Garmin 15 H Series User manual

GPS 15xH/15xL
TECHNICAL
SPECIFICATIONS
190-00266-03_0B
December 2023

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support.garmin.com

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TABLE OF CONTENTS
1Introduction ........................................................Error! Bookmark not defined.
1.1 Caution................................................................................Error! Bookmark not defined.
1.2 Limited Warranty .................................................................Error! Bookmark not defined.
1.3 Overview ............................................................................................................................. 6
1.4 Features .............................................................................................................................. 7
1.5 Technical Specifications...................................................................................................... 7
1.5.1 Physical Characteristics...........................................................................................................7
1.5.2 Electrical Characteristics..........................................................................................................8
1.5.3 Environmental Characteristics .................................................................................................8
1.5.4 GPS Performance....................................................................................................................8
1.5.5 Interfaces .................................................................................................................................8
1.5.6 Antenna Specifications ............................................................................................................9
2GPS 15xH/15xL Wire Descriptions and Wiring Diagrams ........................10
2.1 GPS 15xH/15xL Wire Descriptions ................................................................................... 10
2.2 GPS 15xH/15xL Wiring Diagrams..................................................................................... 11
3Mechanical Characteristics & Mounting ....................................................11
4GPS 15xH/15xL Software Interface.............................................................13
4.1 Received NMEA 0183 Sentences..................................................................................... 13
4.1.1 Almanac Information (ALM) ...................................................................................................13
4.1.2 Sensor Initialization Information (PGRMI)..............................................................................15
4.1.3 Sensor Configuration Information (PGRMC)..........................................................................15
4.1.4 Additional Sensor Configuration Information (PGRMC1) .......................................................16
4.1.5 Output Sentence Enable/Disable (PGRMO) ..........................................................................16
4.2 Transmitted NMEA 0183 Sentences................................................................................. 17
4.2.1 Sentence Transmission .........................................................................................................17
4.2.2 Transmitted Time...................................................................................................................18
4.2.3 Global Positioning System Almanac Data (ALM)...................................................................19
4.2.4 Global Positioning System Fix Data (GGA) ...........................................................................19
4.2.5 GPS DOP and Active Satellites (GSA) ..................................................................................19
4.2.6 GPS Satellites in View (GSV) ................................................................................................20
4.2.7 Recommended Minimum Specific GPS/TRANSIT Data (RMC).............................................20
4.2.8 Track Made Good and Ground Speed (VTG) ........................................................................20
4.2.9 Geographic Position (GLL) ....................................................................................................20
4.2.10Estimated Error Information (PGRME)...................................................................................21
4.2.11GPS Fix Data Sentence (PGRMF) ........................................................................................21
4.2.12Map Datum (PGRMM) ...........................................................................................................21
4.2.13Sensor Status Information (PGRMT) .....................................................................................23
4.2.143D Velocity Information (PGRMV) .........................................................................................23
4.2.15DGPS Beacon Information (PGRMB) ....................................................................................23
Appendix A: Earth Datum List .........................................................................24
Appendix B: Garmin Binary Output Format....................................................27
Appendix C: Changing the Baud Rate in Garmin Mode.................................30

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Appendix D: Ephemeris Data download (Programming Example) ...............31
Synopsis ..........................................................................................................................................31
Garmin Binary Format Review.........................................................................................................31
Ephemeris Download Procedure .....................................................................................................32
Appendix E: GPS 15xH/15xL Windows Serial Mouse Issue ..........................36
Appendix F: Sensor Configuration Software..................................................38
Downloading the Sensor Configuration Software ............................................................................38
Selecting a Model ............................................................................................................................38
Connecting to the Sensor ................................................................................................................38
File Menu .........................................................................................................................................39
Comm Menu ....................................................................................................................................39
Config Menu ....................................................................................................................................39
View Menu .......................................................................................................................................40
Help Menu .......................................................................................................................................40
LIST OF TABLES AND FIGURES
Table 1: GPS 15xH/15xL Wire Descriptions....................................Error! Bookmark not defined.
Figure 1: Computer Serial Port Interconnection.............................................................................11
Figure 2: PDA Serial Port Interconnection.....................................................................................11
Figure 3: Basic NMEA Device Interconnection..............................................................................11
Figure 4: GPS 15xH-F & 15xL-F Dimensions ................................................................................12
Figure 5: GPS 15xH-W & 15xL-W Outline Drawing.......................................................................12
Table 2: NMEA 0183 Output Sentence Order and Size ................................................................18
Table 3: Characters per Second for Available Baud Rates ...........................................................18

