| 摘要 |
The system, in a preferred embodiment, comprises a transmitter, receiver and processor connected to the receiver. The transmitter is arranged to transmit a signal through a medium, the signal comprising a plurality of different frequency components and transmission technologies. The receiver is arranged to receive the signal following propagation through the medium. The processor is arranged to generate, at a first time, one or more transfer functions from the received signal, each transfer function defining values for a predetermined signal parameter at different frequencies. The processor then generates, at a second time, one or more further transfer functions from the received signal and compares a transfer function with the further transfer function for the same signal parameter. An output is generated if the difference between the transfer function and the further transfer function exceeds a preset threshold. |
