Linx Technologies RXM-GPS-FM User Manual

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FM Series

GPS Receiver Module

Data Guide

Page 2

Warning: Some customers may want Linx radio frequency (“RF”)

products to control machinery or devices remotely, including machinery or devices that can cause death, bodily injuries, and/or property damage if improperly or inadvertently triggered, particularly in industrial settings or other applications implicating life-safety concerns (“Life and Property Safety Situations”).

Table of Contents

1 Description 1 Features 1 Applications Include

NO OEM LINX REMOTE CONTROL OR FUNCTION MODULE SHOULD EVER BE USED IN LIFE AND PROPERTY SAFETY SITUATIONS. No OEM Linx Remote Control or Function Module

should be modiﬁed for Life and Property Safety Situations. Such modiﬁcation cannot provide sufﬁcient safety and will void the product’s regulatory certiﬁcation and warranty.

Customers may use our (non-Function) Modules, Antenna and Connectors as part of other systems in Life Safety Situations, but only with necessary and industry appropriate redundancies and in compliance with applicable safety standards, including without limitation, ANSI and NFPA standards. It is solely the responsibility of any Linx customer who uses one or more of these products to incorporate appropriate redundancies and safety standards for the Life and Property Safety Situation application.

Do not use this or any Linx product to trigger an action directly from the data line or RSSI lines without a protocol or encoder/ decoder to validate the data. Without validation, any signal from

another unrelated transmitter in the environment received by the module could inadvertently trigger the action.

All RF products are susceptible to RF interference that can prevent communication. RF products without frequency agility or hopping

implemented are more subject to interference. This module does not have a frequency hopping protocol built in.

Do not use any Linx product over the limits in this data guide. Excessive voltage or extended operation at the maximum voltage could cause product failure. Exceeding the reﬂow temperature proﬁle could cause product failure which is not immediately evident.

Do not make any physical or electrical modiﬁcations to any Linx product. This will void the warranty and regulatory and UL certiﬁcations

and may cause product failure which is not immediately evident.

2 Ordering Information 2 Absolute Maximum Ratings 2 ElectricalSpecications 4 Pin Assignments 4 Pin Descriptions 5 A Brief Overview of GPS 6 Time To First Fix (TTFF) 6 Module Description 7 Backup Battery 7 Power Supply Requirements 7 The 1PPS Output 7 Hybrid Ephemeris Prediction (AGPS) 8 Antenna Considerations 9 Power Control 10 Slow Start Time 11 Interfacing with NMEA Messages 12 NMEA Output Messages 18 Input Messages 32 Typical Applications 33 Microstrip Details 34 Board Layout Guidelines 35 Pad Layout 36 Production Guidelines 36 Hand Assembly 36 Automated Assembly 38 Master Development System

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39 Resources 40 Appendix A

FM Series GPS Receiver

Data Guide

Description

The FM Series GPS receiver module is a self-contained high-performance Global Positioning System receiver. Based on the MediaTek MT3339 chipset, it can simultaneously acquire on 66 channels and track on up to 22 channels. This gives the module fast lock times and high position accuracy even at low signal levels.

The module’s exceptional sensitivity gives it superior performance, even in dense foliage and urban canyons. Its very low power consumption helps maximize runtimes in battery powered applications. The module outputs standard NMEA data messages through a UART interface.

Housed in a compact reﬂow-compatible SMD package, the receiver requires no programming or additional RF components (except an antenna) to form a complete GPS solution. This makes the FM Series easy to integrate, even by engineers without previous RF or GPS experience.

0.512 in

(13.00 mm)

0.087 in

(2.20 mm)

Figure 1: Package Dimensions

0.591 in

(15.00 mm)

RXM-GPS-FM

LOT GRxxxx

Warning: This product incorporates numerous static-sensitive

components. Always wear an ESD wrist strap and observe proper ESD handling procedures when working with this device. Failure to observe this precaution may result in module damage or failure.

Features

• MediaTek chipset

• High sensitivity (–161dBm)

• Fast TTFF at low signal levels

• ±11ns 1PPS accuracy

• Battery-backed SRAM

• 3-day ephemeris prediction

• No programming necessary

Applications Include

• Positioning and Navigation

• Location and Tracking

• Security/Loss-Prevention

• No external RF components

needed (except an antenna)

• No production tuning

• UART serial interface

• Power control features

• Compact SMD package

• Surveying

• Logistics

• Fleet Management

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Revised 3/18/2015

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Ordering Information

Part Number Description

RXM-GPS-FM-x FM Series GPS Receiver Module

MDEV-GPS-FM FM Series GPS Receiver Master Development System

EVM-GPS-FM FM Series Evaluation Module

x = “T” for Tape and Reel, “B” for Bulk

Reels are 1,000 pieces. Quantities less than 1,000 pieces are supplied in bulk

Figure 2: Ordering Information

Absolute Maximum Ratings

Supply Voltage V

+4.3 VDC

Input Battery Backup Voltage +4.3 VDC

VOUT Output Current 50 mA

Operating Temperature −40 to +85 ºC

Storage Temperature −40 to +85 ºC

Exceeding any of the limits of this section may lead to permanent damage to the device. Furthermore, extended operation at these maximum ratings may reduce the life of this device.

Figure 3: Absolute Maximum Ratings

ElectricalSpecications

FM Series GNSS Receiver Speciﬁcations

Parameter Symbol Min. Typ. Max. Units Notes

Power Supply

Operating Voltage V

Supply Current l

Peak 66 mA 1

Acquisition 14 mA 1

Tracking 12 mA 1, 2

Standby 0.150 mA 1

Backup Battery Voltage V

Backup Battery Current I

BAT

Antenna Port

RF Impedance R

3.0 3.3 4.3 VDC

2.0 4.3 VDC

7 µA 2

50 Ω

FM Series GNSS Receiver Speciﬁcations

Parameter Symbol Min. Typ. Max. Units Notes

VOUT Output Voltage V

VOUT Output Current I

Output Low Voltage V

Output High Voltage V

Output Low Current I

Output High Current I

Input Low Voltage V

Input High Voltage V

Input Low Current I

Input High Current I

Minimum RESET Pulse T

OUT

RST

2.7 2.8 2.9 VDC

30 mA 3

0.4 VDC

2.4

2.0 mA

−0.3 0.8 VDC

2.0 3.6 VDC

−1 1 µA 4

1 ms

Receiver Section

Receiver Sensitivity

Tracking −161 dBm

Cold Start −143 dBm

Acquisition Time

Hot Start (Open Sky) 1 s

Hot Start (Indoor) 30 s

Cold Start 32 s

Cold Start, AGPS 15 s

Position Accuracy

Autonomous 3 m

SBAS 2.5 m

1PPS Accuracy −11 11 ns

Altitude 50,000 m

Velocity 515 m/s

Chipset MediaTek MT3339

Frequency L1 1575.42MHz, C/A code

Channels 22 tracking, 66 acquisition

Update Rate 1Hz default, up to 10Hz

Protocol Support NMEA 0183 ver 3.01

1. VCC = 3.3V, without active antenna, ephemeris prediction is off,

2. Position ﬁx is available

IOUT

= 0

3. VCC = 0V

4. No pull-up or pull-down on the lines

Figure 4: Electrical Speciﬁcations

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Pin Assignments

A Brief Overview of GPS

The Global Positioning System (GPS) is a U.S.-owned utility that freely and

NC1 NC2 1PPS3 TX4 RX5 GND21

NC6 NC7 RESET8 NC9 NC10

GND 20

RFIN 19

GND 18

VOUT 17

NC 16

GND 22

NC 15 NC 14 NC 13

VCC 12

VBACKUP 11

continuously provides positioning, navigation, and timing (PNT) information. Originally created by the U.S. Department of Defense for military applications, the system was made available without charge to civilians in the early 1980s. The global positioning system consists of a nominal constellation of 24 satellites orbiting the earth at about 12,000 nautical miles in height. The pattern and spacing of the satellites allow at least four to be visible above the horizon from any point on the Earth. Each satellite transmits low power radio signals which contain three different bits of information; a pseudorandom code identifying the satellite, ephemeris data which contains the current date and time as well as the satellite’s health, and the almanac data which tells where each satellite should be at any time throughout the day.

