Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.naic.edu/~phil/hardware/12meter/AreciboSATexcerpts1-28-10.doc Äàòà èçìåíåíèÿ: Fri Jan 29 22:03:23 2010 Äàòà èíäåêñèðîâàíèÿ: Fri Apr 9 12:55:57 2010 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: ngc 6520

AZIMUTH AXIS VERTICALITY MEASUREMENT


1


2 OVERVIEW

This test is to measure and record the verticality of the Azimuth
Axis, and to determine the angular deviations from theoretically
true azimuth for use as offsets in the controller pointing model.


3


4 AZIMUTH AXIS VERTICALITY MEASUREMENT TEST PROCEDURE

Follow these steps-

1. Set the controller for Manual Pendant control. Drive the
Turning Head so it is pointing due North to establish a
starting measurement position. Drive the Reflector in
elevation to the zenith position.

2. Place a precision 10 arcsec level in-line with North/South
alignment of Turning Head, and shim it to zero its bubble.

3. Drive the Azimuth in the direction which won't encounter a
limit for 360deg of rotation and stop to record the bubble
reading at the azimuth headings of- 0, 30,
60, 90, 120, 150, 180, 210, 240, 270, 300, & 330deg. Goal is
alignment of ˜30arcsec.

4. Last drive the antenna system to 0deg Azimuth heading. Drive
the antenna in Elevation from 88 to 10deg, and record the
change in verticality.



|Azimuth |0 |30 |60 |90 |120 |150 |
|heading | | | | | | |
|Level |2.60 |2.76 |2.80 |2.80 |2.85 |2.90 |
|measure | | | | | | |
|(division) | | | | | | |


|Azimuth |180 |210 |240 |270 |300 |330 |
|heading | | | | | | |
|Level |2.90 |2.95 |2.90 |2.70 |2.60 |2.60 |
|measure | | | | | | |
|(division) | | | | | | |


Axis is Tilt- __8.2_ milli-degrees

Direction- __355__ azimuth degrees



Change in verticality from 88 to 10deg- ___30 arcsec___





SUMMARY OF AZIMUTH VERTICALITY MEASUREMENT RESULTS



|Parameter |Specificati|Pass|
| |on |or |
| | |Fail|
| | | |
|Summary Result of Azimuth Verticality |NA |Pass|
|Measurement | | |


Test Date:

Start Time:

End Time:

Comments:





By- _______________ Date-
__________________









REFLECTOR SURFACE ACCURACY MEASUREMENT


1 OVERVIEW

This test is to measure and record the surface accuracy of the
reflector using photogrammetry. Photogrammetry is a 3-dimensional
coordinate measuring technique that uses photographs for metrology
using the basic principle of triangulation or intersecting lines in
space to compute the location of a point. The camera and software
have the ability to self-calibrate at the time of the measurement
under the environmental conditions that exist by using roll
diversity (some shots taken at 90deg to others), and the
mathematical means to automatically solve any error terms in the
system. Typical accuracies are 25 to 50 microns (.001" to .002") on
a 3-meter object, or as in this application shots taken at 3-meters
away from the object, and using overlaid photos to piece together
the entire image.


2


3 REFLECTOR SURFACE ACCURACY MEASUREMENT TEST PROCEDURE



1. Prepare the antenna with the required photogrammetry
components- 1380 targets, 28 target codes, 4 datum targets,
and a 104in scale bar. Make a setup shot(s) to verify proper
camera and flash settings.

NOTE: Scale Bar used- Brunson 08-CP-300 certified
calibration .0002" for 6pc 104" length used.

2. Set the controller for Manual Pendant control to be able to
position the reflector in azimuth and elevation for the
needed photographs to be taken.

3. Determine a repeatable scheme whereby photos will be taken at
45deg intervals around the reflector at a desired location
approximately 3meters above the rim of the reflector parallel
with the focal axis. Using a EWP(elevated work platform)
maneuver the photographer to the 8 locations and take
approximately 6-8 shots per, overlapping the object in the
view finder so that the combined 8 shots can be linked
together to represent the entire object.

4. Download the photos into the V-Stars Laptop computer and
solve the measurements against an IGES file of the
theoretical paraboloid specified for the design. Verify
accurate scaling, and best-fitting to datum targets. Then use
the software function that will best-fit the points to a
paraboloid of a fixed (or best-fitted) focal distance. Record
the rms of the measurement. Establish a driver file to be
used for subsequent measurements.

