Abstract: A FM broadcast compander system is combined with a conventional denoising system suited for FM receiver, wherein a noise indicator is determined by a subtraction of the conventionally transmitted difference signal Ud(z) from the additionally transmitted difference signal (Uc(z)) which is additionally transmitted according to the companding system. This system gives a noise reduction of 20 dB in a stereo FM broadcast receiver.

Abstract: A stereo demultiplexer is proposed which can be calculation power efficiently implemented in a DSP. Modern digital FM receivers exploit the information content in the in quadrature component of the modulated difference signal for a noise reduction. The proposed stereo demultiplexer derives the in phase component and the in quadrature component of the difference signal with a minimized number of sinus and cosinus calculations by first downconverting the modulated difference signal to a not synchronized complex baseband signal on basis of a fixed frequency, thereafter a complex sampling rate decimation unit sampling rate decimates the not synchronized complex baseband signal with a factor N and a second complex mixer synchronizes and coherent demodulates the sampling rate decimated not synchronized baseband signal on basis of a first complex carrier signal derived on basis of the pilot carrier signal and the fixed frequency.

Abstract: A method to denoise a stereo signal which comprises a stereo sum signal (Us(z)) and a stereo difference signal (Ud(z)), wherein a stereo to mono blending on basis of an attenuation of the stereo difference signal (Ud(z)) is performed, determines an attenuation of the stereo difference signal (Ud(z)) under consideration of the difference signal amplitude. Therefore, a stereo signal noise reducer which performs a stereo to mono blending on basis of an attenuation of the stereo difference signal, comprises an attenuation factor determination unit which determines an attenuation factor (Hatt) under consideration of the difference signal amplitude.

Abstract: The present invention relates to a signal estimation apparatus, a signal deviation estimation apparatus, a signal pre-transmission preparation apparatus and a simulcast broadcasting system as well as corresponding methods and a corresponding computer program product. In particular, the present invention relates to the above, wherein a predetermined non-linearity, e.g. for modelling a transmission of a broadcast signal, is applied to a signal so as to obtain an estimation signal e.g. of a transmitted broadcast signal.

Abstract: A digital filter realization is proposed that consists of only one multiplier, i. e. which operates with a higher clock rate and changes coefficient at the multiplier each clock cycle, but in which the clock rate of the multiplier is reduced in comparison to prior art filters by considering equal filter coefficients, e. g. based on the symmetry of FIR filter coefficients. According to the present invention preferably the samples belonging to equal filter coefficients are added in advance in order to reduce the number of multiplications, which concludes in a reduced clock rate for the filter, a reduced needed calculation power, and therefore a reduced power consumption.

Abstract: A radio transmission signal consisting of signal frames that comprise a dynamic data part and a quasi-static data part according to the present invention is characterized in that the dynamic data part of a respective frame contains an indicator showing in which following frame the quasi-static data part of this respective frame will be repeated. Therewith, an alternative frequency of e.g. a digital shortwave signal like a DRM signal can easily and satisfactorily be checked before a fast seamless switching to this alternative frequency can be performed.

Abstract: Noise and multipath distortions in a broadcast receiver are reduced by an optimal antenna/frequency diversity concept in which the distortions in the audio signal are evaluated to choose a different antenna and/or a different frequency for at least signal parts.

Abstract: An AM simulcast broadcast signal combining a digital transmission signal and an analogue transmission signal in one transmission channel. The digital transmission signal is modulated to one sideband of a carrier of the transmission channel and a correcting signal (C) is modulated to the other sideband of the carrier of the transmission channel, which correcting signal (C) is determined so that the envelope demodulation of the transmission channel represents the analogue transmission signal.

Abstract: A polyphase filter of order x·N that builds N allpass filters of order x·N has a structure of an allpass filter of order x comprising delay elements with a delay of 1 and at least one multiplier, wherein all delay elements with a delay of 1 are replaced by delay elements with a delay of N and the sampling rate of fS?=fs/N with fs being the sampling rate of the input signal. Preferably the multiplier included in the structure of the allpass filter of order x comprises N-time multiplex multiplication coefficients that are used in a predetermined order.

Abstract: A method of denoise a stereo signal comprising a stereo sum signal and a stereo difference signal, performs a frequency selective stereo to mono blending based on the masking effect of the human auditory system. Therefore, a stereo signal noise reducer, comprising a first filter bank (1) to split the stereo difference signal (l?r) into a plurality of subbands, respective first multipliers (CO, . . . , CN) to weight each of the subbands of the stereo difference signal with a respective corresponding control signal (CO, . . . , CN), and a first adder (3) to sum all weighted subbands of the stereo difference signal (l?r) to build a frequency selective weighted stereo difference signal (diff), within which a number and width of the subbands obtained via the first filter bank (1) are choosen according to the properties of the human auditory system, further comprises a weighting factor determination unit which determines a respective control signal (CO, . . .

Abstract: To retrieve RDS information by filtering and transforming an incoming multiplex signal (m(t)) into a RDS baseband signal, an amplitude modulated RDS signal (ma(t), mc(t)) is derived on basis of an intermediate signal (ma(t)) obtained during an extraction of a stereo-difference signal (md(t)) from the incoming multiplex signal (m(t)).