Figure 5: FM Series GPS Receiver Pinout (Top View)

Pin Descriptions

Pin Number Name I/O Description

1, 2, 6, 7, 9,

10, 13, 14,

15, 16

3 1PPS O 1 Pulse Per Second (11nS accuracy)

4 TX O Serial output (default NMEA)

5 RX I Serial input (default NMEA)

8 RESET I

11 VBACKUP P

12 VCC P Supply Voltage

17 VOUT O 2.8V output for an active antenna

18, 20, 21, 22 GND P Ground

19 RFIN I GPS RF signal input

Figure 6: FM Series GPS Receiver Pin Descriptions

NC − No electrical connection

Active low module reset. This line is pulled high internally. Leave it unconnected if it is not used.

Backup battery supply voltage. This line must be powered to enable the module.

A GPS receiver receives and times the signals sent by multiple satellites and calculates the distance to each satellite. If the position of each satellite is known, the receiver can use triangulation to determine its position anywhere on the earth. The receiver uses four satellites to solve for four unknowns; latitude, longitude, altitude and time. If any of these factors is already known to the system, an accurate position (ﬁx) can be obtained with fewer satellites in view. Tracking more satellites improves calculation accuracy. In essence, the GPS system provides a unique address for every square meter on the planet.

A faster Time To First Fix (TTFF) is also possible if the satellite information is already stored in the receiver. If the receiver knows some of this information, then it can accurately predict its position before acquiring an updated position ﬁx. For example, aircraft or marine navigation equipment may have other means of determining altitude, so the GPS receiver would only have to lock on to three satellites and calculate three equations to provide the ﬁrst position ﬁx after power-up.

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Time To First Fix (TTFF)

TTFF is often broken down into three parts:

Cold: A cold start is when the receiver has no accurate knowledge of its position or time. This happens when the receiver’s internal Real Time Clock (RTC) has not been running or it has no valid ephemeris or almanac data. In a cold start, the receiver takes up to 30 seconds to acquire its position.

Warm: A typical warm start is when the receiver has valid almanac and time data and has not signiﬁcantly moved since its last valid position calculation. This happens when the receiver has been shut down for more than 2 hours, but still has its last position, time, and almanac saved in memory, and its RTC has been running. The receiver can predict the location of the current visible satellites and its location; however, it needs to wait for an ephemeris broadcast (every 30 seconds) before it can accurately calculate its position.

Hot: A hot start is when the receiver has valid ephemeris, time, and almanac data. In a hot start, the receiver takes 1 second to acquire its position. The time to calculate a ﬁx in this state is sometimes referred to as Time to Subsequent Fix or TTSF.

Backup Battery

The module is designed to work with a backup battery that keeps the SRAM memory and the RTC powered when the RF section and the main GPS core are powered down. This enables the module to have a faster Time To First Fix (TTFF) when it is powered back on. The memory and clock pull about 6µA. This means that a small lithium battery is sufﬁcient to power these sections. This signiﬁcantly reduces the power consumption and extends the main battery life while allowing for fast position ﬁxes when the module is powered back on.

The backup battery must be installed for the module to be enabled.

Power Supply Requirements

The module requires a clean, well-regulated power source. While it is preferable to power the unit from a battery, it can operate from a power supply as long as noise is less than 20mV. Power supply noise can signiﬁcantly affect the receiver’s sensitivity, therefore providing clean power to the module should be a high priority during design. Bypass capacitors should be placed as close as possible to the module. The values should be adjusted depending on the amount and type of noise present on the supply line.

Module Description

The FM Series GPS Receiver module is based on the MediaTek MT3339 chipset, which consumes less power than competitive products while providing exceptional performance even in dense foliage and urban canyons. No external RF components are needed other than an antenna. The simple serial interface and industry standard NMEA protocol make integration of the FM Series into an end product extremely straightforward.

The module’s high-performance RF architecture allows it to receive GPS signals that are as low as –161dBm. The FM Series can track up to 22 satellites at the same time. Once locked onto the visible satellites, the receiver calculates the range to the satellites and determines its position and the precise time. It then outputs the data through a standard serial port using several standard NMEA protocol formats.

The GPS core handles all of the necessary initialization, tracking, and calculations autonomously, so no programming is required. The RF section is optimized for low level signals, and requires no production tuning.

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The 1PPS Output

The 1PPS line outputs 1 pulse per second on the rising edge of the GPS second when the receiver has an over-solved navigation solution from ﬁve or more satellites. The pulse has a duration of 100ms with the rising edge on the GPS second. This line is low until the receiver acquires a 3D ﬁx. The GPS second is based on the atomic clocks in the satellites, which are monitored and set to Universal Time master clocks. This output and the time calculated from the satellite transmissions can be used as a clock feature in an end product with ±11ns accuracy.

Hybrid Ephemeris Prediction (AGPS)

AGPS is where the receiver uses the ephemeris data broadcast by the satellites to calculate models of each visible satellite’s future location. This allows the receiver to store up to 3 days’ worth of ephemeris data and results in faster TTFF. Having this data reduces the cold start time to less than 15 seconds. Contact Linx for details on this.

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Antenna Considerations

Standby

Cold Start

The FM Series module is designed to utilize a wide variety of external antennas. The module has a regulated power output which simpliﬁes the use of GPS antenna styles which require external power. This allows the designer great ﬂexibility, but care must be taken in antenna selection to ensure optimum performance. For example, a handheld device may be used in many varying orientations so an antenna element with a wide and uniform pattern may yield better overall performance than an antenna element with high gain and a correspondingly narrower beam. Conversely, an antenna mounted in a ﬁxed and predictable manner may beneﬁt from pattern and gain characteristics suited to that application. Evaluating multiple antenna solutions in real-world situations is a good way to rapidly assess which will best meet the needs of your application.

For GPS, the antenna should have good right hand circular polarization characteristics (RHCP) to match the polarization of the GPS signals. Ceramic patches are the most commonly used style of antenna, but there are many different shapes, sizes and styles of antennas available. Regardless of the construction, they will generally be either passive or active types. Passive antennas are simply an antenna tuned to the correct frequency. Active antennas add a Low Noise Ampliﬁer (LNA) after the antenna and before the module to amplify the weak GPS satellite signals.

For active antennas, a 300 ohm ferrite bead can be used to connect the VOUT line to the RFIN line. This bead prevents the RF from getting into the power supply, but allows the DC voltage onto the RF trace to feed into the antenna. A series capacitor inside the module prevents this DC voltage from affecting the bias on the module’s internal LNA.

Maintaining a 50 ohm path between the module and antenna is critical. Errors in layout can signiﬁcantly impact the module’s performance. Please review the layout guidelines section carefully to become more familiar with these considerations.

Power Control

The FM Series GPS Receiver module offers several ways to control the module’s power. A serial command puts the module into a low-power standby mode that consumes only 150µA of current. An external processor can be used to power the module on and off to conserve battery power.

In addition, the module includes a duty cycle mode where the module will power on for a conﬁgurable amount of time to obtain a position ﬁx then power off for a conﬁgurable amount of time. In this way the module can handle all of the timing without any intervention from the external processor.

There are four times that are conﬁgured with duty cycle mode. The on time and standby times are the amount of times that the module is on and in standby in normal operation. There are also cold start on and standby times. These are used to keep the module on longer in the event of a cold start so that it can gather the required satellite data for a position ﬁx. After this, the module uses the normal operation times.

In the event that the module’s stored ephemeris data becomes invalid the module supports and extended receive time to gather the required data from the satellites. Figure 7 shows the power control times.

Cold Start On Time

Figure 7: FM Series GPS Receiver Power Control

The module supports MediaTek’s proprietary AlwaysLocateTM mode. In this mode, the module automatically adapts the on and standby times to the current environmental conditions to balance position accuracy and power consumption. In this mode, any byte sent to the module triggers it to output the current position data.

Standby mode is conﬁgured by command 161. Extended receive time is conﬁgured by command 223. Command 225 conﬁgures which duty cycle mode is used.

Standby Time Standby TimeOn Time On Time Extended RX Time

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Slow Start Time

The most critical factors in start time are current ephemeris data, signal strength and sky view. The ephemeris data describes the path of each satellite as they orbit the earth. This is used to calculate the position of a satellite at a particular time. This data is only usable for a short period of time, so if it has been more than a few hours since the last ﬁx or if the location has signiﬁcantly changed (a few hundred miles), then the receiver may need to wait for a new ephemeris transmission before a position can be calculated. The GPS satellites transmit the ephemeris data every 30 seconds. Transmissions with a low signal strength may not be received correctly or be corrupted by ambient noise. The view of the sky is important because the more satellites the receiver can see, the faster the ﬁx and the more accurate the position will be when the ﬁx is obtained.

