SeaSpace TeraScan 1.5M, Operation And Maintenance Manual

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SeaSpace Corporation
Notes:
a. Only one command can be executed at a time. The reply must be received before the next command
can be issued.
b. The only command that will be correctly answered when the PCU is being initialized is the S or st
(status) command. All other commands will give a time-out.
6.3 S
EA
-G
OING
A
NTENNA
: H
OW
C
HANGES IN
S
HIPHEADING
A
FFECT THE
A
NTENNA
’
S
A
ZIMUTH
P
OSITION
For a sea-going antenna, NMEA shipheading describes the position of the antenna in relation to true north.
When the ship turns, the antenna turns in the opposite direction to keep the same pointing angle. During a pass,
the shipheading is updated in the antenna PCU every 0.5 second. When the pass is over, the shipheading is not
sent to the antenna. To avoid errors in antenna position, the antenna is placed in Satellite Reference Mode
(^0071) when the pass completes. When the pass starts, the antenna is placed in Gyro Reference Mode (^0000)
and Fast Mode (^0070). The power-up state of the sea-going antenna should be Satellite Reference Mode, which
can be set by sending
^0071 and NVRAM to the PCU with the ac command (see Section 7.2.4.4).