Simrad MX521, MX521A, MX521B User Manual

www.simrad-yachting.com A brand by Navico - Leader in Marine Electronics

Manual

Simrad MX521/MX521A/MX521B
GPS/DGPS Sensor

English

Manual

Simrad MX521/MX521A/MX521B
GPS/DGPS Sensor

English

To the best of our knowledge, the content in this
publication was correct at the time of printing.

As we are continuously improving our products we
retain the right to make changes to the product and
the documentation at any time. Updated manuals are
available from our website www.navico.com/commercial
or www.simrad-yachting.com, and are free to download.

© Copyright 2016 by Navico Holding AS.

Document no: 727052

Revision: C

Date: July 2016

The original language for this document is English. In the
event of any discrepancy between translated versions
and the English version of this document, the English
document will be the official version.

2 | Simrad MX521/MX521A/MX521B

IMPORTANT NOTICE!

THE MX521 GPS/DGPS SENSOR IS AN AID TO
NAVIGATION ONLY. Under no circumstances should

it be used in lieu of authorized government charts.
Its accuracy can be affected by many factors such
as equipment defects, environmental conditions, or
improper operation. The user is responsible for safe
navigation of the vessel. This includes consulting
authorized government charts and exercising common
prudence and navigational judgement at all times.

Disclaimer

As Navico is continuously improving this product, we
retain the right to make changes to the product at any
time which may not be reflected in this version of the
manual. Please contact your nearest distributor if you
require any further assistance.

It is the owner’s sole responsibility to install and use the
equipment in a manner that will not cause accidents,
personal injury or property damage. The user of this
product is solely responsible for observing safe boating
practices.

NAVICO HOLDING AS AND ITS SUBSIDIARIES,
BRANCHES AND AFFILIATES DISCLAIM ALL LIABILITY
FOR ANY USE OF THIS PRODUCT IN A WAY THAT MAY
CAUSE ACCIDENTS, DAMAGE OR THAT MAY VIOLATE THE
LAW.

Governing Language: This statement, any instruction
manuals, user guides and other information relating
to the product (Documentation) may be translated
to, or has been translated from, another language
(Translation). In the event of any conflict between any
Translation of the Documentation, the English language
version of the Documentation will be the official version
of the Documentation.

This manual represents the product as at the time of
printing. Navico Holding AS and its subsidiaries, branches
and affiliates reserve the right to make changes to
specifications without notice.

Simrad MX521/MX521A/MX521B | 3

Copyright

Copyright © 2016 Navico Holding AS.

Warranty

The warranty card is supplied as a separate document.

In case of any queries, refer to the our website:
www.navico.com/commercial or
www.simrad-yachting.com

4 | Simrad MX521/MX521A/MX521B

Contents

1 General ....................................................... 6

Supplied Equipment ......................................7

2 Operation ................................................... 8

General .......................................................8

Satellite Based Augmentation System (SBAS) ...8

Receiver Autonomous Integrity Monitoring

(RAIM) ........................................................9

GLONASS Overview (MX521B only) .......... 9

Space Segment ..................................... 9

GPS and GLONASS .............................. 10

3 Installation ............................................... 11

MX521 Antenna Mounting Guidelines ............. 11

MX521 Connector ........................................ 12

Antenna Mounting ....................................... 13

Bracket Mount .................................... 13

Surface Mount .................................... 13

Antenna Cable Selection .............................. 15

Power Requirement ..................................... 16

Antenna Cable Assembly .............................. 16

MX521 Connector Conguration .................... 17

Data Interface to MX420/2 or MK12 CDU ........ 18

Data Interface to MX420/8 or MX420/AIS CDU 19

Data Interface to PC or Other Navigation

Systems .................................................... 20

MX521 Programming Cable ........................... 21

Data Interface to MX5xx CDU ....................... 22

Simrad MX521/MX521A/MX521B | 5

Data Interface to MX61x Junction Box ............ 23

4 Specications ........................................... 25

GPS Receiver ..................................... 25

Beacon Receiver (MX521A DGPS model

only) ................................................. 25

MX521B D/GNSS Receiver .................... 27

5 Data Output .............................................. 31

NMEA 0183 Data Output Sentences ....... 31

List of abbreviations ............................ 37

General | 6

1 General

This manual describes the operation and installation of
the MX521 antenna sensor.

They were designed to work either interactively with MX
Control and Display Unit (MX CDU) or as a stand-alone
positioning device for other non-MX applications.

The MX521 smart DGPS antennas can achieve better
than 2-meter DGPS accuracy in areas with good beacon
differential coverage and autonomous GPS accuracy
better than 5 meters.

