Abstract: In accordance with the present invention, a technique for efficiently utilizing memory in determining which next state accumulated cost to retain, such as in a communication system or a Viterbi decoder. The system includes a memory having a portion of registers allocated to a first array and a portion of registers allocated to a second array. The technique includes retrieving a present state accumulated cost from a storage register of the first array and calculating a next state accumulated cost based on the present state accumulated cost. The next state accumulated cost is stored in a storage register of the second array. The second array is designated as containing present state accumulated costs. A present state accumulated cost is retrieved from a storage register of the second array and used in calculating a subsequent next state accumulated cost. The subsequent next state accumulated cost is stored in a storage register of the first array.

Abstract: A signal processor with an embedded Viterbi co-processor is disclosed. The Viterbi branch metric unit contains embedded metric units which calculate either Euclidean or Manhattan metrics for MLSE or deconvolution operations.

Abstract: A radio modulator/demodulator particularly suitable for TDMA mobile telephone use employs digital techniques for GMSK phase modulation. Phase numbers representative respectively of an intermediate frequency carrier and modulation symbols are combined digitally to combination phase numbers which are subjected to a single folded cosine table to produce a digital trignometric sequence of numbers for modulating the transmitter. Economy of components and memory is achieved and some of the modulator components are used in demodulation which is effected by the single look-up table used in sine and cosine mode alternately.

Abstract: An improved scan converter for converting received echo signals representative of the amplitude of ultrasound energy returning from sampled points along a plurality of spaced apart paths distributed in an image space into signals to be displayed as display pixels in a raster scan display system. The scan converter includes a scan data memory for storing the received echo signals in quadrants of the scan data memory. Each quadrant is associated with even and odd numbered paths and sample row combinations. Sample rows are related to sample points along the spaced apart paths. The scan converter further includes a circuit for determining a gray scale value to be assigned to each selected display pixel based on a predetermined combination of four received echo signals adjacent the selected display pixel and chosen from the quadrants of the scan data memory. The improved scan converter is capable of operation in both linear and sector scan modes, and, when in the sector mode, over 90.degree. and 180.degree.