Abstract: Navigation signals emitted by a navigation transmitter (46), in a first signal path (41), have a time reference generated and, based on this time reference, navigation signals are generated which are subsequently emitted by way of a transmitting device (39, 40). In the event of interferences in the first signal path (41), a switch-over takes place to a second signal path (45) parallel to the first signal path (41). The navigation transmitter (46) receives time reference signals and/or navigation signals, and the received signals are guided by way of the second signal path (45) to the transmitting device (39, 40) and emitted.

Abstract: Navigation signals emitted by a navigation transmitter (46), in a first signal path (41), have a time reference generated and, based on this time reference, navigation signals are generated which are subsequently emitted by way of a transmitting device (39, 40). In the event of interferences in the first signal path (41), a switch-over takes place to a second signal path (45) parallel to the first signal path (41). The navigation transmitter (46) receives time reference signals and/or navigation signals, and the received signals are guided by way of the second signal path (45) to the transmitting device (39, 40) and emitted.

Abstract: An echo suppressor for use in the send path of the four-wire part of a long distance telephone circuit employs frequency-selective center clipping. The bandwidth of the channel in which echo occurs is subdivided in contiguous bands or subchannels by appropriate filtering, and each resulting signal is center clipped by a center clipper. Threshold control voltages are predicted from knowledge of the average speech amplitude distribution characteristic as a function of frequency. This characteristic is subdivided into the same frequency bands as that used by the center clippers, and the ratios of energies in the bands are used to equalize the ratios of the control voltages that determine the center clipper thresholds. This technique is implemented through the use of a peak rectifier, the input of which is coupled to the receive path of the echo suppressor and the output of which is connected to each of the filtered subchannels by a resistive dividing network.