Abstract: An LDPC decoder, applicable to LDPC codes including codes where check nodes within the same group are connected to a common bit node, successively processes groups of check nodes in a particular iteration, including updating bit nodes in that same iteration responsive to messages generated in response to processing a group of check nodes. Within an iteration, the LDPC decoder may also track the number of unresolved parity check equations, and cease iterating or output to an outer block decoder if that number reaches a local minima or standard minimum, falls below a predetermined threshold, or its rate of change falls below a predetermined threshold, indicating a lack of convergence or false convergence condition. The LDPC decoder may also provide a feedback assist to a demodulator. Also, a novel memory configuration may store messages generated by the decoder in the course of check node processing.

Abstract: A multi-channel decoder system has a decoder core at least a portion of which is configurable as a LDPC decoder that, during decoding processing, divides check nodes of a node representation of a LDPC code into a plurality of groups, and, during an iteration, sequentially processes the groups while processing in parallel the check nodes within each group, thus improving decoding throughput.

Abstract: An LDPC decoder, applicable to LDPC codes including codes where check nodes within the same group are connected to a common bit node, successively processes groups of check nodes in a particular iteration, including updating bit nodes in that same iteration responsive to messages generated in response to processing a group of check nodes. Within an iteration, the LDPC decoder may also track the number of unresolved parity check equations, and cease iterating or output to an outer block decoder if that number reaches a local minima or standard minimum, falls below a predetermined threshold, or its rate of change falls below a predetermined threshold, indicating a lack of convergence or false convergence condition. The LDPC decoder may also provide a feedback assist to a demodulator. Also, a novel memory configuration may store messages generated by the decoder in the course of check node processing.

Abstract: A multi-channel decoder system has a decoder core, at least a portion of which comprises or is configurable as a LDPC decoder, a plurality of channels to and from the decoder core, and control logic for controlling application of the decoder core to data carried by one or more of the channels.

Abstract: A demodulator responsive to a symbol containing analog signal includes a pair of relatively inexpensive analog-to-digital converters for sampling I and Q channels of the signal only once per symbol. A derotator responsive to outputs of the converters and a digital signal representing frequency and phase corrections for an input to the demodulator operates in accordance with a CORDIC function to derive I and Q channel digital signals that are compensated by the corrections. A digital phase shifter responsive to at least one of the digital I and Q signals controls when the input is sampled by the converter.

Abstract: A clock is phase shifted by an amount controlled by the value of a control signal by establishing at least several discrete delay times to be imposed on the clock. The control signal value controls selection of the imposed discrete delay time. An analog-to-digital converter of a phase locked loop responds to intelligence representing variable phase bits and the selected phase shifted clock to control the signal value. The selected replica is derived by at least several cascaded substantially equal time delay units. In one embodiment, a multiplexer responds to the clock, and the signal value, which is Gray coded, to control connections from one of the delay units to an output terminal. In another embodiment, the number of cascaded delay units interposed between the clock and an output terminal is controlled by the signal value.