TeeJet RX375P Receiver - Manual (Page 9)

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98-05327-ENUS R0
RX375P
Table 5: Serial Port Settings
Serial Port Baud Rate Data Bits Parity Stop Bits
Interface
Level
Serial Port
A and B
4800* 8 None 1 R2-232C
9600 8 None 1 R2-232C
19200** 8 None 1 R2-232C
38400 8 None 1 R2-232C
57600 8 None 1 R2-232C
115200 8 None 1 R2-232C
*Serial Port A default setting
**Serial Port B default setting
Table 6: GPS Message Output Options
GPS Message Update Rate Elavation Mask
GPS Binary From 1 Hz to 20 Hz 5°
NMEA 0183 From 1 Hz to 20 Hz 5°
NMEA 2000 (CAN) From 1 Hz to 20 Hz 5°
The CAN port will automatically output the NMEA 2000 messages.
Custom Configuration
All aspects of the RX375P may be configured through the serial port
with the use of GPS commands. The user can configure the following
items:
• Selecting one of the two on-board applications
• Selecting the baud rate
• Choosing which NMEA 0183 data message to output on the dual
serial ports and the update rate of each message
NOTE: The changes made to the RX375P will not be saved to memory
for subsequent power-up unless a save command is issued.
NOTE: Contact your local TeeJet Technologies dealer for information
regarding the use of GPS commands to customize
configuration.
Environmental Considerations
The RX375P is designed to withstand various outdoor environments.
However, there are specific environmental limits that should be met
when using the RX375P. Refer to Appendix B for additional information.
ChapteR 3 gps oVeRVIew
For operator convenience, both the GPS and differential correction of
the RX375P are pre-configured. The receiver will work out of the box,
and for most applications, little user setup is required. When powered
for the first time, the RX375P will perform a “cold start” which involves
acquiring the available GPS satellites in view and the SBAS differential
service.
gps opeRatIon
The GPS engine is always operating, regardless of the DGPS mode of
operation. The following sections describe the general operation of the
RX375P’s internal GPS engine.
Automatic Tracking
The GPS engine within the RX375P automatically searches for GPS
satellites, acquires the signals, and manages the navigation information
required for positioning and tracking. This is a hands-free mode of
operation.
Receiver Performance
The RX375P works by finding four or more GPS satellites in the visible
sky and uses the information those satellites provide to compute an
appropriate position (typically within 7-10 ft (2-3 m).) Since there is
some error in the GPS data calculations, the RX375P also tracks a
differential correction. The RX375P uses these corrections to improve
its position to less than 3 ft (1 m).
There are two main aspects of GPS receiver performance:
• Positioning
• Satellite acquisition quality
GPS is essentially a timing system. When the RX375P is properly
positioned on the vehicle, the satellites transmit coded information to
the antenna in a specific frequency that allows the receiver to calculate
a range to each satellite. The ranges are calculated by timing how long
it takes for the GPS signal to reach the GPS antenna.
The GPS receiver uses a complex algorithm incorporating satellite
locations and ranges to each satellite to calculate the geographic
location. Reception of any four or more of these signals allows a GPS
receiver to compute 3-dimensional coordinates.