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1 INTRODUCTION
1.1 CAUTION
The GPS system is operated by the government of the United States, which is solely responsible
for its accuracy and maintenance. The GLONASS system is operated by the government of
Russia, which is solely responsible for its accuracy and maintenance. Although the device is a
precision electronic NAVigation AID (NAVAID), any NAVAID can be misused or misinterpreted,
and therefore become unsafe. Use these products at your own risk. To reduce the risk, carefully
review and understand all aspects of these Technical Specifications before using the device.
When in actual use, carefully compare indications from the GPS to all available navigation
sources including the information from other NAVAIDs, visual sightings, charts, etc. For safety,
always resolve any discrepancies before continuing navigation.
1.2 FCC COMPLIANCE
This device complies with 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 equipment has been tested and found to comply with the limits for a Class B digital device,
pursuant to part 15 of the FCC rules. These limits are designed to provide reasonable protection
against harmful interference in a residential installation. This equipment generates, uses, and can
radiate radio frequency energy and may cause harmful interference to radio communications if
not installed and used in accordance with the instructions. However, there is no guarantee that
interference will not occur in a particular installation. If this equipment does cause harmful
interference to radio or television reception, which can be determined by turning the equipment
off and on, the user is encouraged to try to correct the interference by one of the following
measures:
•Reorient or relocate the receiving antenna.
•Increase the separation between the equipment and the receiver.
•Connect the equipment into an outlet on a circuit different from that to which the receiver
is connected.
•Consult the dealer or an experienced radio/TV technician for help.
This product does not contain any user-serviceable parts. Repairs should only be made by an
authorized Garmin service center. Unauthorized repairs or modifications could result in
permanent damage to the equipment, and void your warranty and your authority to operate this
device under Part 15 regulations.
1.3 LIMITED WARRANTY
The Garmin standard limited warranty applies to this device. For more information, go to
garmin.com/support/warranty.
1.4 OVERVIEW
The GPS 15xH and GPS 15xL sensor boards are designed for a broad spectrum of OEM
(Original Equipment Manufacturer) system applications. Based on the proven technology found in
other Garmin GPS receivers, the GPS 15xH/15xL tracks multiple satellites at a time while
providing fast time-to-first-fix, precise navigation updates, and low power consumption. The GPS
15xH/15xL includes the capability of Wide Area Augmentation System (WAAS) differential GPS.
The GPS 15xH/15xL requires minimal additional components to be supplied by an OEM or
system integrator. A minimum system must provide the GPS with a source of power, an active
GPS antenna, and a clear view of the GPS satellites. The system may communicate with the
GPS 15xH/15xL through its RS-232 asynchronous serial port. End-user interfaces, such as
keyboards and displays, are the responsibility of the application designer.

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1.5FEATURES
•GPS receiver tracks and uses multiple satellites for fast, accurate positioning and velocity
estimates.
•Compact, rugged design ideal for applications with minimal space.
•May be remotely mounted in an out-of-the-way location.
•User initialization is not required. Once installed, this device automatically produces
navigation data.
•On-board backup battery to maintain the non-volatile SRAM and real-time clock for up to 21
days.
•Provision for external power to maintain the charge on the backup battery.
•Configurable parameters include expected position, current time and date, and preferred
position fix type (2D, 3D, or automatic).
1.6 TECHNICAL SPECIFICATIONS
Specifications are subject to change without notice.
1.6.1 Physical Characteristics
1.6.1.1 Size
1.400in. (35.56 mm) wide x 1.805in. (45.85 mm) long x 0.327in. (8.31 mm) high
1.6.1.2 Weight
•GPS 15xH: 0.53 oz. (15.0 g)
•GPS 15xL: 0.50 oz. (14.1 g)
1.6.1.3 Available Connector Options
GPS 15xH-F and GPS 15xL-F: 8-pin LIF (Low Insertion Force) flex connector, 1-millimeter pitch.
For use with common 1-mm pitch, 8-conductor flex cable,
available as Garmin Part Number 310-00040-01. This flex cable
mates with common 1 mm pitch, 8-pin flex connectors, such as
Garmin part number 330-00346-08 or Molex Part Number
52793-0890. Refer to the Molex Web site at www.molex.com.
GPS 15xH-W and GPS 15xL-W:8-pin JST connector, 1-mm pitch. Mating wire harness included
(Garmin Part Number 325-00118-01). The connector housing
used on this harness is equivalent to JST Part Number SHR-
08V-S-B. The 8-wire crimp socket is equivalent to JST Part
Number SSH-003T-P0.2. Refer to the JST Web site at
www.jst.com.
1.6.1.4 Antenna Connector
The GPS 15xH and GPS 15xL series products provide an MCX female connector for connection
to an active GPS antenna. The antenna should be terminated in an MCX male connector. A
suitable antenna is Garmin’s GA 25 MCX (Garmin Part Number 010-10702-00). Other antennas
that are terminated in male BNC connectors may be adapted for use with the GPS 15xH and
GPS 15xL series products by using a Garmin MCX to BNC Adapter Cable (Garmin Part Number
010-10121-00).

