GlobalSat ET-318 User Guide

ET-318

Version 2.0

GPS Engine Board ET-318

Version 2.0

07/19/2007

Globalsat Technology Corporation Headquarters (Far East Century Park)

16F., No. 186, Jian-Yi Road, Chung-Ho City, Taipei Hsien 235, Taiwan

Tel: [phone]/ Fax: [phone]

E-mail : [e-mail]

Website: www.globalsat.com.tw

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ET-318

Version 2.0

1. Product Information

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Product Name: ET-318

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Product Description:

ET-318 is a compact, high performance, and low power consumption GPS engine board. It uses SiRF

Star III chipset which can track up to 20 satellites at a time and perform fast TTFF in weak signal

environments. ET-318 is suitable for the following applications:

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Automotive navigation

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Personal positioning

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Fleet management

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Mobile phone navigation

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Marine navigation

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Product Features:

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SiRF star III high performance GPS Chipset

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Very high sensitivity (Tracking Sensitivity: -159 dBm)

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Extremely fast TTFF (Time To First Fix) at low signal level

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Two serial ports

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Built-in LNA

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Compact size (15.2mm * 14 mm * 2.6mm) suitable for space-sensitive application

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One size component, easy to mount on another PCB board

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Support NMEA 0183 and SiRF binary protocol

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Product Specifications

GPS Receiver

Chipset

Frequency L1, 1575.42 MHz

Code C/A Code

Protocol NMEA 0183 v2.2

SiRF GSC3f/LP

Default:GGA,GSA,GSV,RMC

Support:VTG,GLL,ZDA)

SiRF binary and NMEA Command

Available Baud Rate 4,800 to 57,600 bps adjustable

Channels 20

The Specifications are subject to be changed without notice. Copyright © 2007, GlobalSat Technology.

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Flash 4Mbit

Sensitivity Tracking:-159dBm

Cold Start 42 seconds, average

Warm Start 38 seconds, average

Hot Start 1 second, average

Reacquisition 0.1 second, average

Accuracy Position: 10 meters, 2D RMS

Velocity: 0.1 m/s

Time: 1us synchronized to GPS time

ET-318

5 meters, 2D RMS, WAAS enabled

Version 2.0

Maximum Altitude

Maximum Velocity

Maximum Acceleration

Update Rate 1 Hz

DGPS WAAS, EGNOS, MSAS

Datum WGS-84

I/O Pins 2 serial ports

Type 17-pin stamp holes

Dimensions 15.2 mm * 14 mm * 2.6 mm

Power Supply

Backup Voltage

Power Consumption

＜ 18,000 meter

＜ 515 meter/second

＜ 4G

Interface

Physical Characteristic

DC Characteristics

3.3Vdc ± 5%

2.0 ~ 3.6Vdc ± 10%

Acquisition: 42mA
Tracking: 25mA

Environmental Range

Humidity Range 5% to 95% non-condensing

Operation Temperature

Storage Temperature

-40℃ to 85℃

-40℃ to 125℃

The Specifications are subject to be changed without notice. Copyright © 2007, GlobalSat Technology.

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ET-318

Version 2.0

2. Technical Information

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Block Diagram

The Specifications are subject to be changed without notice. Copyright © 2007, GlobalSat Technology.

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Module Pin Assignment:

ET-318

Version 2.0

Pin

1 GND G Analog Ground

2 RF_IN RF GPS Signal input

3 GND G Analog Ground

4 NRESET I Reset (Active low)

5 VCC_IN PWR DC Supply Voltage input

6 VBAT PWR Backup voltage supply

7 RXB I Serial port B

8 TXB O Serial port B

9 GND G Analog Ground

10 BOOTSEL Boot mode

11 TXA O Serial port A

12 RXA I Serial port A

13 GPIO1 I General –purpose I/O

14 GPIO14 I General –purpose I/O

15 TIMEMARK O One pulse per second

16 GPIO13 I General –purpose I/O

17 GPIO15 I General –purpose I/O

Signal Name

I/O

Description

The Specifications are subject to be changed without notice. Copyright © 2007, GlobalSat Technology.

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Definition of Pin assignment

ET-318

Version 2.0

VCC_IN

This is the main DC supply for a 3.3V +- 5% DC input power module board.

GND

GND provides the ground for digital part.

BOOTSEL

Set this pin to high for programming flash.

RXA

This is the main receiver channel and is used to receive software commands to the board from
SIRFdemo software or from user written software.
PS: Pull up if not used.

RXB

This is the auxiliary receiving channel and is used to input differential corrections to the board to
enable DGPS navigation.
PS: Pull up if not used.

TXA

This is the main transmitting channel and is used to output navigation and measurement data to
SiRFdemo or user written software.

TXB

For user’s application (not currently used).

RF_IN

This pin receiver signal of GPS analog .due to the RF characteristics of the signal the design has to
certain criteria. The line on the PCB from the antenna(or antenna connector) has to be a controlled
microstrip line at 50Ω.

Backup battery (V_BAT)

This is the battery backup input that powers the SRAM and RTC when main power is removed.
Typical current draw is 15uA. Without an external backup battery, the module/engine board will
execute a cold star after every turn on. To achieve the faster start-up offered by a hot or warm start,
a battery backup must be connected. The battery voltage should be between 2.0v and 5.0v.

TIMEMARK

This pin provides one pulse-per-second output from the board, which is synchronized to GPS time.
This is not available in Trickle Power mode.

GPIO Functions

Several I/Os are connected to the digital interface connector for custom applications.

The Specifications are subject to be changed without notice. Copyright © 2007, GlobalSat Technology.

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Application Circuit

ET-318

Version 2.0

GPS Active Antenna Specification(Recommendation)

Frequency: 1575.42+2 MHz

Axial Ratio: 3 dB Typical

output Impedance: 50Ω

Polarization: RHCP

Amplifier Gain :18~22dB Typical

Output VSWR: 2.0 Max.

Noise Figure: 2.0 dB Max

The Specifications are subject to be changed without notice. Copyright © 2007, GlobalSat Technology.

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Dimensions

ET-318

Version 2.0

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Recommend Layout PAD

The Specifications are subject to be changed without notice. Copyright © 2007, GlobalSat Technology.

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