Wireless infrared digital audio system
First Claim
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1. A system for transmitting and receiving digitized samples of the analog signals on a communication medium, while maintaining fidelity of said digitized samples analog signals, comprising:
- a transmission subsystem connected between an external source of the digitized samples of the analog signals and the communication medium comprising;
a sampled data receiver to receive said digitized samples of the analog signals from the external source of the digitized samples analog signals, a data buffer to retain a plurality of the digitized samples analog signals, a data buffer controller connected to the data buffer to control the placement and removal of the plurality of digitized samples of the analog signals within the data buffer, an error correction code generator connected to the data buffer controller to receive multiple digitized samples of the analog signals through said data buffer controller from said data buffer, to generate an error correction word to be appended to said multiple digitized samples analog signals, and to return the multiple digitized samples of the analog signals with the appended error correction word through the data buffer controller to the data buffer, a frame formatter connected to the data buffer controller to receive an interleaved group of the multiple digitized samples of the analog signals and append a preamble timing signal and a start signal before said interleaved group of the multiple digitized samples of the analog signals to form a transmit frame, a pulse position modulator connected to the frame formatter to receive the transmit frame and to modulate according bit values of the transmit frame a pulse position of a carrier signal, and a burst transmitter connected between the pulse position modulator and the communication medium to convey a modulated carrier signal to said communication medium, whereby said modulated carrier signal is transmitted as a burst within a short time period to minimize probability of interference on said communication medium;
a receiver subsystem connected between the communication medium and a digital-to-analog converter for recovering said digitized samples analog signals, comprising;
a receiver connected to the communication medium to recover said modulated carrier signal and extract a modulated transmit frame, a demodulator connected to said receive to demodulate the modulated transmit frame and recover the transmit frame and extract the groups of interleaved multiple digitized samples of the analog signals with the appended error correction code, a received data buffer to retain the group of interleaved multiple digitized samples of the analog signals with the appended error correction code, a received data buffer controller connected to the demodulator and the received data buffer to control transfer of the group of interleaved multiple digitized samples of the analog signals with the appended error correction code from the demodulator to the received data buffer, an error check and correction circuit connected to the received data buffer controller to receive one group of the multiple digitized samples of the analog signals with the appended error correction code, to check and correct errors in said one of the multiple digitized samples analog signals, to replace the corrected one group of the multiple digitized samples of the analog signals to the received data buffer, and to identify any non-correctable group of the multiple digitized samples analog signals, a block recovery circuit connected to the received data buffer controller to interpolate the non-correctable group of the multiple digitized samples of the analog signals to conceal an effect of said non-correctable group of the multiple digitized samples analog signals. a soft muting circuit connected to the received data buffer controller to access those of the multiple digitized samples of the analog signals with non-recoverable and non-concealable errors and those of the multiple digitized samples of the analog signals that are correct and adjacent to the multiple digitized samples of the analog signals with non-correctable and non-concealable errors, to apply a smoothing function to said multiple digitized samples of the analog signals to bring those of the multiple digitized samples of the analog signals with the non-correctable and non-concealable error to a null value, a jitter tracking circuit to compare a block transmission timing signal with a clock signal of said receiver subsystem to determine overrun and underrun of the contents of the group of interleaved multiple digitized samples of the analog signals with the appended error correction code, whereby said block transmission timing signal indicates a boundary between groups of interleaved multiple digitized samples of the analog signals with the appended error correction code, an interpolation and decimation circuit connected to the jitter tracking circuit and the received data buffer controller to generate or eliminate digitized samples of the analog signals if the jitter tracking circuit indicates overrun or underrun of the contents of the group of interleaved multiple digitized samples analog signals, and an interface circuit connected to the received data buffer controller to translate the digitized samples of the analog signals to a format acceptable by subsequent circuitry.
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Abstract
A system for transmitting, receiving, recovering, and reproducing digitized samples of analog signals while concealing unrecoverable digitized samples of analog signals to maintain a level of fidelity in reproducing the analog signals. The digitized samples of the analog signals are burst transmitted such that the probability of interference with the transmission and thus corruption of the digitized samples of the analog signals is minimized. The digitized samples are received without synchronizing a receiving clock with a transmitting clock to capture the digitized samples of the analog signals. The digitized samples are converted from various sampling rates to digitized samples of the analog signals having a rate. Any large groups of digitized samples that are in error or corrupted in transmission are softly muted to avoid annoying clicks. Any long term difference between a transmit clock and a receive clock is tracked and the digitized samples are interpolated or decimated to eliminate any underrun or overrun of the digitized samples.
