Audio Device

Hermes hardware bindings to audio devices offer the option to benchmark complex-valued communication waveforms over affordable consumer-grade audio hardware. The effective available bandwidth is limited to half of the audio devices sampling rate, which is typically either \(44.1~\\mathrm{kHz}\) or \(48~\\mathrm{kHz}\).

class AudioDevice(playback_device, record_device, playback_channels=None, record_channels=None, sampling_rate=48000.0, oversampling_factor=2, **kwargs)

Bases: PhysicalDevice[PhysicalDeviceState], Serializable

HermesPy binding to an arbitrary audio device. Let’s rock!

Parameters:

• playback_device (int) – Device over which audio streams are to be transmitted.

• record_device (int) – Device over which audio streams are to be received.

• playback_channels (Sequence[int] | None) – List of audio channels for signal transmission. By default, the first channel is selected.

• record_channels (Sequence[int] | None) – List of audio channels for signal reception. By default, the first channel is selected.

• sampling_rate (float) – Configured sampling rate. 48 kHz by default.

• oversampling_factor (int) – Oversampling factor for the internal signal processing. 1 by default.

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

Return type:

AudioDevice

Returns:

The deserialized object.

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

state()

Query the immutable physical state of the device.

Returns: The physical device state.

Return type:

PhysicalDeviceState

trigger()

Trigger the device.

Return type:

None

property antennas: AudioDeviceAntennas

Model of the device’s antenna array.

property carrier_frequency: float

Central frequency of the device’s emissions in the RF-band.

Denoted by \(f_c\) with unit \(\left[ f_c \right] = \mathrm{Hz} = \tfrac{1}{\mathrm{s}}\) in the literature.

Raises:

ValueError – On negative carrier frequencies.

property max_sampling_rate: float

Maximal device sampling rate.

Returns: The samplin rate in Hz.

property oversampling_factor: int

Oversampling factor for the internal signal processing.

Raises:

ValueError – For values smaller than one.

property playback_channels: Sequence[int]

Audio channels for signal transmission.

Returns: Sequence of audio channel indices.

Raises:

ValueError – On arguments not representing vectors.

property playback_device: int

Device over which audio streams are to be transmitted.

Returns: Device identifier.

Raises:

ValueError – For negative identifiers.

property record_channels: Sequence[int]

Audio channels for signal reception.

Returns: Sequence of audio channel indices.

Raises:

ValueError – On arguments not representing vectors.

property record_device: int

Device over which audio streams are to be received.

Returns: Device identifier.

Raises:

ValueError – For negative identifiers.

property sampling_rate: float

Sampling rate at which the device’s analog-to-digital converters operate in Hz.

Raises:

ValueError – If the sampling rate is not greater than zero.

class AudioAntenna(mode=AntennaMode.DUPLEX, pose=None)

Bases: Antenna

Antenna model for audio devices.

Parameters:

• mode (AntennaMode) – Antenna’s mode of operation. By default, a full duplex antenna is assumed.

• pose (Transformation | None) – The antenna’s position and orientation with respect to its array.

copy()

Create a deep copy of the antenna.

Return type:

AudioAntenna

Returns:

A deep copy of the antenna.

local_characteristics(azimuth, elevation)

Generate a single sample of the antenna’s characteristics.

The polarization is characterized by the angle-dependant field vector

\[\begin{split}\mathbf{F}(\phi, \theta) = \begin{pmatrix} F_{\mathrm{H}}(\phi, \theta) \\ F_{\mathrm{V}}(\phi, \theta) \\ \end{pmatrix}\end{split}\]

denoting the horizontal and vertical field components. The directional antenna gain can be computed from the polarization vector magnitude

\[\begin{split}A(\phi, \theta) &= \lVert \mathbf{F}(\phi, \theta) \rVert \\ &= \sqrt{ F_{\mathrm{H}}(\phi, \theta)^2 + F_{\mathrm{V}}(\phi, \theta)^2 }\end{split}\]

Parameters:

• azimuth (float) – Considered horizontal wave angle in radians \(\phi\).

• elevation – Considered vertical wave angle in radians \(\theta\).

Return type:

ndarray

Returns:

Two dimensional numpy array denoting the horizontal and vertical ploarization components of the antenna response vector.

class AudioDeviceAntennas(device)

Bases: AntennaArray[AudioAntenna]

Antenna array information for audio devices.

Parameters:

device (AudioDevice) – The audio device to which the antenna array belongs.

property antennas: list[AudioAntenna]

All individual antenna elements within this array.

property num_receive_antennas: int

Number of receiving antenna elements within this array.

property num_transmit_antennas: int

Number of transmitting antenna elements within this array.

property receive_antennas: list[AudioAntenna]

Receiving antennas within this array.

property transmit_antennas: list[AudioAntenna]

Transmitting antennas within this array.