When connected to an MX-CDU (i.e. MX61x or MX51x),
the MX521 can be controlled to function in several
modes, namely;

• GPS only

• Differential correction search mode in Auto, Database
or Manual

• WAAS* (Wide Area Augmentation System-US system)

• EGNOS* (European Geostationary Overlay System)

• RAIM (Receiver Autonomous Integrity Monitoring)

The MX521 sensors were designed to be used as:

• Source of GPS/DGPS positioning for MX CDUs
including MX61x & MX51x series CDUs

• Retrofit of IMO compliant GPS and AIS installation

• Source of position for ECDIS and other charting
software

Before installing the MX521 smart antenna, please read
this manual carefully to ensure proper installation and
operation of the unit.

*Not yet recognized by IMO as official differential correction
system

General | 7

Supplied Equipment

The following items are supplied with the MX521 Kit:

Description Part Number

MX521B GPS smart antenna
with GLONASS 000-11641-001

or,

MX521B DGPS smart antenna
with GLONASS 000-11640-001

The antenna cable assembly is not included and must
be ordered separately. Please specify the cable length
required. Below are available lengths in stock:

20 meters 3508 102 70170

40 meters 3508 102 70180

60 meters 3508 102 70640

80 meters 3508 102 70185

MX521 Kit

Operation | 8

2 Operation

General

This manual covers the MX521, MX521A and MX521B
antenna models and will be generally called MX521. The
MX521 and MX521A antenna models are D/GPS smart
antenna sensor while the MX521B is a combined DGPS/
GLONASS smart antenna sensor. They are fully automatic
and do not require initialization or user intervention. They
will automatically search for available satellites and make a
position fix shortly after power is applied.

The internal 2-channel beacon receiver, in the DGPS
version, initiates an Auto-matic Beacon Search (ABS) on
power on. The primary channel will lock-on to the nearest
beacon station, while the second channel searches for
other available beacon signals. Should it find a superior
signal, it will automatically switch the primary channel to
the new station.

The beacon receiver can be controlled by a Control Display
Unit (CDU) like the MX420, MX500, MX51x, GN70 or MX61x
series, to operate in Automatic Beacon Search, Manual
Tune or Database modes. The Database mode allows the
beacon receiver to store the almanac of 10 stations that
are closest to its present position. This feature complies
with the IEC 61108-4 specifications. The combined
performance of the high-precision GPS and GPS/GLONASS
receivers and 2-channel smart beacon receiver provides a
more accurate position fix, usually within 1 meter or less.

Satellite Based Augmentation System
(SBAS)

In areas where land-based Coast Guard beacon stations
are not available, the MX521 can be controlled to track
the Satellite Based Augmentation Systems (SBAS) like
the WAAS (US), EGNOS (European) and MSAS (Japan)
satellites. These satellites transmit DGPS correction data
(just like the Coast Guard stations) using the same GPS
frequency of 1575.00 MHz. Refer to the MX CDU Operator
Manual for more details. Turning this feature on in the
MX CDU will initiate the MX521 to listen for and track any

Operation | 9

SBAS satellites that are in view.

Receiver Autonomous Integrity
Monitoring (RAIM)

RAIM is a special software algorithm in the MX521
program which gives the operator timely warnings
when the GPS system accuracy is questionable. This
feature requires a minimum of five GPS satellites to
operate properly. If the position solution error exceeds
a preset limit a “RAIM Unsafe (R-)” or ”RAIM Caution
(R?) alarm will be indicated in the MX CDU. This means
that the accuracy of the position cannot be guaranteed
to be very accurate. The operator is advised to use the
GPS cautiously for navigation until the RAIM indicator
switches to (R+) denoting safe RAIM condition. Position
errors may be caused by unhealthy satellites, incorrect
pseudoranges, poor satellite geometry, excessive
atmospheric interference and problems at particular
reference stations.

GLONASS Overview (MX521B only)

GLONASS is a global satellite navigation system
developed by the Soviet Union, providing real-time
position and velocity determination for military and
civilian users. The GLONASS satellites are located
in orbits at 25,510 km altitude with a 64.8 degree
inclination. GLONASS’ orbit makes it especially suited
for use in high latitudes (north or south), where getting
a GPS signal can be problematic. The constellation
operates in three orbital planes, with 8 evenly spaced
satellites on each plane. A fully operational constellation
with global coverage consists of 24 satellites. To get a
position fix the receiver must be in the range of at least
four satellites.

Space Segment

There are 21 satellites that are being used for navigation
with 3 spare satellites. All GLONASS satellites are
operating using the same code but on slightly different
frequencies (L1 signals at 1598.0625 to 1609.3825
while the L2 at 1242.9375-1251.6875 MHz). This is

10 | Operation

a modulation technique known as FDMA (Frequency
Deviation Multiple Access). They have the same
polarization as the GPS signals and have comparable
signal strength.

