Garmin GPS35-LVC, GPS35-LVS, GPS35-HVS TECHNICAL SPECIFICATION

GPS 35 LP TracPak TM

GPS SMART ANTENNA

TECHNICAL SPECIFICATION

Models: GPS35-LVC GPS35-LVS GPS35-HVS

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GARMIN · 1200 E. 151st Street · Olathe, Kansas 66062 · (913) 397-8200 · (913) 397-8282 FAX

electronic or mechanical, including photocopying and recording, for any purpose without the express written permission of GARMIN.

Information in this document is subject to change without notice. GARMIN reserves the right to change or improve their products and to make changes in the content without obligation to notify any person or organization of such changes or improvements.

March, 2000 190-00148-00 Rev. E

CAUTION

The GPS system is operated by the government of the United States which is solely responsible for its accuracy and maintenance. Although the GPS 35LP is a precision electronic NAVigation AID (NAVAID), any NAVAID can be misused or misinterpreted, and therefore become unsafe. Use the GPS 35LP at your own risk. To reduce the risk, carefully review and understand all aspects of this Technical Manual before using the GPS 35LP. When in actual use, carefully compare indications from the GPS 35LP to all available navigation sources including the information from other NAVAIDs, visual sightings, charts, etc. For safety, always resolve any discrepancies before continuing navigation.

NOTE

This device has been tested and found to comply with the limits for a Class B digital device, pursuant to Part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation.

This device generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this device does cause harmful interference to radio or television reception, which can be determined by turning the device off and on, you are encouraged to try to correct the interference by one or more of the following measures:

· Reorient or relocate the receiving antenna.

· Increase the separation between this device and the receiver.

· Connect this device to an outlet on a different circuit than that to which the receiver is connected.

· Consult the dealer or an experienced radio/TV technician for help. This device contains no user-serviceable parts. Repairs should only be performed by an authorized

GARMIN service center. Unauthorized repairs or modifications to this device could void your warranty and your authority to operate this device under Part 15 regulations.

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TABLE OF CONTENTS

1. Introduction 1

1.1 Overview 1

1.2 Features 1

1.3 Naming Conventions 2

1.4 Technical Specifications 2

1.5 Application 4

2. Operational Characteristics 5

2.1 Self Test 5

2.2 Initialization 5

2.3 Navigation 5

2.4 Satellite Data Collection 6

3. Hardware Interface 8

3.1 Mechanical Dimensions 8

3.2 Mounting Configurations and Options 9

3.3 Connection Wiring Description 13

4. Software Interface 14

4.1 NMEA Received Sentences 14

4.2 NMEA Transmitted Sentences 18

4.3 Baud Rate Selection 23

4.4 One-Pulse-Per-Second Output 23

4.5 RTCM Received Data 23

A. Earth Datums 24 B. GPS 35LP Evaluation Kits 27 C. Phase Data Output 29

SECTION 1

INTRODUCTION

1.1 OVERVIEW

The GARMIN GPS 35LP is a complete GPS receiver, including an embedded antenna, designed for a broad spectrum of OEM (Original Equipment Manufacturer) system applications. Based on the proven technology found in other GARMIN 12 channel GPS receivers, the GPS 35LP will track up to 12 satellites at a time while providing fast time-to-first-fix, one second navigation updates and low power consumption. Its far reaching capability meets the sensitivity requirements of land navigation as well as the dynamics requirements of high performance aircraft.

The GPS 35LP design utilizes the latest technology and high level circuit integration to achieve superior performance while minimizing space and power requirements. All critical components of the system including the RF/IF receiver hardware and the digital baseband are designed and manufactured by GARMIN to ensure the quality and capability of the GPS 35LP. This hardware capability combined with software intelligence makes the GPS 35LP easy to integrate and use.

The GPS 35LP is designed to withstand rugged operating conditions and is completely water resistant. The GPS 35LP is a complete GPS receiver that requires minimal additional components be supplied by an OEM or system integrator. A minimum system must provide the GPS 35LP with a source of power and a clear view of the GPS satellites. The system may communicate with the GPS 35LP via a choice of two RS-232 compatible full duplex communication channels (-xVS series), or two full duplex CMOS channels (-xVC series). Internal memory backup allows the GPS 35LP to retain critical data such as satellite orbital parameters, last position, date and time. End user interfaces such as keyboards and displays are added by the application designer.

1.2 FEATURES

The GPS 35LP provides a host of features that make it easy to integrate and use.

1) Full navigation accuracy provided by Standard Positioning Service (SPS)

2) Compact design ideal for applications with minimal space

3) High performance receiver tracks up to 12 satellites while providing fast first fix and low power consumption

4) Differential capability utilizes real-time RTCM corrections producing 3-10 meter position accuracy

5) Internal clock and memory are sustained by a rechargeable memory backup battery. The battery recharges during normal operation.

