Patent ID: 7382822

Claim:
A code acquisition device using a two-step search process in a Direct Sequence-Code Division Multiple Access (DS-CDMA) Ultra Wide Band (UWB) modem, the device comprising: an I/Q channel symbol generating unit for, in a first search process, generating a plurality (i) of n th I/Q channel symbols (Y I,n (i), Y Q,n (i)) consistent with a plurality (i) of code phases for a multi-path reception signal (r(t)) by using six spread code sequences, and in a second search process, generating a plurality of n th I/Q channel symbols (Y I,n (i), Y Q,n (i)) consistent with a plurality (i) of code phases for the multi-path reception signal (r(t)) by using a spread code having a maximal value among six spread codes acquired in the first search process; a spread code selecting unit for, in the first search process, receiving the plurality of n th I/Q channel symbols (Y I,n (i), Y Q,n (i)) from the I/Q channel symbol generating unit to respectively combine the received channel symbols (Y I,n (i), Y Q,n (i)) at N NC1 times, and summing a respective combined result value (Z i ) at each of the six spread codes to generate six symbol energies (Em, m=1,2, . . . , 6) consistent with the six spread codes, and deciding the spread code having a maximal value among the six symbol energies (Em, m=1,2, . . . , 6), as a spread code of a piconet coordinator; an N NC2 N S tap I/Q channel symbol matched filter unit having an Ns-length tap and for, in the second search process, receiving the plurality (i) of nth I/Q channel symbols (Y I,n (i), Y Q,n (i)) from the I/Q channel symbol generating unit to generate a result value (S n,k (i)) through a predetermined arithmetic operation, and performing a noncoherent combining to the result value (S n,k (i)) at N NC2 times to output an arbitrary result value (X n (i)); a switching unit disposed between the I/Q channel symbol generating unit and the N NC2 N S tap I/Q channel symbol matched filter unit, for changing an opened state of the first search process to a closed state of the second search process to connect the I/Q channel symbol generating unit with the N NC2 N S tap I/Q channel symbol matched filter unit; and a super frame and symbol boundary time deciding unit for deciding a super frame time and a symbol boundary time by using the output values (X n (i)) of the plurality of N NC2 N S tap I/Q channel symbol matched filters in the second search process.