If the receiver is in a very poor location, such as inside a building, urban canyon, or dense foliage, then the time to ﬁrst ﬁx can be slowed. In very poor locations with poor signal strength and a limited view of the sky with outdated ephemeris data, this could be on the order of several minutes. In the worst cases, the receiver may need to receive almanac data, which describes the health and course data for every satellite in the constellation. This data is transmitted every 15 minutes. If a lock is taking a long time, try to ﬁnd a location with a better view of the sky and fewer obstructions. Once locked, it is easier for the receiver to maintain the position ﬁx.

Interfacing with NMEA Messages

Linx modules default to the NMEA protocol. Output messages are sent from the receiver on the TX line and input messages are sent to the receiver on the RX line. By default, output messages are sent once every second. Details of each message are described in the following sections.

The NMEA message format is as follows: <Message-ID + Data Payload + Checksum + End Sequence>. The serial data structure defaults to 9,600bps, 8 data bits, 1 start bit, 1 stop bit, and no parity. Each message starts with a $ character and ends with a <CR> <LF>. All ﬁelds within each message are separated by a comma. The checksum follows the * character and is the last two characters, not including the <CR> <LF>. It consists of two hex digits representing the exclusive OR (XOR) of all characters between, but not including, the $ and * characters. When reading NMEA output messages, if a ﬁeld has no value assigned to it, the comma will still be placed following the previous comma. For example, {,04,,,,,2.0,} shows four empty ﬁelds between values 04 and 2.0. When writing NMEA input messages, all ﬁelds are required, none are optional. An empty ﬁeld will invalidate the message and it will be ignored.

Reading NMEA output messages:

• Initialize a serial interface to match the serial data structure of the GPS receiver.

• Read the NMEA data from the TX pin into a receive buffer.

• Separate it into six buffers, one for each message type. Use the

characters ($) and <CR> <LF> as end points for each message.

• For each message, calculate the checksum as mentioned above to compare with the received checksum.

• Parse the data from each message using commas as ﬁeld separators.

• Update the application with the parsed ﬁeld values.

• Clear the receive buffer and be ready for the next set of messages.

Writing NMEA input messages:

• Initialize a serial interface to match the serial data structure of the receiver.

• Assemble the message to be sent with the calculated checksum.

• Transmit the message to the receiver on the RX line.

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NMEA Output Messages

The following sections outline the data structures of the various NMEA messages that are supported by the module. By default, the NMEA commands are output at 9,600bps, 8 data bits, 1 start bit, stop bit, and no parity.

Six messages are output at a 1Hz rate by default. These messages are shown in Figure 8.

NMEA Output Messages

Name Description

GGA Contains the essential ﬁx data which provide location and accuracy

GLL Contains just position and time

GSA Contains data on the Dilution of Precision (DOP) and which satellites are used

GSV

RMC Contains the minimum data of time, position, speed and course

Figure 8: NMEA Output Messages

Details of each message and examples are given in the following sections.

Contains the satellite location relative to the receiver and its signal to noise ratio. Each message can describe 4 satellites so multiple messages may be output depending on the number of satellites being tracked.

VTG Contains the course and speed over the ground

GGA – Global Positioning System Fix Data

Figure 9 contains the values for the following example:

$GPGGA,053740.000,2503.6319,N,12136.0099,E,1,08,1.1,63.8,M,15.2,M,,0000*64

Global Positioning System Fix Data Example

Name Example Units Description

Message ID $GPGGA GGA protocol header

UTC Time 053740.000 hhmmss.sss

Latitude 2503.6319 ddmm.mmmm

N/S Indicator N N=north or S=south

Longitude 12136.0099 dddmm.mmmm

E/W Indicator E E=east or W=west

Position Fix Indicator 1 See Figure 10

Satellites Used 08 Range 0 to 33

HDOP 1.1 Horizontal Dilution of Precision

MSL Altitude 63.8 meters

Units M meters

Geoid Separation 15.2 meters

Units M meters

Age of Diff. Corr. second Null ﬁelds when DGPS is not used

Diff. Ref. Station 0000

Checksum *64

<CR> <LF> End of message termination

Figure 9: Global Positioning System Fix Data Example

Position Indicator Values

Value Description

0 Fix not available or invalid

1 GPS SPS Mode, ﬁx valid

2 Differential GPS, SPS Mode, ﬁx valid

3–5 Not supported

6 Dead Reckoning Mode, ﬁx valid (requires external hardware)

Figure 10: Position Indicator Values

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GLL – Geographic Position – Latitude / Longitude

Figure 11 contains the values for the following example:

$GPGLL,2503.6319,N,12136.0099,E,053740.000,A,A*52

Geographic Position – Latitude / Longitude Example

Name Example Units Description

Message ID $GPGLL GLL protocol header

Latitude 2503.6319 ddmm.mmmm

N/S Indicator N N=north or S=south

Longitude 12136.0099 dddmm.mmmm

E/W Indicator E E=east or W=west

UTC Time 053740.000 hhmmss.sss

Status A A=data valid or V=data not valid

Mode A

Checksum *52

<CR> <LF> End of message termination

Figure 11: Geographic Position – Latitude / Longitude Example

A=autonomous, D=DGPS, N=Data not valid, R=Coarse Position, S=Simulator

GSA – GPS DOP and Active Satellites

Figure 12 contains the values for the following example:

$GPGSA,A,3,24,07,17,11,28,08,20,04,,,,,2.0,1.1,1.7*35

GPS DOP and Active Satellites Example

Name Example Units Description

Message ID $GPGSA GSA protocol header

Mode 1 A See Figure 13

Mode 2 3 1=No ﬁx, 2=2D, 3=3D

ID of satellite used 24 Sv on Channel 1

ID of satellite used 07 Sv on Channel 2

... ...

ID of satellite used Sv on Channel N

PDOP 2.0 Position Dilution of Precision

HDOP 1.1 Horizontal Dilution of Precision

VDOP 1.7 Vertical Dilution of Precision

Checksum *35

<CR> <LF> End of message termination

Mode 1 Values

Value Description

M Manual – forced to operate in 2D or 3D mode

A Automatic – allowed to automatically switch 2D/3D

Figure 13: Mode 1 Values

GSV – GPS Satellites in View

Figure 14 contains the values for the following example:

$GPGSV,3,1,12,28,81,285,42,24,67,302,46,31,54,354,,20,51,077,46*73

$GPGSV,3,2,12,17,41,328,45,07,32,315,45,04,31,250,40,11,25,046,41*75

$GPGSV,3,3,12,08,22,214,38,27,08,190,16,19,05,092,33,23,04,127,*7B

GPS Satellites in View Example

Name Example Units Description

Message ID $GPGSV GSV protocol header

Total number of

messages

Message number

Satellites in view 12

Satellite ID 28 Channel 1 (Range 01 to 196)

Elevation 81 degrees Channel 1 (Range 00 to 90)

Azimuth 285 degrees Channel 1 (Range 000 to 359)

SNR (C/No) 42 dB–Hz

Satellite ID 20 Channel 2 (Range 01 to 196)

Elevation 51 degrees Channel 2 (Range 00 to 90)

Azimuth 077 degrees Channel 2 (Range 000 to 359)

SNR (C/No) 46 dB-Hz

Checksum *73

<CR> <LF> End of message termination

1. Depending on the number of satellites tracked, multiple messages of GSV data may be required.

Figure 14: GPS Satellites in View Example

3 Range 1 to 4

1 Range 1 to 4

Channel 1 (Range 00 to 99, null when not tracking)

Channel 2 (Range 00 to 99, null when not tracking.

