Abstract: A method for fire prevention in a sauna includes the steps of monitoring a rise of heat radiation from a sauna heater, comparing the rise of the heat radiation to a normal set heat radiation rise curve, determining whether the rise of the heat radiation of the sauna heater deviates from a normal rise in heat radiation, and switching the sauna heater off if the rise of the heat radiation deviates from the normal rise. The invention is further directed to a system for carrying out said method.

Abstract: The present invention relates to a method of changing the telecommunication settings of a subscriber station in a radio system providing a wireless subscriber interface. For easy and swift changing of the telecommunication settings the subscriber station is equipped with means for changing its telecommunication settings as a response to a message received by the subscriber station over the radio path, a message is transmitted to the subscriber station including new telecommunication settings, and an acknowledgment of the implementation of the new telecommunication settings is awaited from the subscriber station.

Abstract: The invention relates to a radio system realizing a wireless subscriber interface, the system including a subscriber station (1) which comprises means (8, TRX) for forwarding, on the radio path, a supervisory signal received on the radio path, a base station (5) which monitors the connection to the subscriber station by means of the supervisory signal, and a subscriber network element (6) for transmitting communication signals between a communication system (PSTN) and the subscriber station (1).

Abstract: A method of preventing an adaptive echo canceler from diverging in a noisy environment, including determining an average noise level (-45 dBmO) in the echo path, determining an attenuation (A.sub.e) of the echo path and preventing an adaptation of the echo canceller, if the level of the signal (x(i)) to be transmitted to the echo path and causing echo (r(i)) is lower than a predetermined threshold level, which is to the extent of a preset margin and the echo path attenuation above the average noise level.

Abstract: The operation of an echo canceller (4A to 4D) is controlled by a call control (2) of a telephone exchange over an internal control bus (3, 5) of the telephone exchange. The exchange then attends to the necessary signalling and the echo canceller does not need to know how the associated signalling is routed in the telephone network.

Abstract: A disable tone detection method for an echo canceller, in which the disable tone signal is within a predetermined tolerance range from a nominal frequency and includes phase inversions occurring at predetermined intervals. The method includes the steps of a) removing frequencies outside the tolerance range from an input signal (S.sub.in, R.sub.in) by band-pass filtering (33), b) sampling (34) the filtered signal at a sampling frequency, the sampling frequency being about half of the nominal frequency, so as to alise the sample signal to the vicinity of the zero frequency, c) creating a substantially in-phase version of the aliased sample signal component, d) delaying the in-phase version by about 2n sample signal periods, where n is a positive integer, e) detecting (34) a phase inversion in the disable tone signal using an XOR operation executed on the aliased sample signal component and the delayed version thereof.

Abstract: Non-linear signal processing is provided in an echo canceller, in which the level of the signals passing through the echo canceller from the near end to the far end is attenuated to a predetermined blocking level, when the level of the near end signals is lower than a given threshold level. The level of the signal passing through the echo canceller from the near end to the far end is raised in a ramp-like manner from the blocking level back to the normal level (T.sub.SUP), when the level (L.sub.Sin) of the near end signals again exceeds the given threshold level or in a double talk situation.

Abstract: Converging of an echo canceller (4A-D) integrated into a telephone exchange (1, 2) is initiated at the start of a telephone call by an internal command of the telephone exchange given by a call control (2) of the telephone exchange as soon as the call control (2) has observed an off-hook state of a called subscriber connection. The command causes the echo canceller (4A-D) to transmit a test signal to the echo path for converging the echo canceller before appearance of the speech signal.