Filters

Radio-Frequency (RF) filters selectively pass spectral signal components of desired frequency ranges while attenuating undesired frequencies. They are commonly used to remove out-of-band noise, suppress interference, and shape signal spectra in communication and radar systems.

This module provides various numerical models of filters commonly applied in front-ends.

class HPF(cutoff_frequency, filter_order=4, noise_model=None, noise_level=None, seed=None)

Bases: Filter

A radio-frequency block that applies a high-pass filter during signal propagation.

Parameters:

• cutoff_frequency (float) – Cutoff frequency of the high-pass filter in Hz.

• noise_model (NoiseModel | None) – Thermal noise model applied after signal propagation. If not specified, i.e. None, AWGN is assumed.

• filter_order (int) – Order of the high-pass filter. Refer to the documentation of scipy.signal.butter() for details.

• noise_level (NoiseLevel | None) – Thermal noise level applied after signal propagation. If not specified, i.e. None, thermal noise at 300 K is assumed.

• seed (int | None) – Seed with which to initialize the block’s random state.

realize(bandwidth, oversampling_factor, carrier_frequency)

Return the current state of the radio-frequency block.

Parameters:

• bandwidth (float) – Bandwith of the proecessed signals in Hz.

• oversampling_factor (int) – Oversampling factor of the modeling.

• carrier_frequency (float) – Target carrier frequency of the modeled radio front-end in Hz.

Return type:

FilterRealization

Returns:

Current state of the radio-frequency block.

property cutoff_frequency: float

Cutoff frequency of the high-pass filter in Hz.

Raises:

ValueError – If the cutoff frequency is not positive.

property filter_order: int

Order of the high-pass filter.

Refer to the documentation of scipy.signal.butter() for details.

Raises:

ValueError – If the filter order is less than 1.

class Filter(noise_model=None, noise_level=None, seed=None)

Bases: RFBlock

A radio-frequency block that applies an arbitrary filter during signal propagation.

Parameters:

• numerator_coefficients – Coefficients of the filter’s numerator.

• denominator_coefficients – Coefficients of the filter’s denominator.

• noise_model (NoiseModel | None) – Thermal noise model applied after signal propagation. If not specifiedm, i.e. None, AWGN is assumed.

• noise_level (NoiseLevel | None) – Thermal noise level applied after signal propagation. If not specified, i.e. None, thermal noise at 300 K is assumed.

• seed (int | None) – Seed with which to initialize the block’s random state.

property i: RFBlockPort[Filter]

Input port of the filter block.

property num_input_ports: int

Number of physical ports feeding into this radio-frequency block.

If the returned number is negative, the block can accept an arbitrary number of input ports.

property num_output_ports: int

Number of physical ports emerging from this radio-frequency block.

property o: RFBlockPort[Filter]

Output port of the filter block.

class FilterRealization(numerator_coefficients, denominator_coefficients, bandwidth, oversampling_factor, noise_realization)

Bases: RFBlockRealization

Realization of a radio-frequency filter block.

Parameters:

• numerator_coefficients (ndarray) – Coefficients of the filter’s numerator.

• denominator_coefficients (ndarray) – Coefficients of the filter’s denominator.

• bandwidth (float) – Bandwidth of the simulation in Hz.

• oversampling_factor (int) – Oversampling factor of the simulation.

• noise_realization (NoiseRealization) – Noise realization applied to the filter.

property denominator_coefficients: ndarray

Coefficients of the filter’s denominator.

property numerator_coefficients: ndarray

Coefficients of the filter’s numerator.