Testing the integrity of a radio apparatus using a loop-back test method

摘要

In a loop back test system for a radio apparatus a transmit signal is sent by a transmitter 15 to a receiver 16. The received signal is compared 22 to the transmit signal in order to detect any errors in the received signal. No errors indicates that the apparatus is functioning normally. When the transmit signal is not being transmitted an interference detector 23 detects any unrelated interference received at the receiver. If interference is detected then the result of the comparison is invalidated. Interference is detected when the reception field intensity is above a predetermined level. In a TDD or TDMA system loopback testing and interference detection occur alternately in the same time slot of successive time frames. Alternatively interference detection occurs in all time slots not used for the loop back test. In FDMA systems interference on different frequencies can be received in order to judge the validity of the loop back test.