533results about "Amplitude demodulation by homodyne/synchrodyne circuits" patented technology

An enhanced 8-VSB reception system and E8-VSB data demultiplexing method, by which an E8-VSB signal can be stably received as well as a previous ATSC 8VSB signal, is disclosed. Herein, the enhanced data are coded at ½ code rate and ¼ code rate in the new E8-VSB transmission system compatible with the conventional ATSC 8VSB system, respectively. The ½ and ¼ enhanced data are multiplexed by 164-byte packet unit according to the previously determined multiplexing format and further pre-processed to output as the format of the MPEG transport packet. And, the pre-processed enhanced data and the main data are multiplexed again by 188-byte packet unit according to the previously determined multiplexing format. The E8-VSB map information, which was inserted in the field sync section in the E8-VSB transmission system to be transmitted, is extracted to generate the information indicating the attributes of the respective E8-VSB data. The normal data, ½ enhanced data, and ½ enhanced data are separated from each other to be decoded in the channel decoder.

An enhanced VSB transmitter includes a data attribute generator which generates data attribute information based on a current enhanced mode map, and a VSB pre-processor which codes first and second supplemental data for error correction, interleaves the coded supplemental data, and expands the interleaved data at first and second rates, respectively, according to the data attribute information. The transmitter further includes a multiplexer which multiplexes main data with the expanded supplemental data according to the data attribute information, and a VSB processor which codes the data multiplexed by the multiplexer for error correction.

A robust data extension, added to a standard 8VSB digital television signal, is used to improve the performance of a digital television receiver. Robust data packets are encoded at a 1 / 3-trellis rate as compared to normal data packets that are encoded at a 2 / 3-trellis rate. In addition to delivery of robust data for mobile applications, the redundant robust data packets also improve the performance of the receiver in the normal tier of service. In particular, the robust data packets improve the performance of the receiver equalizer filter in the presence of rapidly changing transient channel conditions such as dynamic multipath for both robust data packets and normal data packets. The robust data packets improve the performance of the carrier recovery loop and the symbol timing recovery loop. Backward compatibility with existing receivers is maintained for 1) 8VSB signaling, 2) trellis encoding and decoding, 3) Reed Solomon encoding and decoding, and 4) MPEG compatibility.

Improved decision feedback equalizer and decision directed timing recovery systems and methods suitable for use in connection with a dual mode QAM / VSB receiver system are disclosed. A trellis decoder operates in conjunction with a decision feedback equalizer circuit on trellis coded 8-VSB modulated signals. The trellis decoder includes a 4-state traceback memory circuit outputting a maximum likelihood decision as well as a number of intermediate decisions based upon the maximum likelihood sequence path. Any number of decisions, along the sequence, may be provided as an input signal to timing recovery system loops, with the particular decision along the sequence chosen on the basis of its delay through the trellis decoder. Variable delay circuitry is coupled to the other input of the timing recovery system loops in order to ensure that both input signals bear the same timestamp. Final decisions are output from the trellis decoder to a DFE in order to enhance the DFE's ability to operate in low SNR environments. A decision sequence estimation error signal is also generated and used to drive the tap updates of both the DFE and an FFE portion of the equalizer.

An efficient decoding of vector signaling codes is obtained using a circuit that ranks received signal levels, designates ranked values as representing particular code elements, and translates those particular code elements into a decoded result. An optimized ranking circuit combines analog crossbar switching of signal values with comparators that provide digital results. These elements may be repetitively tiled into processing arrays capable of larger ranking operations, or iteratively applied to selected portions of the data set under control of a sequencer or controller.

An integrated multimode radio includes a multimode receiver and a multimode transmitter. The multimode receiver includes a shared receiver front-end, a receiver multiplexor, and a plurality of receiver IF stages. The multimode transmitter includes a shared transmitter front-end, a transmitter multiplexor, and a plurality of transmitter IF stages.

