RM Series
GPS Receiver Module
Data Guide
Warning:
Linx radio frequency (“RF”) products may be
used 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. No Linx
Technologies product is intended for use in any application without
redundancies where the safety of life or property is at risk.
The customers and users of devices and machinery controlled with
RF products must understand and must use all appropriate safety
procedures in connection with the devices, including without limitation,
using appropriate safety procedures to prevent inadvertent triggering by
the user of the device and using appropriate security codes to prevent
triggering of the remote controlled machine or device by users of other
remote controllers.
All RF products are susceptible to RF interference that can prevent
communication.
Lack of good sight of the GPS satellites (open sky)
can affect the accuracy of a position fix or prevent a fix entirely.
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.
!
Table of Contents
1
Description
1
Features
1
Applications Include
2
Ordering Information
2
Absolute Maximum Ratings
2
Electrical Specifications
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
8
Antenna Considerations
9
Power Control
10
Slow Start Time
11
Interfacing with NMEA Messages
12
NMEA Output Messages
13
14
14
15
16
17
17
20
GGA – Global Positioning System Fix Data
GLL – Geographic Position – Latitude / Longitude
GSA – GPS DOP and Active Satellites
GSV – GPS Satellites in View
RMC – Recommended Minimum Specific GPS Data
VTG – Course Over Ground and Ground Speed
Start-up Response
101 – Hot Re-start
102 – Warm Re-start
103 – Cold Re-start
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.
18
Input Messages
A large-print version of this document is available at
www.linxtechnologies.com.
20
20
20
20
21
22
23
24
25
26
27
28
29
30
104 – Restore Default Configuration
161 – Standby Mode
220 – Position Fix Interval
223 – Extended Receive Time
225 – Receiver Duty Cycle
251 – Baud Rate
Position Fix Interval
DGPS Source
SBAS Enable
NMEA Output Messages
Set Datum
Static Navigation Threshold
RM Series GPS Receiver
Data Guide
Description
The RM Series GPS receiver module is a
self-contained high-performance Global
Positioning System receiver. Based on
the MediaTek MT3337 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.
0.591 in
(15.00 mm)
0.512 in
(13.00 mm)
RXM-GPS-RM
LOT GRxxxx
0.087 in
(2.20 mm)
31
Typical Applications
32
Master Development System
33
Microstrip Details
34
Board Layout Guidelines
35
Pad Layout
36
Production Guidelines
36
Hand Assembly
36
Automated Assembly
37
37
37
Reflow Temperature Profile
Shock During Reflow Transport
Washability
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 RM Series easy to
integrate, even by engineers without previous RF or GPS experience.
Figure 1: Package Dimensions
38
Appendix A
46
Resources
46
46
46
Support
RF Design Services
Antenna Factor Antennas
Features
•
•
•
•
•
•
MediaTek chipset
High sensitivity (–161dBm)
Fast TTFF at low signal levels
±11ns 1PPS accuracy
Battery-backed SRAM
No programming necessary
•
•
•
•
•
No external RF components
needed (except an antenna)
No production tuning
UART serial interface
Power control features
Compact SMD package
47
Notes
Applications Include
•
•
•
Positioning and Navigation
Location and Tracking
Security/Loss-Prevention
•
•
•
Surveying
Logistics
Fleet Management
–
1
–
Revised 10/17/2013
Ordering Information
Ordering Information
Part Number
RXM-GPS-RM-x
MDEV-GPS-RM
EVM-GPS-RM
Description
RM Series GPS Receiver Module
RM Series GPS Receiver Master Development System
RM Series Evaluation Module
RM Series GPS Receiver Specifications
Parameter
VOUT Output Voltage
VOUT Output Current
Output Low Voltage
Output High Voltage
Output Low Current
Output High Current
Input Low Voltage
Input High Voltage
Input Low Current
Input High Current
Minimum RESET Pulse
+4.3
+4.3
50
−40 to +85
−40 to +85
VDC
VDC
mA
ºC
ºC
Antenna Port
RF Impedance
Receiver Section
Receiver Sensitivity
Tracking
Cold Start
Acquisition Time
Hot Start (Open Sky)
Hot Start (Indoor)
Cold Start
Position Accuracy
Autonomous
SBAS
1PPS Accuracy
Typ.
3.3
Max.
4.3
44
14
12
0.135
V
BAT
I
BAT
–
2
–
2.0
6
4.3
Units
VDC
mA
mA
mA
mA
VDC
µA
2
1
1
1
1
Notes
Altitude
Velocity
V
CC
l
CC
3.0
Chipset
Frequency
Channels
Update Rate
Protocol Support
1.
2.
3.
-11
Min.
1
30
32
3
2.5
11
50,000
515
MediaTek MT3337
L1 1575.42MHz, C/A code
22 tracking, 66 acquisition
1Hz default, up to 10Hz
NMEA 0183 ver 3.01
s
s
s
m
m
ns
m
m/s
–161
–143
dBm
dBm
R
IN
50
Ω
Symbol
V
OUT
I
OUT
V
OL
V
OH
I
OL
I
OH
V
IL
V
IH
I
IL
I
IH
T
RST
–0.3
2.0
–1
–1
1
2.4
2.0
2.0
0.8
3.6
1
1
Min.
2.7
Typ.
2.8
Max.
2.9
30
0.4
V
CC
mA
mA
VDC
VDC
µA
µA
ms
3
3
Units
VDC
mA
VDC
1
Notes
x = “T” for Tape and Reel, “B” for Bulk
Reels are 1,500 pieces. Quantities less than 1,500 pieces are supplied in bulk
Figure 2: Ordering Information
Absolute Maximum Ratings
Absolute Maximum Ratings
Supply Voltage V
CC
Input Battery Backup Voltage
VCC_RF Output Current
Operating Temperature
Storage Temperature
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 Specifications
RM Series GPS Receiver Specifications
Parameter
Power Supply
Operating Voltage
Supply Current
Peak
Acquisition
Tracking
Standby
Backup Battery Voltage
Backup Battery Current
Symbol
V
CC
= 3.3V, without active antenna, position fix is available
V
CC
= 0V
No pull-up or pull-down on the lines
Figure 4: Electrical Specifications
–
3
–
Pin Assignments
1
2
3
4
5
21
6
7
8
9
10
NC
NC
1PPS
TX
RX
GND
NC
NC
RESET
NC
NC
GND
RFIN
GND
VOUT
NC
GND
NC
NC
NC
VCC
VBACKUP
20
19
18
17
16
22
15
14
13
12
11
A Brief Overview of GPS
The Global Positioning System (GPS) is a U.S.-owned utility that freely and
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.
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.
Figure 5: RM Series GPS Receiver Pinout (Top View)
Pin Descriptions
Pin Descriptions
Pin Number
1, 2, 6, 7, 9,
10, 13, 14,
15, 16
3
4
5
8
11
12
17
18, 20, 21, 22
19
Name
NC
1PPS
TX
RX
RESET
VBACKUP
VCC
VOUT
GND
RFIN
I/O
−
O
O
I
I
P
P
O
P
I
Description
No electrical connection
1 Pulse Per Second
Serial output (default NMEA)
Serial input (default NMEA)
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.
Supply Voltage
2.8V output for an active antenna
Ground
GPS RF signal input
Figure 6: RM Series GPS Receiver Pin Descriptions
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4
–
–
5
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