| 摘要 |
PURPOSE:To ensure synchronization by dividing a modulation signal into I and Q components with a different phase, integrating them separately, obtaining a bit timing error and correcting the deviation of bit timing so as to make the error zero. CONSTITUTION:A PCM-PSK modulation signal is inputted to the circuit, shifted by a 90 deg. phase shifter 2 in both polarities by using a signal generated from a local oscillator 1 to obtain I and Q components whose phases differ by 180 deg.. Then the l and Q components are given to adders 9/11, digitized by A/D converters 7/8 respectively and the I and Q components are integrated for a bit timing period in a prescribed timing. Then a phase angle thetak of a modulation carrier obtained based on the sum output of the I and Q components is obtained by a tan computing element 17 to detect the presence of deviation of the bit timing. Moreover, a computing element 20 corrects the deviation of the bit timing so that the bit timing error obtained based on the phase angle thetak and the timing error of the I and Q components are made zero thereby securing the synchronization of the bit timing. Thus, the synchronization of the modulation carrier is not required and the synchronization is secured. |