Figure 12: GPS DOP and Active Satellites Example

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RMC – Recommended Minimum Speciﬁc GNSS Data

Figure 15 contains the values for the following example:

$GPRMC,053740.000,A,2503.6319,N,12136.0099,E,2.69,79.65,100106,,,A*53

VTG – Course Over Ground and Ground Speed

Figure 16 contains the values for the following example:

$GPVTG,79.65,T,,M,2.69,N,5.0,K,A*38

Recommended Minimum Speciﬁc GNSS Data Example

Name Example Units Description

Message ID $GPRMC RMC protocol header

UTC Time 053740.000 hhmmss.sss

Status A A=data valid or V=data not valid

Latitude 2503.6319 ddmm.mmmm

N/S Indicator N N=north or S=south

Longitude 12136.0099 dddmm.mmmm

E/W Indicator E E=east or W=west

Speed over ground 2.69 knots TRUE

Course over ground 79.65 degrees

Date 100106 ddmmyy

Magnetic Variation degrees Not available, null ﬁeld

Variation Sense E=east or W=west (not shown)

Mode A

Checksum *53

<CR> <LF> End of message termination

Figure 15: Recommended Minimum Speciﬁc GNSS Data Example

A=autonomous, D=DGPS, E=DR, N= Data not valid, R=Coarse Position, S=Simulator

Course Over Ground and Ground Speed Example

Name Example Units Description

Message ID $GPVTG VTG protocol header

Course over ground 79.65 degrees Measured heading

Reference T TRUE

Course over ground degrees Measured heading (N/A, null ﬁeld)

Reference M Magnetic

Speed over ground 2.69 knots Measured speed

Units N Knots

Speed over ground 5.0 km/hr Measured speed

Units K Kilometer per hour

Mode A

Checksum *38

<CR> <LF> End of message termination

Figure 16: Course Over Ground and Ground Speed Example

A=autonomous, D=DGPS, N= Data not valid, R=Coarse Position, S=Simulator

Start-up Response

The module outputs a message when it starts up to indicate its state. The normal start-up message is shown below and the message formatting is shown in Figure 17.

$PMTK010,001*2E<CR><LF>

Start-up Response Example

Name Example Description

Message ID $PMTK010 Message header

System Message

Message MSG

Checksum CKSUM

End Sequence <CR> <LF> End of message termination

Figure 17: Start-up Response Example

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0 = Unknown 1 = Start-up 2 = Notiﬁcation for the host supporting EPO 3 = Transition to Normal operation is successful

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Input Messages

The following outlines the serial commands input into the module for conﬁguration. There are 3 types of input messages: commands, writes and reads. The module outputs a response for each input message.

The commands are used to change the operating state of the module. The writes are used to change the module’s conﬁguration and the reads are used to read out the current conﬁguration. Messages are formatted as shown in Figure 18. All ﬁelds in each message are separated by a comma.

Serial Data Structure

Name Example Description

Start Sequence $PMTK

Message ID <MID>

Payload DATA Message speciﬁc data.

Checksum CKSUM

End Sequence <CR> <LF>

Figure 18: Serial Data Structure

Figure 19 shows the input commands.

Input Commands

Name Description

101 Hot Re-start

102 Warm Re-start

103 Cold Re-start

104 Restore Default Conﬁguration

161 Standby Mode

220 Position Fix Interval

223 Ephemeris Data Receive Time

225 Receiver Duty Cycle

251 Baud Rate

Message Identiﬁer consisting of three numeric characters.

CKSUM is a two-hex character checksum as deﬁned in the NMEA speciﬁcation, NMEA-0183 Standard for Interfacing Marine Electronic Devices. Checksums are required on all input messages.

Each message must be terminated using Carriage Return (CR) Line Feed (LF) (\r\n, 0x0D0A) to cause the receiver to process the input message. They are not printable ASCII characters, so are omitted from the examples.

The write and read messages are shown in Figure 20. A write message triggers an acknowledgement from the module. A read message triggers a response message containing the requested information.

Input Write and Read Messages

Description Write ID Read ID Response ID

Position Fix Interval 300 400 500

DGPS Source 301 401 501

SBAS Enable 313 413 513

NMEA Output Messages 314 414 514

Set Datum 330 430 530

Static Navigation Threshold 386 447 527

Enable Ephemeris Prediction 869 869 869

Figure 20: Input Write and Read Messages

The module responds to commands with response messages. The acknowledge message is formatted as shown in Figure 21.

Acknowledge Message

Name Example Description

Start Sequence $PMTK

Message ID 001 Acknowledge Identiﬁer

Command CMD The command that triggered the acknowledge

Flag indicating the outcome of the command

Flag Flg

Checksum CKSUM

End Sequence <CR> <LF>

Figure 21: Acknowledge Message

0 = Invalid Command 1 = Unsupported Command 2 = Valid command, but action failed 3 = Valid command and action succeeded

CKSUM is a two-hex character checksum as deﬁned in the NMEA speciﬁcation, NMEA-0183 Standard for Interfacing Marine Electronic Devices. Checksums are required on all input messages.

Figure 19: Input Commands

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18 19

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Page 13

101 – Hot Re-start

This command instructs the module to conduct a hot re-start using all of the data stored in memory. Periodic mode and static navigation settings are returned to default when this command is executed.

$PMTK101*32<CR><LF>

102 – Warm Re-start

This command instructs the module to conduct a warm re-start that does not use the saved ephemeris data. Periodic mode and static navigation settings are returned to default when this command is executed.

220 – Position Fix Interval

This command sets the position ﬁx interval. This is the time between when the module calculates its position. This is the same as write message 300.

Position Fix Interval Command and Response

Command

Start Msg ID Interval Checksum End

$PMTK 220 ,Ival *Cksum <CR><LF>

Response

Start Msg ID CMD Flag Checksum End

$PMTK 001 ,220 ,Flg *Cksum <CR><LF>

$PMTK102*31<CR><LF>

103 – Cold Re-start

This command instructs the module to conduct a cold re-start that does not use any of the data from memory. Periodic mode and static navigation settings are returned to default when this command is executed.

$PMTK103*30<CR><LF>

104 – Restore Default Conﬁguration

This command instructs the module to conduct a cold re-start and return all conﬁgurations to the factory default settings.

$PMTK104*37<CR><LF>

161 – Standby Mode

This command instructs the module to enter a low power standby mode. Any activity on the RX line wakes the module.

$PMTK161,0*28<CR><LF>

The module outputs the startup message when it wakes up.

Figure 22: Position Fix Interval Command and Response

Ival = the interval time in milliseconds.

The interval must be larger than 100ms. Faster rates require that the baud rate be increased, the number of messages that are output be decreased or both. The module automatically calculates the required data bandwidth and returns an action failed response (Flg = 2) if the interval is faster than the module can output all of the required messages at the current baud rate. The following example sets the interval to 1 second.

$PMTK220,1000*1F<CR><LF>

$PMTK010,001*2E<CR><LF>

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20 21

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Page 14

223 – Extended Receive Time

This command extends the amount of time that the receiver is on when in duty cycle mode. This allows the module to refresh its stored ephemeris data by staying awake until it received the data from the satellites.

Extended Receive Time Command and Response

Command

Start Msg ID SV

$PMTK 223 ,SV ,SNR ,EXT ,EXG *Cksum <CR><LF>

Response

Start Msg ID CMD Flag Checksum End

$PMTK 001 ,223 ,Flg *Cksum <CR><LF>

Figure 23: Extended Receive Time Command and Response

Extended Receive Time Fields

Field Description

SNR

EXT

EXG

Figure 24: Extended Receive Time Fields

The minimum number of satellites required to have valid ephemeris data. The extend time triggers when the number of satellites with valid ephemeris data falls below this number. The value is 1 to 4.

The minimum SNR of the satellites used for a position ﬁx. The module will not wait for ephemeris data from any satellites whose SNR is below this value.

The extended time in ms to stay on to receive ephemeris data. This value can range from 40000 to 180000.

The minimum time in ms between a subsequent extended receive period. This value can range from 0 to 3600000.

Time

Extend

Time

Extend

Gap

Checksum End

The following example conﬁgures an extended on time to trigger if less than 1 satellite has valid ephemeris data. The satellite must have a signal to noise ratio higher than 30dB–Hz in order to be used. The module will stay on for 180,000ms and will have a gap time of 60,000ms.

$PMTK223,1,30,180000,60000*16<CR><LF>

225 – Receiver Duty Cycle

This command places the module into a duty cycle where it stays on for a period of time and calculates it position then goes to sleep for a period of time. This conserves battery power without the need for an external microcontroller to manage the timing.

Receiver Duty Cycle Command and Response

Command

Start Msg ID Mode

$PMTK 225 ,Mde ,TO ,TS ,CO ,CS *Cksum <CR><LF>

Response

Start Msg ID CMD Flag Checksum End

$PMTK 001 ,225 ,Flg *Cksum <CR><LF>

Figure 25: Receiver Duty Cycle Command and Response

Receiver Duty Cycle Fields

Field Description

Operation Mode

Mde

TO Receiver on time (ms)

TS Receiver standby time (ms)

CR and CS can be null values. In this case the module uses the TO and TS values.

Figure 26: Receiver Duty Cycle Fields

0 = Normal Mode 2 = Duty Cycle Mode 8 = AlwaysLocate

Receiver on time in the event of a cold start (ms). Allows more time for the module to receive ephemeris data in the event of a cold start.

Receiver off time in the event of a cold start (ms). Allows more time for the module to receive ephemeris data in the event of a cold start.

