RESEARCH CONCEPTS RC2000A DUAL AXIS Instructions Manual page 77

RC2000A Dual Axis Antenna Controller
- - - - - - - -
0 1 0 0
0 0 1 0
0 1 1 1
0 0 1 1
s s s s
The definition of the ssss bits is dependent on the type of polarization control device. For No
Polarization Control device these bits will be zeroes. These bits will also be zeroes if a
Polarotor or rotating feed control device is present and the polarization position is at or beyond
a limit.
If a polarization control device is present and the polarization position is not at or beyond a limit
the usage of these bits are as defined below ...
For the POLAROTOR, the polarization position value reported via the user interface and the
comm port (bytes 24 and 25 of the device status pol command reply) is a value in the range of 0
to 98, 'CW' (for clockwise limit) or 'CC' (for counter clockwise limit). The controller's internal
polarization position representation, however, is a value in the range of 0 to 661. An internal
position of 0 corresponds to the CW limit and an internal position of 661 corresponds to the CC
limit. Internal position values in range of 1 to 660 are scaled to display as a value of 0 to 98 on
both the user interface and via bytes 24 and 25 of the device status poll reply. To obtain the
internal position from this byte and bytes 24 and 25, use the following formula ...
internal_position = ((byte_24_25_position * 661) / 99) + ls_nibble_byte_32
where ...
internal_position ... is the controller's internal polarotor position representation.
byte_24_25_position ... is the polarotor position reported via byte 24 and 25 of the
device status poll reply and displayed on the user interface (a value in the range of 0 to
98).
ls_nibble_byte_32 ... is the least significant nibble (lower 4 bits) of this byte.
Note that in the above equation the division is an integer division which means that the result of
the division should be rounded DOWN to the closest integer value (i.e. (39 * 661) / 99 = 260).
For the ROTATING FEED, the internal polarization position and the polarization position
displayed via the user interface are the same and will be a value in the range of 0 to 1023. For
the rotating feed the user is prompted to set CW and CC limits. When the polarization position
is less than or equal to the CW limit specified by the user the 'CW' banner will be displayed.
When the polarization position is greater than or equal to the CC limit specified by the user, the
CC banner will be displayed.
The polarization position given by bytes 24 and 25 of the device status poll reply will be a value
in the range of 0 to 92. When the rotating feed is at a limit (or beyond) the byte 24,25 values
will be 'CW' or 'CC'. To obtain the internal polarization position for the rotating feed from this
byte and the value in bytes 24 and 25, use the following formula ...
internal_position = (byte_24_25_position * 11) + ls_nibble_byte_32
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Appendix E
No polarization control device is present in
this system.
The system is configured for a Polarotor type
polarization control device.
A single port rotating feed device is present
is this system.
A two port rotating feed is present in this
system.
The usage of these bits is dependent on the type of
polarization control device present in the system as described
in the next section.
Communications Protocol
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