DRS CENSE User Manual

DRS CENSE User Guide

DRS CENSE is a simple GPS device that displays your
current position to better than 5 metres accuracy. This
can be transcribed quickly and easily onto any form for later data capture.

Getting started

Unpack the device carefully, and if required attach the supplied lanyard by
slipping the loop through the slot in the top right corner, and then passing it
through to secure it.

Fit three AAA batteries by opening the flap at the back. If rechargeable
batteries are used these must be 1.5v. Ensure that the positive (+) terminals
are correctly aligned with the markings. The device will start up – if it not to be
used immediately, switch it off to save power. A set of high quality alkaline

batteries will last for approximately 15 hours of continuous use; since the
device is not designed to operate indoors, remember to switch it off when it

is not needed to save power! DRS CENSE will turn off automatically after 5
minutes if the GPS signal is lost, but may for instance continue to operate if
left on a car dashboard.

To switch on, press the power button. To switch off hold the power button
until the display goes blank.

The DRS CENSE display

1

Satellite tracking
indicator

Flashes until satellites have been located, or if satellite data
is being downloaded

2

Fix precision
indicator

Shows approximate precision of fix:

0 bars – very poor – accurate within 50 metres
1 bar – poor – accurate within 20 metres
2 bars – fair – accurate within 15 metres
3 bars – good – accurate within 10 metres
4 bars – excellent – accurate within 5 metres

3

Battery level

15 hours maximum – each segment shows about 3 hours

4

Latitude

Decimal degrees North or South of the equator

5

Longitude

Decimal degrees East or West of the meridian

Note that the display may be difficult to see through polarised sunglasses!

1 2 3 4 5

COLD and WARM start

COLD START When the batteries are first inserted and the device activated

outdoors, it will seek out satellites and download information. This “Time To

First Fix” will typically take up to 5 minutes, but can take considerably longer

(possibly up to 30 minutes) in poor conditions. Note that if the device is
unused for several months a cold start may be required even if the batteries
are left in.

WARM START This will usually take 2 seconds in an optimum clear sky. New

satellite data is downloaded on an incremental basis.

Conditions and accuracy

The accuracy of the device will depend on the conditions in which it is

operating. “Good conditions” means that the device can “see” most of the sky,

and satellites are positioned for optimal triangulation.
Accuracy can be affected by buildings or trees which can block satellite

signals, but is not affected by weather conditions or cloud cover.
DRS CENSE uses a cutting edge GPS chip, the Fastrax UP500. The key

GPS receiver specifications are:

General:

L1 frequency, C/A code (SPS)

14 independent tracking channels

Update rate:

1 fix/s (user configurable, up to 5 fix/s

Accuracy:

Position:

1.8m (CEP95)

Sensitivity:

Acquisition (cold):

-146dBm

Navigation:

-159dBm

Tracking:

-159dBm

Protocol:

NMEA 0183, 9600 baud

Chip set:

MediaTek MT3318

DRS CENSE specifications

Accuracy:

Better than 5 metres

Battery life:

15 hours continuous with supplied high quality alkaline batteries

Weight:

115g

Dimensions:

87 x 70 x 26mm

Operating temp:

0 to +40C

Display update:

1Hz (once a second)

Storage temp:

-10 to +40C

Cold start:

Typically <5 minutes depending on conditions

Warm start:

Usually 2 seconds in an optimum clear sky

Environmental:

Splash proof

Colour:

White

DRS CENSE is subject to continuous improvement leading to changes in this specification

DRS Data Services Limited, 1 Danbury Way, Linford Wood, Milton Keynes MK14 6LR, England

Tel: [phone]
Fax: [phone]

[e-mail]

www.drs.co.uk