| 摘要 |
PURPOSE:To make the device small and to make the cost inexpensive, by switching contstants of a low pass filter and a frequency-dividing ratio according to types of communication, in a radio communication modulator for FM and PSK modulation. CONSTITUTION:In starting communication, based on a switching control signal SS at first, the 1st and 2nd frequency dividing ratio switching type frequency- dividers 33 and 344, and a low pass filter 342 are set to the frequency dividing ratio and cut-off frequency for PSK modulation, and the signal SS is given to a switch circuit 31 to supply a data signal DS as a call out signal and a response signal to be transmitted to a voltage controlled oscillator 343 as a PSK modulation signal and to operate the modulator as a PSK modulator. In setting a communication path to an opposing party, through the switching control signal SS generated depending on the type of communication, when an audio signal VS is transmitted and FM modulation is taken and in case of data communication DS, as the PSK modulation, the frequency dividing ratio and the cut-off frequency of the frequency dividers 33 and 344 and the filter 342 are set and the signals VS and DS are transmitted by using a phase locked loop 34. |
