| 摘要 |
The invention relates to a device (11) for looping a radio-frequency quadrature-modulated test signal transmitted by a transmitter section in a duplex type transceiver to a receiver section for testing the transceiver. The device (11) of the invention comprises a quadrature-demodulator (23) for demodulating the transmitting-frequency signal into two base-frequency quadrature-phase signals (I, Q); and a quadrature-modulator (28) for modulating said base-frequency signals into a receiving-frequency quadrature-modulated test signal. Electronic delay lines (26A, 26B) are connected between the demodulator (23) and the modulator (28) for delaying both base-frequency signals (I, Q) separately with a period of time corresponding to the time difference required between the transmission and reception of the transceiver. |
