| 摘要 |
PURPOSE:To realize a high-quality communication line easily by monitoring a line connecting signaling signal and an audio out-band noise level when receiving diversity switching control is performed in SCPC communication. CONSTITUTION:Input signals (a) and (b) are modulated receiving carrier band signals corresponding to two transmission lines. Channel units 11 and 12 demodulate the input carrier signals (a) and (b) to transmit the receiving demodulated signals (c) and (d) of an audio channel band. These two line connecting signaling signals are detected by signaling signal detecting filters 13 and 14, and two noise levels are detected by noise detecting filters 15 and 16, and detected signals (e), (f), (g), and (h) are sent to a line signal switching control circuit 17. The line signal switching control circuit 17 discriminates the quality of input signal (a) and (b) on a basis of four sent detection signals (e), (f), (g), and (h) and generates a switching control signal (i). |