The signal of the GLONASS satellite includes the Satellite
ID, Positioning, velocity, acceleration, satellite health,
time and time offset and almanac of all GLONASS
satellites.

The GLONASS system is based on 24 satellites using
12 different frequencies. This was made possible by
using the same frequency on antipodal satellites. These
are satellites that are in the same orbital plane but are
separated by 180°.

Antipodal Satellites

Both satellites are transmitting
on the same frequency

GPS and GLONASS

Combining the GPS and GLONASS system provides the
following advantages:

• Better signal acquisition times

• Better position and time accuracy

• Reduces the physical blocking of signal in urban cities
where tall buildings are the norms

• Better satellite geometry resulting in better HDOP

Installation | 11

3 Installation

MX521 Antenna Mounting Guidelines

The MX521 antenna housing is weather-resistant and
must be located outside where it will have a good view of
the sky around it. Use a standard 1”-14 TPI bracket for
mounting.

• Install the MX521 antenna where it has a clear view of
the sky around it.

• Locate the antenna for easy access and maintenance.

• Stay away from high-power energy sources such as
radar, SSB, INMARSAT and other transmitting radio
antennas by 5 meters or more.

• Locate the antenna at least 10 meters away from and
out of the transmitting beam of radar, INMARSAT and
other high-power transmitters.

• Mount the antenna low to avoid excessive position and
speed errors while underway.

• Mount the antenna as far away as possible from large
metal structures.

• Mount the antenna about 1 meter away from the
compass.

If you are not sure if the chosen location is appropriate,
you can mount the antenna temporarily and operate it
with the CDU. Monitor the operation of the MX521 while
you turn on other on-board electronic equipment. Move
the antenna around until the MX521 operates
satisfactorily then mount it permanently.

12 | Installation

MX521 Connector

The 10-pin male connector located at the underside
of the antenna unit provides the means to connect to
external power and the data interface. Please refer to the
chart below for the pin numbers, wire colors codes and
signal assignments.

Pin # Wire

Color

MX521 DGPS

Antenna

MX521 GPS

Antenna

1 BLK Negative Ground

2 RED +9 - 32 VDC

3 BLU MX Proprietary Message (MPM In (-)

4 BRN MX Proprietary Message (MPM In (+)

5 ORG GP S O ut (-)

6 GRN GP S O ut (+)

7 YEL Beacon Status Out (-) Not used

8 WHT Beacon Status Out (+) Not used

9 PRPL RT CM I N (+)

10 PRPL/

GRY

RTC M I N (-)

•

1

0

m

e

t

e

r

(

m

i

n

.

)

10m(min.)

RADAR ANT.

3 m

MOUNT THE MX521

10 m (min.) FORWARD OF MAIN MAST

1 m

10 m

MAIN
MAST

INMARSAT

ANT.

VHF OR MF

ANT.

MX ANT.

Installation | 13

Antenna Mounting

Bracket Mount

The MX521 mounting thread is an industry standard
fitting for VHF antenna mounting (1inch, 14 TPI). This
enables the antenna to be mounted on a wide range of
mounting brackets, including the swivel joints, commonly
used for angled surface. Refer to the figure below for
bracket mounting illustration.

Hand-tighten the antenna onto the bracket until snug.
Do not overtighten.

A 10-pin (male) plastic connector is mounted at the
underside of the antenna for power and data connection.

MX521 Bracket Mounting

Surface Mount

The MX521 can also be surface-mounted. Make sure
there is at least 5-inch clearance underneath the
mounting surface to accommodate the lower section of
the MX521 housing, connector and cable. Refer to the
figure below for surface mounting considerations. Cut a 5

Mounting
Surface

1” Diameter/14 TPI
Metal Mounting
Bracket
(not supplied)

Drill 1/2” diameter hole
for cable access

Secure cable
with plastic
tie-wraps
(not supplied)

14 | Installation

1/4 inch diameter hole on a horizontal mounting surface
and drill the four mounting screw holes as shown.

Fasten the antenna by using 2-mm size stainless steel
metric screws (4 places). Use a marine grade caulking
compound to seal between the mounting surface and the
bottom of the antenna housing.

Choose a location for the antenna that has a clear view
of the sky. Make sure there are no major obstructions
or metal fixtures in the immediate proximity to the
antenna. The GPS antenna relies on direct ‘line-of-sight’
signal reception. If you are unsure if the chosen location
is suitable, it is advisable to mount the antenna in a
temporary manner to verify correct operation.

