension than another of the stored constellations. The constellations are used individually or together to support a plurality of different modem data rates. In a preferred embodiment, in addition to the constellation matrix memory, the mapper includes a logic block, a constellation controller, a PAM code generation block, and an output register. The logic block receives incoming bits of information, groups the bits as a function of the desired or agreed upon bit rate as indicated by the constellation controller, and provides a plurality of each group of bits to the PAM code generation block, and one or more sign bits to the output register.