Modem coding and modulation techniques have greatly improved the transmission and reception of signals. A method is described including receiving a signal de-mapping the signal into a first and second substream, decoding the first and second substream using a low density parity check decoding process, and combining the first and second decoded substream into a single data stream. An apparatus is described including a symbol de-mapper that receives a signal de-maps the modulation symbols in the signal into a first and second substream, a first decoder that decodes the first substream using a low density parity check coding process at a first decoding rate, a second decoder that decodes the second substream at a second encoding rate, and a combiner that combines the first substream and the second substream into a single data stream.

A differential radio frequency signal transmitter is provided. The differential radio frequency signal transmitter includes an oscillator, a modulator and an amplifier module. The oscillator generates a pair of differential oscillation signals. The modulator generates a pair of differential modulated signals according to an input signal and the pair of differential oscillation signals. The input signal is a digital signal. When the input signal is at a first state, the modulator outputs the pair of differential oscillation signals as the pair of differential modulated signals, and when the input signal is at a second state, the modulator outputs a constant voltage signal as the pair of differential modulated signals. The amplifier module receives and amplifies the pair of differential modulated signals and generates a pair of differential radio frequency signals, accordingly.

Provided is a method for transmitting data in a communication or broadcasting system using a linear block code by generating a codeword by encoding input information data bits, interleaving the codeword; outputting modulation signal-constituting bits by bit-mapping the interleaved codeword using a bit-mapping table predetermined depending on a modulation scheme and a coding rate, outputting a modulation signal by modulating the modulation signal-constituting bits and transmitting the modulation signal via a transmit antenna.

A carrier and symbol timing recovery apparatus usable in a VSB (Vestigial Side Band) receiver, and a method thereof. For a carrier and symbol timing recovery, error information is detected using a pilot signal, an upper sideband and a lower sideband of a received signal. Each of the detected error information is multiplied by a predetermined weight, respectively, and the results of the respective multiplications are added / combined. Therefore, even though the pilot signal may be corrupted, the carrier recovery can nevertheless be accurately performed. Additionally, even though the upper sideband of a received VSB-modulated signal may be corrupted, the lower sideband can be utilized to perform the symbol timing recovery. As a result, performance of a receiving system can be improved even under unfavorable channel characteristics. Moreover, since the carrier recovery and the symbol timing recovery are executed through a single apparatus, it becomes possible to simplify a hardware implementation thereof.

Transmitter apparatus transmits metadata together with data, at least part of which metadata specifies the version of coded orthogonal frequency-division modulation (COFDM) broadcasting standard it uses for transmitting. Some of the metadata is conveyed by prescribed signature modulation of pilot carrier waves dispersed in one or another of prescribed patterns among the COFDM carrier waves that convey interleaved forward-error-correction coded digital signals. Receiver apparatus detects that metadata by searching for a prescribed signature modulation of the continual pilot carrier waves in those transmissions. Preferably, Barker modulation of the continual pilot carriers near the conclusion of each COFDM frame signals the start of the next COFDM frame to the receiver apparatus.

A communication system includes a transmitter that transmits both wideband data and narrowband data on a link and a receiver that receives the wideband data and the narrowband data on the link. The receiver demultiplexes the wideband data and the narrowband data into separate data streams so that the link effects transmission of a narrowband channel and a wideband channel. The system achieves high link availability on a link using bandwidth efficient modulation by using a more robust modulation format for the narrowband channel to enable higher link availability for the narrowband channel (carrying the narrowband data on the link) than for the wideband channel. The link may employ bandwidth efficient modulation or may be compatible with prior art wideband modulation formats.

Processing a received optical signal in an optical communication network includes equalizing a received optical signal to provide an equalized signal, demodulating the equalized signal according to an m-ary modulation format to provide a demodulated signal, decoding the demodulated signal according to an inner code to provide an inner-decoded signal, and decoding the inner-decoded signal according to an outer code. Other aspects include other features such as equalizing an optical channel including storing channel characteristics for the optical channel associated with a client, loading the stored channel characteristics during a waiting period between bursts on the channel, and equalizing a received burst from the client using the loaded channel characteristics.

