Abstract: A receiver recovers local service data symbols from first Orthogonal Frequency Division Multiplexed (OFDM) symbols in the presence of second OFDM symbols. The second OFDM symbols carry national broadcast data symbols and modulated on to the sub-carriers of the second OFDM symbols using a first modulation scheme. The first OFDM symbols carry the national broadcast data symbols and the local service data symbols from a local insertion pipe and modulated on to the sub-carriers of the first OFDM symbols using a second modulation scheme. The receiver comprises an OFDM detector which includes an equalizer to recover local service modulated sub-carriers of the second modulation scheme.

Abstract: A receiver detects and recovers data from Orthogonal Frequency Division Multiplexed (OFDM) symbols, which include pilot sub-carriers as well as data bearing sub-carriers. The receiver comprises a channel estimation processor and a channel estimate post processor. The channel estimation processor includes a pilot acquisition unit adapted to generate a sample of the channel transfer function for each pilot sub-carrier in a received OFDM symbol, and a channel estimator which is arranged to generate an estimate of the channel transfer function providing samples of the channel transfer function at each sub-carrier position in the received OFDM symbol from the pilot derived samples provided by the pilot acquisition unit. The channel estimate post processor is arranged to process the estimate of the channel transfer function received from the channel estimation processor to generate a processed version of the channel transfer function.

Abstract: A transmitter communicating data using Orthogonal Frequency Division Multiplexed (OFDM) symbols including plural sub-carrier symbols in the frequency domain for modulating with data to be carried. The transmitter includes a modulator to receive data symbols from a first data pipe according to a first communications channel, to receive data symbols from a local service insertion data pipe according to a local communications channel, and to modulate the sub-carrier signals of the OFDM symbols with either the data symbols from the first data pipe or from both the first data pipe and the local service insertion pipe; modulation from the first data pipe maps the data symbols is according to a first modulation scheme, and modulation from the first data pipe and the local service insertion pipe maps the data symbols is according to a second modulation scheme.

Abstract: A receiver for receiving a sequence of OFDM symbols transmitted via a channel. Each OFDM symbol comprises a plurality of data bearing sub-carriers and a plurality of pilot bearing sub-carriers. The receiver includes a channel estimator, and the channel estimator includes a pilot data extractor, a pilot data extrapolator and a pilot data interpolator operable to process the pilot data by interpolating between the extrapolated pilot data in time and frequency. The receiver also comprises a discontinuity detector for detecting a discontinuity in the pilot data processed by the channel estimator, and a controller, which upon detection of a pilot data discontinuity by the discontinuity detector, is operable to provide a control signal to the channel estimator which causes at least one of the pilot data extractor, the pilot data extrapolator and the pilot data interpolator to compensate for the discontinuity in the pilot data.

Abstract: A receiver detects and recovers data from Orthogonal Frequency Division Multiplexed (OFDM) symbols, which include pilot sub-carriers as well as data bearing sub-carriers. The receiver comprises a channel estimation processor and a channel estimate post processor. The channel estimation processor includes a pilot acquisition unit adapted to generate a sample of the channel transfer function for each pilot sub-carrier in a received OFDM symbol, and a channel estimator which is arranged to generate an estimate of the channel transfer function providing samples of the channel transfer function at each sub-carrier position in the received OFDM symbol from the pilot derived samples provided by the pilot acquisition unit. The channel estimate post processor is arranged to process the estimate of the channel transfer function received from the channel estimation processor to generate a processed version of the channel transfer function.

Abstract: A receiver for receiving a sequence of OFDM symbols transmitted via a channel. Each OFDM symbol comprises a plurality of data bearing sub-carriers on which data is transmitted and a plurality of pilot bearing sub-carriers on which pilot data. The pilot sub-carriers are distributed throughout the OFDM symbols of the sequence in accordance with a pilot sub-carrier pattern. The receiver includes a channel estimator, and the channel estimator includes a pilot data extractor for extracting pilot data from the pilot sub-carriers of each OFDM symbol; a pilot data extrapolator for generating extrapolated pilot data based on pilot data extracted from the pilot data sub-carriers; and a pilot data interpolator operable to process the pilot data by interpolating between the extrapolated pilot data in time and frequency to produce an estimate of the channel.