MX521 Surface Mount

2 mm mounting
screws (4 places)

Recommended
clearance under
the antenna

Mounting
surface

5 1/4

"

5.0”

1

6

9

1 0

2

3

8

4

7

5

5 1/4”

2 mm screw
(4 places)

Installation | 15

Antenna Cable Selection

The antenna cable assembly for the MX521 antenna is
not included in the kit and must be ordered separately.
Several cable lengths are available in stock. To assist you
in ordering the correct cable length, please refer to the
antenna cable list below for cable description and part
number.

Antenna Cable with One 10-Pin Connector (for all
models):

Part Number Description

3508 102 70170 20 meter

3508 102 70180 40 meter

3508 102 70640 60 meter

3508 102 70185 80 meter

Antenna Cable with both ends terminated with
10-Pin Connectors (for direct connection to MX5xx
Series CDU):

Part Number Description

500 100 1006 20 meter

500 100 1007 40 meter

16 | Installation

Power Requirement

External power supplied to the MX521 must be within

10.5-32 VDC for best operation. To protect the circuitry
in the MX521, the voltage level must be within these
limits. Negative grounding is required. The MX521 draws
less than 300 mA. at 12 VDC. An in-line fuse or circuit
breaker rated at 2 amp. is recommended for overload
protection.

When the MX521 is connected to an MX control and
display unit (CDU), the 12 VDC antenna power is supplied
by the CDU unit.

The red wire connects to the (+) DC power, while the
black wire is the negative return. Although the MX521
has a reverse polarity protection, it is prudent to make
sure that proper polarity is observed before making the
connection.

Reverse polarity connection may damage the unit.

Antenna Cable Assembly

Below is a diagram showing the pins and wire color­coding of the antenna cable assembly.

Power/Data Cable Assembly

10-Pin Female Connector

Antenna cable Assy.

Pin#

10
9
8
7
6
5
4
3
2
1

* Not available with MX521G models

Wire

Prpl/Gry
Purple
White
Yellow
Green
Orange
Brown
Blue
Red
Black

Signal

Ext. RTCM IN ­Ext. RTCM IN+
Beacon status Out +*
Beacon Status Out -*
GPS Out +
GPS Out ­MPM In+
MPM In ­+12-32VDC
Negative GND

Installation | 17

MX521 Connector Conguration

Refer to the diagram below for the POWER-DATA
connector located at the underside of the MX521A:

MX521 POWER-DATA Connector

Where:

Pins 1 & 2: Negative GND and +12 VDC power input.

Pins 3 & 4: MX proprietary message (MPM)
input port.

Pins 5 & 6: GPS output to the MX420 or other NMEA
0183 compatible devices.

Pins 7 & 8: Beacon monitoring signal output. Sends

the SNR, Signal and Frequency to the CDU.
Connects to Cable B of the MX420/8 CDU.

Pins 9 & 10: External RTCM Correction (Input).

1

6

9

1 0

2

3

8

4

7

5

Pin# Wire Signal

10

P

rpl/Gry

9

Purple

8

White

Beacon Status Out +*

7

Yellow

Beacon Status Out -*-

6

Green

GPS Out +

5

Orange

GPS Out -

4

Brown

MPM IN+

3

Blue

MPMIN-

2

Red

+9~32 VDC

1

Black

Negative GND.

Ext. RTCM IN­Ext. RTCM IN+

*

Not available with MX521G models

18 | Installation

Data Interface to MX420/2 or MK12
CDU

Use the diagram below to interface the MX521A to an
MX420/2 or MK12 CDU.

MX521 Interface to MX420/2 or MK12 CDUs

(2) Red

Red (+12 VDC)

(16) Red/Wht
(1) Blk/Shield

Blk

(GND)
Grn (GPS Out +)
Org (GPS Out -)

Brn (MPM In +)
Blu (MPM In -)

(8) Org
(9) Org/Wht
(10) Yel
(11) Yel/Blk

In (A)

In (A)

In (B)

In (B)

Out (A)

Out (A)

Out (B)

Out (B)

(4) Brn
(5) Brn/Wht

NMEA2 Tx (RS-232)

Ext. Alarm

(6) Prpl
(7) Prpl/Wht
(12) Grn
(13) Grn/Wht

(14) Blu
(15) Blu/wht
(17) Gry
(18) Blk/Wht
(3) Blk

12~32 VDC

Supply

+

-

NMEA1 I/O

NMEA2 I/O

MX420/2 or
Mk12 CDU

Cable A

Terminal

strip

(User supplied)

Installation | 19

Data Interface to MX420/8 or MX420/
AIS CDU

Use the diagram below to interface the MX521A to
an MX420/8 or MX420/AIS CDU. The external RTCM
connection is optional.

