| 摘要 |
1,187,607. Frequency modulation. R.C.A. CORPORATION. 10 Nov., 1967 [30 Nov., 1966], No. 51216/67. Heading H3R. A frequency modulator comprises a switch 25, 26 connected between an oscillator, point C, and a source of modulating signal, point A, the switch being operated during alternate half cycles of the oscillator frequency. If the potential at A is the same as that at C, actuation of the switch 25, 26 will have no effect on the operation of the circuit. If the potential at A differs from that at C, actuation of the switch will apply to point C a signal at the oscillation frequency whose amplitude depends on the difference between the potentials at A and C and whose phase will be 0 or 180 degrees depending on whether A is greater or less than C. This signal is equivalent to shunting the tuned circuit 21, 22 with a positive or negative reactance whose magnitude is proportional to the difference between the modulating potential at A and the fixed potential at C. |
