Abstract: An apparatus for frequency-selective occupancy detection of a channel in a frequency band includes a detector for detecting a receive spectrum in the frequency band, a provider for providing node frequencies, a determiner for determining node level values, a determiner for determining the threshold curve and a comparer. The provider provides the node frequencies for a threshold curve with respect to a noise floor in the frequency band. The determiner determines the node level values at the node frequencies based on receive level values of the receive spectrum. The determiner determines the threshold curve in the frequency band based on the provided node frequencies and the node level values at the node frequencies. The comparer compares a current power of the receive level values in the channel with a reference power in the channel predetermined by the threshold curve to detect occupancy or non-occupancy of the channel depending on the comparison.

Abstract: An apparatus for simulating a signal composed of a plurality of individual signals from respective signal locations at a simulation location, having a provider for providing the plurality of individual signals in the time domain, a transformer for transforming the individual signals to the frequency domain, a processor for processing the individual signals transformed to the frequency domain each depending on a signal channel existing between the simulation location and the respective signal location, a combiner for combining the processed individual signals transformed to the frequency domain to a combined signal, and a transformer for transforming the combined signal to the time domain for generating the simulated combined signal at the simulation location.

Abstract: A device for predistorting a transmission signal to be transmitted over a nonlinear transmission path comprises an estimator for determining an error signal depending on the transmission signal and a previously registered transfer characteristic of the nonlinear transmission path. The error signal represents an estimate of an error generated due to the nonlinearity of the trans-mission path. A time-dispersive element is provided to produce a correction signal by a temporal extension of the error signal. A combiner is provided to combine the transmission signal and the correction signal. As a result of the temporal extension of the error signal, an error signal segment in the frequency spectrum of a transmission signal transmitted by the nonlinear transmission path is shifted away from the useful frequency range of the transmission signal.

Abstract: The aim of the invention is to improve the performance of heat exchangers such that lost heat is discharged from a cabinet or device, whereby the rise of the inner temperature for each discharged watt of power loss is only slight. The invention also relates to a flat refrigerating set. The temperature of the heated air (SL,) can be reduced in the counterflow (L4;L3;k1;k2 . . . ) by means of counterflowing cooling air (KL) without the cooling air physically entering into contact with the heated air flow (L1,L3,L5) that is to be cooled. The air flow to be cooled (SL) can be supplied to several parallel first chambers (k1,k3,k7) via an inlet area (13). The parallel first and parallel second chambers alternate in the direction of the height or density (h) of the refrigerating unit. The alternating chambers (k1,k2,k3,k4, . . . ) also extend into a section of the flat cooling unit (l13), which is located between the inlet area (13) and a closer end (40,41) of the refrigerating unit.

Abstract: A device for pretreating a signal to be transmitted over a transmission path, wherein the transmission path comprises a band-pass filter whose pass-band width is smaller than a predetermined bandwidth and a non-linear amplifier, includes a linearization means for performing a linearization of the signal to be transmitted before the transmission of the same, such that a non-linearity caused by the non-linear amplifier is counteracted. Further, the device includes a signal-shaping means downstream to the linearization means comprising a frequency response such that the overall frequency response of the signal-shaping means and the band-pass filter corresponds to the frequency response of a filter whose pass-band width is at least equal to the predetermined bandwidth.

Abstract: A device for pretreating a signal (S1) to be transmitted over a transmission path, wherein the transmission path comprises a band-pass filter (14) whose pass-band width is smaller than a predetermined bandwidth and a non-linear amplifier (16), includes a linearization means (20) for performing a linearization of the signal (S1) to be transmitted before the transmission of the same, such that a non-linearity caused by the non-linear amplifier (16) is counteracted. Further, the device includes a signal-shaping means (22) downstream to the linearization means (20) comprising a frequency response such that the overall frequency response of the signal-shaping means (22) and the band-pass filter (14) corresponds to the frequency response of a filter whose pass-band width is at least equal to the predetermined bandwidth.

Abstract: In a method for estimating a non-linear characteristic of an amplifier, an input signal is provided, a reference signal is determined based on the power of the input signal, the input signal is amplified using said amplifier in order to produce an amplified signal, a measurement signal is determined based on the power of the amplified signal and respective samples of the measurement signal are associated with respective samples of the reference signal. A gain value of said amplifier for each sample is determined from the respective samples of the reference signal and the measurement signal. An operating range of the amplifier is divided into a plurality of power sections and an averaged gain value is produced for each power section. Thereafter, a measure of the deviation of the gain values associated with a power section from said averaged gain value is determined. Then, averaged gain values are rejected which have a measure of the deviation which exceeds a predetermined threshold.

Abstract: A circuit for pre-distorting an input signal v to be transmitted via a power amplifier having a non-linear transmission characteristic to produce a pre-distorted input signal y comprises an estimator (10) for determining an estimation signal (22) based on the power of said input signal v. A look-up table (20) is provided for storing complex pre-distortion coefficients BR and AI which depend on the power of the input Signal v and the non-linear transmission characteristic of the power amplifier determined in advance. For BR, the relation BR=AR−K, K being a constant with 0<K <2 applies, and AR and AI are the real and imaginary parts of a complex pre-distortion function which provides a pre-distortion of the input signal v such that the distortion introduced by the non-linear transmission characteristic of the power amplifier is substantially compensated according to magnitude and phase.

Abstract: A circuit for reducing adjacent-channel interference by pre-linearizing and pre-distorting an input signal to be transmitted via a power amplifier having a non-linear transmission characteristic is disclosed. A portion of the input signal exceeding a dynamic range of the power amplifier is determined and expanded along the time axis to produce an expanded version thereof. The expanded version and the input signal are combined, such that the expanded version is subtracted from the input signal, to produce a pre-linearized signal. The circuit further has a pre-distorting unit for pre-distorting the pre-linearized signal using complex pre-distortion coefficients, such that the distortion introduced by the non-linear transmission characteristic of the power amplifier is substantially compensated for according to magnitude and phase.

Abstract: In a coding method and a coder for introducing a non-audible data signal into an audio signal, the audio signal is first transformed to a spectral range and the masking threshold of the audio signal is determined. A pseudo-noise signal and a data signal are provided and multiplied with each other so a to provide a frequency-spread data signal. The spread data signal is weighted with the masking threshold, and thereafter the audio signal and the weighted data signal are superimposed. In a method and a decoder for decoding a data signal introduced into an audio signal in non-audible manner, the audio signal is first sampled and thereafter the sampled audio signal is filtered in non-recursive manner. The filtered audio signal is subsequently compared to a threshold value so as to retrieve the data signal.

Abstract: A circuit for predistorting a signal to be transmitted via a non-linear channel comprises an envelope detector for detecting an envelope of the signal. A quantization for forming quantized envelope values on the basis of the detected envelope is connected to the envelope detector as well as to a table for supplying complex predistortion coefficients which depend on the quantized envelope values and on a previously detected transmission function of the non-linear channel. An evaluation circuit separated from the non-linear channel and used for the complex evaluation of the signal to be transmitted via the non-linear channel with the complex predistortion coefficients permits the distortion introduced by the non-linear channel to be substantially compensated according to amount and phase.

Abstract: A consumption recording system affixed to a wall comprises a consumption ording device and a radio module, which is connected to the consumption recording device. A microstrip antenna is connected to the radio module. The microstrip antenna is placed within a non-metallic casing cover of the consumption recording device in such a way that the main radiation direction of the microstrip antenna is directed perpendicularly away from the wall.