ALARM DETECTION RELAY USING PILOT TONE IN RADIO COMMUNICATION SYSTEM

摘要

PURPOSE: An alarm detection relay using a pilot tone in a radio communication system is provided which is able to judge whether the relay is in an abnormal state or not without constructing an additional port for detecting an alarm signal within the radio relay or base station. CONSTITUTION: An alarm detection relay(210) using a pilot tone in a radio communication system includes a duplexer(212) for combining transmission and reception signals into one signal, a pre-amplifier(213) for amplifying a weak signal received from a terminal, and a band pass filter(214) for passing only signals in a reception band. The relay further has an attenuator(215) for appropriately controlling the signal intensity, a reception route configured of a main amplifier(216) for finally amplifying the reception signal to a required level, and a transmission route for transmitting signals to the terminal with signals flowing opposite to the signals which flow through the reception route. The relay also has a pilot tone generating circuit for generating a pilot tone, and an alarm detection circuit for detecting the pilot tone.