MX521 Interface to MX420/8 or MX420/AIS CDUs

(2) Red

(4) Brn

White*
Yellow*

Purple
Purple/Gray

(5) Brn/Wht

Terminal

Strip

(User Supplied)

Red (+12 VDC)

(16) Red/Wht
(1) Blk/Shield

Blk (GND)
Grn (GPS Out +)
Org (GPS Out -)

Brn (LPM In +)

Blu (LPM In -)

(8) Org
(9) Org/Wht
(10) Yel
(11) Yel/Blk

In (A)

In (A)

In (B)

In (B)

Out (A)

Out (A)

Out (B)

Out (B)

(4) Brn
(5) Brn/Wht

NMEA2 Tx (RS-232)
Ext. Alarm

(6) Prpl
(7) Prpl/Wht
(12) Grn
(13) Grn/Wht
(14) Blu
(15) Blu/wht
(17) Gry
(18) Blk/Wht
(3) Blk

12~32 VDC

Supply

+

-

NMEA1 I/O

NMEA2 I/O

MX420/8 CDU

Ext. RTCM (+)

Ext. RTCM (-)

(Optional)

Note: * Not available with MX521G models

20 | Installation

Data Interface to PC or Other
Navigation Systems

The figure below shows the power and data output
connections to the serial port of a PC or other navigation
systems using a dB9 connector and a terminal strip (user
supplied items).

MX521 Interface to Other Navigation Systems

Red (+12 VDC)

BLk (GND)

Grn (GPS Out + )
Org (GPS

)

Brn (MPM In +)

Blu (MPM In -)

12~32 VDC

Supply

+

-

1 2 3 4 5 6 7 8 9

9dB PC Connector

Installation | 21

MX521 Programming Cable

The programming cable is used for upgrading the
software of the GPS and Beacon PCBs inside the MX521
smart antenna. The figure below shows the programming
cable diagram and equipment setup. Please note that
external 12 volt DC is required to power up the MX521.
Connect the red wire to +12 VDC and Black wire to
negative GND. The RS422-RS232 converter may be
powered from the PC serial port or from an external 12
volt power supply.

MX521 Programming Cable Diagram

GRN

ORG

BRN

BLU

RED

BLK

+12-32VDC

NEG

TD(A)

TD(B)

RD(A)

RD(B)

GND

+12V

RS422

RS232

B&B Electronics
RS422-RS232
Converter
Model 422LP9TB

10-pin Male Connector

TO PC

TO MX521

22 | Installation

Data Interface to MX5xx CDU

Use the diagram below to interface the MX521 to an
MX500, MX510 or MX512 CDU. Antenna cable assembly
with two 10-Pin connectors are available in 3, 20 and 40
meter lengths.

MX5xx Antenna Interface to MX521

RED

RED

BLK BLK
BLU

BLU

BRNBRN

ORG

ORG

YEL YEL

PRPL

PRPL

GRY

GRY

GRN GRN

WHT

WHT

P/N 3508 102 70150

10-PIN CABLE ASSY.

(3 METERS)

MX5xx CDU

MX5xx CDU

MX521

MX521

UPPER/LOWER

GRN

MX500 JUNCTION BOX

NOTE: OTHER COMPONENTS AND CONNECTIONS IN THE MX 500 JUNCTION BOX ARE NOT SHOWN

AUX

ANT

PWR/DATA

Installation | 23

Data Interface to MX61x Junction Box

Use the diagram below to interface the MX521 to GN70/
MX61x CDU via MX61x JB.

GN70/MX61x, MX61xJB and MX521 diagram

T

T

12/24V DC

MX61xJB

12/24V DC

Where:

N2K Backbone
Drop line
NMEA 0183 line

GN70/MX61x

MX521
MX521A
MX521B

Ports 3&4

Port 2

Port 1

MX525
MX525A

MXB5
ANT.

Coax
Cable

Option

24 | Installation

Normal operation
approx. 1 Hz flashing.

RX data, flashing
when receiving data
from antenna.

Supply
before
fuse steady
green.

MX521 to MX61xJB wiring diagram

Specications | 25

4 Specications

GPS Receiver MX521A

Type: ............ L1, C/A Code (SPS) with carrier phase smoothing

Frequency: ....................................................... 1575.42 MHz

Channels: ..................................12 Channels, parallel tracking

Update rate: ................................................................. 1 Hz

RTCM Input: .......................................... RTCM SC-104 format

Satellite measurement use: ......... 12 channel parallel automatic

selection

Antenna type: ................................................. Ceramic Patch

Dynamic Range: .......................................................... 90 dB

Time to first fix:

Cold start (no almanac or RTCM): ......... 60 second (typical)

Reacquisition ..................................... <10 second (typical)

Position accuracy:

With differential corrections from:

Beacon Stations: <1 meters (2D-RMS) typical depending on

distance from differential base station.

