Chapter 3
Theory of Operation
Trimble S, VX, SPS & RTS Service Manual3 - 70 P/N 57150002, Revision 5.0
F
Fig. 3-63 TPB board block diagram
The TPB board generates and transmits the laser pulse, also generates two measurement pulses to
PRB for measuring of the reference- and target pulses, conducts coarse distance measurement.
Specific constants
The TCXO ppm offset and a transmitter control constant are individual measured constants linked to
the TPB board. The receiver and system constants are also measured. These variables are stored in
the flash memory on the TPB board.
PRB - Receiver board
The PRB board includes the following functions:
• Receiver diode (APD)
• Measuring of received signal
• Reference fibre
• Comparator for coarse measurement mode
Coarse
measurement
Measurement
pulse 1
Measurement
pulse 2
Transmitter unit
incl. TX diode
VCXO1
VCXO2
TCXO
Controller
PRB
PRB
Coax cable
Coax cable
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