NorthStar 2505 User manual

2505 Beacon/WAAS
Position Sensor
Installation Manual
Revision A
Part Number GM2505
Northstar Technologies
30 Sudbury Road
Acton, Massachusetts 01720
800/628-4487
978/897-6600
www.northstarcmc.com

Limited warranty policy
Northstar Technologies, Inc. warrants the Northstar 2505 to be free from defects in materials and
workmanship for a period of two (2) years. This warranty applies to the original purchaser and to any
subsequent owner during the warranty period, which begins on the date of shipment of the unit,
F.O.B. Acton, Massachusetts, to an authorized Northstar dealer.
Systems may not be returned to Northstar without a Returned Materials Authorization (RMA) num-
ber. Call the Northstar dealer or Northstar for instructions.
During the unit’s warranty period, Northstar will repair or replace, at its option, any part of the unit it
finds to be defective due to faulty material(s) or workmanship. All such repairs and/or replacements
will be promptly performed by Northstar free-of-charge to the owner, excluding freight costs
incurred in shipping to the factory. Return shipments from Northstar to points within the United
States are made via ground transportation, freight prepaid. Special shipping charges (overnight,
two-day, and so on) are the responsibility of the owner.
To be covered by this warranty, the Northstar equipment must have been in normal use. This war-
ranty does not apply to units with defects caused by improper installation, physical damage, abuse,
tampering, lightning or other abnormal electrical discharge, or to units with defaced or altered serial
numbers, or to units repaired by unauthorized persons or repaired in a manner that violates North-
star’s recommended service procedures.
All repairs and/or replacements made under this warranty must be performed at Northstar’s facilities
in Acton, Massachusetts. Performance of warranty work elsewhere will not be authorized, and North-
star will not pay for any charges for such work. Northstar will not be responsible for payment of any
charges imposed by a Northstar dealer or other party for services requested by and/or performed for
a unit’s owner in connection with this warranty. Such services might include removal of the unit
from a vessel, inspection, packaging, handling, reinstallation, and the like.
Northstar Technologies, Inc. assumes no responsibility for any consequential losses of any nature
with respect to any of its products or services sold, rendered, or delivered. The foregoing is the only
warranty expressed or implied. No other warranty exists.

2505 INSTALLATION MANUAL, Revision A Page i
Table of Contents
List of Figures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
SECTION ONE Introducing the 2505. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
Who should read this manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
Scope of this manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
Getting technical support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
Servicing the Northstar 2505. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Returning a 2505 for service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Introducing the 2505 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
SECTION TWO Installing and interfacing the 2505 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Before installing the 2505. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Installing the 2505. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Installing the AN205-P antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Interfacing the 2505 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Troubleshooting the installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Appendix A Technical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Appendix B Data characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Input/output ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Appendix C NMEA output protocol. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
GPS receiver’s NMEA message format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Input sentences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Output sentences. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Page ii 2505 INSTALLATION MANUAL, Revision A

2505 INSTALLATION MANUAL, Revision A Page iii
List of Figures
Figure 1: 2505 case and mounting dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Figure 2: Northstar GPS/DGPS combo antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Page iv 2505 INSTALLATION MANUAL, Revision A

2505 INSTALLATION MANUAL, Revision A Page v
List of Tables
Table 1: Contacting Northstar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Table 2: 2505 parts list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Table 3: Standard connector pinouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Table 4: 2505 alternate connector pinouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Table 5: Sensor signals and I/O ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Table 6: Standard configurations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Table 7: Connector pin assignments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Table 8: NMEA field definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Table 9: Primary port input messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Table 10: NVM elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
Table 11: Primary port output sentences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40

Page vi 2505 INSTALLATION MANUAL, Revision A

2505 INSTALLATION MANUAL, Revision A Page 1
SECTION ONE
Introducing the
2505
The Northstar 2505 Beacon/WAAS Position Sensor Installation
Manual describes how to properly mount, interface, and
troubleshoot the Northstar 2505 and Northstar AN205-P
combination GPS/beacon antenna.
Also described are the 2505’s configuration options, the
physical, mechanical, and electrical characteristics, and the
serial protocol used to communicate with a host device.
Who should read
this manual
This manual is intended for installation technicians who are
installing, connecting, and troubleshooting the 2505.
Scope of this
manual
In this manual, you’ll find information about the following:
•the 2505’s operating modes
•mounting the 2505
•interfacing the 2505 with a host device
•installing the GPS/DGPS antenna