Time

Standby

Time

Cold On

Cold

Checksum End

Sleep

This example sets the mode to duty cycle with an on time of 3s, and off time of 12s, a cold start on time of 18s and a cold start off time of 72s.

$PMTK225,2,3000,12000,18000,72000*15<CR><LF>

The following example sets the mode to normal operation.

$PMTK225,0*2B<CR><LF>

The following example sets the module into AlwaysLocateTM mode.

$PMTK225,8*23<CR><LF>

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22 23

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Page 15

251 – Baud Rate

This command sets the serial port baud rate.

Serial Port Baud Rate Command and Response

Command

Start Msg ID Rate Checksum End

$PMTK 251 ,Rate *Cksum <CR><LF>

Response

Start Msg ID CMD Flag Checksum End

$PMTK 001 ,251 ,Flg *Cksum <CR><LF>

Figure 27: Serial Port Baud Rate Command and Response

Rate = serial port baud rate 0 = default setting (9,600bps) 4800 9600 14400 19200 38400 57600 115200

The following example sets the baud rate to 57,600bps.

$PMTK251,57600*2C<CR><LF>

Position Fix Interval

This conﬁgures the position ﬁx interval. This is the time between when the module calculates its position. This is the same as write message 220.

Position Fix Interval Command and Response

Write Message

Start Msg ID Interval Data Checksum End

$PMTK 300 ,Ival ,0,0,0,0 *Cksum <CR><LF>

Acknowledge Response Message

Start Msg ID CMD Flag Checksum End

$PMTK 001 ,300 ,Flg *Cksum <CR><LF>

Read Message

Start Msg ID Checksum End

$PMTK 400 *36 <CR><LF>

Response Message

Start Msg ID Interval Data Checksum End

$PMTK 500 ,Ival ,0,0,0,0 *Cksum <CR><LF>

Figure 28: Position Fix Interval Command and Response

Ival = the interval time in milliseconds.

The following example sets the interval to 1 second.

$PMTK300,1000,0,0,0,0*1C<CR><LF>

The following example reads the current position ﬁx interval and the module responds with an interval time of 1 second (1,000ms)

$PMTK400*36<CR><LF>

$PMTK500,1000,0,0,0,0*1A<CR><LF>

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24 25

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Page 16

DGPS Source

This enables or disables DGPS mode and conﬁgures its source.

SBAS Enable

This enables and disables SBAS.

DGPS Souce Command and Response

Write Message

Start Msg ID Mode Checksum End

$PMTK 301 ,Mode *Cksum <CR><LF>

Acknowledge Response Message

Start Msg ID CMD Flag Checksum End

$PMTK 001 ,301 ,Flg *Cksum <CR><LF>

Read Message

Start Msg ID Checksum End

$PMTK 401 *37 <CR><LF>

Response Message

Start Msg ID Mode Checksum End

$PMTK 501 ,Mode *Cksum <CR><LF>

Figure 29: DGPS Source Command and Response

Mode = DGPS source mode 0 = No DGPS source 1 = RTCM 2 = WAAS

Differential Global Positioning System (DGPS) enhances GPS by using ﬁxed, ground-based reference stations that broadcast the difference between the positions indicated by the satellite systems and the known ﬁxed positions. The Radio Technical Commission for Maritime Services (RTCM) is an international standards organization that has a standard for DGPS. Wide Area Augmentation System (WAAS) is maintained by the FAA to improve aircraft navigation. This setting automatically switches among WAAS, EGNOS, MSAS and GAGAN when detected in covered regions

SBAS Enable Command and Response

Write Message

Start Msg ID Mode Checksum End

$PMTK 313 ,Mode *Cksum <CR><LF>

Acknowledge Response Message

Start Msg ID CMD Flag Checksum End

$PMTK 001 ,313 ,Flg *Cksum <CR><LF>

Read Message

Start Msg ID Checksum End

$PMTK 413 *34 <CR><LF>

Response Message

Start Msg ID Mode Checksum End

$PMTK 513 ,Mode *Cksum <CR><LF>

Figure 30: SBAS Enable Command and Response

Mode = SBAS Mode 0 = disabled 1 = enabled

A satellite-based augmentation system (SBAS) sends additional information in the satellite transmissions to improve accuracy and reliability. Ground stations at accurately surveyed locations measure the satellite signals or other environmental factors that may impact the signal received by users. Correction information is then sent to the satellites and broadcast to the users. Disabling this feature also disables automatic DGPS.

The following example enables SBAS.

The following example sets the DGPS source to RTCM.

$PMTK301,1*2D<CR><LF>

The following example reads the current DGPS source and the module responds with the DGPS source as RTCM.

$PMTK401*37<CR><LF>

$PMTK501,1*2B<CR><LF>

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26 27

$PMTK313,1*2E<CR><LF>

The following example reads the current SBAS conﬁguration and the module responds with SBAS is enabled.

$PMTK413*34<CR><LF>

$PMTK513,1*28<CR><LF>

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Page 17

NMEA Output Messages

This conﬁgures how often each NMEA output message is output.

Set Datum

This conﬁgures the current datum that is used.

NMEA Output Messages Command and Response

Write Message

Msg

Start

$PMTK 314 ,GLL ,RMC ,VTG ,GGA ,GSA ,GSV ,0,0,0,0,0,0,0,0,0,0,0,0,0, *CK <CR><LF>

Acknowledge Response Message

Start

$PMTK 001 ,314 ,Flg *CK <CR><LF>

Read Message

Start

$PMTK 414 *33 <CR><LF>

Response Message

Start

$PMTK 514 ,GLL ,RMC ,VTG ,GGA ,GSA ,GSV ,0,0,0,0,0,0,0,0,0,0,0,0,0, *CK <CR><LF>

Figure 31: NMEA Output Messages Command and Response

GLL RMC VTG GGA GSA GSV DATA CK End

Msg

CMD Flag CK End

Msg

CK End

Msg

GLL RMC VTG GGA GSA GSV DATA CK End

Each ﬁeld has a value of 1 through 5 which indicates how many position ﬁxes should be between each time the message is output. A 1 conﬁgures the message to be output every position ﬁx. A value of 2 conﬁgures the message to be output every other position ﬁx and a value of 5 conﬁgures it to be output every 5th position ﬁx. This along with message 220 or 300 sets the time between message outputs.

Set Datum Command and Response

Write Message

Start Msg ID Datum Checksum End

$PMTK 330 ,Datum *Cksum <CR><LF>

Acknowledge Response Message

Start Msg ID CMD Flag Checksum End

$PMTK 001 ,330 ,Flg *Cksum <CR><LF>

Read Message

Start Msg ID Checksum End

$PMTK 430 *35 <CR><LF>

Response Message

Start Msg ID Datum Checksum End

$PMTK 530 ,Datum *Cksum <CR><LF>

Figure 32: Set Datum Command and Response

Datum = the datum number to be used.

Reference datums are data sets that describe the shape of the Earth based on a reference point. There are many regional datums based on a convenient local reference point. Different datums use different reference points, so a map used with the receiver output must be based on the same datum. WGS84 is the default world referencing datum.

The module supports 223 different datums. These are listed in Appendix A.

A value of 0 disables the message.

The example below sets all of the messages to be output every ﬁx.

$PMTK314,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0*28<CR><LF>

The following example reads the current message conﬁguration and the module responds that all supported messages are conﬁgured to be output on every position ﬁx.

$PMTK414*33<CR><LF>

$PMTK514,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0*2E<CR><LF>

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28 29

The following example sets the datum to WGS84.

$PMTK330,0*2E<CR><LF>

The following example reads the current datum and the module replies with datum 0, which is WGS84.

$PMTK430*35<CR><LF>

$PMTK530,0*28<CR><LF>

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Page 18

Static Navigation Threshold

This conﬁgures the speed threshold to trigger static navigation. If the measured speed is below the threshold then the module holds the current position and sets the speed to zero.

Static Navigation Threshold Command and Response

Write Message

Start Msg ID Thold Checksum End

$PMTK 386 ,Thold *Cksum <CR><LF>

Acknowledge Response Message

Start Msg ID CMD Flag Checksum End

$PMTK 001 ,386 ,Flg *Cksum <CR><LF>

Read Message

Start Msg ID Checksum End

$PMTK 447 *35 <CR><LF>

Response Message

Start Msg ID Thold Checksum End

$PMTK 527 ,Thold *Cksum <CR><LF>

Enable Ephemeris Prediction

This enables or disables the module’s built-in ephemeris prediction.

