Signal correlation means
Data transmission system operating on the spread spectrum principle Patent #: 4346475
ApplicationNo. 06/222992 filed on 01/06/1981
US Classes:708/5, Correlation, convolution, or transformation375/150, Correlation-type receiver375/343, Correlative or matched filter375/367, Pseudo noise708/425, Using tapped delay line708/813Correlation or convolution
ExaminersPrimary: Ruggiero, Joseph
Attorney, Agent or Firm
International ClassG06J 1/00 (20060101)
AbstractA segmented, transversal correlator for use in a spread spectrum communications system accurately synchronizes to an incoming spread signal by passively searching for a particular section of a known reference PN code sequence. To achieve correlator lengths of greater than one data bit long, the correlator may comprise a plurality of correlation subsections, each including a loading register for storing a different section of the overall reference PN code sequence. A section of the PN code sequence is transferred into a circulating register in each subsection through a parallel transfer. The dynamic, circulating PN code sequence is then correlated against statically stored analog samples of the incoming spread signal. When the dynamic PN reference code sequence is aligned with the corresponding PN sequence in the analog samples, a correlation signal is produced and magnitude detected to form a signal which is applied to a summation circuit. The summation circuit receives the outputs of each of the correlator subsections and produces a correlation output signal for the entire correlator.