An enhanced 8-VSB reception system and E8-VSB data demultiplexing method, by which an E8-VSB signal can be stably received as well as a previous ATSC 8VSB signal, is disclosed. Herein, the enhanced data are coded at ½ code rate and ¼ code rate in the new E8-VSB transmission system compatible with the conventional ATSC 8VSB system, respectively. The ½ and ¼ enhanced data are multiplexed by 164-byte packet unit according to the previously determined multiplexing format and further pre-processed to output as the format of the MPEG transport packet. And, the pre-processed enhanced data and the main data are multiplexed again by 188-byte packet unit according to the previously determined multiplexing format. The E8-VSB map information, which was inserted in the field sync section in the E8-VSB transmission system to be transmitted, is extracted to generate the information indicating the attributes of the respective E8-VSB data. The normal data, ½ enhanced data, and ½ enhanced data are separated from each other to be decoded in the channel decoder.

The system in one embodiment relates to tightly integrating parameter estimation, symbol hypothesis testing, decoding, and rate identification. The present invention provides Turbo-decoding for joint signal demodulation based on an iterative decoding solution that exploits error correction codes. The system iteratively couples an initial amplitude estimator, a symbol estimator, a bank of decoders, and a joint amplitude estimator to produce the symbol estimates.

A receiving circuit mainly available in a digital modulation type communication system having a plurality of channels, which is capable of reducing power in a receiving system, simplifying the circuit and reducing the power consumption. Upside and downside frequencies corresponding to a central value between channels are separately supplied from a local frequency signal generating circuit 4 to first and second frequency converting circuits 2, 3 so that two output signals are developed with respect to one of a desired wave, upside channel and downside channel. The desired wave present in common in the first and second frequency converting circuits 2, 3 is extracted in a common wave extracting circuit 5, and a frequency offset of omegao existing in the output of the common wave extracting circuit 5 is removed a frequency offset circuit 6 and further an unnecessary frequency component is filtered by a filter 8. In addition, the common wave extracting circuit 5 has transformers and, using its inductances, raises the difference between the common wave and the non-common wave within the circuit to more than two times that of a prior art.

The present invention discloses a receiving system and a method of processing data to receiving and processing mobile service data. The receiving system may include a signal receiving unit, a demodulating unit, a data processor, and a middleware engine. The signal receiving unit receives a broadcasting signal, which includes IP packets, payload of the IP packets including a DSM-CC module data part and a DSM-CC header, the DSM-CC module data part including a plurality of DSM-CC objects, and the DSM-CC header including identification information for identifying the DSM-CC module. The demodulating unit demodulates the received broadcasting signal including IP packets. The data processor extracts a plurality of DSM-CC objects of a corresponding payload with reference to DSM-CC header information of the IP packets demodulated by the demodulating unit and configuring a DSM-CC module, which includes identification information and the extracted DSM-CC objects. The middleware engine provides a data broadcasting service by driving application corresponding to the DSM-CC module.

A method of receiving Multiple Input Multiple Output—Orthogonal Frequency Division Multiple Accessing (MIMO-OFDMA) signals using a single receiver rather than multiple receivers and performing measurements specific to various parts of MIMO-OFDMA systems using all measurable parameters of MIMO-OFDMA systems is disclosed. In addition, a method of receiving and completing impairment estimation of WiMAX MIMO signals using a single receiver according to the IEEE 802.16 standards is provided.

Processing a received optical signal in an optical communication network includes equalizing a received optical signal to provide an equalized signal, demodulating the equalized signal according to an m-ary modulation format to provide a demodulated signal, decoding the demodulated signal according to an inner code to provide an inner-decoded signal, and decoding the inner-decoded signal according to an outer code. Other aspects include other features such as equalizing an optical channel including storing channel characteristics for the optical channel associated with a client, loading the stored channel characteristics during a waiting period between bursts on the channel, and equalizing a received burst from the client using the loaded channel characteristics.