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1.6.2 Electrical Characteristics
1.6.2.1 Input Voltage
•GPS 15H: 8.0 Vdc to 40 Vdc unregulated
•GPS 15L: 3.3 Vdc to 5.4 Vdc (must have less than 100 mV peak-to-peak ripple)
1.6.2.2 Input Current
•GPS 15H: 60 mA peak, 50 mA nominal @ 8.0 Vdc
40 mA peak, 33 mA nominal @ 12 Vdc
15 mA peak, 12 mA nominal @ 40 Vdc
•GPS 15L: 100 mA peak, 85 mA nominal @ 3.3 to 5.0 Vdc
1.6.2.3 GPS Receiver Sensitivity
-185 dBW minimum
1.6.3 Environmental Characteristics
•Operating Temperature: From -22° to 176°F (from -30° to +80°C)
•Storage Temperature: From -40° to 194°F (from -40° to +90°C)
1.6.4 GPS Performance
1.6.4.1 Receiver
WAAS-enabled GPS receiver continuously tracks and uses multiple satellites to compute and
update your position.
1.6.4.2 Acquisition Times
•Reacquisition: Less than 2 seconds
•Hot: Approx. 1 second (all data known)
•Warm: Approx. 38 seconds (initial position, time, and almanac known; ephemeris
unknown)
•Cold: Approx. 45 seconds
1.6.4.3 Update Rate
1 second default; NMEA 0183 output interval configurable from 1 to 900 seconds in 1-second
increments
1.6.4.4 Accuracy
•GPS Standard Positioning Service (SPS)
Position: < 15 meters, 95% typical (100 meters with Selective Availability on)
Velocity: 0.1 knot RMS steady state DGPS (USCG/RTCM)
Position: 3-5 meters, 95% typical
Velocity: 0.1 knot RMS steady state
•DGPS (WAAS)
Position: <3 meters, 95% typical
Velocity: 0.1 knot RMS steady state
•PPS Time: ±1 microsecond at rising edge of MPO pulse (subject to Selective Availability)
•Dynamics: 999 knots velocity (only limited at altitude greater than 60,000 feet), 3g dynamics
1.6.5 Interfaces
1.6.5.1 GPS 15xH/15xL Electrical Characteristics
•True RS-232 output (Port 2 output not used at time of publication), asynchronous serial input
compatible with RS-232 or TTL voltage levels, RS-232 polarity.
•Factory setting is 4800 baud. User-selectable baud: 4800, 9600, 19200, 38400.

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1.6.6 Antenna Specifications
The active antenna used with the GPS 15xH/15xL should have the following specifications:
Gain: Antenna should provide between 10 dB to 30 dB net gain between the
antenna feed point and the connection to the GPS 15xH/15xL. All
amplifier gains, filter losses, cable losses, etc. must be considered
when calculating the gain.
RF Connection: GPS 15xH/15xL RF Connection: MCX Female connector (on the
GPS 15xH/15xL board)
Antenna Connection: MCX Male connector (on the end of the antenna
cable)
Garmin Antenna: GA 25 MCX (Garmin Part Number 010-10702-00) provides the required
MCX Male connector. Other Garmin antennas terminated in a BNC
Male connector may also be used if a Garmin MCX to BNC Adapter
Cable (Garmin Part Number 010-10121-00) is used. Place the MCX to
BNC Adapter Cable between the connector on the end of the antenna
cable and the connector on the GPS 15xH/15xL.
Noise Figure/Gain: The total noise on the external antenna should be less than 3 dB with a
gain between 10 dB and 30 dB.
Should be properly biased by your choice of:
Power from on-board source: 3.0 Vdc minus the voltage drop across a 7.2 ohm series
resistance due to the current drawn by the antenna. The antenna
must not draw more than 60 mA.
Power from external source:From 3.5 Vdc to 8.0 Vdc bias through the series combination of
an on-board ~5.6 Ohm current sensing resistance, a saturated
PNP silicon transistor and a Schottky diode. The antenna must
not draw more than 60 mA. The external source of antenna bias
voltage should not have any significant noise or interference
power in the GPS band (20 MHz bandwidth centered at 1.57542
GHz).

