Asynchronous DS-CDMA receiver

摘要

Methods, apparatus, and systems are provided for collecting data from a plurality of downhole sensors located in a wellbore utilizing an asynchronous direct-sequence code division multiple access (DS-CDMA)-based communication scheme. One example method includes receiving a superposed signal comprising asynchronous signals from the downhole sensors, wherein a spreading sequence has been applied to data generated by each of the downhole sensors to form each of the asynchronous signals; sampling the received superposed signal; and processing the sampled superposed signal using decorrelation to determine the data from at least one of the downhole sensors before the spreading sequence was applied.

主权项

1. A method for downhole sensing, comprising:
receiving a superposed signal comprising asynchronous signals from a plurality of downhole sensors located in a well bore, wherein a spreading sequence has been applied to data generated by each of the downhole sensors to form each of the asynchronous signals; sampling the received superposed signal; and processing the sampled superposed signal using decorrelation to determine the data from at least one of the downhole sensors before the spreading sequence was applied, wherein processing the sampled superposed signal comprises:
applying a plurality of matched filters to the sampled superposed signal, each of the matched filters based on a different spreading sequence;estimating a period of the asynchronous signals from the plurality of downhole sensors;sampling outputs of the plurality of matched filters based on the estimated period; andapplying a decorrelation matrix to a block of matched filter sampled outputs to determine the data.