Without differential corrections <3 m (2D-RMS) (with S/A off)

Serial Ports: ................................... 2 duplex NMEA 0183 ports

Baud Rates: ................................ 4800 (default), 9600, 19200

Data I/O Protocol: ........................................ NMEA 0183 V3.0

Correction I/O Protocol: .....................................RTCM SC-104

Datum: ..................................................................... WGS84

NMEA messages: GGA, GRS, GSA, GSV, GST, RMC, VTG, ZDA &

PMVXG,GBS (MX Marine proprietary)

Beacon Receiver (MX521 DGPS model only)

Frequency: ................... 283.5 to 325.0 kHz. 2-channel Auto or

Manual selection (500 Hz steps)

Sensitivity: ...........................2.5 uV/m for 6dB SNR @ 200 bps

Operating Modes: .................... Automatic, Manual or Database

Dynamic Range: ........................................................100 dB

Adjacent Channel Rejection: ......................61 dB @ f + 400 Hz

26 | Specications

Channel spacing: ........................................................500 Hz

Frequency offset tolerance: ........................................ + 5 Hz

Antenna type: ........................................................... H-Field

MSK rates: ..............................................50, 100 and 200 bps

Environmental

Operating temperature:..................................... -30 to +70 °C

Storage Temperature: ......................................... -40 to 85 °C

Humidity: ............................ “Exposed Category” (IEC 60945)

Mechanical

Dimensions:

Height .................................................... 102 mm (4.0 in.)

Diameter ..............................................182 mm (7 1/8 in)

Weighs: (MX521 DGPS) ...... 820 grams (1.8 lbs.) (without cable)

(MX521G ) ................... 600 grams (1.3 lbs.) (without cable)

Mount: ..... 1”-14 TPI pole mount. Surface mounting 5 1/4 “ hole

Electrical

Operating voltage range: ................................. 10.5 to 32 VDC

Operating current: ............................< 230 mA at 12.0 VDC,

Power Consumption: ............................................... < 3 W a t t s

Certications

96/98 EC as amended by directive (EU) 2015/559

CE and FCC compliant

1-14 TPI

182 mm

102 mm

Specications | 27

MX521B D/GNSS Receiver

Key features:

• IMO type approved

• Flexibility for easy integration into NMEA 0183 interfaces

• More satellite tracking for better geometry

• Maintain position lock when more of the sky is blocked

• COAST technology maintains differentially-corrected
positioning for 40 minutes or more after loss of differential
signal

GNSS Sensor Specications

Receiver Type: .......................................... GNSS L1 Receiver

Signals Received: .......................................... GPS, GLONASS

Channels: ..................................................................... 270

GPS Sensitivity: .................................................... -142 dBm

SBAS Tracking: .............................2-channel, parallel tracking

Update Rate: ............................ 1 Hz standard (20 Hz optional)

Positioning Accuracy:

RMS (67%): Horizontal Vertical

Single Point:

1

1.2 m 2.5 m

SBAS (WAAS):

2

0.3 m 0.6 m

Code Differential DGPS:

3

0.3 m 0.6 m

Compass Safe

Distance: ......................................... 75 cm (with enclosure)

4

Cold Start: ...................................... 60 s (no almanac or RTC)

Warm Start: ............................20 s typical (almanac and RTC)

Hot Start: ....................1 s typical (almanac, RTC and position)

Maximum Speed: ....................................1,850 mph (999 kts)

Maximum Altitude: ............................... 18,288 m (60,000 ft)

28 | Specications

Beacon Sensor Specications

Channels: ..................................... 2-channel, parallel tracking

Frequency Range: ........................................ 283.5 to 325 kHz

Operating Modes: ...................Manual, automatic and database

Compliance: ...............................IEC 61108-4 beacon standard

Communications

Baud Rates: ....................................................4800 - 115200

Correction I/O Protocol: ............................. RTCM v2.3 (DGPS)

Data I/O Protocol: ............................................... NMEA 0183

Power

Input Voltage: ................................................ 10.5 to 32 VDC

Power Consumption: ..... 4.3 W nominal (GPS L1 + GLONASS L1)

4.6 W nominal (GPS L1 + GLONASS L1 + Beacon)

Current Consumption: . . 0.36 A nominal (GPS L1 + GLONASS L1)

0.38 A nominal (GPS L1 + GLONASS L1 + Beacon)

Power Isolation: .....................................Isolated to enclosure

Reverse Polarity Protection: ..............................................Yes

Environmental

Operating Temperature: ..... -30°C to + 70°C (-22°F to + 158°F)

Storage Temperature: ........ -40°C to + 85°C (-40°F to + 185°F)

Humidity: ..............................................95% non-condensing

Shock and Vibration: ....Mechanical Shock: EP455 Section 5.14.1

Vibration: EP455 Section 5.15.1 Random

EMC: ......................... CE (IEC 60945 Emissions and Immunity)

