Abstract: The circuit arrangement comprises a tuner with a control amplifier and a mixer connected downstream, and an automatic gain control. The automatic gain control contains a weighting filter, which is connected to the output of the mixer, upstream of an intermediate frequency filter, and which supplies the control signal for the control amplifier of the tuner via a detector. The weighting filter has, in particular, a passband, which corresponds to the passband of the intermediate frequency filter and at least partly encompasses at least one or two adjacent program channels. As a result of this, the control amplifier is better tuned under difficult reception conditions, since, by means of the weighting filter, adjacent channels, relative to the passband of the intermediate frequency filter, are also concomitantly included in the control signal.

Abstract: A circuit for breaking a signal path has not only a switching means but also a low-pass or bandpass filter whose frequency characteristic is switchable or bypassable. The insulation between the input and the output when the switching means is open, which decreases with frequency in the case of ordinary switching means, is compensated for by the filter which is then connected. In one embodiment of the circuit, an out-of-band signal is applied to the circuit in addition to the useful signal. The out-of-band signal is intended to be supplied permanently to an evaluation circuit, regardless of the switching position of the switching means. To this end, the out-of-band signal is tapped off downstream of the filter, and the filter is designed such that the out-of-band signal can pass through the filter. In the case of a circuit for selecting one of two inputs, at least one of the inputs is provided with a switchable or bypassable filter, and the switching means is a selection means.

Abstract: A single conversion tuner suitable for receiving RF signals having different requirements as to selectivity, linearity and image rejection is presented. Tuners of this kind are particularly useful for digital terrestrial as well as cable reception, where different modulation schemes require very high image rejection ratios on one hand and high linearity or pass band flatness on the other hand. The inventive tuner features a double-tuned tuneable filter in combination with an image reject mixer. The double-tuned filter provides excellent pass band flatness, while the image reject mixer provides a high intrinsic image rejection. The image rejection ratio of the combination of image reject mixer and tuneable filter is very high and fulfils the requirements of commonly used modulation schemes such as 8VSB, while the pass band flatness is compliant with the requirements for modulation schemes such as QAM.

Abstract: A circuit for breaking a signal path has not only a switching means but also a low-pass or bandpass filter whose frequency characteristic is switchable or bypassable. The insulation between the input and the output when the switching means is open, which decreases with frequency in the case of ordinary switching means, is compensated for by the filter which is then connected. In one embodiment of the circuit, an out-of-band signal is applied to the circuit in addition to the useful signal. The out-of-band signal is intended to be supplied permanently to an evaluation circuit, regardless of the switching position of the switching means. To this end, the out-of-band signal is tapped off downstream of the filter, and the filter is designed such that the out-of-band signal can pass through the filter In the case of a circuit for selecting one of two inputs, at least one of the inputs is provided with switchable or bypassable filter, and the switching means is a selection means.

Abstract: A single conversion tuner suitable for receiving RF signals having different requirements as to selectivity, linearity and image rejection is presented. Tuners of this kind are particularly useful for digital terrestrial as well as cable reception, where different modulation schemes require very high image rejection ratios on one hand and high linearity or pass band flatness on the other hand. The inventive tuner features a double-tuned tuneable filter in combination with an image reject mixer. The double-tuned filter provides excellent pass band flatness, while the image reject mixer provides a high intrinsic image rejection. The image rejection ratio of the combination of image reject mixer and tuneable filter is very high and fulfils the requirements of commonly used modulation schemes such as 8VSB, while the pass band flatness is compliant with the requirements for modulation schemes such as QAM.

Abstract: In apparatuses (1, 2, 3) controlled or operated via an I2 C bus, it may be necessary to take measures to suppress interference signals at the data signal input/output of the respective apparatus without impairing the data transport at the same time. The data line at the data signal input/output contains an RC element, in the form of a low-pass filter, with a diode connected in parallel with the RC element, the low-pass filter action allowing the arrangement to be used to suppress interference signals acting on the data signal input/output, and, secondly, the transmissive action of the diode meaning that the arrangement does not impair a data signal leaving the data signal input/output.

Abstract: The circuit arrangement comprises a tuner with a control amplifier and a mixer connected downstream, and an automatic gain control. The automatic gain control contains a weighting filter, which is connected to the output of the mixer, upstream of an intermediate frequency filter, and which supplies the control signal for the control amplifier of the tuner via a detector. The weighting filter has, in particular, a passband, which corresponds to the passband of the intermediate frequency filter and at least partly encompasses at least one or two adjacent program channels. As a result of this, the control amplifier is better tuned under difficult reception conditions, since, by means of the weighting filter, adjacent channels, relative to the passband of the intermediate frequency filter, are also concomitantly included in the control signal.