Enable Ephemeris Prediction Command and Response

Write Message

Start Msg ID CMD Enable Checksum End

$PMTK 869 ,1 ,Enable *Cksum <CR><LF>

Acknowledge Response Message

Start Msg ID CMD Flag Checksum End

$PMTK 001 ,869 ,Flg *Cksum <CR><LF>

Read Message

Start Msg ID CMD Enable Checksum End

$PMTK 869 ,0 ,Enable *Cksum <CR><LF>

Response Message

Start Msg ID CMD Enable Checksum End

$PMTK 869 ,2 ,Enable *Cksum <CR><LF>

Figure 34: Enable Ephemeris Prediction Command and Response

Figure 33: Static Navigation Threshold Command and Response

Thold = speed threshold, from 0 to 2.0m/s. 0 = disabled.

The following example sets the threshold to 1.2m/s.

$PMTK386,1.2*3E<CR><LF>

The following example reads the static navigation threshold and the module responds with 1.2m/s

$PMTK447*35<CR><LF>

$PMTK527,1.20*03<CR><LF>

This message is formatted slightly differently from the other messages. The same Message ID is used for the read, write and response and the ﬁrst payload ﬁeld (CMD) indicates which type of message it is. A 0 is a read, a 1 is a write and a 2 is a response to a read.

Enable = enable ephemeris prediction 0 = disabled 1 = enabled

The following example enables prediction.

$PMTK869,1,1*35<CR><LF>

The following example reads the conﬁguration.

$PMTK869,0*29<CR><LF>

The module responds with the ﬁrst example if prediction is disabled and the second if it is enabled.

$PMTK869,2,0*37<CR><LF>

$PMTK869,2,1*36<CR><LF>

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Page 19

Typical Applications

VCC

Figure 35 shows the FM Series GPS receiver in a typical application using a passive antenna.

GND

1 2 3 4 5 21

6 7 8 9 10

NC NC 1PPS TX RX GND

NC NC RESET NC NC

VBACKUP

µP

GND

VCC

Figure 35: Circuit Using the FM Series Module with a Passive Antenna

A microcontroller UART is connected to the receiver’s UART for passing data and commands. A 3.3V coin cell battery is connected to the VBACKUP line to provide power to the module’s memory when main power is turned off.

GND

RFIN

GND

VOUT

GND

NC NC NC

VCC

20 19 18 17 16 22

15 14 13 12 11

GND

VCC

GND

Microstrip Details

A transmission line is a medium whereby RF energy is transferred from one place to another with minimal loss. This is a critical factor, especially in high-frequency products like Linx RF modules, because the trace leading to the module’s antenna can effectively contribute to the length of the antenna, changing its resonant bandwidth. In order to minimize loss and detuning, some form of transmission line between the antenna and the module should be used unless the antenna can be placed very close (<1⁄8in) to the module. One common form of transmission line is a coax cable and another is the microstrip. This term refers to a PCB trace running over a ground plane that is designed to serve as a transmission line between the module and the antenna. The width is based on the desired characteristic impedance of the line, the thickness of the PCB and the dielectric constant of the board material. For standard 0.062in thick FR-4 board material, the trace width would be 111 mils. The correct trace width can be calculated for other widths and materials using the information in Figure 37 and examples are provided in Figure 38. Software for calculating microstrip lines is also available on the Linx website.

Trace

Board

Ground plane

Figure 36 shows the module using an active antenna.

VCC

µP

GND

VCC

GND

1 2 3 4 5 21

6 7 8 9 10

NC NC 1PPS TX RX GND

NC NC RESET

NC NC

VBACKUP

GND

RFIN

GND

VOUT

GND

NC NC NC

VCC

20 19 18 17 16 22

15 14 13 12 11

Ferrite Bead

GND

VCC

GND

300Ω

Figure 36: Circuit Using the FM Series Module with a an Active Antenna

A 300Ω ferrite bead is used to put power from VOUT onto the antenna line to power the active antenna.

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32 33

Figure 37: Microstrip Formulas

Example Microstrip Calculations

Dielectric Constant

Width/Height

Ratio (W/d)

4.80 1.8 3.59 50.0

4.00 2.0 3.07 51.0

2.55 3.0 2.12 48.0

Figure 38: Example Microstrip Calculations

Effective Dielectric

Constant

– –

Characteristic

Impedance (Ω)

Page 20

Board Layout Guidelines

The module’s design makes integration straightforward; however, it is still critical to exercise care in PCB layout. Failure to observe good layout techniques can result in a signiﬁcant degradation of the module’s performance. A primary layout goal is to maintain a characteristic 50-ohm impedance throughout the path from the antenna to the module. Grounding, ﬁltering, decoupling, routing and PCB stack-up are also important considerations for any RF design. The following section provides some basic design guidelines which may be helpful.

During prototyping, the module should be soldered to a properly laid-out circuit board. The use of prototyping or “perf” boards will result in poor performance and is strongly discouraged.

The module should, as much as reasonably possible, be isolated from other components on your PCB, especially high-frequency circuitry such as crystal oscillators, switching power supplies, and high-speed bus lines.

Each of the module’s ground pins should have short traces tying immediately to the ground plane through a via.

Bypass caps should be low ESR ceramic types and located directly adjacent to the pin they are serving.

A 50-ohm coax should be used for connection to an external antenna. A 50-ohm transmission line, such as a microstrip, stripline or coplanar waveguide should be used for routing RF on the PCB. The Microstrip Details section provides additional information.

In some instances, a designer may wish to encapsulate or “pot” the product. There is a wide variety of potting compounds with varying dielectric properties. Since such compounds can considerably impact RF performance and the ability to rework or service the product, it is the responsibility of the designer to evaluate and qualify the impact and suitability of such materials.

When possible, separate RF and digital circuits into different PCB regions. Make sure internal wiring is routed away from the module and antenna, and is secured to prevent displacement.

Do not route PCB traces directly under the module. There should not be any copper or traces under the module on the same layer as the module, just bare PCB. The underside of the module has traces and vias that could short or couple to traces on the product’s circuit board.

The Pad Layout section shows a typical PCB footprint for the module. A ground plane (as large and uninterrupted as possible) should be placed on a lower layer of your PC board opposite the module. This plane is essential for creating a low impedance return for ground and consistent stripline performance.

Use care in routing the RF trace between the module and the antenna or connector. Keep the trace as short as possible. Do not pass under the module or any other component. Do not route the antenna trace on multiple PCB layers as vias will add inductance. Vias are acceptable for tying together ground layers and component grounds and should be used in multiples.

Pad Layout

The pad layout diagram in Figure 39 is designed to facilitate both hand and automated assembly.

0.036

(0.92)

0.020

(0.50)

0.028

(0.70)

0.512

(13.00)

0.036

0.050

(1.27)

Figure 39: Recommended PCB Layout

(0.92)

0.050

(1.27)

0.045

(1.15)

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Page 21

Production Guidelines

The module is housed in a hybrid SMD package that supports hand and automated assembly techniques. Since the modules contain discrete components internally, the assembly procedures are critical to ensuring the reliable function of the modules. The following procedures should be reviewed with and practiced by all assembly personnel.

Hand Assembly

Pads located on the bottom of the module are the primary mounting surface (Figure 40). Since these pads are inaccessible during mounting, castellations that run up the side of the module have been provided to facilitate solder wicking to the module’s underside. This allows for very quick hand soldering for prototyping and small volume production. If the recommended pad guidelines have been followed, the pads will protrude slightly past the edge of the module. Use a ﬁne soldering tip to heat the board pad and the castellation, then introduce solder to the pad at the module’s edge. The solder will wick underneath the module, providing reliable attachment. Tack one module corner ﬁrst and then work around the device, taking care not to exceed the times in Figure 41.

Soldering Iron Tip

Solder

PCB Pads

Figure 40: Soldering Technique

Castellations

Reﬂow Temperature Proﬁle

The single most critical stage in the automated assembly process is the reﬂow stage. The reﬂow proﬁle in Figure 42 should not be exceeded because excessive temperatures or transport times during reﬂow will irreparably damage the modules. Assembly personnel need to pay careful attention to the oven’s proﬁle to ensure that it meets the requirements necessary to successfully reﬂow all components while still remaining within the limits mandated by the modules. The ﬁgure below shows the recommended reﬂow oven proﬁle for the modules.

Peak: 240+0/-5°C

220°C

Preheat:

150 - 200°C

120 - 150sec

2 - 4°C/sec

30°C

Figure 42: Maximum Reﬂow Temperature Proﬁle

2 - 3°C/sec

25 - 35sec

60 - 80sec

Warning: Pay attention to the absolute maximum solder times.