FCC Part 15, Subpart B CISPR22

IMO Wheelmark Certification: .........................................Yes

6

Mechanical

Power/Data Connector: .............10-pin, environmentally sealed

1 Depends on multipath environment, number of satellites in
view, satellite geometry, no SA, and ionospheric activity

Specications | 29

2 Depends on multipath environment, number of satellites in
view, WAAS coverage and satellite geometry

3 Based on a 40 second time constant

4 This is the minimum safe distance measured when the

product is placed in the vicinity of the steering magnetic

compass. The ISO 694 denes “vicinity” relative to the compass

as within 5 m (16.4 ft) separation

6 NMEA 0183 only

Simrad reserves the right to make changes in its

products and specications without notice.

30 | Specications

Blank page

Data output | 31

5 Data Output

The MX521 data output conforms to the NMEA 0183 V3.0
at 4800 baud. Below is a list of the NMEA sentences
output:

GGA, GSA, GSV, GST, RMC, VTG and PMVXG,GBS (an
MX proprietary sentence used for RAIM)

NMEA 0183 Data Output Sentences

(1) GGA - Global Positioning System Fix Data

Time, position and fix related data for a GPS receiver.

Notes: 1 ----- UTC of position

2,3 --- Latitude - N/S

4,5 --- Longitude - E/W

6 ----- GPS Quality Indicator:

0 = Fix not available or invalid

1 = GPS SPS Mode, fix valid

2 = Differential GPS, SPS Mode, fix valid

3 = GPS PPS Mode, fix valid

7 ----- Number of Satellites in use, 00-12, may

be different from the number in view

8 ----- Horizontal Dilution of Precision (HDOP)

9 ---- Antenna altitude/mean-sea-level (geoid)

10---- Units of antenna altitude, Meters

11,12- Geoidal Height, Meters

13---- Age of Differential GPS Data

14 --- Differential Reference Station ID

$GPGGA,hhmmss,llll.llll,a,yyyyy.yyyy,a,x,xx,x.x,x.x,M,x.x,M,x.x,xxxx*hh<CR><LF

1 2 3 4

5

6 7 8 9 10 11 12 13 14

32 | Data output

(2) GRS - GNSS Range Residual

This message is used to support RAIM.

Notes: 1 ---- UTC time of GGA or GNS fix associated with

this sentence

2 ---- Mode 0 = residuals were used to calculate

the position given in the matching GGA or
GNS.

1 = residuals were computed after the GGA

or GNS position was computed.

3 ---- Range residuals in meters for sat. used

in navigation solution. Order must match
the order of the satellite ID numbers in
GSA. When GRS is used GSA and GSV are
generally required.

(3) GSA - GPS DOP and Active Satellites

GPS receiver operating mode, satellites used in the
navigation solution reported by the $GPGGA sentence,
and DOP values.

Notes: 1---- Mode: M = Manual, forced to operate in 2D
or 3D Mode

A = Automatic, allowed to automatically
switch 2D/3D

2 ---- Mode: 1 = Fix not available, 2 = 2D, 3 = 3D

3-14 -PRN numbers of satellites used in solution

(null for unused fields)

15 ---PDOP

16 ---HDOP

17 ---VDOP

$GPGRS,hhmmss,x,x.x,x.x,x.x,x.x,x.x,x.x,x.x,x.x,x.x,x.x,x.x,x.x*hh<CR><LF>

1 2 3

$GPGSA,a,x,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,x.x,x.x,x.x*hh<CR><LF>

13

14

15

123 4

5

6 7 8 9 10 11 12

16 17

Data output | 33

(4) GSV - GPS Satellite in View

Number of satellites (SV) in view, PRN numbers,
elevation, azimuth and SNR values. Four satellites
maximum per transmission, additional satellite data sent
in second or third message. Total number of messages
being transmitted and the number of the message
transmitted are indicated in the first two fields.

Notes: 1 -----Total number of messages, 1 to 3

2 ---- Message number, 1 to 3

3 ---- Total number of satellites in view

4 ----- Satellite PRN number

5 ----- Elevation, degrees, 90 degrees maximum

6 ------Azimuth, degrees True, 000 to 359

7 ------SNR (C/No) 00-99 dB, null when not
tracking

8 ------2nd and 3rd SV

9,10,11,12 - 4th SV

(5) RMC - Recommended Minimum Specific GPS Data

Time, date, position, course and speed data provided by
a GPS navigation receiver. This sentence is transmitted
at intervals not exceeding 2 seconds. All data fields
must be provided: null fields used only when data is
temporarily unavailable.