5. Repeat steps 3 & 4 for 15, 50, & 88deg elevation angles.
Record in the table below-



|ITEM |SPECIFICATI|Pass|
| |ON |or |
| | |Fail|
| | | |
|Reflector Surface Accuracy rms |˜ .015in |Pass|

Results-


|Elevation Angle |10 |50 |88 |
| Surface rms |.012 |.012 |.015 |






|ITEM |SPECIFICATI|Pass|
| |ON |or |
| | |Fail|
| | | |
|Best-Fit Paraboloid Vertex to Nominal |none |NA |
|Hub Datum Vertex | | |


4 Results-




| |X |Y |Z |Angle* |
|10deg |.056 |-.090 |-.006 |-.0256? |
|Elevation | | | | |
|50deg |.067 |-.048 |-0- |-.0164? |
|Elevation | | | | |
|88deg |.067 |.085 |-.002 |-0- |
|Elevation | | | | |
5


6 *Note- This is angular droop toward ground due to gravity.


7 SUMMARY OF REFLECTOR SURFACE ACCURACY MEASUREMENT





Test Date:

Start Time:

End Time:

Weather Conditions during Test:

Comments:





By- _________________ Date- _______________





SUB-REFLECTOR AND FEED POSITION AND ALIGNMENT
MEASUREMENT


1


2 OVERVIEW

This test is to measure and record the positions of the sub-
reflector and feed horn using photogrammetry. XYZ locations of
targets placed on the sub-reflector and feed horn will be studied
to determine position and axial alignment to the best-fit
paraboloid reflector shape. The study will be done at 10, 50, and
88deg elevation angles.


3


4 SUB-REFLECTOR/FEED POSITION AND ALIGNMENT MEASUREMENT TEST PROCEDURE



1. Use the same photo sessions used in the reflector surface
measurement to measure the targets of the feed system.

2. Download the photos into the V-Stars Laptop computer and
solve the measurements. Create construction lines, planes,
and circles from which position, and axial measurements can
be determined from.

3. Repeat process for the 10, 50, and 88deg elevation angles.



SubReflector Measurement-

|ITEM |SPECIFICATI|Pass|
| |ON |or |
| | |Fail|
| | | |
|Sub-reflector position to Best-Fit |˜ +/- .08in|Pass|
|Paraboloid at nominal 50deg Elevation | | |
|position | | |


Results-

| |X |Y |Z |angle |
|Theoretical Position|0 |0 |175.45in|-0- |
|of Sub-reflector | | | | |
|Datum Targets | | | | |
|Measured Position of|.013 |-.071 |175.50 |-0- |
|Sub-reflector | | | | |



|ITEM |SPECIFICATI|Pass|
| |ON |or |
| | |Fail|
| | | |
|Sub-reflector position change |˜ +/- |P |
|measurement |.120in | |
|throughout elevation range of motion | | |


Results-

|Elevation Angle |10 |50 |88 |
|Sub-reflector Position |-.022 |-0- |+.031 |
|change from nominal (in)| | | |




|ITEM |SPECIFICATI|Pass|
| |ON |or |
| | |Fail|
| | | |
|Sub-reflector angular alignment change |˜ .05 deg |Pass|
|measurement | | |
|Throughout elevation range of motion | | |

Results-

|Elevation Angle |10 |50 |88 |
|Angular change from |-.013deg |-0- |+.042deg |
|nominal (deg) | | | |
5


6

Feed System Measurement -

|ITEM |SPECIFICATI|Pass|
| |ON |or |
| | |Fail|
| | | |
|Feed Horn phase center position to |˜ .080in |Pass|
|Best-Fit Paraboloid at nominal 50deg | | |
|Elevation position | | |

Results-

| |X |Y |Z |angle |
|Theoretical Position|0 |0 |145.21in|NA |
|of Feed Phase Center| | | | |
|Measured Position of|.013 |-.071 |* |NA |
|Feed Phase Center | | | | |




|ITEM |SPECIFICATI|Pass|
| |ON |or |
| | |Fail|
| | | |
|Feed position change measurement |˜ +/- |Pass|
|throughout elevation range of motion |.100in | |


Results-

|Elevation Angle |10 |50 |88 |
|Feed Position change |+.01 |-0- |+.094 |
|from nominal (in) | | | |




7


8 SUMMARY OF SUB-REFLECTOR/FEED POSITION AND ALIGNMENT MEASUREMENT





Test Date:

Start Time:

End Time:

Weather Conditions during Test:

Comments:





By- __ ________________ Date- ______________