SECTION ONE Introducing the 2505
Page 2 2505 INSTALLATION MANUAL, Revision A
•troubleshooting
•NMEA output protocol
Getting technical
support
After you’ve followed the instructions in this manual, if you
need additional technical or operations support, or if you have
any other service-related questions, please contact your dealer
or the Northstar Service Department. You can reach Northstar
by email, fax, U.S. mail, or phone as described in Table 1 below.
You can also visit Northstar’s website for additional
service-related information.
Please have the 2505’s serial number available and be as
complete and accurate as possible when describing the
problem. This ensures that a Northstar service technician can
research the issue and provide the quickest possible response.
Northstar’s Service Department is available between 9:00 AM
and 5:00 PM Eastern Time, Monday through Friday, excluding
major holidays.
If you’re looking for an authorized Northstar dealer, or product
information and brochures, contact the Northstar Sales
Department.
You can email the
Northstar Service
Department directly from
Northstar’s website,
www.northstarcmc.com.
Here, you also can access
additional technical
information under either
the Support or Manuals
link (from this link you can
automatically open
manuals online using
Adobe’s Acrobat Reader.
Table 1: Contacting Northstar
Email:
Service: [e-mail]
Sales: [e-mail]
Fax:
Service: 978/897-1595
Sales: 978/897-7241
Telephone:
Main number: 978/897-6600 or 800/628-4487
U.S. mail:
30 Sudbury Road
Acton, MA 01720
Website:
www.northstarcmc.com (you can send email to
Northstar directly from this site)

SECTION ONE Introducing the 2505
2505 INSTALLATION MANUAL, Revision A Page 3
Using the Dealer
Express web pages
You can visit the Dealer Express area on Northstar’s website for
online service-related information (contact Northstar for a
dealer password before clicking on the Dealer Express link),
including the following:
•service bulletins (for known issues and solutions)
•software update information (for new software features)
•service request form (for sending products back)
•service status request form (for products currently under
repair)
•warranty registration form (for registering new products)
Hearing from you Your feedback is important and helps Northstar ensure that this
manual is a valuable resource for all installation technicians.
Send your questions, comments, or suggestions about this
manual to:
[e-mail]
Ordering parts To order spare, replacement, or missing parts, call the Northstar
Sales Department at 978/897-0770 or 800/628-4487.
Servicing the
Northstar 2505
The 2505 is repaired only by authorized Northstar dealers or
the Northstar factory. Service includes a complete hardware
and software check-out.
For a 2505 under warranty, shipping charges to the factory are
the only cost for factory repair. The repaired 2505 will be
returned via prepaid economy ground freight (freight for units
returned overseas is chargeable).
A 2505 and any accessories returned for warranty repair that
are determined to be without fault are subject to a handling
charge.
NOTE: For 2505’s still under warranty, field repairs are not
authorized and will void the warranty!

SECTION ONE Introducing the 2505
Page 4 2505 INSTALLATION MANUAL, Revision A
Returning a 2505
for service
The 2505 is covered by a two-year hardware-only warranty,
which, in summary, states that if the 2505 is returned to the
Northstar factory by the owner or dealer during the warranty
period, Northstar will repair or replace, free of charge, any part
found to be defective due to faulty materials or workmanship if
the system has been properly installed and hasn’t been abused.
See the Limited Warranty Policy at the front of this manual for
further details. The only cost to the owner will be the one-way
shipping charges and any associated charges that may be
imposed by the dealer. If you have overnight or second-day
shipping requirements, before shipping the 2505, please call
Northstar for turnaround time, freight charges, and payment
arrangements.
The 2505 should be shipped only in a properly designed carton
with packing material. Shipments to the Northstar factory
should be made to the following address:
Northstar Technologies
Service Department
30 Sudbury Road
Acton, MA 01720 USA
Introducing the
2505
Northstar’s 2505 Beacon/WAAS Position Sensor comprises a
high-performance, fully automatic 12-channel GPS/WAAS
receiver, and a two-channel beacon receiver, packaged together
into a self-contained ruggedized enclosure. The 2505 provides
accurate GPS position data worldwide—in any weather, 24
hours a day—for such applications as soil sampling, yield
monitoring, field mapping, vehicle tracking, and so on. Position
measurements will be accurate to about 3 meters 95 percent of
the time, speed measurements to about 0.1 miles per hour, and
course-over-ground (COG) to about 0.5 degrees. In areas where
WAAS or beacon differential is available, accuracy will be better
than 2 meters.
The 2505 is easy to install and configure: Just connect the
external antenna and cables for your particular application, and
supply the power. The 2505 is fully automatic so you won’t
Before returning the 2505
to the Northstar factory, to
prevent delays it is critical
that you first obtain a
Return Materials
Authorization (RMA)
number from the Northstar
Service Department. If you
purchased the 2505
through a dealer, to get an
RMA number, call the
dealer with the 2505 serial
number, which is located
on the 2505’s label.
Shipments without a
proper RMA number will
not be accepted!