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2 WIRE DESCRIPTIONS AND WIRING DIAGRAMS
The GPS 15xL-F and GPS 15xH-F use an eight contact flex circuit LIF connector. The GPS 15xL-
W and GPS 15xH-W use an eight pin JST connector (mating wire harness included). (See 1.5.1.3
for details.)
2.1 WIRE DESCRIPTIONS
GPS
15xH/15x
L
Pin #
Signal Name Description
1
BACKUP
POWER
This input provides external power to the battery-backed SRAM
and real-time clock. This enables the user to provide backup
power if needed for longer than the on-board rechargeable battery
will provide (roughly 21 days). Input voltage must be between +2.8
and +3.4 Vdc.
2
GROUND
Power and Signal Ground
3
POWER
GPS 15xL: +3.3 to +5.4 Vdc (±100 mV ripple) input. Peak
operating current is 100 mA. Nominal operating current is 85 mA.
This voltage drives an LDO with a nominal 3.0 Vdc output.
GPS 15xH: Unregulated 8.0 to 40.0 Vdc input. Peak operating
current is 40 mA @ 12 Vdc input. Nominal operating current is 33
mA @ 12 Vdc input. This voltage drives a switching regulator with
a nominal 3.3 Vdc output. Although a regulated supply is not
required, the peak-to-peak voltage ripple on this line should be
kept to less than 100 mV.
4
PORT 1
DATA OUT
Asynchronous Serial Output.
RS-232 compatible output normally provides serial data which is
formatted per NMEA 0183, Version 2.0. This output is also
capable of outputting phase data information; see Appendix B:
Garmin Binary Output Format for details. The NMEA 0183 baud
rate is selectable in the range of 300 to 38400 baud. The default
baud rate is 4800.
5
PORT 1
DATA IN
First Asynchronous Serial Input.
RS-232 compatible with maximum input voltage range of -25 < V <
25. This input may also be directly connected to standard 3 to 5
Vdc CMOS logic that uses RS-232 polarity. The low signal voltage
requirement is < 0.6 Vdc, and the high signal voltage requirement
is > 2.4 V. Minimum load impedance is 500 Ω. This input may be
used to receive serial initialization/ configuration data as specified
in Section 4.1 Received NMEA 0183 Sentences.
6
RF BIAS
This input allows the user to externally apply an RF bias to the
active antenna. By default, the unit will use an internal voltage to
power the active antenna. If an external voltage greater than the
internal voltage of the center pin of the antenna (between 3.5 Vdc
and 8.0 Vdc) is detected at this input, the GPS 15xH/15xL will
automatically changes to the external voltage. The antenna must
not draw more than 60 mA.
7
MPO
Measurement Pulse Output.
Typical voltage rise and fall times are 300 ns. Impedance is 150 Ω.
Open circuit output voltage is low = 0 Vdc and high = Vin in the
GPS 15xL, and low = 0 Vdc and high = 5.0 Vdc in the GPS 15xH.
The default format is a 100 ms wide active-high pulse at a 1 Hz
rate; the pulse width is configurable in 20 ms increments. The
rising edge is synchronized to the start of each GPS second. This
output provides between 800 mVp-p to 1.7 Vp-p for GPS 15xL and
1.4 Vp-p for the GPS 15xH into a 50 Ω load. The pulse time
measured at the 50% voltage point will be about 50 ns earlier with
a 50 Ω load than with no load.

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8
PORT 2
DATA IN
Second Serial Asynchronous Input.
This input may be used to receive serial differential GPS data
formatted per RTCM SC-104 Recommended Standards For
Differential Navstar GPS Service, Version 2.2 (see Section 4.5 for
more details).
2.2 WIRING DIAGRAMS
Figure 1: Computer Serial Port Interconnection
Figure 2: PDA Serial Port Interconnection
Figure 3: Basic NMEA Device Interconnection
3 MECHANICAL CHARACTERISTICS & MOUNTING

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1. Dimensions in millimeters [inches]
2. Dimension tolerance: +/-0.25 mm [±0.01in.]
3. Use M2 mounting screws.
Figure 4: GPS 15xH-F & 15xL-F Dimensions
1. Dimensions identical to GPS 15xH-F and GPS 15xL-F
2. Use M2 mounting screws.
Figure 5: GPS 15xH-W & 15xL-W Outline Drawing

