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Aug 5th, 2009 at 11:15am
I'm not sure quite what you mean by auto-pointing antenna. Maybe one that finds the satellite and peaks up at the initial installation. After that the VSAT remains fixed pointing. Such antennas might be able to re-peak themselves by manual intervention.
VSATs do not need auto-tracking unless they are operating to inclined orbit satellites.
If your remote sites are mobile, the antennas need to have real-time auto-tracking to respond to rapid angular changes due to vehicle or boat movement. Such antennas typically have a mechanically spinning, monopulse, or electronic beam squint feed that provides real time pointing error information to the tracking controller which then drives the motors in a "tracking servo control loop".
If your site is a very large teleport size antenna or you are working with inclined orbit satellites then you need auto-track, but in this case slow periodic step track is sufficient. The time interval between peaking up may vary, typically several minutes. Over a day or so, the tracking computer learns the orbit and then peaks up the dish only when needed, which saves wear on the motors and gear boxes. If a large teleport tracking system goes wrong it may lose the satellite from time to time or peak up on a sidelobe. In dire fault cases the operators may have to manually repeak the antenna every 15 min or so, or as and when the signal drops too far.
"If you see this problem", I would suggest you investigate the real cause of the problem rather than suggesting people change from auto-pointing to autotracking hardware. Autotracking is expensive and only necessary for very large teleport dishes, mobile VSATs and VSATs operating to inclined orbit satellites. Investigate properly first and find the real cause. The problem might simply be periodic interference!
Best regards, Eric.
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