Patent ID: 8265126

Claim:
A receiving device for spread spectrum communication and for receiving a signal spread and modulated with a first spreading code, the receiving device comprising: a phase determining unit calculating a cross correlation between the received signal and a second spreading code and determining a phase P(0) of the received signal based on the cross correlation, the phase P(0) being a synchronizing point with the first spreading code; and a data demodulating unit synchronizing the phase P(0) and the first spreading code and despreading and demodulating the received signal with the first spreading code, wherein: the number of components in each of the first spreading code and the second spreading code is defined as Y; Y is an integer greater than or equal to 2; the phase determining unit includes a cross-correlation calculating element; the cross correlation calculating element selects a combination of N phases from the received signal; the combination of N phases is defined as {P(x 1 ), P(x 2 ), . . . , P(x N )}; x 1 , x 2 , . . . , x N represent phase shifting amounts from the phase P(0) and each of the phase shifting amounts is not specified before the phase P(0) is determined; a phase shifting difference between two of the phase shifting amounts is a predetermined number of chips; the cross-correlation calculating element calculates a product sum of the received signal for Y chips included in each of the N phases {P(x 1 ), P(x 2 ), . . . , P(x N )} and the second spreading code so that a combination of N cross-correlation values defined as {Q(x 1 ), Q(x 2 ), . . . , Q(x N )} corresponding to the combination of N phases {P(x 1 ), P(x 2 ), . . . , P(x N )} is obtained; the combination of N cross-correlation values {Q(x 1 ), Q(x 2 ), . . . ,Q(x N )} provides a specific combination corresponding to the phase shifting amount x 1 ; the cross-correlation calculating element specifies the phase shifting amount x 1 based on the combination of N cross-correlation values {Q(x 1 ), Q(x 2 ), . . . , Q(x N )}; the cross-correlation calculating element determines the phase P(0) as a phase shifted by the phase shifting amount x 1 from the phase P(x 1 ); and N represents a predetermined integer that is less than Y and that is set so that the phase shifting amount x 1 is specified as one of 0, 1, . . . , (Y−1) when a changing pattern of the combination of N cross-correlation values {Q(x 1 ), Q(x 2 ), . . . , Q(x N )} is determined.