AUTOMATIC FREQUENCY CONTROL UNIT

摘要

PURPOSE:To enable to decrease the closed loop gain into 1 or less for the thread, by inserting the input and output repetitive addition circuit on the way of loop. CONSTITUTION:The objective frequency f1 is converted into the intermediate frequency fIF with mixing the local frequency (f2+f3) at the main mixer 15. The frequency difference between the objective frequency f1 and the transmission frequency f2 is converted into a voltage at the frequency discriminator 17 and stored in the high speed sample hold circut 21 and fed to the addition circuit 22. The output of the addition circuit 22 is stored in the first sample hold circuit 23 and the memory content is moved to the second sample hold circuit 24 and it is fed back to the addition circuit 22 and new input is added. The operation like this is repetitively made to increase the output of the addition circuit 25. The output of the input and output repetitive addition circuit 25 controls the high frequency voltage controlled oscillator 27 and converted into the transmission frequency f2.