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4 GPS 15XH/15XL SOFTWARE INTERFACE
The factory default interface protocol of the GPS 15xH/15xL serial com port 1 is based on the
National Marine Electronics Association’s NMEA 0183 ASCII interface specification. This
standard is fully defined in NMEA 0183, Version 2.30. Copies may be obtained from NMEA,
www.nmea.org.
In addition to the standard NMEA 0183 sentences, the GPS 15xH/15xL may also be configured to
transmit information over their serial interface using NMEA 0183 compliant Garmin proprietary
sentences. These proprietary sentences begin with the characters, “$PGRM”, instead of the
characters “$G” that are typical of the standard NMEA 0183 sentences. The characters “$P”
indicate that the sentence is a proprietary implementation and the characters and “GRM” indicate
that it is Garmin’s proprietary sentence. The character (or characters) that follow the characters
“$PGRM” uniquely identifies that particular Garmin proprietary sentence.
It is also possible to configure the GPS 15xH/15xL to transmit Garmin binary data over their serial
com port 1 interface. See Appendix B: Garmin Binary Output Format for details.
The following sections describe the NMEA 0183 data format of each sentence transmitted and
received by the GPS 15xH/15xL.
4.1 RECEIVED NMEA 0183 SENTENCES
The following paragraphs define the sentences that can be received on the GPS sensors’ port.
Null fields in the configuration sentence indicate no change in the particular configuration
parameter. All sentences received by the GPS sensor must be terminated with <CR><LF>.
Please note that <CR> and <LF> denote the ASCII characters for carriage return (0D
hexadecimal) and line feed (0A hexadecimal), respectively. So, <CR> and <LF> are each
transmitted as single bytes.
The checksum *hh is used for parity checking data and is not required, but is recommended for
use in environments containing high electromagnetic noise. It is generally not required in normal
PC environments. When used, the parity bytes (hh) are the ASCII representation of the upper and
lower nibbles of the exclusive-or (XOR) parity, computed over all of the characters between the
“$” and “*” characters, non-inclusive. The hexadecimal representation uses capital letters, such
as 3D instead of 3d. Sentences may be truncated by <CR><LF> after any data field and valid
fields up to that point will be acted on by the sensor.
4.1.1 Almanac Information (ALM)
The $GPALM sentence can be used to initialize the GPS sensor’s stored almanac information in
the event of non-volatile memory loss or after storing longer than six months without tracking
GPS satellites.
$GPALM,<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>,<10>,<11>,<12>,<13>,<14>,<15>*hh<CR><L
F>
<1>
Total number of ALM sentences to be transmitted by the GPS sensor during almanac
download. This field can be null or any number when sending almanac to the GPS
sensor.
<2>
Number of current ALM sentence. This field can be null or any number when sending
almanac to the GPS sensor.
<3>
Satellite PRN number, 01 to 32
<4>
GPS week number
<5>
SV health, bits 17–24 of each almanac page
<6>
Eccentricity
<7>
Almanac reference time
<8>
Inclination angle
<9>
Rate of right ascension
<10>
Root of semi major axis
<11>
Omega, argument of perigee
<12>
Longitude of ascension node
<13>
Mean anomaly

14
<14>
af0 clock parameter
<15>
af1 clock parameter

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4.1.2 Sensor Initialization Information (PGRMI)
The $PGRMI sentence provides information used to initialize the GPS sensor’s last known
position and to set the time on the real time clock. This information is used by the GPS receiver
on the next power cycle to predict which satellites will be visible in the sky as an aid for more
rapid satellite acquisition. Receipt of this sentence by the GPS sensor during satellite acquisition
causes the software to restart the satellite acquisition process. If there are no errors in the
sentence, it will be echoed upon receipt. If an error is detected, the echoed PGRMI sentence will
contain the current default values. Current PGRMI defaults (with the exception of the Receiver
Command, which is a command rather than a mode) can also be obtained by sending
$PGRMIE<CR><LF> or $PGRMIE*04<CR><LF> to the GPS sensor.
$PGRMI,<1>,<2>,<3>,<4>,<5>,<6>,<7>*hh<CR><LF>
<1>
Latitude, ddmm.mmm format (leading zeros must be transmitted)
<2>
Latitude hemisphere, N or S
<3>
Longitude, dddmm.mmm format (leading zeros must be transmitted)
<4>
Longitude hemisphere, E or W
<5>
Current UTC date, ddmmyy format
<6>
Current UTC time, hhmmss format
<7>
Receiver Command, A = Auto Locate, R = Unit Reset
4.1.3 Sensor Configuration Information (PGRMC)
The $PGRMC sentence provides information used to configure the GPS sensor’s operation.
Configuration parameters are stored in non-volatile memory and retained between power cycles.
The GPS sensor will echo this sentence upon its receipt if no errors are detected. If an error is
detected, the echoed PGRMC sentence will contain the current default values. Current default
values can also be obtained by sending $PGRMCE<CR><LF> or $PGRMCE*0E<CR><LF> to
the GPS sensor.
$PGRMC,<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>,<10>,<11>,<12>,<13>,<14>*hh<CR><LF>
<1>
Fix mode, A = Automatic, 3 = 3D exclusively
<2>
Altitude above/below mean sea level, -1500.0 to 18000.0 meters
<3> Earth datum index. If the user datum index (96) is specified, fields <4> through <8> must
contain valid values. Otherwise, fields <4> through <8> must be null. Refer to Appendix A:
Earth Datum List for a list of earth datum and the corresponding earth datum index.
<4> User earth datum semi-major axis, 6360000.000 to 6380000.000 meters (.001 meters
resolution)
<5>
User earth datum inverse flattening factor, 285.0 to 310.0 (10
-9
resolution)
<6> User earth datum delta x earth centered coordinate, -5000.0 to 5000.0 meters (1 meter
resolution)
<7> User earth datum delta y earth centered coordinate, -5000.0 to 5000.0 meters (1 meter
resolution)
<8> User earth datum delta z earth centered coordinate, -5000.0 to 5000.0 meters (1 meter
resolution)
<9> Differential mode, A = Automatic (output DGPS data when available, non-DGPS otherwise),
D = Differential exclusively (output only differential fixes)
<10>
NMEA 0183 Baud rate, 3 = 4800, 4 = 9600, 5 = 19200, 8 = 38400
<11> No Effect (This field is not used on the GPS 15xH/15xL and is included only for compatibility
with other models.)
<12>
PPS mode, 1 = No PPS, 2 = 1 Hz
<13>
PPS pulse length, 0-48 = (n+1)*20 ms. Example: n = 4 corresponds to a 100 ms wide pulse
<14>
Dead reckoning valid time 1 to 30 seconds
All configuration changes take effect after receipt of a valid value except baud rate. Baud rate
changes take effect on the next power cycle or an external reset event.

