RECEIVING DEVICE

• Main Author: HARAGUCHI TADASHI
• Format: Patent
• Language: English
• Published: 10.06.1997
• Edition: 6
• Subjects: ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; TRANSMISSION

PROBLEM TO BE SOLVED: To improve a double-signal characteristic and to make a reception signal loss min. by attenuating a noise component through the use of a reception element without using a diode switch. SOLUTION: A reception signal S11 to be a target is inputted to a high frequency amplifier circuit 11 together with a noise signal and frequency- converted into an IF band signal S12 by a local oscillation circuit 13 and a mixer 12 after amplifying. A noise signal, after selecting a frequency which is different from a reception target signal frequency and also where another communication is not executed, amplifying the frequency by the high frequency amplifier circuit 21 and, after that, oscillating it by the local oscillation frequency so as to obtain the same frequency as an IF band frequency in the local oscillation circuit 23, is converted into the IF band signal S13 by the mixer 12. A high frequency transformer 14 synthesizes the IF band signals S12 and S13 by an opposite phase. Therefore, the loss of the target signal is made to be min. so that the noise component is attenuated. The reception target signal where the noise component is attenuated is inputted to a narrow band BPF 15 and inputted to an intermediate frequency amplifier and a detection circuit.