RADIO TRANSMITTING AND RECEIVING DEVICE

摘要

PURPOSE:To decrease the number of necessary crystal oscillators by using the same crystal oscillator to obtain the 1st local transmission frequency of a reception system and the wave to be modulated of a transmission system. CONSTITUTION:The 1st local oscillation frequency F1 of a superheterodyne reception system is modulated by the information to be transmitted and radiated through an antenna. While the modulation of the same degree as that applied to the frequency F1 is also applied to the 2nd local oscillation frequency F3. Then the modulation components of transmission information mixed into the frequency F1 are offset by the 2nd mixing circuit 3. As a result, a crystal oscillator can be shared. This can decrease rationally the number of crystal oscilators.