Absolute Maximum Solder Times

Hand Solder Temperature: +427ºC for 10 seconds for lead-free alloys

Reﬂow Oven: +240°C max (see Figure 42)

Figure 41: Absolute Maximum Solder Times

Automated Assembly

For high-volume assembly, the modules are generally auto-placed. The modules have been designed to maintain compatibility with reﬂow processing techniques; however, due to their hybrid nature, certain aspects of the assembly process are far more critical than for other component types. Following are brief discussions of the three primary areas where

caution must be observed.

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36 37

Shock During Reﬂow Transport

Since some internal module components may reﬂow along with the components placed on the board being assembled, it is imperative that the modules not be subjected to shock or vibration during the time solder is liquid. Should a shock be applied, some internal components could be lifted from their pads, causing the module to not function properly.

Washability

The modules are wash-resistant, but are not hermetically sealed. Linx recommends wash-free manufacturing; however, the modules can be subjected to a wash cycle provided that a drying time is allowed prior to applying electrical power to the modules. The drying time should be sufﬁcient to allow any moisture that may have migrated into the module to evaporate, thus eliminating the potential for shorting damage during power-up or testing. If the wash contains contaminants, the performance may be adversely affected, even after drying.

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Page 22

Master Development System

The FM Series Master Development System provides all of the tools necessary to evaluate the FM Series GPS receiver module. The system includes a fully assembled development board, an active antenna, development software and full documentation.

Figure 43: The FM Series Master Development System

The development board includes a power supply, a prototyping area for custom circuit development, and an OLED display that shows the GPS data without the need for a computer. A USB interface is also included for use with a PC running custom software or the included development software.

Resources

Support

For technical support, product documentation, application notes, regulatory guidelines and software updates, visit www.linxtechnologies.com

RF Design Services

For customers who need help implementing Linx modules, Linx offers design services including board layout assistance, programming, certiﬁcation advice and packaging design. For more complex RF solutions, Apex Wireless, a division of Linx Technologies, creates optimized designs with RF components and ﬁrmware selected for the customer’s application. Call +1 800 736 6677 (+1 541 471 6256 if outside the United States) for more information.

Antenna Factor Antennas

Linx’s Antenna Factor division has the industry’s broadest selection of antennas for a wide variety of applications. For customers with specialized needs, custom antennas and design services are available along with simulations of antenna performance to speed development. Learn more at www.linxtechnologies. com.

Figure 44: The Master Development System Software

The Master Development System software enables conﬁguration of the receiver and displays the satellite data output by the receiver. The software can select from among all of the supported NMEA protocols for display of the data.

Full documentation for the board and software is included in the development system, making integration of the module straightforward.

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Page 23

Appendix A

The following datums are supported by the FM Series.

FM Series GPS Receiver Supported Datums

Number Datum Region

0 WGS1984 International

1 Tokyo Japan

2 Tokyo

3 User Setting User Setting

4 Adindan Burkina Faso

5 Adindan Cameroon

6 Adindan Ethiopia

7 Adindan Mali

8 Adindan Mean for Ethiopia, Sudan

9 Adindan Senegal

10 Adindan Sudan

11 Afgooye Somalia

12 Ain El Abd1970 Bahrain

13 Ain El Abd1970 Saudi Arabia

14 American Samoa1962 American Samoa Islands

15 Anna 1 Astro1965 Cocos Island

16 Antigua Island Astro1943 Antigua(Leeward Islands)

17 Arc1950 Botswana

18 Arc1950 Burundi

19 Arc1950 Lesotho

20 Arc1950 Malawi

21 Arc1950

22 Arc1950 Swaziland

23 Arc1950 Zaire

24 Arc1950 Zambia

25 Arc1950 Zimbabwe

26 Arc1960 Mean For Kenya Tanzania

27 Arc1960 Kenya

28 Arc1960 Tanzania

29 Ascension Island1958 Ascension Island

30 Astro Beacon E 1945 Iwo Jima

Mean for Japan, South Korea, Okinawa

Mean for Botswana, Lesotho, Malawi, Swaziland, Zaire, Zambia, Zimbabwe

FM Series GPS Receiver Supported Datums

Number Datum Region

31 Astro Dos 71/4 St Helena Island

32 Astro Tern Island (FRIG) 1961 Tern Island

33 Astronomical Station 1952 Marcus Island

34 Australian Geodetic 1966 Australia, Tasmania

35 Australian Geodetic 1984 Australia, Tasmania

36 Ayabelle Lighthouse Djibouti

37 Bellevue (IGN) Efate and Erromango Islands

38 Bermuda 1957 Bermuda

39 Bissau Guuinea-Bissau

40 Bogota Observatory Colombia

41 Bukit Rimpah Indonesia (Bangka and Belitung Ids)

42 Camp Area Astro Antarctica (McMurdi Camp Area)

43 Campo Inchauspe Argentina

44 Canton Astro1966 Phoenix Island

45 Cape South Africa

46 Cape Canaveral Bahamas, Florida

47 Carthage Tunisia

48 Chatham Island Astro1971 New Zealand (Chatham Island)

49 Chua Astro Paraguay

50 Corrego Alegre Brazil

51 Dabola Guinea

52 Deception Island Deception Island, Antarctica

53 Djakarta (Batavia) Indonesia (Sumatra)

54 Dos 1968 New Georgia Islands (Gizo Island)

55 Easter Island 1967 Easter Island

56 Estonia Coordinate System1937 Estonia

57 European 1950 Cyprus

58 European 1950 Egypt

59 European 1950

60 European 1950

61 European 1950 Finland, Norway

62 European 1950 Greece

63 European 1950 Iran

England, Channel Islands, Scotland, Shetland Islands

England, Ireland, Scotland, Shetland Islands

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FM Series GPS Receiver Supported Datums

Number Datum Region

64 European 1950 Italy (Sardinia)

65 European 1950 Italy (Sicily)

66 European 1950 Malta

Mean For Austria, Belgium, Denmark,

67 European 1950

68 European 1950

69 European 1950

70 European 1950 Portugal, Spain

71 European 1950 Tunisia,

72 European 1979

73 Fort Thomas 1955 Nevis St Kitts (Leeward Islands)

74 Gan 1970 Republic Of Maldives

75 Geodetic Dataum 1970 New Zealand

76 Graciosa Base SW1948

77 Guam1963 Guam

78 Gunung Segara Indonesia (Kalimantan)

79 Gux l Astro Guadalcanal Island

80 Herat North Afghanistan

81 Hermannskogel Datum Croatia-Serbia, Bosnia-Herzegoivna

82 Hjorsey 1955 Iceland

83 Hongkong 1963 Hong Kong

84 Hu Tzu Shan Taiwan

85 Indian Bangladesh

86 Indian India, Nepal

87 Indian Pakistan

88 Indian 1954 Thailand

89 Indian 1960 Vietnam (Con Son Island)

90 Indian 1960 Vietnam (Near 16 deg N)

91 Indian 1975 Thailand

92 Indonesian 1974 Indonesian

Finland, France, W Germany, Gibraltar, Greece, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland

Mean For Austria, Denmark, France, W Germany, Netherland, Switzerland

Mean For Iraq, Israel, Jordan, Lebanon, Kuwait, Saudi Arabia, Syria

Mean For Austria, Finland ,Netherlands ,Norway, Spain, Sweden, Switzerland

Azores (Faial, Graciosa, Pico, Sao, Jorge, Terceria)

FM Series GPS Receiver Supported Datums

Number Datum Region

93 Ireland 1965 Ireland

94 ISTS 061 Astro 1968 South Georgia Islands

95 ISTS 073 Astro 1969 Diego Garcia

96 Johnston Island 1961 Johnston Island

97 Kandawala Sri Lanka

98 Kerguelen Island 1949 Kerguelen Island

99 Kertau 1948 West Malaysia and Singapore

100 Kusaie Astro 1951 Caroline Islands

101 Korean Geodetic System South Korea

102 LC5 Astro 1961 Cayman Brac Island

103 Leigon Ghana

104 Liberia 1964 Liberia

105 Luzon Philippines (Excluding Mindanao)

106 Luzon Philippines (Mindanao)

107 M'Poraloko Gabon

108 Mahe 1971 Mahe Island

109 Massawa Ethiopia (Eritrea)

110 Merchich Morocco

111 Midway Astro 1961 Midway Islands

112 Minna Cameroon

113 Minna Nigeria

114 Montserrat Island Astro 1958 Montserrat (Leeward Island)

115 Nahrwan Oman (Masirah Island)

116 Nahrwan Saudi Arabia

117 Nahrwan United Arab Emirates

118 Naparima BWI Trinidad and Tobago

119 North American 1927 Alaska (Excluding Aleutian Ids)

120 North American 1927

121 North American 1927

122 North American 1927

123 North American 1927 Bahamas (San Salvador Islands)

124 North American 1927 Canada (Alberta, British Columbia)

125 North American 1927 Canada (Manitoba, Ontario)

Alaska (Aleutian Ids East of 180 degW)