Abstract: In apparatuses (1, 2, 3) controlled or operated via an I2C bus, it may be necessary to take measures to suppress interference signals at the data signal input/output of the respective apparatus without impairing the data transport at the same time. The data line (SDA) at the data signal input/output contains an RC element (RS, C), in the form of a low-pass filter, with a diode (D) connected in parallel with the RC element (RS, C), the low-pass filter action allowing said arrangement to be used to suppress interference signals acting on the data signal input/output, and, secondly, the transmissive action of the diode (D) meaning that said arrangement does not impair a data signal (ACK) leaving the data signal input/output.

Abstract: According to the invention a digital signal path includes a first filter and an analog signal path includes a second filter. For analog reception both filters are connected in cascade, the first filter aiding the second filter in achieving a desired selectivity. Additional selection devices are obviated. Preferably the filters are surface acoustic wave filters.

Abstract: Amplifier circuit arrangement for alternatively processing a digital signal or an analog signal.

Abstract: In an OFDM system, the so-called self-noise component, which represents that noise component of the respective carrier which is caused by the carrier itself and is mapped onto itself, can be estimated and corrected by shifting all the carriers back in the receiver by multiplication by a factor which is determined by averaging. The so-called external-noise component, which is caused by adjacent carrier interference from the so-called leakage effect of the Fast Fourier transform (FFT2) used in the receiver for demodulation cannot be corrected using this method. In addition to the demodulation FFT, a further FFT (FFT1) is used in the receiver to estimate the self-noise component (&psgr;e). The estimated self-noise component is used to reproduce the orthogonality between the carriers by correction before the demodulation FFT, to thereby prevent crosstalk. The additional FFT (FFT1) may have a shorter length than the demodulation FFT (FFT2), so that the additional complexity is negligible.

Abstract: In the case of the OFDM method, a large number of modulated carriers are transmitted using frequency division multiplexing, a spectrum having a virtually rectangular shape being produced as a result of the large number of carriers. In order to separate the carriers from one another again in the receiver, a Fast-Fourier-Transformation is carried out, it then being possible to separate each carrier cleanly from the others provided the carriers are exactly orthogonal with respect to one another. The carrier orthogonality can, however, be disturbed by various causes. Furthermore, the wanted signal must be separated from the undesired adjacent channel signals by analog or digital filtering in the receiver. In order to improve carrier and channel separation, the selectivity of the FFT filtering can be increased by enlarging the number of FFT components. However, this normally leads to an undesirably sharp increase in the computation complexity.

Abstract: Components for analog or digital input signals are in each case connected by switchable means to a controllable oscillator. The switch condition of the switchable means is set automatically and/or manually as a function of the input signal.

Abstract: A tuner is used in common for both terrestrial and satellite television reception. A second mixing stage is switched as a mixer for signal conversion into a second intermediate frequency during terrestrial television reception and is switched as a component of a FM-PLL demodulator during satellite television reception. The tuner is particularly suitable for television receivers and video recorders which receive signals from both a terrestrial antenna/signal source and from a satellite antenna/signal source.

Abstract: A filter circuit having an amplifier stage, an upstream filter and a downstream bandpass filter. The filter includes, inter alia, a rejection circuit tuned to an intermediate frequency and a series circuit, tuned to an image frequency and formed by a capacitor and a .lambda./4 coaxial stub. The inductance formed by the coaxial stub is shared by the series circuit and the rejection circuit.

Abstract: An arrangement for aligning an antenna by determining an extreme value maximum or minimum of a predetermined physical dimension which is dependent on the alignment of the antenna. A voltage is generated in proportion in the magnitude of the physical parameter or dimension, and this voltage is applied to a voltage-to-frequency converter which converts this voltage into an acoustical signal. This acoustical signal has a frequency which is inversely proportional to the voltage. The acoustical signal is applied to the control input of an electronic switch which is actuated by an oscillator. Groups of pulses in the output signal from the oscillator are obtainable at the output of the electronic switch, in synchronization with the acoustical signal. When the antenna is misaligned, the acoustical signal has a relatively high frequency, while the voltage has a relatively low level.