Tyco Electronics A1029, Руководство пользователя

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GPS Receivers A1029
Page 26 of 43 User’s Manual V3.2 - 02/06
6.2 Gyro and Gyro Signal
The gyro is of utmost importance for the performance of the DR system. The follow-
ing data shall provide a guideline for selecting the right gyro:
Basic gyro data
•
Supply voltage: 5V (more gyros available, also used in the example) or 3V
•
Current draw: < 20mA
•
Max. angular velocity: ± 80 deg./ s
•
Output at angular velocity 0: 1.5V (or 2.5V and according divider, as shown
in the example)
•
Resolution: ~ 0.1 deg/sec
•
Scale factor: ~ 25mV / deg / s (smaller values possible, e.g. 12.5mV / deg / s
at supply voltage 3V)
Important for system performance as well:
•
Temperature coefficient of scale factor: max. ± 10% at -30° to +80°C
•
Linearity: ± 0.5% full scale
•
Offset drift: e.g. Melexis MLX90609-N +/- 2.5 % of Zero Rate Output at 25°
(smaller values desirable)
•
Response: max. 10Hz
•
Noise level; max. 10mVp-p
In the example (also the DR1030A board), the Melexis MLX90609-N is used, a 5V
gyro with an output of 2.5V at 0°/s angular velocity. To allow the complete output
range to fit into the input range of the internal ADC, a 2:1 divider is used.
Figure 13: Connecting a gyro and the gyro signal based on the
Melexis MLX90609-N (recommended solution)