Search for and tag FSS oscillations before lockloss

Look at PSL-FSS_TPD_DC_OUT_DQ for dips below 0.3 within 5 seconds before lockloss and creates tag if it finds any. These FSS-related locklosses are fast, and the glitch is expected to occur very close to the refined lockloss time. For this reason it depends on a strong lockloss refinement, which may preclude LLO from getting good use of this followup.

locklost/config.py

@@ -70,6 +70,7 @@ TAG_COLORS = {
     'MICROSEISMIC': ('yellow', 'black'),
     'ANTHROPOGENIC': ('red', 'black'),
     'ADS_EXCURSION': ('mediumvioletred', 'plum'),
+    'FSS_OSCILLATION': ('69650b', 'palegoldenrod'),
     'SEI_BS_TRANS': ('sienna', 'orange'),
     'COMMISSIONING': ('lightseagreen', 'darkslategrey'),
     'MAINTENANCE': ('lightseagreen', 'darkslategrey'),

locklost/plotutils.py

@@ -12,6 +12,10 @@ def set_thresh_crossing(ax, thresh_crossing, gps, segment):
         lw=5,
     )
     x_fraction = (thresh_crossing-segment[0])/(segment[1]-segment[0])
+    if x_fraction < 0.05:
+        align = 'left'
+    else:
+        align = 'center'
     ax.annotate(
         'First threshold crossing',
         xy=(x_fraction, 1),
@@ -19,6 +23,7 @@ def set_thresh_crossing(ax, thresh_crossing, gps, segment):
         horizontalalignment='center',
         verticalalignment='bottom',
         bbox=dict(boxstyle="round", fc="w", ec="red", alpha=0.95),
+        ha=align,
     )
 
 

locklost/plugins/__init__.py

@@ -64,6 +64,9 @@ register_plugin(check_ads)
 from .sei_bs_trans import check_sei_bs
 register_plugin(check_sei_bs)
 
+from .fss_oscillation import check_fss
+register_plugin(check_fss)
+
 # add last since this needs to wait for additional data
 from .seismic import check_seismic
 register_plugin(check_seismic)

locklost/plugins/fss_oscillation.py

+import logging
+import numpy as np
+import matplotlib.pyplot as plt
+
+from gwpy.segments import Segment
+
+from .. import config
+from .. import data
+from .. import plotutils
+
+FSS_SEARCH_WINDOW = [-5, 5]
+FSS_CHANNELS = [
+    '{}:PSL-FSS_FAST_MON_OUT_DQ'.format(config.IFO)
+]
+FSS_THRESH = 3
+
+##############################################
+
+def check_fss(event):
+    """Checks for FSS oscillations.
+
+    Checks FSS PD for counts below threshold and
+    creates a tag/plot if below said threshold.
+
+    """
+    plotutils.set_rcparams()
+
+    mod_window = [FSS_SEARCH_WINDOW[0], FSS_SEARCH_WINDOW[1]]
+    segment = Segment(mod_window).shift(int(event.gps))
+    buf = data.fetch(FSS_CHANNELS, segment)[0]
+
+    thresh_crossing = segment[1]
+    srate = buf.sample_rate
+    t = np.arange(segment[0], segment[1], 1/srate)
+    thresh_ref = buf.data[np.where(t-event.gps <= -1)]
+    thresh_above = np.mean(thresh_ref)+FSS_THRESH
+    thresh_below = np.mean(thresh_ref)-FSS_THRESH
+    glitches = np.where((thresh_ref <= thresh_below) | (thresh_ref >= thresh_above))[0]
+    if any(glitches):
+        glitch_time = t[glitches[0]]
+        thresh_crossing = min(glitch_time, thresh_crossing)
+        event.add_tag('FSS_OSCILLATION')
+    else:
+        logging.info('no fss oscillations')
+
+    fig, ax = plt.subplots(1, figsize=(22,16))
+    t = np.arange(segment[0], segment[1], 1/srate)
+    ax.plot(
+        t-event.gps,
+        buf.data,
+        label=buf.channel,
+        alpha=0.8,
+        lw=2,
+    )
+    ax.axhline(
+        thresh_below,
+        linestyle='--',
+        color='black',
+        label='FSS oscillation threshold',
+        lw=5,
+    )
+    ax.axhline(
+        thresh_above,
+        linestyle='--',
+        color='black',
+        lw=5,
+    )
+    ax.grid()
+    ax.set_xlabel('Time [s] since lock loss at {}'.format(event.gps), labelpad=10)
+    ax.set_ylabel('Voltage [V]')
+    ax.legend(loc='best')
+    ax.set_title('FSS stability check', y=1.04)
+    ax.set_xlim(segment[0]-event.gps, segment[1]-event.gps)
+    if thresh_crossing != segment[1]:
+        plotutils.set_thresh_crossing(ax, thresh_crossing, event.gps, segment)
+
+    fig.tight_layout()
+
+    fig.savefig(event.path('fss.png'))

locklost/web/templates/event.tpl

@@ -92,6 +92,17 @@
       <p>LPY plots not created due to lack of saturating suspension channels.</p>
 % end
 
+<!-- FSS oscillations -->
+<hr />
+<div class="container">
+<br />
+<div class="row">
+% has_tag = event.has_tag('FSS_OSCILLATION')
+% board_plot = [event.url('fss.png')]
+% include('collapsed_plots.tpl', title ='FSS oscillation plot', id='fss', plots=board_plot, size=5, expand=has_tag, section='main')
+</div>
+</div>
+
 <!-- BRS glitch -->
 <hr />
 <div class="container">