Zodiac Aerospace GPS, Руководство пользователя, Страница: 14 / 36

10 GPS — User’s Manual
Data Acquisition
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Once the desired parameter selected, the user can choose the different following options:
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Refresh Mode
Defines the method to output the parameter from GPS module.
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Synchronous: Parameter is sent periodically with a rate of 1Hz.
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Asynchronous: Parameter is sent after its extraction in the corresponding NMEA frame
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Endianess
Describes the order of byte transmission over a digital link.
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Big Endian: The most significant byte is send first. (Most common format).
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Little Endian: The least significant byte is sent first.
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Base (only for Date, Time and Date & Time predefined parameters)
Describe the data format.
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Binary format
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BCD format
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Date&Time format (only for Date & Time predefined parameter)
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XMA
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GPS
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IRIG-106 Chapter 4
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Length (for information)
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Date & Time predefined parameter:
- XMA: 48 bits
- GPS: 64 bits
- IRIG-106 Chapter 4: 64 bits
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Other predefined parameters: 32 bits
VDOP [15:8] integer part [0;99]
[7:0] decimal part [0;9]
HDOP [15:8] integer part [0;99]
[7:0] decimal part [0;9]
#Sat used [7:0] # satellite [0;32]
#Sat viewed [7:0] # satellite [0;32]
ValidFix [7:0] state 1=no fix / 2=2D / 3=3D
Height of geoid [31:16] integer part [0;9999]m
[15:0] decimal part [0;99]
1. The output format of DATE and TIME parameters can be considered via a single DATE&TIME parameter
based on the IRIG-106 Chap.4 (48 bits) format or on the XMA (48 bits) format - conversion from data fields
DATA and UTC TIME extracted from the NMEA frame.
Each parameter correspond to a 32-bit word (except dor Date&Time)
Note:
This parameter has impact over the compatibility with output data streams.
For more details, refer to the Output Data Stream Chapter of RD3 .
Parameter name Bits field Parameter description