Appendix

Appendix

Positioning technology

pulse. So you connect the speed pulse without

Positioning by GPS

fail to get the accuracy of positioning.

p The position of the speed detection circuit

The Global Positioning System (GPS) uses a

vary depending on the vehicle model. For

network of satellites orbiting the Earth. Each

details, consult your authorized Pioneer

of the satellites, which orbit at a height of

dealer or an installation professional.

21 000 km, continually broadcasts radio sig-

p Some types of vehicles may not output a

nals giving time and position information. This

speed signal while driving at just a few kilo-

ensures that signals from at least three can be

meters per hour. In such a case, the current

picked up from any open area on the earth’s

location of your vehicle may not be dis-

surface.

played correctly while in traffic congestion

The accuracy of the GPS information depends

or in a parking lot.

on how good the reception is. When the sig-

 

nals are strong and reception is good, GPS

How do GPS and dead

can determine latitude, longitude and altitude

reckoning work together?

for accurate positioning in three dimensions.

But if signal quality is poor, only two dimen-

For maximum accuracy, your navigation sys-

sions, latitude and longitude, can be obtained

tem continually compares GPS data with your

and positioning errors are somewhat greater.

estimated position as calculated from the data

 

 

 

of built-in sensor. However, if only the data

 

 

 

from the built-in sensor is available for a long

 

 

 

period, positioning errors are gradually com-

 

 

 

pounded until the estimated position becomes

 

 

 

unreliable. For this reason, whenever GPS sig-

 

 

 

nals are available, they are matched with the

 

 

 

data of the built-in sensor and used to correct

 

 

 

it for improved accuracy.

 

 

 

p If you use chains on your wheels for winter

 

 

 

driving or put on the spare wheel, errors

 

 

 

may suddenly increase because of differ-

 

 

 

ence in wheel diameter. Initialize the sensor

Positioning by dead reckoning

status and it may recover the accuracy to

The built-in sensor in the navigation system

normal condition.

= For details, refer to Clearing status on

also calculates your position. The current loca-

page 149.

tion is measured by detecting driving distance

 

with the speed pulse, the turning direction

 

with the gyro sensor and inclination of the

 

road with the G sensor.

 

The built-in sensor can even calculate

 

changes of altitude, and correct the discrepan-

 

cies in the distance traveled caused by driving

 

along winding roads or up slopes.

 

If you use this navigation system with connect-

 

ing the speed pulse, the system will become

 

more accurate than no connection of speed

 

198 En