Notes: 1 ---- UTC of Position fix

2 ---- Status: A = data valid

V = Navigation receiver warning

3,4 -- Latitude, N/S

$GPGSV,x,x,xx,xx,xx,xxx,xx,....................,xx,xx,xxx,xx*hh<CR><LF>

123 4

5

6 7 8 9 10 11 12

$GPRMC,hhmmss.ss,A,llll.llll,a,yyyyy.yyyy,a,x.x,x.x,xxxxxx,x.x,a*hh<CR><LF>

1

2

3 4

5

6 7 8 9 10 11

34 | Data output

5,6 -- Longitude, E/W

7 ---- Speed over ground, knots

8 ---- Course Over Ground, True

9 ---- Date: dd/mm/yy

10,11 - Magnetic variation, degrees E/W.

Easterly variation (E) subtracts from
True course, Westerly variation (W) adds
to True course.

(6) GST - GNSS Pseudorange Error Statistics

This message is used to support Receiver Autonomous
Integrity Monitoring (RAIM). Pseudorange measurement
error statistics can be translated in the position domain
in order to give statistical measures of the quality of the
position solution.

If only GPS, GLONASS, etc. is used for the reported
position solution, the talker ID is GP, GL, etc., and the
error data pertains to the individual system. If satellites
from multiple systems are used to obtain the reported
position solution, the talker ID is GN and the errors
pertain to the combined solution.

Notes: 1 ---- UTC time of the GGA or GNS fix associated

with this sentence.

2 ---- RMS value of the standard deviation of the

range inputs to the navigation process.
Range inputs include preudoranges &
DGNSS corrections.

3 ---- Standard deviation of semi-major axis of

error ellipse (meters)

4 ---- Standard deviation of semi-minor axis of

error ellipse (meters)

5 ---- Orientation of semi-major axis of error

ellipse (degrees from true north)

6 ---- Standard deviation of latitude error

(mete rs)

$GPGST,hhmmss.ss,x.x,x.x,x.x,x.x,x.x,x.x,x.x*hh<CR><LF>

1

2

3 4

5

6 7 8

Data output | 35

7 ---- Standard deviation of longitude error

(mete rs)

8 ---- Standard deviation of altitude error

(mete rs)

(7) VTG - Course Over Ground and Ground Speed

The actual course and speed relative to the ground.

Notes: 1,2 ---- Course over ground, degrees True

2,3 ---- Course over ground, degrees Magnetic

5,6 ---- Speed over ground, knots

7,8 ---- Speed over ground, km/hr

9 ------ Mode indicator: A = Autonomous mode

D = Differential mode

E = Estimated (DR)

M = Manual input mode

S = Simulator mode

N = Data not valid

(8) ZDA -Time and Date

UTC, day, month, year and local time zone

Notes: 1 --- UTC

2, 3, 4 --- Day, month & year

5 --- Local zone hours, 00 to + 13 hrs.

6 --- Local zone in minutes, 00 to +59.

$GPVTG,x.x,T,x.x,M,x.x,N,x.x,K,a*hh<CR><LF>

1

2

3 4

5

6 7 9

8

$GPZDA,hhmmss,xx,xx,xxxx,xx,xx*hh<CR><LF>

1

2

3 4

5

6

36 | Data output

(9) GBS - GNSS Satellite Fault Detection (Modified MX
ver sion)

This message is used to support Receiver Autonomous
Integrity Monitoring (RAIM) feature in the MX420 CDU. A
special character flag was added for proper RAIM status
determination.

Notes: 1 ----- UTC time of the GGA or GNS fix
associated with this sentence.

2 ----- Expected error in Latitude (meters)

3 ----- Expected error in Longitude (meters)

4 ----- Expected error in Altitude (meters)

5 ----- ID number of most likely failed satellite

6 ----- Probability of missed detection for most
likely failed satellite

7 ----- Estimate of bias in meters on most likely
failed satellite

8 ----- Standard deviation of bias estimate

9 ----- RAIM status mode; 0=safe, 1=caution,
2=unsafe

$PMVXG,GBS,hhmmss.ss,x.x,x.x,x.x,xx,x.x,x.x,x.x,x*hh<CR><LF>

1

2

3 4

5

6 7 9

8

Data output | 37

List of abbreviations

CDU Control Display Unit

DGPS Differential Global Positioning System

FDMA Frequency Deviation Multiple Access

GLONASS Global Orbiting Navigation Satellite System

GNSS Global Navigation Satellite System

GPS Global Positioning System

HDOP Horizontal Dilution Of Precision

IMO International Maritime Organization

NMEA National Marine Electronic Association

PDOP Positional Dilution Of Precision

RAIM Receiver Autonomous Integrity Monitoring

RTCM Radio Technical Commission For Maritime

SBAS Satellite Based Augmentation System

VDOP Vertical Dilution Of Precision

Doc.no.727052, Rev.C