16
4.1.4 Additional Sensor Configuration Information (PGRMC1)
The $PGRMC1 sentence provides additional information used to configure the GPS sensor
operation. Configuration parameters are stored in non-volatile memory and retained between
power cycles. The GPS sensor will echo this sentence upon its receipt if no errors are detected. If
an error is detected, the echoed PGRMC1 sentence will contain the current default values.
Current default values can also be obtained by sending $PGRMC1E<CR><LF> or
PGRMC1E*3F<CR><LF> to the GPS sensor.
$PGRMC1,<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>,<10>,<11>,<12>,<13>*hh<CR><LF>
<1>
NMEA 0183 output time 1 to 900 (sec).
<2>
Garmin Binary Output, 1 = Off, 2 = On.
<3> No Effect (This field is not used on the GPS 15xH/15xL and is included only for
compatibility with other models.)
<4> No Effect (This field is not used on the GPS 15xH/15xL and is included only for
compatibility with other models.)
<5> No Effect (This field is not used on the GPS 15xH/15xL and is included only for
compatibility with other models.)
<6> No Effect (This field is not used on the GPS 15xH/15xL and is included only for
compatibility with other models.)
<7>
NMEA 0183 version, 1 = version 2.20 (factory default), 2 = version 2.30
<8> DGPS WAAS mode, A = Automatic, W = WAAS Only , R = RTCM Only, N = None (DGPS
Disabled)
<9>
Power Save Mode, P = Power Save mode, N = Normal
<10>
No Effect (This field is not used on the GPS 15xH/15xL and is included only for
compatibility with other models.)
<11>
No Effect (This field is not used on the GPS 15xH/15xL and is included only for
compatibility with other models.)
<12>
No Effect (This field is not used on the GPS 15xH/15xL and is included only for
compatibility with other models.)
<13>
PPS Auto Off Mode, 1 = Off, 2 = On
<14> No Effect (This field is not used on the GPS 15xH/15xL and is included only for
compatibility with other models.)
Configuration changes take effect immediately, with the exception of Garmin Binary Output,
which takes effect on the next power cycle or a reset event. Send the sentence
$PGRMI,,,,,,,R<CR><LF> or $PGRMI,,,,,,R*3F<CR><LF> to command a reset (refer to 4.1.2). If
the GPS sensor is in the Garmin binary data mode, it is necessary to send the following eight-
byte data stream to temporarily change the data format to NMEA 0183:
10 0A 02 26 00 CE 10 03 (Hexadecimal)
Follow by sending a PGRMC1 sentence that turns off the Garmin Binary Output format:
$PGRMC1,,1<CR><LF> or $PGRMC1,,1*4B<CR><LF>
4.1.5 Output Sentence Enable/Disable (PGRMO)
The $PGRMO sentence provides the ability to enable and disable specific output sentences. The
following sentences are enabled at the factory: GPGGA, GPGSA, GPGSV, GPRMC, and
PGRMT.
This sentence is not intended for turning on and off sentences as a means of polling while the
receiver is in use; instead, it is intended to allow systems integrators to initialize the GPS receiver
so it produces only the sentences required by the target application.

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$PGRMO,<1>,<2>*hh<CR><LF>
<1>
Target sentence description (for example, PGRMT, GPGSV, etc.)
<2>
Target sentence mode, where:
0 = Disable specified sentence,
1 = enable specified sentence,
2 = Disable all output sentences,
3 = Enable all output sentences (except GPALM),
4 = Restore factory default output sentences
The following notes apply to the PGRMO input sentence:
If the target sentence mode is “2” (Disable all), “3” (Enable all), or “4” (Restore defaults), the
target sentence description is not checked for validity. In this case, an empty field is allowed (for
example, $PGRMO,,3), or the mode field may contain from 1 to 5 characters.
If the target sentence mode is “0” (Disable) or “1” (Enable), the target sentence description field
must be an identifier for one of the sentences that can be output by the GPS sensor.
If either the target sentence mode field or the target sentence description field is not valid, the
PGRMO sentence will have no effect.
$PGRMO,GPALM,1<CR><LF> will cause the GPS sensor to transmit all stored almanac
information. All other NMEA 0183 sentence transmission will be suspended temporarily.
$PGRMO,,G<CR><LF> will cause the COM port to change to Garmin Binary Output mode for the
duration of the power cycle or until 10 0A 02 26 00 CE 10 03 (Hexadecimal) is sent to the GPS receiver in
order to return to NMEA 0183 mode as described in Section 4.1.4 . Garmin binary mode is required for
GPS 15xH/15xL series product software updates.
4.2 TRANSMITTED NMEA 0183 SENTENCES
The subsequent paragraphs define the sentences that can be transmitted on COM 1 by the GPS
sensor.
4.2.1 Sentence Transmission
Sentences are transmitted with respect to the user selected baud rate.
Regardless of the selected baud rate, the information transmitted by the GPS sensor is
referenced to theUTC second boundary immediately preceding the GPRMC sentence, or
whichever sentence is
output first in the burst (see Table 3 below).
The GPS sensor will transmit each sentence (except where noted in particular transmitted
sentence descriptions) at a periodic rate based on the user selected baud rate and user selected
output sentences. The GPS sensor will transmit the selected sentences contiguously. The length
of the transmission can be determined by the following equation and Tables 3 and 4:
total characters to be transmitted
length of transmission = ---------------------------------------------
characters transmitted per second