Systems and methods for receiving layered modulation for digital signals are presented. An exemplary apparatus comprises a tuner for receiving a layered signal and producing a layered in-phase signal and a layered quadrature signal therefrom, an analog-to-digital converter for digitizing the layered in-phase signal and the layered quadrature signal and a processor for decoding the layered in-phase signal and the layered quadrature signal to produce one or more discrete layer signals.

A digital broadcasting transmission system processes dual transport stream (TS) including multi turbo streams. The digital broadcasting transmission system includes a turbo processor to detect a turbo stream from a dual transport stream (TS) which includes a multiplexed normal stream and a turbo stream, encoding the detected turbo stream and stuffing the encoded turbo stream into the dual TS; and a transmitter to trellis-encode the processed dual TS, and to output the resultant stream, wherein the turbo processor encodes the turbo stream using a plurality of turbo processors. Accordingly, a plurality of turbo streams may be processed in parallel.

A system that blends a hybrid radio signal may provide reduced audio content skipping and may determine an audio correlation between analog and digital signal components in the hybrid radio signal before blending from the analog signal component to the digital signal component. The system may reduce volume level transitions during blending by adjustment of blend and cross-fade variables, as well as setting a hysteresis mode to prevent undesirable sequential jumping from digital mode back to analog mode. The system also may compensate for digital AM frequency quality issues by adjustment of a filter bandwidth when the receiver blends an AM signal from analog to digital mode.

An output of an equalizer is decoded to produce first decoded data having a first accuracy. The output of the equalizer is further decoded to produce second decoded data having a second accuracy, and the second accuracy is greater than the first accuracy. Tap weights for the equalizer are calculated using the first and second decoded data. The calculated tap weights are applied to the taps of the equalizer.

The invention relates to a method of reducing Peak-to-Average. Power Ratio in a transmitting device of a filter-hank multi-carrier system, which includes the steps of: performing constellation modulation (210) on data to be transmitted; performing K-point Discrete Fourier Transform (220) on a vector composed of K constellation symbols resulting from the constellation modulation: and performing Offset-Quadrature Amplitude Modulation (230) on a data vector resulting from the Discrete Fourier Transform, wherein the parameter K represents the number of subcarriers allocated for transmission of the data to be transmitted. With the solution proposed by the invention. PAPR of a signal can be significantly reduced without adding a large number of operations to thereby improve the efficiency of a power amplification circuit, to improve effective transmission, power and to alleviate nonlinear distortion of the signal during a power amplification.

A closed loop power control system for a radio frequency (RF) transmitter comprises a first variable gain element located in a power control loop and configured to receive a power level signal and an inverse representation of a power control signal, a second variable gain element located in the power control loop and configured to receive an error signal and the power control signal, and a third variable gain element configured to receive an amplitude modulated (AM) signal and the power control signal, the third variable gain element having a gain characteristic configured to operate to reduce the gain applied to the AM signal when the power control signal falls below a minimum predetermined value, and to provide the AM signal as a reference signal.

An adjustable K-factor-improvement (KFI) filter having a sparse kernel composed of non-zero weighting coefficients of substantially equal amplitudes is included in a receiver for digital television signals or the like. The receiver includes apparatus for measuring the channel impulse response (CIR) or cepstrum of the signal as received. The respective polarities of the non-zero weighting coefficients in the sparse kernel of the adjustable KFI filter are adjusted responsive to the measured CIR. The differential delay between each successive pair of non-zero weighting coefficients in the sparse kernel of the adjustable K-factor-improvement filter is adjusted responsive to the measured CIR. The adjustment is such that the KFI filter response has a principal component with substantially more energy than any of its echo components. The KFI filter response is applied as input signal to subsequent adaptive equalization filtering in the receiver.