| 摘要 |
The invention relates to a device for looping a radio-frequency test signal transmitted by the transmitter section in a transceiver to a receiver section for testing the transceiver. In the device of the invention, a transmitting-frequency test signal is first demodulated (23) to a base frequency and then to a receiving-frequency test signal. A control means (38) applies frequency setting signals to two frequency synthesizers (44, 45) before the beginning of each test interval and monitors the locking of the output frequencies of the synthesizers, thus preventing the output signal of the modulator (28) from being applied to the receiver section during the test interval if the output frequencies of the oscillator means (44, 45) have not locked to local oscillator frequencies determined by the frequency setting signals before the beginning of the test interval. |
