Motec M GPS BL User Manual

MoTeC USA GPS

Part # M GPS BL
Available in 10 Hz or 20 Hz.

USER MANUAL Version 1.4

MoTeC USA GPS

 Copyright – Motec Systems USA – 2008

The information in this document is subject to change without notice.

While every effort is taken to ensure correctness, no responsibility will be taken for the consequences

of any inaccuracies or omissions in this manual.

15 August, 2008

MoTeC USA GPS 2

Contents

Introduction.........................................................3

Warm Up Time ............................................................................ 3

Status LEDs ................................................................................ 4

20 Hz Update Option................................................................... 4

RS-232 Serial Output .................................................................. 4

Speed Output Pulse .................................................................... 5

Speed Ready Output................................................................... 5

Variable Voltage Option .............................................................. 5

Installation...........................................................6

GPS Receiver ............................................................................. 6

Antenna....................................................................................... 6

Loss of Signal.............................................................................. 7

Connection .................................................................................. 7

Connection to ADL2 / SDL / ACL ................................................ 8

Connection to M400 / M600 / M800 ............................................ 9

Connection to ADL ...................................................................... 9

“i2” Analysis Math............................................10

Appendix ...........................................................12

GPS Engine Specifications ....................................................... 12

Power Supply ............................................................................ 12

Operating Temperature............................................................. 12

Physical..................................................................................... 13

Connection ................................................................................13

MoTeC USA GPS 3

Introduction

Thank you for purchasing a MoTeC USA GPS receiver. This user’s
guide was written to help you understand how the MoTeC USA GPS
(Global Positioning System) device works. Please read it thoroughly.
Installation is very important, and understanding how GPS works will
help you get the most from this sensor.

The GPS device uses an
antenna on top of the vehicle to
track satellites in orbit around
earth. It takes a minimum of
three satellites to identify your
position on earth, and a fourth to
calculate accurate timing.
Satellites are constantly moving, and a satellite which the antenna sees
at the start of the race might not be visible 60 minutes later. Satellites
used in the GPS solution are dynamically added or dropped based on
signal quality. Ideally you should have 8 or more satellites being
tracked in order to get good results. Anything under 6 satellites is poor.
With more satellites, there is more information to correctly identify your
position with less error. So it’s easy to see the importance of your
antenna having a clear line of sight to the satellites in the sky.

The system is a 12 channel receiver, but two of the tracked
satellites are special geostationary SBAS which provide DGPS
(differential GPS) via WAAS correction. Therefore the maximum
reported satellites in the data will be 10. Differential GPS uses those
additional satellites to more accurately calculate your position.
Positional accuracy goes from 3 meters to under 1 meter with
Differential GPS.

Warm Up Time

When the GPS receiver is first powered, it will start searching for
satellites to lock onto. This process takes time. It will take longer the
first time you power up at a new location from where you had previously
turned it off. Normal “cold” start up times, meaning being in a new area
from the previous location, can be anywhere from 2 to 10 minutes.
Subsequent “warm” start up times at the same location normally takes
30 seconds to 2 minutes. If you are outside of North American, expect
the very first time to take up to 30 minutes.

MoTeC USA GPS 4

Status LEDs

There are 4 LEDs on the front face of the unit
labeled as follows:

• POWER (red): Unit has power.

• GPS (yellow): GPS signals have been

acquired and calculated data is being
sent out.

• DIFF (yellow): SBAS differential satellite available.

• DGPS (green): Differential corrections are active, resulting in

improved data. This is the light you really want to see on.

There are only two required lights for operation, one is POWER and the
other GPS. The DIFF and DGPS lights indicate increased accuracy of
the data. With differential correction, you will get the most accurate
data. Therefore best operation is achieved with these lights on.

20 Hz Update Option

This option allows the following four channels to update at a true
20 Hz rate:

• GPS Latitude

• GPS Longitude

• GPS Speed

• GPS Heading

It’s best to buy this option at the time of purchase. If you buy it
afterwards, the unit must be sent to MoTeC for updating.

RS-232 Serial Output

Standard NMEA-0183 message strings GPGGA and GPRMC are
sent out by default at a baud rate of 57,600. The baud rate and type of
messages can be changed by sending the unit back to MoTeC.