| 摘要 |
The digitised multi-frequency signals are divided into the different frequency signals by means of digital filters and their reception is determined via frequency detectors. The signals are then digitally integrated and limited to a maximum and minimum value. While the integrated signals are passing through a defined range of values, at least one marking pulse is generated. The number of integration time intervals and the beginning of the predetermined value range determine the time of detection of a multi-frequency signal. If marking pulses are present within one integration time interval, the extent is investigated to which the received frequency combination corresponds to a correspondingly coded multi-frequency signal and the detected multi-frequency signal is forwarded to the processing device. If the integrated signals allocated to the detected multi-frequency combination drop below a predetermined value, the end of signal is detected. <IMAGE> |
