Index
tilt_meter [on=false|true, limit=?]
Specify how and if the azimuth tilt meters are to be used.
- Mandatory Arguments:
- (none)
- Optional Arguments:
-
Boolean on
- If this argument is
true
, then the azimuth tilt
meter readouts will be used to correct the pointing. If it is
false
then they will be ignored.
Double limit
- If the magnitude of either tilt meter readout is greater
than the magnitude of this number, then the tilt correction
won't be made and the overflow condition will be recorded in
the tracker.corflags register.
Example 1:
The following example enables the use of the tilt meters in the
pointing model, and specifies that if either of the tilt meter
outputs is outside of the range -100..100 arcseconds, this will
be considered an error.
tilt_meter on=true, limit=0:1:40
Example 2:
The following example stops the tilt meter from being used in the
pointing model.
tilt_meter on=false
Context:
In addition to a fixed misalignment of the azimuth axis, the
azimuth axis also tilts by varying amounts as the ground beneath
the telescope shifts and as the load on the front of the azimuth
platform changes with elevation. The former fixed tilt is
corrected by a constant term in the pointing model, whereas the
varying tilt is computed from on-line measurements of tilt meters
located on the azimuth platform. This command enables or disables
the use of the tilt meters to correct for the variable tilt.
To prevent a broken tilt meter from sending the telescope all over
the sky, a readout limit is required.
Note that the tilt meter is disabled and has a limit of zero
degrees when the system starts. An example of a suitable limit
would be about 100 arcseconds. The appropriate limit could be set
in the reboot file
(see load_reboot_script).
Martin Shepherd (6-Jul-2000)