6) User initialization is not required

7) Navigation mode (2D or 3D) may be configured by the user

8) Two communication channels and user selectable baud rates allow maximum interface capability and flexibility

9) Highly accurate one-pulse-per-second output for precise timing measurements. Pulse width is configurable in 20 msec increments from 20 msec to 980 msec.

10) Binary Format Phase Data Output on TXD2

11) Flexible input voltage levels of 3.6Vdc to 6.0Vdc with overvoltage protection in the -LVx versions, and 6.0Vdc to 40Vdc in the -HVx versions.

12) FLASH based program memory. New software revisions upgradeable through serial interface.

1.3 Naming Conventions

The GPS 35LP Series TrackPack™ receivers are delineated with a three letter extension to designate the operating voltage range and the serial data voltage specification.

High Voltage - GPS35-HVx designation indicates that the unit will accept a high input voltage. The internal switching regulator will operate from a 6VDC to 40VDC unregulated supply.

Low Voltage - GPS35-LVx designation indicates that the unit is designed to operated from a low voltage 3.6VDC to 6.0VDC supply. Operation at about 4VDC is the most power efficient mode of operation for the GPS35LP receiver. The unit is protected if a high voltage is inadvertently applied to the input.

RS-232 Serial Data - GPS35-xVS designation means that the two bi-directional serial data ports are true RS-232 ports conforming to the RS-232E standard.

CMOS Serial Data - GPS35-xVC designation means that the two bi-directional serial data ports use CMOS output buffers. The input buffers will accept either CMOS(TTL) voltage levels or RS232 voltage levels. This configuration is adequate for communicating directly with serial devices over short cable lengths (less than 20 meters).

1.4 TECHNICAL SPECIFICATIONS

Specifications are subject to change without notice.

1.4.1 Physical Characteristics

1) Single construction integrated antenna/receiver.

2) Weight: 4.4 oz, (124.5 g), not including cable

3) Size: 2.230" (w) x 3.796" (l) x 1.047" (h), (56.64 mm x 96.42 mm x 26.60 mm)

1.4.2 Environmental Characteristics

1) Operating temperature: -30°C to +85°C (internal temperature)

2) Storage temperature: -40°C to +90°C

1.4.3 Electrical Characteristics

1) Input voltage: +3.6VDC to 6.0VDC regulated, 150mV ripple -LVx versions. +6.0VDC to 40VDC unregulated -HVx version.

2) Input current: 120 mA typical 140 mA max -LVx versions, 20 mA while in power down. 870mW typical 1000mW max -HVx version, 300uA while in power down.

3) Backup power: 3V Rechargeable Lithium cell battery, up to 6 month charge.

4) Power Down Input: 2.7V threshold

1.4.4 Performance

1) Tracks up to 12 satellites (up to 11 with PPS active)

2) Update rate: 1 second

3) Acquisition time

- 15 seconds warm (all data known)

- 45 seconds cold (initial position, time and almanac known, ephemeris unknown)

- 5.0 minutes AutoLocate TM (almanac known, initial position and time unknown)

- 5 minutes search the sky (no data known)

4) Position accuracy: Differential GPS (DGPS): 5 meters RMS Non-differential GPS: 15 meters RMS (100 meters with Selective Availability on)

5) Velocity accuracy: 0.2 m/s RMS steady state (subject to Selective Availability)

6) Dynamics: 999 knots velocity, 6g dynamics

7) One-pulse-per-second accuracy: +/-1 microsecond at rising edge of PPS pulse (subject to Selective Availability)

1.4.5 Interfaces

1) Dual channel CMOS/TTL level (-xVC versions) or RS-232 compatible level (-xVS versions), with user selectable baud rate (300, 600,1200, 2400, 4800, 9600, 19200)

2) NMEA 0183 Version 2.0 ASCII output (GPALM, GPGGA, GPGSA, GPGSV, GPRMC, GPVTG, PGRME, PGRMT, PGRMV, PGRMF, LCGLL, LCVTG)

Inputs

- Initial position, date and time (not required)

- Earth datum and differential mode configuration command, PPS Enable, almanac Outputs

- Position, velocity and time

- Receiver and satellite status

- Differential Reference Station ID and RTCM Data age

- Geometry and error estimates

3) Real-time Differential Correction input (RTCM SC-104 message types 1,2,3 and 9)

4) One-pulse-per-second timing output

5) Binary Format Phase Data

1.5 APPLICATION

Fig. 1, TYPICAL APPLICATION ARCHITECTURE

SECTION 2

OPERATIONAL CHARACTERISTICS

This section describes the basic operational characteristics of the GPS 35LP. Additional information regarding input and output specifications are contained in Section 4.

