FMCW

class FMCW(num_chirps=10, chirp_duration=1.5e-06, pulse_rep_interval=1.5e-06, adc_sampling_rate=None)

Bases: RadarWaveform

Frequency Modulated Continuous Waveform Radar Sensing with stretch processing.

This class generates a frame consisting of a sequence of unmodulated chirps. They are used for radar detection with stretch processing, i.e., mixing the received signal with the transmitted sequence, (under)sampling and applying an FFT. S A minimal example configuring an FMCW radar waveform illuminating a single target within the context of a Simulation would look like this:

from hermespy.radar import Radar, FMCW, ReceiverOperatingCharacteristic
from hermespy.simulation import Simulation, N0
from hermespy.channel import SingleTargetRadarChannel

# Create a new simulated scenario featuring a single device
simulation = Simulation()
device = simulation.new_device(noise_level=N0(2.5e-6), carrier_frequency=60e9, bandwidth=1e9)

# Configure the device to transmit and reveive radar waveforms
radar = Radar()
radar.waveform = FMCW(num_chirps=3, chirp_duration=1e-6, pulse_rep_interval=1.1e-6)
device.add_dsp(radar)

# Create a new radar channel with a single illuminated target
target = SingleTargetRadarChannel(1, 1., attenuate=True)
simulation.scenario.set_channel(device, device, target)

# Create a new detection probability evaluator
simulation.add_evaluator(ReceiverOperatingCharacteristic(radar, device, device, target))

# Run the simulation

Parameters:

• num_chirps (int) – Number of dedicated chirps within a single radar frame. \(10\) by default.

• chirp_duration (float) – Duration of every chirp in seconds. \(1.5~\mathrm{\mu s}\) by default.

• pulse_rep_interval (float) – Repetition interval of the individual chirps in seconds. \(1.5~\mathrm{\mu s}\) by default.

• adc_sampling_rate (float | None) – Sampling rate of the analog-digital conversion in Hz. If not specified, the adc sampling rate will be equal to the bandwidth.

classmethod Deserialize(process)

Deserialize an object’s state.

Objects cannot be deserialized directly, instead a Factory must be instructed to carry out the deserialization process.

Parameters:

process – The current stage of the deserialization process. This object is generated by the Factory and provides an interface to deserialization methods supporting multiple backends.

Returns:

The deserialized object.

energy(bandwidth, oversampling_factor)

Energy of the radar waveform.

Parameters:

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

• oversampling_factor (int) – Oversampling factor of the radar waveform.

Return type:

float

Radar energy in \(\mathrm{Wh}\).

estimate(signal, state)

Generate a range-doppler map from a single-stream radar frame.

Parameters:

• signal (Signal) – Single-stream signal model of a single propagated radar frame.

• state (ReceiveState) – State of the device the radar is assigned to.

Return type:

ndarray

Returns:

Numpy matrix (2D array) of the range-doppler map, where the first dimension indicates discrete doppler frequency bins and the second dimension indicates discrete range bins.

frame_duration(bandwidth)

Duration of a single radar frame in seconds.

Parameters:

bandwidth (float) – Bandwidth of the radar waveform in Hz.

Return type:

float

Denoted by \(T_{\mathrm{F}}\) of unit \(\left[ T_{\mathrm{F}} \right] = \mathrm{s}\) in literature.

max_range(bandwidth)

The waveform’s maximum detectable range in meters.

Parameters:

bandwidth (float) – Bandwidth of the radar waveform in Hz.

Return type:

float

Denoted by \(R_{\mathrm{Max}}\) of unit \(\left[ R_{\mathrm{Max}} \right] = \mathrm{m}\) in literature.

ping(state)

Generate a single radar frame.

Parameters:

state (TransmitState) – State of the device the radar is assigned to.

Return type:

Signal

Returns:

Single-stream signal model of a single radar frame.

range_bins(bandwidth)

Discrete sample bins of the radial range sensing.

Parameters:

bandwidth (float) – Bandwidth of the radar waveform in Hz.

Return type:

ndarray

Returns:

A numpy vector (1D array) of discrete range bins in meters.

range_resolution(bandwidth)

Resolution of the radial range sensing in meters.

Parameters:

bandwidth (float) – Bandwidth of the radar waveform in Hz.

Return type:

float

Denoted by \(\Delta R\) of unit \(\left[ \Delta R \right] = \mathrm{m}\) in literature.

samples_per_frame(bandwidth, oversampling_factor)

Number of samples in a single radar frame.

Parameters:

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

• oversampling_factor (int) – Oversampling factor of the radar waveform.

Return type:

int

Returns:

Number of samples in a single radar frame.

serialize(process)

Serialize this object’s state.

Objects cannot be serialized directly, instead a Factory must be instructed to carry out the serialization process.

Parameters:

process (SerializationProcess) – The current stage of the serialization process. This object is generated by the Factory and provides an interface to serialization methods supporting multiple backends.

Return type:

None

property adc_sampling_rate: float

Sampling rate at the ADC in Hz.

Raises:

ValueError – If sampling rate is smaller than zero.

property chirp_duration: float

Duration of a single chirp within the FMCW frame.

In combination with pulse_rep_interval the chirp duration determines the guard interval between two consecutive chirps:

(Source code)

(png, hires.png, pdf)

(png, hires.png, pdf)

Raises:

ValueError – For durations smaller or equal to zero.

property max_relative_doppler: float

Maximum relative detectable radial doppler frequency shift in Hz.

\[\Delta f_\mathrm{Max} = \frac{v_\mathrm{Max}}{\lambda}\]

property num_chirps: int

Number of chirps per transmitted radar frame.

Changing the number of chirps per frame will result in a different radar frame length:

(Source code)

(png, hires.png, pdf)

(png, hires.png, pdf)

Raises:

ValueError – If the number of chirps is smaller than one.

property power: float

Power of the radar waveform.

Radar power in \(\mathrm{W}\).

property pulse_rep_interval: float

Pulse repetition interval in seconds.

The pulse repetition interval determines the overall frame duration. In combination with the chirp_duration the pulse repetition interval it determines the guard interval between two consecutive chirps:

(Source code)

(png, hires.png, pdf)

(png, hires.png, pdf)

Raises:

ValueError – If interval is smaller or equal to zero.

property relative_doppler_bins: ndarray

Realtive discrete sample bins of the radial doppler frequency shift sensing.

A numpy vector (1D array) of discrete doppler frequency bins in Hz.

property relative_doppler_resolution: float

Relative resolution of the radial doppler frequency shift sensing in Hz.

\[\Delta f_\mathrm{Res} = \frac{v_\mathrm{Res}}{\lambda}\]