NON-SYNCHRONOUS INTERPOLATION METHOD

摘要

PURPOSE:To attain the effective interpolation for the optimum discrimination value by dividing each B (Baud) rate processing into the minimum integer times larger than m (an integer) from a base band signal having 1:m between B rate and sampling rates. CONSTITUTION:The demodulated input signals I and Q which are converted into base band areas by preprocessing are supplied 1 and 2, and the phases of these signals are turned 3 by means of the phase error information 6 calculated by a carrier reproduction circuit 9. A clock 8 is reproduced and extracted by means of phase-corrected I and Q signals 4 and 5. These procedures are carried out for every sampling period. Then the linear interpolation processing 10 is carried out by means of signals 4 and 5 and the clock 8 to obtain the optimum discrimination values 11 and 13 for each B rate. The detection of phase difference and the carrier reproduction 9 including a loop filter are carried out with use of the values 11 and 13. In addition, I and Q output signals 15 and 16 for discrimination are obtained through an eliminating circuit 14 which deletes the uncertainness of the absolute phase of demodulation. Thus an easy interpolation is possible for an optimum discrimination point.