beautypg.com

3 pin 3 – direction f/r sensor, 4 pin 4 – reserved, 5 pin 5 – speed pulses – Navman LA000507 User Manual

Page 15: 6 pin 6 – ground, 0 acronyms used in this document, Table 5-1 gyro input specifications

background image

15

LA000510C © 2006 Navman NZ Ltd. All rights reserved. Proprietary information and specifications subject to change without notice.

The gyro should be mounted so that its sensitive axis is as near vertical as practical. Deviations

from the vertical will reduce sensitivity for heading changes in the horizontal direction.

Experiments have shown that acceptable performance can be achieved with mounting

deviations of several degrees, but a better performance is achieved when the gyro is mounted

closer to vertical.

Characteristics

Symbol

Condition

Minimum Standard Maximum

Unit

Supply voltage

Vcc

+4.5

+5.0

+5.5

VDC

Max. angular velocity

ω max

–80

+80

deg/s

Output

Vo

angular velocity = 0 at –30

~ 80°C

2.200

2.500

2.800

VDC

Scale factor

Sv

at –30 ~ 80°C

19.3

22.2

25.1

mV/deg/s

Asymmetry CW & CCW

3

deg/s

Temp coefficient scale

factor

reference temp:

–30 ~ 80°C

±10

%FS

Temp coefficient drift

reference temp:

–30 ~ 80°C

9

deg/s

Noise level

7kHz noise

20

mVrms

Linearity

in the maximum angular

velocity range

0.5

%FS

Operating temp range

Topr

–40

85

°C

Table 5-1 Gyro input specifications

5.1.3 Pin 3 – Direction F/R sensor

Input from a signal that is normally at +0 V, but rises to +3 V when the vehicle is in the reverse

gear. Use of this signal is optional; if it is not used, the effect of occasional reversing by the

vehicle will not significantly degrade navigation performance. To ensure minimum current under

backup power, be sure that this input is not pulled up external to the board.

If this signal is not connected, switch SW3.2 should be left on, with DIP switch 2 also on to

select ‘forward’.

5.1.4 Pin 4 – Reserved
5.1.5 Pin 5 – Speed pulses

The input to this pin is a pulse train generated in the vehicle. If this signal is derived from the

vehicle’s electrical system, external level shifting for this signal is required. The pulse frequency

is proportional to the vehicle velocity. These pulses, or wheel ticks, are generated in most

vehicles by the ABS (Anti-lock Braking System), the transmission, or the drive shaft. System

design must restrict the pulses between 0 and 3 V.

Detection limits are as follows:

• Minimum detectable rate: 1 Hz
• Maximum detectable rate: 4 kHz

5.1.6 Pin 6 – Ground

6.0 Acronyms used in this document

1PPS: One Pulse Per Second
DGPS: Differential Global Positioning System
GPIO: General Purpose Input Output
GPS: Global Positioning System
NMEA: National Marine Electronics Association
RTC: Real Time Clock
RTCM: Radio Technical Commission for Maritime services