Device and method for fast transition from preamble synchronization to data demodulation in direct sequence spread spectrum (DSSS) communications
First Claim
1. A device for fast transition from preamble synchronization of a received signal to demodulation of the received signal, comprising:
- a chip tracking loop to generate an offset tracking value to track any initial chip phase offset and Doppler-caused chip frequency drift associated with the received signal;
a numerical controlled oscillator to correct any Doppler-caused phase rotation associated with the received signal;
a preamble synchronization unit to detect a preamble of the received signal, and to measure a chip phase offset and a Doppler frequency shift associated with the received signal, wherein the chip phase offset is used to set an initial chip phase offset value of the chip tracking loop so that the chip tracking loop starts with approximately a zero pull-in error, and the Doppler frequency shift is used to set initial frequency offset values in the chip tracking loop and the numerical controlled oscillator so that both start with near-zero offset errors for demodulation of the received signal; and
an output device to output the data demodulated from the received signal.
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Accused Products
Abstract
A device for fast transition from preamble synchronization of a received baseband signal to demodulation of the received baseband signal may include a baseband chip tracking loop to generate an offset tracking value to track any initial chip phase offset and Doppler-caused baseband chip frequency drift associated with the received baseband signal. The device may also include a numerical controlled oscillator to correct any Doppler-caused phase rotation associated with the received signal. The device may additionally include a preamble synchronization unit to detect a preamble of the received baseband signal, and to measure a chip phase offset and a baseband Doppler frequency shift associated with the received baseband signal. The chip phase offset may be used to set an initial chip phase offset value of the chip tracking loop so that the chip tracking loop starts with approximately a zero pull-in error. The baseband Doppler frequency shift may be used to set initial frequency offset values in the chip tracking loop and the numerical controlled oscillator so that both start with substantially near-zero offset errors for substantially immediate demodulation of the received signal. The device may further include an output device to output the data demodulated from the received baseband signal.
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Citations
24 Claims
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1. A device for fast transition from preamble synchronization of a received signal to demodulation of the received signal, comprising:
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a chip tracking loop to generate an offset tracking value to track any initial chip phase offset and Doppler-caused chip frequency drift associated with the received signal; a numerical controlled oscillator to correct any Doppler-caused phase rotation associated with the received signal; a preamble synchronization unit to detect a preamble of the received signal, and to measure a chip phase offset and a Doppler frequency shift associated with the received signal, wherein the chip phase offset is used to set an initial chip phase offset value of the chip tracking loop so that the chip tracking loop starts with approximately a zero pull-in error, and the Doppler frequency shift is used to set initial frequency offset values in the chip tracking loop and the numerical controlled oscillator so that both start with near-zero offset errors for demodulation of the received signal; and an output device to output the data demodulated from the received signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A communications device, comprising:
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a receiver to receive a communications signal; a preamble synchronization stage to detect a preamble of the received communications signal; a data demodulation stage to demodulate the received communications signal; and a burst modem architecture for transition from the preamble synchronization stage to the data demodulation stage in Direct Sequence Spread Spectrum (DSSS) communication with a significant Doppler frequency shift, wherein the preamble synchronization stage measures a chip phase offset and a Doppler frequency shift associated with the received communications signal, wherein the chip phase offset is used to set an initial chip phase offset value of a chip tracking loop so that the chip tracking loop starts with approximately a zero pull-in error, and the Doppler frequency shift is used to set initial frequency offset values in the chip tracking loop and a numerical controlled oscillator so that both start with near-zero offset errors for demodulation of the received communications signal; and an output device to output the demodulated data. - View Dependent Claims (15, 16)
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17. A method for fast transition from preamble synchronization of a received signal to demodulation of the received signal, comprising:
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detecting a preamble of the received signal; measuring a chip phase offset and a Doppler frequency shift associated with the received signal; setting an initial chip phase offset value of a chip tracking loop in response to the measured chip phase offset so that the chip tracking loop starts with approximately a zero pull-in error; setting initial frequency offset values in the chip tracking loop and a numerical controlled oscillator in response to the measured Doppler frequency shift so that the chip tracking loop and the numerical controlled oscillator start with near-zero offset errors for demodulation of the received signal; demodulating the received signal to extract payload data; and
outputting the payload data. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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Specification