From 0792d5a097efd4dea67b4a3f2b0a06d77d63dc5f Mon Sep 17 00:00:00 2001
From: "E. Joshua Rigler" <erigler@usgs.gov>
Date: Wed, 18 Sep 2024 17:27:11 -0600
Subject: [PATCH] Remove sensitivity/response; fixes issue #117.
Remove instrument_sensitivity if it exist. If it doesn't exist, then
an instrument_polynomial must describe the response, which is how the
Geomagnetism Program specifies an offset and gain response. We do not
attempt to remove any frequency-depenent response since these all seem
tailored to seismic data (e.g., no DC/zero-frequency response).
---
geomagio/edge/FDSNFactory.py | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/geomagio/edge/FDSNFactory.py b/geomagio/edge/FDSNFactory.py
index 618395c4..7425cd46 100644
--- a/geomagio/edge/FDSNFactory.py
+++ b/geomagio/edge/FDSNFactory.py
@@ -258,6 +258,25 @@ class FDSNFactory(TimeseriesFactory):
data = self._rotate_and_return_requested_channel(
data, sncl, starttime, endtime, channel
)
+
+ for trace in data:
+ response = trace.stats.response
+ if response.instrument_sensitivity:
+ if response.instrument_sensitivity.input_units == "T":
+ # some ASL stations produce data in Teslas, not nanoteslas
+ response.instrument_sensitivity.value /= 1e9
+ response.instrument_sensitivity.input_units = "nT"
+ # apply total gain/sensitivity, ignore any frequency response
+ trace.remove_sensitivity()
+ else:
+ # according to fdsn docs, if no instrument_sensitivity,
+ # the response must be an instrument_polynomial
+ # https://docs.fdsn.org/projects/stationxml/en/latest/reference.html#instrumentsensitivity
+
+ # Geomag Program observatories use 2nd order instrument_polynomial
+ # to capture both offset and scale, but no frequency response
+ data.remove_response()
+
if data.count() == 0 and add_empty_channels:
data += self._get_empty_trace(
starttime=starttime,
--
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