Alaska (Aleutian Ids West of 180 degW)

Bahamas (Except San Salvador Islands)

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Page 25

FM Series GPS Receiver Supported Datums

Number Datum Region

126 North American 1927

127 North American 1927

128 North American 1927 Canada (Yukon)

129 North American 1927 Canal Zone

130 North American 1927 Cuba

131 North American 1927 Greenland (Hayes Peninsula)

132 North American 1927

133 North American 1927

134 North American 1927 Mean for Canada

135 North American 1927 Mean for Conus

136 North American 1927

137 North American 1927

138 North American 1927 Mexico

139 North American 1983 Alaska (Excluding Aleutian Ids)

140 North American 1983 Aleutian Ids

141 North American 1983 Canada

142 North American 1983 Conus

143 North American 1983 Hawaii

144 North American 1983 Mexico, Central America

145 North Sahara 1959 Algeria

146 Observatorio Meteorologico 1939 Azores (Corvo and Flores Islands)

147 Old Egyptian 1907 Egypt

148 Old Hawaiian Hawaii

149 Old Hawaiian Kauai

150 Old Hawaiian Maui

151 Old Hawaiian Mean for Hawaii, Kauai, Maui, Oahu

152 Old Hawaiian Oahu

153 Oman Oman

Canada (New Brunswick, Newfoundland, Nova Scotia, Quebec)

Canada (Northwest Territories, Saskatchewan)

Mean For Antigua, Barbados, Barbuda, Caicos Islands, Cuba, Dominican, Grand Cayman, Jamaica, Turks Islands

Mean for Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua

Mean for Conus (East of Mississippi, River Including Louisiana, Missouri, Minnesota)

Mean for Conus (West of Mississippi, River Excluding Louisiana, Minnesota, Missouri)

FM Series GPS Receiver Supported Datums

Number Datum Region

154 Ordnance Survey Great Britain 1936 England

155 Ordnance Survey Great Britain 1936 England, Isle of Man, Wales

156 Ordnance Survey Great Britain 1936

157 Ordnance Survey Great Britain 1936 Scotland, Shetland Islands

158 Ordnance Survey Great Britain 1936 Wales

159 Pico de las Nieves Canary Islands

160 Pitcairn Astro 1967 Pitcairn Island

161 Point 58 Mean for Burkina Faso and Niger

162 Pointe Noire 1948 Congo

163 Porto Santo 1936 Porto Santo, Madeira Islands

164 Provisional South American 1956 Bolivia

165 Provisional South American 1956 Chile (Northern Near 19 deg S)

166 Provisional South American 1956 Chile (Southern Near 43 deg S)

167 Provisional South American 1956 Colombia

168 Provisional South American 1956 Ecuador

169 Provisional South American 1956 Guyana

170 Provisional South American 1956

171 Provisional South American 1956 Peru

172 Provisional South American 1956 Venezuela

173 Provisional South Chilean 1963 Chile (Near 53 deg S) (Hito XVIII)

174 Puerto Rico Puerto Rico, Virgin Islands

175 Pulkovo 1942 Russia

176 Qatar National Qatar

177 Qornoq Greenland (South)

178 Reunion Mascarene Island

179 Rome 1940 Italy (Sardinia)

180 S-42 (Pulkovo 1942) Hungary

181 S-42 (Pulkovo 1942) Poland

182 S-42 (Pulkovo 1942) Czechoslavakia

183 S-42 (Pulkovo 1942) Lativa

184 S-42 (Pulkovo 1942) Kazakhstan

185 S-42 (Pulkovo 1942) Albania

186 S-42 (Pulkovo 1942) Romania

187 S-JTSK Czechoslavakia (Prior 1 Jan1993)

Mean For England, Isle of Man, Scotland, Shetland Island, Wales

Mean for Bolivia Chile, Colombia, Ecuador, Guyana, Peru, Venezuela

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FM Series GPS Receiver Supported Datums

Number Datum Region

188 Santo (Dos) 1965 Espirito Santo Island

189 Sao Braz Azores (Sao Miguel, Santa Maria Ids)

190 Sapper Hill 1943 East Falkland Island

191 Schwarzeck Namibia

192 Selvagem Grande 1938 Salvage Islands

193 Sierra Leone 1960 Sierra Leone

194 South American 1969 Argentina

195 South American 1969 Bolivia

196 South American 1969 Brazil

197 South American 1969 Chile

198 South American 1969 Colombia

199 South American 1969 Ecuador

200 South American 1969 Ecuador (Baltra, Galapagos)

201 South American 1969 Guyana

Mean For Argentina, Bolivia, Brazil,

202 South American 1969

203 South American 1969 Paraguay

204 South American 1969 Peru

205 South American 1969 Trinidad and Tobago

206 South American 1969 Venezuela

207 South Asia Singapore

208 Tananarive Observatory 1925 Madagascar

209 Timbalai 1948 Brunei, E Malaysia (Sabah Sarawak)

210 Tokyo Japan

211 Tokyo

212 Tokyo Okinawa

213 Tokyo South Korea

214 Tristan Astro 1968 Tristam Da Cunha

215 Viti Levu 1916 Fiji (Viti Levu Island)

216 Voirol 1960 Algeria

217 Wake Island Astro 1952 Wake Atoll

218 Wake-Eniwetok 1960 Marshall Islands

219 WGS 1972 Global Deﬁnition

Chile, Colombia, Ecuador, Guyana, Paraguay, Peru, Trinidad and Tobago, Venezuela

Mean for Japan, South Korea, Okinawa

FM Series GPS Receiver Supported Datums

Number Datum Region

220 WGS 1984 Global Deﬁnition

221 Yacare Uruguay

222 Zanderij Suriname

Figure 45: Supported Datums

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Linx Technologies

159 Ort Lane

Merlin, OR, US 97532

Phone: +1 541 471 6256

Fax: +1 541 471 6251

www.linxtechnologies.com

Disclaimer

Linx Technologies is continually striving to improve the quality and function of its products. For this reason, we reserve the right to make changes to our products without notice. The information contained in this Data Guide is believed to be accurate as of the time of publication. Speciﬁcations are based on representative lot samples. Values may vary from lot-to-lot and are not guaranteed. “Typical” parameters can and do vary over lots and application. Linx Technologies makes no guarantee, warranty, or representation regarding the suitability of any product for use in any speciﬁc application. It is the customer’s responsibility to verify the suitability of the part for the intended application. NO LINX PRODUCT IS INTENDED FOR USE IN ANY APPLICATION WHERE THE SAFETY

OF LIFE OR PROPERTY IS AT RISK.

Linx Technologies DISCLAIMS ALL WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL LINX TECHNOLOGIES BE LIABLE FOR ANY OF CUSTOMER’S INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING IN ANY WAY FROM ANY DEFECTIVE OR NON-CONFORMING PRODUCTS OR FOR ANY OTHER BREACH OF CONTRACT BY LINX TECHNOLOGIES. The limitations on Linx Technologies’

liability are applicable to any and all claims or theories of recovery asserted by Customer, including, without limitation, breach of contract, breach of warranty, strict liability, or negligence. Customer assumes all liability (including, without limitation, liability for injury to person or property, economic loss, or business interruption) for all claims, including claims from third parties, arising from the use of the Products. The Customer will indemnify, defend, protect, and hold harmless Linx Technologies and its ofﬁcers, employees, subsidiaries, afﬁliates, distributors, and representatives from and against all claims, damages, actions, suits, proceedings, demands, assessments, adjustments, costs, and expenses incurred by Linx Technologies as a result of or arising from any Products sold by Linx Technologies to Customer. Under no conditions will Linx Technologies be responsible for losses arising from the use or failure of the device in any application, other than the repair, replacement, or refund limited to the original product purchase price. Devices described in this publication may contain proprietary, patented, or copyrighted techniques, components, or materials. Under no circumstances shall any user be conveyed any license or right to the use or ownership of such items.

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