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Citations
23 Claims
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1. A system for transmitting and receiving digitized samples of the analog signals on a communication medium, while maintaining fidelity of said digitized samples analog signals, comprising:
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a transmission subsystem connected between an external source of the digitized samples of the analog signals and the communication medium comprising;
a sampled data receiver to receive said digitized samples of the analog signals from the external source of the digitized samples analog signals, a data buffer to retain a plurality of the digitized samples analog signals, a data buffer controller connected to the data buffer to control the placement and removal of the plurality of digitized samples of the analog signals within the data buffer, an error correction code generator connected to the data buffer controller to receive multiple digitized samples of the analog signals through said data buffer controller from said data buffer, to generate an error correction word to be appended to said multiple digitized samples analog signals, and to return the multiple digitized samples of the analog signals with the appended error correction word through the data buffer controller to the data buffer, a frame formatter connected to the data buffer controller to receive an interleaved group of the multiple digitized samples of the analog signals and append a preamble timing signal and a start signal before said interleaved group of the multiple digitized samples of the analog signals to form a transmit frame, a pulse position modulator connected to the frame formatter to receive the transmit frame and to modulate according bit values of the transmit frame a pulse position of a carrier signal, and a burst transmitter connected between the pulse position modulator and the communication medium to convey a modulated carrier signal to said communication medium, whereby said modulated carrier signal is transmitted as a burst within a short time period to minimize probability of interference on said communication medium;
a receiver subsystem connected between the communication medium and a digital-to-analog converter for recovering said digitized samples analog signals, comprising;
a receiver connected to the communication medium to recover said modulated carrier signal and extract a modulated transmit frame, a demodulator connected to said receive to demodulate the modulated transmit frame and recover the transmit frame and extract the groups of interleaved multiple digitized samples of the analog signals with the appended error correction code, a received data buffer to retain the group of interleaved multiple digitized samples of the analog signals with the appended error correction code, a received data buffer controller connected to the demodulator and the received data buffer to control transfer of the group of interleaved multiple digitized samples of the analog signals with the appended error correction code from the demodulator to the received data buffer, an error check and correction circuit connected to the received data buffer controller to receive one group of the multiple digitized samples of the analog signals with the appended error correction code, to check and correct errors in said one of the multiple digitized samples analog signals, to replace the corrected one group of the multiple digitized samples of the analog signals to the received data buffer, and to identify any non-correctable group of the multiple digitized samples analog signals, a block recovery circuit connected to the received data buffer controller to interpolate the non-correctable group of the multiple digitized samples of the analog signals to conceal an effect of said non-correctable group of the multiple digitized samples analog signals. a soft muting circuit connected to the received data buffer controller to access those of the multiple digitized samples of the analog signals with non-recoverable and non-concealable errors and those of the multiple digitized samples of the analog signals that are correct and adjacent to the multiple digitized samples of the analog signals with non-correctable and non-concealable errors, to apply a smoothing function to said multiple digitized samples of the analog signals to bring those of the multiple digitized samples of the analog signals with the non-correctable and non-concealable error to a null value, a jitter tracking circuit to compare a block transmission timing signal with a clock signal of said receiver subsystem to determine overrun and underrun of the contents of the group of interleaved multiple digitized samples of the analog signals with the appended error correction code, whereby said block transmission timing signal indicates a boundary between groups of interleaved multiple digitized samples of the analog signals with the appended error correction code, an interpolation and decimation circuit connected to the jitter tracking circuit and the received data buffer controller to generate or eliminate digitized samples of the analog signals if the jitter tracking circuit indicates overrun or underrun of the contents of the group of interleaved multiple digitized samples analog signals, and an interface circuit connected to the received data buffer controller to translate the digitized samples of the analog signals to a format acceptable by subsequent circuitry. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification
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Current AssigneeFreeSystems Pte Ltd.
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Original AssigneeFreeSystems Pte Ltd.
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InventorsChua, Bena Huat, Chan, Chee Oei, Lee, Kah Yong, Siew, Chee Kong
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Primary Examiner(s)Pham, Chi
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Assistant Examiner(s)TRAN, KHANH C
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Application NumberUS09/425,315Time in Patent Office1,184 DaysField of Search375/259, 375/260, 375/261, 375/295, 375/316, 375/302, 375/322, 375/354, 455/66, 455/103, 455/110, 455/112, 455/131, 455/93, 455/102, 381/77, 381/105, 381/102, 381/80, 381/81US Class Current375/259CPC Class CodesH04J 3/0632 Synchronisation of packets ...H04L 1/0057 Block codes H04L1/0061, H04...H04L 7/0066 detection of error based on...
