| 摘要 |
PURPOSE:To narrow a band width of a BPF, and to realize a receiving performance with high S/N and high sensitivity by inserting a pilot signal into the output of an antenna, and using only a signal containing said signal as a detecting signal. CONSTITUTION:An RF signal in one frequency range is received by an antenna 10 and 12, the RF signal is heterodyne-detected by a local oscillating signal which is frequency-modulated by a continuous pilot signal from a generator 44, and an IF signal is led out 14, 22. This IF signal is tuning-amplified 18, 26, the amplified output is heterodyne-detected 28 by a local oscillating signal swept by frequency of a prescribed sweep speed, a detecting output is extracted by a BPF 34 having a prescribed band width, frequency-modulated, and a tone burst of the pilot signal is discriminated 38. Subsequently, a continuous signal is reproduced 42 from the tone burst of the demodulated pilot signal, a phase comparison 46 of the continuous pilot signal and this reproduced continuous signal is executed, and in accordance with the compared output, the reception of the RF signal is informed by a buzzer or displayed by a lamp. |
