Patent ID: 6859502

Claim:
A transmitting and receiving apparatus comprising: modulating means for modulating an input digital data; first frequency converting means for converting a signal output from said modulating means into a signal of a predetermined frequency, amplifying/branching means for amplifying and branching a signal output from said first frequency converting means; second frequency converting means for converting a signal output from said amplifying branching means, into a signal of a predetermined frequency; and demodulating means for demodulating a digital data from a signal output from said second frequency converting means, wherein each of said first and second frequency converting means comprises a PLL frequency synthesizer, said demodulating means has a carrier recovery section, and natural angular frequencies of said PLL frequency synthesizers are set to be equal to a maximum frequency of mechanical vibrations which are externally applied, or in a predetermined width above and below the maximum frequency, or a loop filter bandwidth of said carrier recovery section is set to be higher by a predetermined amount than the maximum frequency of mechanical vibrations which are externally applied.