RadiansToStrain

class of dascore.transform.strain
inherits from: PatchProcessor, DascoreBaseModel, pydantic.main.BaseModel

RadiansToStrain(
    *args ,
    gauge_length: Any = None,
    wave_length: float = 1.5500000000000002e-06,
    stress_constant: float = 0.79,
    refractive_index: float = 1.445,
)-> None

Convert data in radians to strain (rate).

This applies the simple formula found in Lindsey, Rademacher, and Ajo-Franklin (2020) to convert data whose units have a radians component to strain.

Parameters

Parameter	Description
gauge_length (\(L_g\))	The gauge length in meters. Only used for phase that is not already normalized per unit length (rad or rad/s); ignored for rad/m and rad/(m*s).
wave_length (\(\lambda\))	The laser wavelength in m.
stress_constant (\(\zeta\))	The stress constant.
refractive_index (\(n\))	The refractive index of the cable.

Examples

import dascore as dc
patch = (
    dc.get_example_patch()
    .update_attrs(data_units="rad", gauge_length=10)
    .radians_to_strain()
)
assert patch.attrs.data_type == "strain"

Note

Equation 3 of Lindsey, Rademacher, and Ajo-Franklin (2020): \[ \epsilon_{xx}(t, x_j) = \frac{\lambda}{4 \pi n L_{g} \zeta} \Delta \Phi \]

For phase already normalized per length (rad/m or rad/(m*s)), the gauge-length division is omitted. Outputs are strain or strain/s, respectively; no time integration is performed.

The output data_type is set from the converted data units; it is “strain_rate” when they are strain per unit time (eg rad/s becomes strain/s) and “strain” otherwise.

Methods

Name	Description
check	Refuse a patch which does not carry what the operation needs.
get_metadata	Return strain metadata and the factor for phase units.
kernel	Return scaled strain data, or unchanged non-phase data.
model_copy	Copy the model, dropping cached values the update invalidates.
new	Create new instance with some attributed updated.
radians_to_strain	Convert data in radians to strain (rate).
reconcile	Return metadata or a patch holding the final data; default as is.
run	Run the operation: check, get_metadata, kernel, reconcile, record.

References

Lindsey, Nathaniel J, Horst Rademacher, and Jonathan B Ajo-Franklin. 2020. “On the Broadband Instrument Response of Fiber-Optic DAS Arrays.” Journal of Geophysical Research: Solid Earth 125 (2): e2019JB018145.