Status Bit Definitions for HRC
- Event from Next-in-Line Telemetry Mode
Event time-tag may be incorrect
- No Trigger on axis
Event coarse position is unreliable as there was no signal large enough
on the axis to generate a trigger.
- Outside of commanded coarse position range
The HRC has commandable coarse position limits on each axis that can
be used to flag events which lie outside the limits.
- Width
Width of the event charge cloud is wider than expected for a good
event; the event position is unreliable.
- ANTICO Shield Active
The anti-coincidence photomultiplier is registering the event
indicating a likely cosmic ray.
- Above ULD
The event lies above the upper level discriminator.
- Below LLD
The event lies below the lower level discriminator.
- Event in Bad Region
The position of the event indicates that it is coming from an area
known to generate bad data (hot-spot or dead region).
- Amplifier Sum <= 0 in either axis
The sum of the amplifiers on either axis (i.e. av1+av2+av3 or
au1+au2+au3) is less than or equal to 0. Event does not have a reliable
position.
- Bad Center
The center of the event has not been correctly identified,
specifically the value of one of the wing amplifiers is greater than
the central amplifier, i.e. av1 or av3 > av2. Event does not have a reliable
position.
- Ratio of PHA to Amplifier Sum
A comparison of the event PHA to the sum of the position signals from the
grid indicates that the event may be due to a cosmic ray.
- PHA=0
Event pulse height value of 0 was telemetered; the event does not
appear to be valid.
- Ratio of V Amplifiers to U Amplifiers
A comparison of the sum of the V-axis amplifiers to the sum of the
U-axis amplifiers indicates that the event may be due to a cosmic ray.
- Amplifier Sum
Sum of U- and V-axis amplifiers is 0; event position is not reliable.
- PI>255
(currently the PI column is not being filled in)
- Time Tag Out of Sequence
Event time information is not correct.
- Flatness Test
The event is "too flat". Specifically the ratio of the wing amplifiers
to the central amplifier (amp1/amp2 AND amp3/amp2) is greater than 0.5
(v1 of filtering coefficient).
- Saturation Test
The values of two of the amplifiers in an axis do not lie between 20
and 4000 for AMP_SFs 0 through 2 and between 20 and 3550 for amp_sf 3
(v2 of filtering coefficients).
- H-Test
X-ray event positions are measured
using a crossed grid charge detector (CGCD). For each axis, the
signals from three amplifiers centered at the coarse position of the
event electron cloud are digitized and written to the telemetry
stream. Event positions are well determined if they lie within the
locus of points empirically determined to be "well positioned".
This locus is a hyperbola, defined by the function:
H(F1)=B*[({F1-H}/A)**2-1]**0.5
where
F1=amp2/(amp1+amp2+amp3)
and the coefficients of the curve (v3 for HRC-I and v4 for HRC-S) are:
| HRC-I | |
HRC-S |
| axis | B | H | A | deltaH | |
axis | B | H | A | deltaH |
| U | 0.3030 | 1.0580 | 0.3110 | 0.0350 | |
U | 0.2620 | 1.0180 | 0.27060 | 0.0350 |
| V | 0.2730 | 1.10 | 0.3050 | 0.0350 | |
V | 0.2480 | 1.0710 | 0.27060 | 0.0350 |
If F2 defined as
F2=ABS[(amp3-amp1)/(amp1+amp2+amp3)]
then "poorly located" data is anything where either
((F1 - (H + deltaH))/A)**2 - (F2/B)**2 < 1
or
((F1 - (H - deltaH))/A)**2 - (F2/B)**2 > 1
Note that this is reasonably straightforward to implement as a filter
with the FTOOL "fselect".
