33 results about "Discrete time filtering" patented technology

A discrete-time receiver includes: a sampling mixer sampling an input signal according to a sampling clock; a discrete-time filter adjusting a decimation rate by using a control signal and filtering the sampled signal by using a filter clock; and a clock generator generating a sampling clock to be supplied to the sampling mixer, and generating the control signal and the filter clock by comparing the frequency of the sampling clock with a pre-set output frequency. Over a broadband input signal, a dynamic range of an output signal can be improved.

The invention relates to a discrete-time filter for filtering an input signal, the discrete-time filter comprising a switched capacitor network, the switched capacitor network comprising an input (102) and an output (104), a number of switched capacitor paths (101, 103, 105, 107) arranged in parallel between the input (102) and the output (104), each switched capacitor path (101, 103, 105, 107) comprising a capacitor, and a switch circuitry (121, 125, 127) for switching each capacitor at a different time instant for outputting a filtered input signal.

A receiver includes a sample and hold module, a discrete time filter module, and a wireless frequency to baseband conversion module. The sample and hold module is operable to sample and hold an inbound wireless signal at a rate corresponding to a multiple of a carrier frequency of the inbound wireless signal to produce a frequency domain sample pulse train. The discrete time filter module is operable to filter the frequency domain sample pulse train to produce a wireless frequency pulse. The wireless frequency to baseband conversion module is operable to convert the wireless frequency pulse to a baseband digital signal.

A receiver includes a bandpass filter module, a sample and hold module, first and second discrete time filter modules, and first and second conversion modules. The bandpass filter module is operable to filter an inbound wireless signal. The sample and hold module is operable to sample and hold the filtered inbound wireless signal to produce a frequency domain sample pulse train. The first discrete time filter module is operable to filter the frequency domain sample pulse train to produce a first filtered sample pulse. The second discrete time filter module is operable to filter the frequency domain sample pulse train to produce a second filtered sample pulse. The first conversion module is operable to convert the first filtered sample pulse into a first inbound baseband signal. The second conversion module is operable to convert the second filtered sample pulse into a second inbound baseband signal.

A receiver includes a sample and hold circuit that receives a signal (continuous time signal) that has been subject to frequency division multiplexing modulation, converts the signal to a discrete time signal, and outputs the discrete time signal, a discrete time filter that receives the signal output from the sample and hold circuit and attenuates a frequency component of a subcarrier different from a specified subcarrier, and a demodulation unit that extracts a digital baseband from a signal that has passed through the discrete time filter to complete a demodulation operation within one data symbol reception period.

A receiver includes a sample and hold module, a discrete time filter module, and a conversion module. The sample and hold module is operable to sample and hold a first inbound wireless signal and a second inbound wireless signal to produce a frequency domain sample pulse train. The discrete time filter module is operable to filter the frequency domain sample pulse train to produce a first filtered sample pulse corresponding to the first inbound wireless signal and to produce a second filtered sample pulse corresponding to the second inbound wireless signal. The conversion module is operable to convert the first filtered sample pulse into a first inbound baseband signal and to convert the second filtered sample pulse into a second inbound baseband signal.

An RF signal reception device including: a transposition device of signals of frequency f_RF to a first intermediate frequency IF1<f_RF; a first bandpass filter centered on IF1; a sampler at a frequency fs<IF1; a second discrete-time filter centered on a second intermediate frequency IF2=α·fs/M+fs/(M·n); a decimation device of a factor M; an analog-digital convertor to operate at a frequency fs/M; where α, n and M are strictly positive real numbers chosen such that: α<fs/(2·BW_ch·M), and BW_ch/2<fs/M·n), with BW_ch: bandwidth of a channel of the received RF signals.

The discrete-time receiver system includes: a voltage current conversion device low-noise-amplifying an input voltage signal, and converting the amplified signal into a current signal; a first filter performing IIR filtering on the current signal output from the voltage current conversion device; a discrete-time filter performing FIR filtering on a signal output from the first filter; and a second filter performing IIR filtering on a signal output from the discrete-time filter, wherein the discrete-time filter includes a plurality of current supply units generating a current having a size obtained by multiplying an input current by a determined gain, respectively, an adding unit adding currents supplied from the plurality of current supply units, and a plurality of controllers connecting the plurality of current supply units and the adding unit and controlling the flow of current supplied from the current supply units to the adding unit.