Abstract: A radio transmission signal consisting of signal frames that comprise a dynamic data part and a quasi-static data part according to the present invention is characterized in that the dynamic data part of a respective frame contains an indicator showing in which following frame the quasi-static data part of this respective frame will be repeated. Therewith, an alternative frequency of e.g. a digital shortwave signal like a DRM signal can easily and satisfactorily be checked before a fast seamless switching to this alternative frequency can be performed.

Abstract: An OFDM telecommunication device, i.e. a receiver, transmitter or transceiver for OFDM—(Orthogonal Frequency-Division Multiplex) signals that generally employs the Inverse Fourier Transformation (IFT) technique to encode and transmit time-division multiplex signals and the Fourier Transformation (FT) technique to decode the received signals into time-division multiplex signals comprises a transformation unit (2) that incorporates at least an analog multiplication step and at least an analog convolution step of a multiplication convolution multiplication algorithm or a convolution multiplication convolution signal to perform a fourier transformation for demodulation and/or an inverse fourier transformation for modulation into the analog stage of said OFDM telecommunication device.

Abstract: A method to denoise a stereo signal comprising a stereo sum signal and a stereo difference signal, performs a frequency selective stereo to mono blending based on the masking effect of the human auditory system. Therefore, a stereo signal noise reducer, comprising a first filter bank (1) to split the stereo difference signal (1?r) into a plurality of subbands, respective first multipliers (20, . . . , 2N) to weight each of the subbands of the stereo difference signal with a respective corresponding control signal (C0, . . . , CN), and a first adder (3) to sum all weighted subbands of the stereo difference signal (1?r) to build a frequency selective weighted stereo difference signal (diff), within which a number and width of the subbands obtained via the first filter bank (1) are choosen according to the properties of the human auditory system, further comprises a weighting factor determination unit which determines a respective control signal (C0, . . .

Abstract: In a stereo demultiplexer receiving a frequency demodulated stereo-multiplex signal (m(t)) which comprises at least a stereo-difference signal (md(t)), a stereo-sum signal (ms(t)) and a pilot carrier, a PLL-circuit (4) to recover the pilot carrier and/or at least one harmonic thereof receives the sampling rate decimated stereo-sum signal (ms(t)) as input signal, which is sampling rate decimated by a decimation factor of D. Therefore, the sampling rate decimation filter in the sum path is used for the sampling rate decimation to generate the 2nd harmonic or any other harmonic of the pilot carrier. This sampling rate decimation filter is available anyway and therefore the sampling rate decimation of the pilot carrier can be performed without an additional filter.

Abstract: An automatic gain control loop for a radio receiver, comprising a switchable lowpass filter (21) to reduce distortions in an analogue gain control signal (6) by switching said switchable lowpass filter (21) to a low time constant in case a change of a gain control signal (6) of the automatic gain control loop lies above a predetermined threshold, which low time constant is lower than a normally used time constant, comprises a hold unit (24) which affects that said switchable lowpass filter (21) uses said low time constant a predetermined time after a change of the gain control signal (6) of the automatic gain control loop lies below said predetermined threshold.

Abstract: For the noise reduction of an audio signal generated by stereo-demultiplexing of a frequency-modulated stereo multiplex signal (SFM(t)) a filtering within the signal path to generate the stereo difference signal (ud(t)) is performed that determines a weight with which the upper sideband (ud,u(t)) and the lower sideband (ud,l(t)) of the amplitude modulated stereo-difference signal are weighted with different weighting factors that are dependent on the frequency.

Abstract: Many broadcast stations transmit their programs via a variety of different frequencies. The invention relates to monitoring alternative frequencies during the reception of a broadcast signal at a present frequency. Whenever the broadcast signal at an alternative frequency is checked, the receiver's gain is instantaneously switched from a present gain value corresponding to the present frequency to a second gain value corresponding to the alternative frequency. Said second gain value is adapted to the supposed signal strength of the broadcast signal at the alternative frequency.

Abstract: A method for preprocessing a signal and for signal processing are suggested, wherein an iterative process with at least one iteration is performed to generate an output signal (O) based on an input signal (I). In each iteration a preceding intermediate output signal (PIO) and said input signal (I) are received (S21). A process (g) is applied (S22) to said preceding intermediate output signal (PIO) to transform the latter according to a given transfer function (h) so as to generate a transformed preceding intermediate output signal (TPIO). Then, said input signal (I) is subtracted (S23) from said transformed intermediate output signal (TPIO). Thereby, an intermediate error signal (IE) is generated and then added to said intermediate output signal (PIO) so as to generate a succeeding intermediate output signal (SIO) which is used as an output signal (O) after the iterative process stopped.

Abstract: A radio transmission signal consisting of signal frames that comprise a dynamic data part and a quasi-static data part according to the present invention is characterized in that the dynamic data part of a respective frame contains an indicator showing in which following frame the quasi-static data part of this respective frame will be repeated. Therewith, an alternative frequency of e.g. a digital shortwave signal like a DRM signal can easily and satisfactorily be checked before a fast seamless switching to this alternative frequency can be performed.