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Sentenc
e
Output by Default?
Maximum Characters
GPRMC

74
GPGGA

82
GPGSA

66
GPGSV

70
PGRME
35
GPGLL
44
GPVTG
42
PGRMV
32
PGRMF
82
PGRMB
40
PGRMM
32
PGRMT
Once per minute
50
Table 2: NMEA 0183 Output Sentence Order and Size
Baud
Characters per Second
4800
480
9600
960
19200
1920
38400
3840
Table 3: Characters per Second for Available Baud Rates
The maximum number of fields allowed in a single sentence is 82 characters including delimiters.
Values in the table include the sentence start delimiter character “$” and the termination delimiter
<CR><LF>. The factory set defaults result in a once per second transmission at the NMEA 0183
specification transmission rate of 4800 baud.
4.2.2 Transmitted Time
The GPS sensor outputs Coordinated Universal Time (UTC) date and time of day in the
transmitted sentences. Before the initial position fix, the on-board clock provides the date and
time of day. After the initial position fix, the date and time of day are calculated using GPS
satellite information and are synchronized with the closest UTC second boundary.
The GPS sensor uses information obtained from the GPS satellites to add or delete UTC leap
seconds and correct the transmitted date and time of day. The transmitted date and time of day
for leap second correction follow the guidelines in “National Institute of Standards and
Technology Special Publication 432 (Revised 1990)” (for sale by the Superintendent of
Documents, U.S. Government Printing Office, Washington, D.C., 20402, U.S.A.).
When a positive leap second is required, one second is inserted at the beginning of the first hour
(0h 0m 0s) of the day that the positive leap is occurring. The minute containing the leap second is
61 seconds long. The GPS sensor would have transmitted this information for the leap second
added December 31, 1998 as follows:
$GPRMC,235959,A,3851.3651,N,09447.9382,W,000.0,000.0,311298,003.3,E*65
$GPRMC,000000,A,3851.3651,N,09447.9382,W,000.0,000.0,010199,003.3,E*64
$GPRMC,000000,A,3851.3651,N,09447.9382,W,000.0,000.0, 010199,003.3,E*64
$GPRMC,000001,A,3851.3651,N,09447.9382,W,000.0,000.0, 010199,003.3,E*65
If a negative leap second should be required, one second will be deleted at the end of some UTC
month. The minute containing the leap second will be only 59 seconds long. In this case, the GPS
sensor will not transmit the time of day 0h 0m 0s (the “zero” second) for the day from which the

19
leap second is removed. For example, if a negative leap second had been required on December
31, 1998, the result would have been as follows:
$GPRMC,235959,A,3851.3651,N,09447.9382,W,000.0,000.0,311298,003.3,E*65
$GPRMC,000001,A,3851.3651,N,09447.9382,W,000.0,000.0,010199,003.3,E*65
$GPRMC,000002,A,3851.3651,N,09447.9382,W,000.0,000.0,010199,003.3,E*66
4.2.3 Global Positioning System Almanac Data (ALM)
Almanac sentences are not normally transmitted. Send the GPS sensor a $PGRMO,GPALM,1
command to initiate almanac transmission. Upon receipt of this command, the GPS sensor will
transmit available almanac information on GPALM sentences. During the transmission of
almanac sentences, other NMEA 0183 data output is suspended temporarily.
$GPALM,<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>,<10>,<11>,<12>,<13>,<14>,<15>*hh<CR><L
F>
<field information> can be found in Section 4.1.1 Almanac Information (ALM).
4.2.4 Global Positioning System Fix Data (GGA)
$GPGGA,<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>,M,<10>,M,<11>,<12>*hh<CR><LF>
<1>
UTC time of position fix, hhmmss format
<2>
Latitude, ddmm.mmmm format (leading zeros will be transmitted)
<3>
Latitude hemisphere, N or S
<4>
Longitude, dddmm.mmmm format (leading zeros will be transmitted)
<5>
Longitude hemisphere, E or W
<6> GPS quality indication, 0 = fix not available, 1 = Non-differential GPS fix available, 2 =
Differential GPS (WAAS) fix available, 6 = Estimated
<7>
Number of satellites in use, 00 to 12 (leading zeros will be transmitted)
<8>
Horizontal dilution of precision, 0.5 to 99.9
<9>
Antenna height above/below mean sea level, -9999.9 to 99999.9 meters
<10>
Geoidal height, -999.9 to 9999.9 meters
<11>
Null (Differential GPS)
<12>
Null (Differential Reference Station ID)
4.2.5 GPS DOP and Active Satellites (GSA)
$GPGSA,<1>,<2>,<3>,<3>,<3>,<3>,<3>,<3>,<3>,<3>,<3>,<3>,<3>,<3>,<4>,<5>,<6>*hh<CR><
LF>
<1>
Mode, M = Manual, A = Automatic
<2>
Fix type, 1 = not available, 2 = 2D, 3 = 3D
<3> PRN number, 01 to 32, of satellite used in solution, set to null if unused (leading zeros
will be transmitted)
<4>
Position dilution of precision, 0.5 to 99.9
<5>
Horizontal dilution of precision, 0.5 to 99.9
<6>
Vertical dilution of precision, 0.5 to 99.9

