Implications for the Construction of a Track Model

• Method
  
  The data obtained so far show that Point-Wise data has the greatest accuracy and repeatability and we must adopt this method for obtaining the data with which to form the track model. The Continuous data may be obtained very rapidly, but is too noisy to be used to create the model. However, it is very useful for rapid confirmation, or otherwise, of the validity of the current track model.

• Resolution
  
  The old track model, and the current model created with the new system, have azimuth resolutions of 1degree, but it is clear that 0.2degree resolution is needed to fully describe the worst of the track joints. The time required to obtain such data is now no longer prohibitive (12 hours). Taking data with mixed resolutions is too problematic to be considered at this stage.

• New Revelations
  
  Our old thinking held that the A-frames were essentially independent. The new data suggest that we might have to incorporate the connectedness of the A-frames into the theory that helps convert inclinometry data from the A-frames to motion of the elevation axis.
  
  For instance, we have until now assumed that pure geometry can be used in determining the yaw of the elevation axis from the Y-axis data of the A-frame inclinometers. To confirm this it was considered prudent to calculate roll from the same data and compare it with the measured roll from the TMU (X-axis). However, if, as seems possible, the TMU roll is just the same as the A-frame roll (a quantity not considered previously, or, at best, dismissed as having zero size) then there is apparently no additional roll generated by A-frame rocking. The conversion factors from A-frame rocking to elevation axis roll would then apparently be zero, implying that the yaw expected to result from A-frame rocking would also be zero.
  
  The conclusions regarding the relationship between A-frame rocking and yaw are sensitive to the adopted calibration scales, which are to be redetermined as soon as possible.
  
  The single observation that the (L) A-frame also sways when the antenna is slewed in elevation is a cause of some concern and needs confirming. It may be related to the observations that the A-frame bottom beams roll, even during antenna rotation at the same elevation. If true, it could imply elevation-dependent terms in the track model, which will make any track model impossibly complex. The same is true if the small (1") systematic errors seen in the data taken at 45degree prove repeatable. There is much still to be done to get a complete picture of the antenna's behaviour.

• Location of Inclinometers
  
  As a result of all the above problems it is still not clear where the optimal locations are for the inclinometers. Further experimentation is to be performed and undoubtedly new revelations will be added to the above list that will influence the final decision.