| 摘要 |
PURPOSE:To make the intermediate frequency and the transmission reception frequency stable and to take synchronization easily by using a local oscillation frequency in common for the transmission reception circuit for all terminal equipments. CONSTITUTION:An intermediate frequency signal is inputted to a frequency conversion circuit 11 of a transmission circuit 1 of a specific terminal equipment, the signal is mixed with a local oscillation signal selected by a changeover circuit 16 among signals from plural local oscillators 12a, 12b,... and converts the result into a high frequency transmission signal. The changeover circuit 16 selects any local oscillation frequency signal synchronously with the signal clock, a high frequency transmission signal outputted from the frequency conversion circuit 11 is amplified by an amplifier circuit 13, the amplified signal is inputted to a mixture circuit 18, in which the signal is mixed with a local oscillation frequency signal from an amplifier circuit 17 and the mixed signal radiates in air from an antenna 15 via an output circuit 14. Moreover, other terminal equipment generates a local oscillation frequency signal for the frequency conversion between the transmission reception frequency signal and the intermediate frequency signal based on a received reference signal. |