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4.2.6 GPS Satellites in View (GSV)
$GPGSV,<1>,<2>,<3>,<4>,<5>,<6>,<7>,...<4>,<5>,<6>,<7>*hh<CR><LF>
<1>
Total number of GSV sentences to be transmitted
<2>
Number of current GSV sentence
<3>
Total number of satellites in view, 00 to 12 (leading zeros will be transmitted)
<4>
Satellite PRN number, 01 to 32 (leading zeros will be transmitted)
<5>
Satellite elevation, 00 to 90 degrees (leading zeros will be transmitted)
<6>
Satellite azimuth, 000 to 359 degrees, true (leading zeros will be transmitted)
<7>
Signal to noise ratio (C/No) 00 to 99 dB (leading zeros will be transmitted)
Note: Items <4>,<5>,<6>, and <7> repeat for each satellite in view to a maximum of four (4)
satellites per sentence. Additional satellites in view information must be sent in subsequent
GPGSV sentences. Individual fields may be set to null if the corresponding data is unavailable.
4.2.7 Recommended Minimum Specific GPS/TRANSIT Data (RMC)
$GPRMC,<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>,<10>,<11>,<12>*hh<CR><LF>
<1>
UTC time of position fix, hhmmss format
<2>
Status, A = Valid position, V = NAV receiver warning
<3>
Latitude, ddmm.mmmm format (leading zeros will be transmitted)
<4>
Latitude hemisphere, N or S
<5>
Longitude, dddmm.mmmm format (leading zeros will be transmitted)
<6>
Longitude hemisphere, E or W
<7>
Speed over ground, 000.0 to 999.9 knots (leading zeros will be transmitted)
<8>
Course over ground, 000.0 to 359.9 degrees, true (leading zeros will be transmitted)
<9>
UTC date of position fix, ddmmyy format
<10>
Magnetic variation, 000.0 to 180.0 degrees (leading zeros will be transmitted)
<11>
Magnetic variation direction, E or W (westerly variation adds to true course)
<12>
Mode indicator (only output if NMEA 0183 version 2.30 active), A = Autonomous, D =
Differential, E + Estimated, N = Data not valid
4.2.8 Track Made Good and Ground Speed (VTG)
$GPVTG,<1>,T,<2>,M,<3>,N,<4>,K,<5>*hh<CR><LF>
<1>
True course over ground: 000 to 359 degrees (leading zeros will be transmitted)
<2>
Magnetic course over ground: 000 to 359 degrees (leading zeros will be transmitted)
<3>
Speed over ground: 000.0 to 999.9 knots (leading zeros will be transmitted)
<4>
Speed over ground: 0000.0 to 1851.8 kilometers per hour (leading zeros will be
transmitted)
<5>
Mode indicator (only output if NMEA 0183 version 2.30 active), A = Autonomous,
D = Differential, E = Estimated, N = Data not valid
4.2.9 Geographic Position (GLL)
$GPGLL,<1>,<2>,<3>,<4>,<5>,<6>,<7>*hh<CR><LF>
<1>
Latitude, ddmm.mmmm format (leading zeros must be transmitted)
<2>
Latitude hemisphere, N or S
<3>
Longitude, dddmm.mmmm format (leading zeros must be transmitted)
<4>
Longitude hemisphere, E or W
<5>
UTC time of position fix, hhmmss format
<6>
Status, A = Valid position, V = NAV receiver warning
<7>
Mode indicator (only output if NMEA 0183 version 2.30 active), A = Autonomous,
D = Differential (WAAS), E = Estimated, N = Data not valid