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US 7,072,414 B1Granted
Gaussian minimum shift keying (GMSK) precoding communication method
AssigneeThe Aerospace Corporation
InventorsGee L. Lui, Kuang Tsai
Life of this patent
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Abstract
A premodulation precoding method precodes a data sequence in a Gaussian minimum shift keying (GMSK) modulator to improve the bit error rate performance of a coherent Viterbi receivers generating estimates of the communicated data sequence without the use of differential decoding while preserving the spectrum of 2-ary and 4-ary GMSK signals over a wide range of bandwidth time products.
Claims19
A method for communicating a data stream, the method comprising the steps of,
- generating a sequence of data symbols from the data stream,
- precoding the sequence of data symbols into a sequence of precoded data symbols,
- modulating the sequence of precoded data symbols into a continuous phase modulated signal,
- transmitting the continuous phase modulated signal,
- receiving the continuous phase modulated signal, and
- filtering the continuous phase modulated signal into a sequence of filtered signals having absolute phase for indicating the sequence of data symbols, wherein,
- the generating step comprises the steps of receiving the data stream of data bits, formatting the data stream into the sequence of formatted data pulses as a sequence of data symbols within an M-ary symbol set,
- the modulating step comprises the steps of Gaussian filtering and frequency modulating for generating the continuous phase modulated signal, the Gaussian filter step filters the precoded sequence of data symbols into pulse responses continuously accumulated over a finite memory time as a filter response, the Gaussian filtering step is defined by a bandwidth time product inversely defining the finite memory time, the frequency modulating step frequency modulates a carrier reference by the filter response by a modulation index for converting the filter response into the continuous phase modulated signal,
- the continuous phase modulated signal is up converted from baseband during the transmitting step and is down converted to baseband during the receiving step using a local carrier, and
- the filtering step is a matched filtering step for matched filtering of the received continuous phase modulated signal into the filtered signal, the matched filtering is matched by pulse amplitude modulation representation to the Gaussian filtering step, the filtered signal has an absolute phase at a periodic sampling time for indicating the sequence of data symbols.
7 more elements
A method for communicating a data stream, the method comprising the steps of,
- generating a sequence of data symbols from the data stream by formatting the data stream into the sequence of formatted data pulses as a sequence of data symbols within a 2-ary symbol set,
- precoding the sequence of data symbols into a sequence of precoded data symbols,
- Gaussian filtering the precoded sequence of data symbols into pulse responses continuously accumulated over a finite memory time as a filter response, the Gaussian filtering is defined by a bandwidth time product inversely defining the finite memory time,
- frequency modulating a carrier reference by the filter response by a modulation index for converting the filter response into a continuous phase modulated signal, and
- matched filtering the received continuos phase modulation signal into a filtered signal, the matched filtering is matched by pulse amplitude modulation representation to the Gaussian filtering, the filtered signal has an absolute phase at a periodic sampling time for indicating the sequence of data symbols.
2 more elements
A method for communicating a data stream, the method comprising the steps of,
- generating a sequence of data symbols from the data stream by formatting the data stream into the sequence of formatted data pulses as a sequence of data symbols within a 4-ary symbol set,
- precoding the sequence of data symbols into a sequence of precoded data symbols,
- Gaussian filtering the precoded sequence of data symbols into pulse responses continuously accumulated over a finite memory time as a filter response, the Gaussian filtering is defined by a bandwidth time product inversely defining the finite memory time,
- frequency modulating a carrier reference by the filter response by a modulation index for converting the filter response into a continuous phase modulated signal,
- matched filtering the continuous phase modulated signal into a filtered signal, the matched filtering is matched by pulse amplitude modulation representation to the Gaussian filtering, the filtered signal has an absolute phase at a periodic sampling time for indicating the sequence of data symbols, and
- demodulating the sequence of data symbols into an estimate of the data steam.
3 more elements
Dependencies are inferred from the claim text.