Robert Boschgmbh

Ant Nachrichtentechnik Gmbh

Siemens Medical Instruments Pte. Ltd.

Heinz Goeckler

Thomas Alberty

Henning Puder

Wolfgang Sörgel

Daniel Alfsmann

Klaus Hildebrand

Thomas Hallman

Robert Baüml

Thomas Kurbiel

Erwin Bayha

A filter bank configuration for a hearing device has filters in an analysis filter bank and corresponding filters in a synthesis filter bank that are coupled pair-wise to form a channel in each case. In order to compensate for a hearing loss, sub-band signals are amplified in the individual channels with the aid of multipliers. In the process, an audible distortion of an output signal Y of the filter bank configuration as a result of differences between amplification factors of the multipliers of neighboring channels should be prevented. Here, at least one channel changes a phase of a sub-band signal transmitted by the channel such that a difference between a group delay of the filter bank configuration and a prescribable reference value is reduced for at least one predetermined frequency. The filter bank configuration is particularly suited to hearing aids.

Filter bank configuration for a hearing device

The circuit complexity or the filter order, respectively, of an analysis/synthesis filter bank system especially for hearing aids is to be reduced. For this reason, the stop-band attenuation of at least one of the transfer functions of the analysis filter bank is composed of a separately configurable, frequency-independent analysis basic attenuation component and a separately configurable frequency-dependent analysis attenuation component. Furthermore, the stop-band attenuation of at least one of the transfer functions of the synthesis filter bank is composed of a separately configurable, frequency-independent synthesis basic attenuation component, a separately configurable, frequency-dependent first synthesis attenuation component and a separately configurable, frequency-dependent second synthesis attenuation component which is also dependent on the manipulation of the sub-band signals. As a result, the stop-band attenuation can be reduced in dependence on frequency and the filter order can be correspondingly reduced.

Filter bank system having specific stop-band attenuation components for a hearing aid

A method for preparing an intermediate position delivered analog band pass signals includes the steps of sampling analog/digital conversion, frequency shift, and digital filtering. To advantageously ensure an efficient processing of frequency signals of different transmission norms, certain conditions for the sampling frequency and the utility spectral portion are preferably specified.

Method for preparing a band pass signal

Multiplexer device for frequency bands

Frequency- and phase regulator device for VSB receivers

For preparation of sampled values represented as two's complements, a two's complement clipping of the least significant bits(LSB) occurs. In place of the removed bits (LSB), the synchronization information (s(k)) is added with an average value depending on the quantization step. No dominant spectral lines for frequencies f greater than zero are permitted to occur in the useful spectrum for this synchronization information. Errors which are caused by removal of the least significant bits and by addition of the synchronization information are largely compensated by these features.

Process for preparation of sampled values

The filter circuit arrangement provides the properties of an FIR filter of length N, with K (K.gtoreq.2) cascaded FIR-filter members. One FIR-filter member (5.K) is formed as an equalizer filter of length N.sub.A and the remaining FIR-filter members (5.1 to 5.(K-1)) are 1/M band filters of length N.sub.k, so that ##EQU1## wherein

Filter circuit arrangement having a plurality of cascaded FIR filters

The switchable dividing network includes two individual filters whose center frequencies are selected from the group consisting of f.sub.a /8, 3f.sub.a /8, 5f.sub.a /8 and 7f.sub.a /8. The passband of its transmission function is shiftable to other frequency ranges by changing signs of a few coupling devices.

Switchable dividing network

In a demodulator for a complex-value vestigial sideband signal, a Nyquist slope filter which consists of two subfilters (Ra, Ia) is used, a filter device (FBASTP) being connected downstream of, or also capable of being integrated in, the said Nyquist slope filter, in order to suppress subcarriers, specifically in such a way that the real parts (Ra) and imaginary parts (Ia) of the sub-filters can be combined in each case.

Demodulator for a complex-value vestigial sideband signal

A device for digital demodulation of the video and audio elements of a television signal has a digital preprocessing stage for conditioning a complex digital signal for digital demodulation of a television signal at intermediate frequency, a first complex mixing device shifting the video sub-carrier to the frequency 0, a common mixing device used on the input side for the demodulation of the audio signals, and the audio signal processing is not split until after this mixing device. Therefore, fully digital signal processing is possible for television signals from the intermediate frequency, with limited filter complexity.

Device for digital demodulation of video and audio elements of

A device for processing a modulated real analog television signal has a digital preprocessing stage for conditioning a complex digital signal for digital demodulation of a television signal at intermediate frequency. The digital signal preprocessing is carried out such that subsequent demodulation of the video and audio elements can be carried out at a favorable cost. Therefore a fully-digital signal processing for television signals, from the intermediate frequency, with a limited filter cost is possible.

Device for processing modulated rail analog television signal

A device for digital demodulation of the video and audio elements of a television signal has a digital preprocessing stage for conditioning a complex digital signal for digital demodulation of a television signal at intermediate frequency, mixing devices for video and audio elements of the complex digital signal shifting the video sub-carrier and the audio sub-carrier, which is offset by the video sub-carrier frequency, to the frequency 0, digital audio-FM demodulators and parallel paths of mixing devices for the demodulation of the audio signals, so that fully digital signal processing of television signals from the intermediate frequency, with limited filter complexity can be performed.

The present invention relates to a multicarrier demodulator for separating and demodulating a digitalized frequency multiplexed signal into a plurality (L) of individual channel signals, with the separation being performed using a frequency division demultiplexer (FDM). The separated channel signals are each filtered using bandwidth limitation filters and thereafter demodulated using a synchronous demodulator. Following demodulation, the signals are filtered by interpolation filters, data (Nyquist) filters, and subsequently decided upon in a decider. The invention is characterized by the fact that the demodulator operates upon a pair of phase displaced complex channel signals.

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Backnang, Germany

Heinz Goeckler