Abstract: The present device provides for a gas composition and temperature compensated acoustic measurement of the level of a liquid in a tank. The device comprises a transmitter, a receiver, a processing circuitry, a waveguide for guiding acoustic signals from the transmitter to the liquid level surface and for guiding reflections of the acoustic signals back to the receiver. The waveguide comprises a first end connected to the transmitter, a second end adapted to extend into the liquid, at least one inlet for introducing gas originating from the liquid in the tank into the waveguide, and an outlet for discharging gas out from the waveguide into the tank. The outlet is arranged closer to the first end than at least one of said at least one inlet.

Abstract: The present device provides for a gas composition and temperature compensated acoustic measurement of the level of a liquid in a tank. The device comprises a transmitter, a receiver, a processing circuitry, a waveguide for guiding acoustic signals from the transmitter to the liquid level surface and for guiding reflections of the acoustic signals back to the receiver. The waveguide comprises a first end connected to the transmitter, a second end adapted to extend into the liquid, at least one inlet for introducing gas originating from the liquid in the tank into the waveguide, and an outlet for discharging gas out from the waveguide into the tank. The outlet is arranged closer to the first end than at least one of said at least one inlet.

Abstract: A method for determining the starting instant (t0) of a periodically oscillating signal response (E2; E2?), wherein the signal response comprises a first set of half periods (E2a-d; E2?a-d) having a polarity equal to a polarity of the first half period (E2a; E2?a) in the signal response, and a second set of half periods (E2e-h; E2?e-h) having a polarity opposite to the polarity of the first half period (E2a; E2?a) in the signal response. The method comprises the steps of: determining a peak half period (E2e; E2?f) as the half period with the highest amplitude in a selected one of the first and second sets; determining a zero-crossing instant (ZC1; ZC?1) of the signal response occurring a known time distance from the peak half period (E2e; E2?f); determining the starting instant (t0) of the signal response (E2; E2?) based on the zero-crossing instant (ZC1; ZC?1) and a relationship between the peak half period (E2e; E2?f) and the starting instant (t0).

Abstract: A method for determining the starting instant (t0) of a periodically oscillating signal response (E2; E2?), wherein the signal response comprises a first set of half periods (E2a-d; E2?a-d) having a polarity equal to a polarity of the first half period (E2a; E2?a) in the signal response, and a second set of half periods (E2e-h; E2?e-h) having a polarity opposite to the polarity of the first half period (E2a; E2?a) in the signal response. The method comprises the steps of: determining a peak half period (E2e; E2?f) as the half period with the highest amplitude in a selected one of the first and second sets; determining a zero-crossing instant (ZC1; ZC?1) of the signal response occurring a known time distance from the peak half period (E2e; E2?f); determining the starting instant (t0) of the signal response (E2; E2?) based on the zero-crossing instant (ZC1; ZC?1) and a relationship between the peak half period (E2e; E2?f) and the starting instant (t0).

Abstract: Method in a multi-tone transmission system wherein a usable frequency range of a channel is separated into a plurality of frequency bands, an analogue signal in each sub band being filtered out by a plurality of band pass filters at a receiving side. The method comprises the steps of converting separately the analogue signal in each sub band into a digital signal in a plurality of Analogue-Digital converters (11), each Analogue-Digital converter being associated to one sub band, and activating and deactivating each Analogue-Digital converter in dependence of the presence of a signal in the associated sub band. A plurality of bandpass filters (10) is operatively connected to an analogue line (12) at a receiving side. Each bandpass filter is operatively connected to an Analogue-Digital converter (11) for converting an analogue signal into a digital signal. A control unit (13) is operatively connected to each of said Analogue-Digital converters (11) for activating and deactivating each converter.