| 摘要 |
The invention relates to a device for looping a radio-frequency test signal transmitted by a transmitter section in a full duplex type transceiver to a receiver section for testing the transceiver. The device of the invention comprises mixing means (23, 28) for converting a test signal from a transmitting frequency to a receiving frequency and switching means (312 to 314, 316 to 317) by means of which the test signal can be connected from the output of the mixing means (23, 28) to a device output (13) and therethrough to the receiver section through two alternative signal paths with different fixed attenuations and gains. |
