[evlatests] Band Change Times

[Rick Perley]

     One of the benefits of the band switch test is a good idea of how 
long it takes to change band (without changing source).  I used the 
system flags to determine this, for each of the 28 band pair 
combinations (not including 4-P band).   The times given below are the 
typical *maximum* duration of flagged data.  Since there was no antenna 
motion in this test, the times reflect how long it takes the 
subreflectors to move (rotate and focus) between the band pairs.

     Below the 'move matrix', with durations in seconds

      L     S     C     X     U     K     A     Q

L    x  21    24   23    25   25   25    25

S          x    18   16    17   16   17   17

C                 x    12    14    17  18   16

X                         x    16   18   16   16

U                                 x   10   12   11

K                                        x   11   10

A                                              x    10

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     It is clear from this that the dominating factor for L and S bands 
is the focus movement, rather than the subreflector rotation.

     For all combinations, there is a fairly wide range of times, 
depending on the antennas.  For the Ku/K/Ka/Q band combinations, many 
antennas complete the movement in 4 seconds or even less. This again 
must reflect the range of focus positions.