| 摘要 |
PURPOSE:To suppress dominant wave energy invariably within a specific band through simple constitution by switching and outputting pulses of the 1st and the 2nd frequencies according to an external switching signal, and outputting a pulse signal with constant width by a monostable multivibrator by using either of its leading and trailing edges as a trigger signal. CONSTITUTION:A reference clock generator 21 has its oscillation frequency set N (integer) times as large as the least common multiple of a mark frequency fM and a space frequency fS. Reference clock pulses outputted by this reference clock generator 23 are converted by a 1/m frequency divider 22 and a 1/n frequency divider 23 into pulse signals SM and SS of different frequencies N.fM and N.fS. Those two pulse signals SM and SS are switched and outputted according to an external switching signal SD and supplied to the monostable multivibrator 25. Either of leading and trailing edges of the input to this monostable multivibrator 25 is used as a trigger to output on pulse with constant pulse width. The output of the monostable multivibrator 25 is frequency-divided by a 1/N frequency divider 26 by N and led out as an FSK modulated signal. |
