Inclinometer Temperatures

The table below shows temperatures recorded during the 1998 inclinometry runs to date. Recall that the probes are located in quite different environments :

• T_amb is recorded near the front of the apron, but shielded from direct insolation,
• T_leg is the mean temperature of the 8 probes buried in the surface of the antenna legs, 2 to each leg, one in the lower segment, one in the upper,
• TT is in the receiver cabin,
• LT, and usually RT, are under cardboard boxes on the A-frames in the plinth well, although,
• since March, RT is the 4th inclinometer mounted in the open on a radial arm, but still in the plinth area.

   date       HST      T_amb     T_leg      TT      LT      RT   
             hh:mm       deg      deg      ---- millivolts --- 

  980124     12:30      14.6      8.4      147     110     116  
             14:00      13.8      9.6      160     116     122
             15:30      12.2     10.4      169     124     123
             `````      ````     ````      ```     ```     ```
             range      -2.4      2.0       22      14       7
             `````````````````````````````````````````````````
  980222     10:45       4.6      1.8       95      87      83
             12:15       6.2      2.6      101      90      88
             13:45       6.4      3.6      107      93      89
             `````      ````     ````      ```     ```     ```
             range       1.8      1.8       12       6       6
             `````````````````````````````````````````````````
  980224     02:40       0.6      0.7       99      82      80
             04:10       0.8      0.4       82      80      80
             05:40       1.2      0.1       76      77      76
             `````      ````     ````      ```     ```     ```
             range       0.6     -0.6      -13      -5      -4
             `````````````````````````````````````````````````
  980301     10:00       5.3      1.2       97      86      79
             11:30       6.0      2.5      102      86      86
             13:00       6.4      3.6      111      92      91
             `````      ````     ````      ```     ```     ```
             range       1.1      2.4       14       6      11
             `````````````````````````````````````````````````
  980314     11:20       6.5      3.6      109      94      95
             12:50       8.1      5.0      118     100     102
             14:20       9.0      6.1      129     106     106
             `````      ````     ````      ```     ```     ```
             range       2.5      2.5       20      22      21
             `````````````````````````````````````````````````
  980322     11:00       5.9     -0.5       71      50      55
             12:30       5.4      0.5       76      54      60
             14:00       4.5      1.5       84      60      66
             `````      ````     ````      ```     ```     ```
             range      -1.4      2.0       13      10      11
             `````````````````````````````````````````````````
  980405     13:30       5.5      5.6      120      78      80
             15:00       5.9      6.4      128      83      86
             16:30       6.7      7.0      136      86      85
             `````      ````     ````      ```     ```     ```
             range       1.2      1.4       16       8       5
             `````````````````````````````````````````````````

The voltages should probably be divided by 10 to give degrees Centigrade.

Given the diversity of environment, the table shows understandable relationships between the voltages recorded from the temperature channels of the inclinometers, and, for instance, mean leg temperatures and ambient temperatures recorded by the antenna and building systems. There is often not a huge variation in temperature in the 3 hours needed to collect inclinometry data, so often the various data channels are not in perfect agreement, but when the range of reading is large (say, 2 degrees) the agreement is noticeable.

The manufacturer suggests deriving absolute inclinometer temperatures by dividing the voltages by 10; it seems that this provides acceptable temperature estimates for the inclinometers.