DAY 3 from AO9 4GHz bw

25may19

Links:
intro
the scan pattern

filtering out points not on the dish

plotting range vs elevation

fitting for the center and radius of the sphere
Summary



Intro

    Data was taken from AO9 (center of the dish) on day3 (24may18) starting around 11:15 . A 4 GHz bandwidth scan was done. The scan included the dish, ground screen, hills behind ground screen, below the dish (through the panel holes), and a few shots of the platform.

    An uncalibrated data set was left for AO to play with. 11 .las files were provided:

    The following plots were made from this data.  The final calibration is being done by blackmore back in Montana

Scan pattern

   The scanner coordinate system was:

 The first set of plots shows the scan pattern (.ps) (.pdf)

    Scan Pattern summary:

processing: x101/blackmore/ao9_4g/plot_scanpat.pro

Filtering out points not on the dish

    A number of recorded points did not come from reflections off the dish. They include:

limiting in x,y,z and elevation:

    A first attempt at  limiting the points was to limit the x,y,z , and elevation of the data points:

Median filtering:

    We expect the x,y,z values to change slowly as we scan across the dish. Exceptions to this will occur if:

    To remove sharp jumps:

    The plots show an example of the median  filtering (.ps) (.pdf)

Filtering results

processing: x101/blackmore/ao9_4g/loaddata.pro, chkdata_distVsEl.pro

Plotting range vs elevation

    A histogram was made of the measured elevation values (using .01 degree bin size). The reverse index output of the
histogram provided a list of all of the points in each bin.

    The  plot shows the histogram of elevation and range vs elevation (.ps)  (.pdf)

summary range vs elevation:

processing: x101/blackmore/ao9_4g/chkdata_distVsEl.pro

fitting the center and radius of sphere.

    The primary reflector is supposed to have a radius of 870 feet (265.176 meter). A09 should be at the x,y center of the reflector. The base of A09 is about .5 meters above the bottom of the dish. The scanner was mounted on  AO9. 

    A non-linear least squares fit was done to the filtered data points to find the center and radius of the sphere. The fitting function was:

    Two types of fits were done:

Results of the fit

Results from Fitting for Sphere

iteration
Npnts
x offset
(meters)
y offset
(meters)
z offset
(meters)
radius
(meters)
data-fit
(meters)
(Radius-Zoffset)
Scanner Z offset
from dish
value
sigma
value
sigma
value
sigma
value
sigma
sigma
meters
Fit all 4 parameters

1
76177741
1.2445
.0005
1.3728
.0005
262.8752
.0022
263.2814
.0021
.5668
.406
2
71291522
1.2472
.0006
1.3739
.0006 261.8788
.0023
262.4015
.0021
.0721
.523
3
70592209
1.2457
.0006
1.3723
.0006 261.8628
.0023 262.3871
.0022
.0692
.524
Fit 3 parameters. radius fixed at 265.176m


1
76177741
1.2403
.0006
1.3733
.0005
264.8558
.0001
265.1760
0.0000
.5763
.320
2
42050976
1.2608
.0007
1.3976
.0007
264.8239
.0002
.1095
.352
3
40547882
1.2669
.0007
1.4056
.0007
264.8160
.0002
.1032
.360

To do:

processing:x101/blackmore/ao94g/chkdatafit.pro


Summary

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