| 摘要 |
PURPOSE:To reduce the cost by using a shift register, switching the output in response to a modulation signal at a prescribed number of stages, outputting respectively a mark frequency and a space frequency so as to obtain a modulated wave thereby simplifying the circuit constitution. CONSTITUTION:An output of a basic frequency f0 is inputted as a clock (a) to a shift register 2 from an oscillator 1 for shift operation, and an H signal is given to the 1st inhibition gate 3 and an AND circuit 4 in a logical circuit A from output sections Qm, Qn at the m-th, n-th stages. Only the 1st inhibition gate 3 is opened in the logical circuit A and the output of the m-th stage is outputted via an OR circuit 5 as the 1st switching output. When a modulation signal (i) is logical 1 in the output circuit B, a mark frequency fH in which an output level of the duty cycle changes timewise is outputted in response to the m-th or the n-th stage output only as the 1st switching output and when the signal (i) is logical 0, a space frequency fL in which m/f0 and n/f0 change timewise is outputted in response to the 2nd switching output. |