2.1 SELF TEST

After input power has been applied to the GPS 35LP and periodically thereafter, the unit will perform critical self test functions and report the results over the output channel(s). The following tests will be performed:

1) RAM check

2) FLASH memory test

3) Receiver test

4) Real-time clock test

5) Oscillator check In addition to the results of the above tests, the GPS 35LP will report software version information.

2.2 INITIALIZATION

After the initial self test is complete, the GPS 35LP will begin the process of satellite acquisition and tracking. The acquisition process is fully automatic and, under normal circumstances, will take approximately 45 seconds to achieve a position fix (15 seconds if ephemeris data is known). After a position fix has been calculated, valid position, velocity and time information will be transmitted over the output channel(s).

Like all GPS receivers, the GPS 35LP utilizes initial data such as last stored position, date and time as well as satellite orbital data to achieve maximum acquisition performance. If significant inaccuracy exists in the initial data, or if the orbital data is obsolete, it may take 5.0 minutes to achieve a navigation solution. The GPS 35LP AutolocateTM feature is capable of automatically determining a navigation solution without intervention from the host system. However, acquisition performance can be improved if the host system initializes the GPS 35LP following the occurrence of one or more of the following events:

1) Transportation over distances further than 1500 kilometers

2) Failure of the internal memory battery without system standby power

3) Stored date/time off by more than 30 minutes

See Section 4 for more information on initializing the GPS 35LP.

2.3 NAVIGATION

After the acquisition process is complete, the GPS 35LP will begin sending valid navigation information over its output channels. These data include:

1) Latitude/longitude/altitude

2) Velocity

3) Date/time

4) Error estimates

5) Satellite and receiver status Normally the GPS 35LP will select the optimal navigation mode (2D or 3D) based on available satellites

and geometry considerations. The host system, at its option, may command the GPS 35LP to choose a specific mode of navigation, such as 2D. The following modes are available:

1) 2D exclusively with altitude supplied by the host system (altitude hold mode)

2) 3D exclusively with altitude computed by the GPS 35LP

3) Automatic mode in which the board set determines the desired mode based on satellite availability and geometry considerations

When navigating in the 2D mode (either exclusive or automatic), the GPS 35LP utilizes the last computed altitude or the last altitude supplied by the host system, whichever is newer. The host system must ensure that the altitude used for 2D navigation is accurate since the resulting position error may be as large as the altitude error. See Section 4 for more information on altitude control.

The GPS 35LP will default to automatic differential mode – “looking” for real-time differential corrections in RTCM SC-104 standard format, with message types 1,2,3, or 9, then attempt to apply them to the satellite data, in order to produce a differential (DGPS) solution. The host system, at its option, may also command the GPS 35LP to choose differential only mode. When navigating in the differential only mode, the GPS 35LP will output a position only when a differential solution is available.

2.4 SATELLITE DATA COLLECTION

The GPS 35LP will automatically update satellite orbital data as it operates. The intelligence of the GPS 35LP combined with its hardware capability allows these data to be collected and stored without intervention from the host system. A few key points should be considered regarding this process:

1) If the receiver is not operated for a period of six (6) months or more, the unit will “search the sky”

in order to collect satellite orbital information. This process is fully automatic and, under normal circumstances, will take 3-4 minutes to achieve a navigation solution. However, the host system should allow the board set to remain on for at least 12.5 minutes after the first satellite is acquired (see Section 4 for more information on status indications).

2) If the memory backup battery fails, the receiver will search the sky as described above. Should

the memory battery discharge, the unit needs to be powered on for several days to insure a sufficient recharge to maintain several months of clock operation and memory storage. System configuration information will not be lost due to battery discharge, only previous position, time and almanac data will be lost.

3) If the initial data is significantly inaccurate, the receiver perform an operation known as

AutoLocate™. This procedure is fully automatic and, under normal circumstances, will require 1.5

minutes to calculate a navigation solution. AutoLocate™, unlike search the sky, does not require that the receiver continue to operate after a fix has been obtained.

SECTION 3

HARDWARE INTERFACE

3.1 MECHANICAL DIMENSIONS

The GPS 35LP is a complete GPS receiver including antenna in a uniquely styled waterproof package.

3.1.1 GPS 35 Dimensions

(General tolerance ±±0.50mm)

Fig. 2 GPS 35LP Dimensions

3.2 MOUNTING CONFIGURATIONS AND OPTIONS

The following mounting options are available for the GPS 35LP. Mounting is user configurable.

3.2.1 Magnetic Mount

The magnetic mount provides a firm, removable mounting attachment to any ferrous metal surface.

Fig. 3, Magnetic Mount Attachment

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