There is provided a communication receiver comprising: an input for receiving a radio frequency, RF, input signal; and at least one finite impulse response, FIR, discrete time filter, DTF. The at least one FIR DTF comprises: an input circuit comprising an input port for sampling the RF input signal at a sampling frequency that is comparable to the input RF input signal; and N parallel branches, each branch having a set of input unit sampling capacitances, where each unit sampling capacitance is independently selectively coupleable to an output summing node. The input circuit is configured to convert an equivalent input impedance of the at least one FIR DTF around the sampling frequency to a real impedance.

Methods and apparatus for shaping and filtering quantization errors conjointly in space and time to produce a higher-precision output in a spatially and temporally oversampled array. A space-time error-shaping array system has an array of sensors, each sensor producing a temporal signal comprising quantized waveforms. A multi-input multiple-output (MIMO) discrete-time filter structure with multiple inputs, each coupled to a sensor of the array of sensors, shapes quantization errors of the array of sensors on the basis of temporal aspects of the quantized waveforms conjointly with spatial aspects of the quantized waveforms.

A receiver includes a sample and hold module, a discrete time filter module, and a conversion module. The sample and hold module includes a sample switching module, an impedance module, and a hold switching module. The sample switching module outputs samples of an inbound wireless signal in accordance with a sampling clock signal. The impedance module temporarily stores the samples. The hold switching module outputs a filtered representation of the samples in accordance with a hold clock signal to produce a frequency domain sample pulse train, wherein a filter response of the sample and hold module is in accordance with a ratio between the sampling clock signal and the hold clock signal. The discrete time filter module, which may be programmable, filters the frequency domain sample pulse train. The conversion module, which may be programmable, converts the filtered sample pulse into an inbound baseband signal.

What is provided is a subtractor, as a re-quantization device, which is configured to detect re-quantization noise, a discrete time filter which is configured to perform frequency weighting on the detected re-quantization noise, an adder which is configured to add an additional signal to quantization noise, and an additional signal selector which is configured to select a value at the present time of a column of an additional signal for minimizing the magnitude of quantization noise having been subjected to frequency weighting evaluated one sampling or more later.

Equalization methods and equalizers employing discrete-time filters are provided with dynamic perturbation effect based adaptation. Tap coefficient values may be individually perturbed during the equalization process and the effects on residual ISI monitored to estimate gradient components or rows of a difference matrix. The gradient or difference matrix components may be assembled and filtered to obtain components suitable for calculating tap coefficient updates with reduced adaptation noise. The dynamic perturbation effect based updates may be interpolated with pre-calculated perturbation effect based updates to enable faster convergence with better accommodation of analog component performance changes attributable to variations in process, supply voltage, and temperature.

The invention provides a method for transforming a continuous-time filter to a discrete-time filter. The method includes: sampling input quantity and output quantity of a controlled system, and utilizing an identification algorithm for obtaining a continuous-time model of the system; constructing the continuous-time filter according to the continuous-time model; adopting a partial differential equation method to compute a coefficient matrix of the discrete-time filter according to coefficients in a continuous-time filter equation and adopted time of a discrete system; and constructing a discrete-time filter structure. The discrete-time filter is obtained by performing discrete transformation to the designed continuous-time filter. Compared with an existing discrete-time filter design method, the method has the advantages that discretization processes of a controlled object and filter designing processes based on the discrete system are decreased, and by utilizing advantages of a filter design theory based on a continuous-time system, the filter excellent in performances can be designed, system design and development time can be saved, and the method is particularly suitable for practical engineering application of digital control systems.

A method and system for designing a discrete-time filter having a transfer function which approximates that of an analog shelf filter is disclosed. Prior art methods include applying the bilinear transform to the analog filter, which has the drawback of warping high-frequency features of the desired transfer function. In an embodiment of the present invention, an analog filter is designed which anticipates the warping imposed by the bilinear transform. For filters whose features approach the Nyquist limit, the inventive method provides a closer approximation to the analog response than direct application of the bilinear transform.