SECTION ONE Introducing the 2505
2505 INSTALLATION MANUAL, Revision A Page 5
need to see it, touch it, or send commands to it. By eliminating
virtually all of the attention needed to operate the 2505, you
can devote more time to other aspects of your work.
Understanding differential The 2505 receives differential WAAS corrections from
strategically located ground-based transmitters called beacons,
as well as from satellites transmitting WAAS differential signals.
The 2505’s advanced beacon/WAAS engine provides greater
accuracy than GPS alone.
Beacon differential
The Global Positioning System (GPS) uses a system of 24
satellites (with three spares) operating in three orbital planes at
about 11,000 miles elevation. Position is determined by
measuring the time delay of the 1575-mHz signal from at least
three of the satellites, and computing position based on known
satellite locations. Beacon differential signal corrections are
generated by ground-based reference stations, at precisely
surveyed locations, and transmitted to the end user via
minimal shift keyed 300-kHz U.S. Coast Guard beacons
(ground-based).
WAAS differential
As with the Coast Guard radiobeacons, the Wide Area
Augmentation System (WAAS) satellites use surveyed reference
stations to monitor GPS signals from each visible satellite and
determine if errors exist, and then develop corrections.
However, unlike Coast Guard radiobeacons or other land-based
transmitters on other frequencies, WAAS uses a network of
geostationary communication satellite transponders, in fixed
positions at approximately twice the distance from the earth’s
surface as the orbiting GPS satellites, on the same frequency as
GPS (1575 mHz). These satellite-based transmissions provide
consistent position corrections over a much greater contiguous
geographic location than the other radiobeacons. WAAS
differential corrections maintain a position accuracy of better
than 3 meters 2dRMS, without the signal interference problems
periodically experienced with low-frequency, shore-based
radiobeacon differential signals.
Standard 2505 features The 2505’s standard features include the following:
•12-channel, high-performance GPS engine receiver with
integral two-channel WAAS differential reception and
position processing

SECTION ONE Introducing the 2505
Page 6 2505 INSTALLATION MANUAL, Revision A
•2-channel, fully automatic beacon differential GPS
reception for accuracy better than 2 meters 95 percent of
the time
•user-selectable (via switch) WAAS-only or WAAS with
beacon back-up
•WAAS accuracy better than 2 meters 2dRMS 95 percent of
the time
•fully automatic operating modes; no user intervention
required
•NMEA GGA and VTG messages at 5-Hz data rate
•internal beacon/GPS antenna splitter
For a complete list of the 2505’s technical specifications, see
“Appendix A Technical specifications” on page 19.
2505 operating modes The 2505’s GPS engine has seven operating modes:
•Self-test
•Initialization
•Acquisition
•Navigation (includes four sub-modes: Differential 3-D,
Differential 2-D, 3-D Nav, and Altitude-Hold)
•WAAS/beacon differential
•Dead-reckoning
•Fault
The 2505 automatically switches between modes, and reports
the current operating and navigation modes through its host
port. The nine operating modes are described in detail below.
Self-test mode
The 2505 enters the self-test mode upon a host’s request, using
an NMEA message, via the GPS primary port, using either
RS-232 or RS-422. This test requires no more than 15 seconds.
When the self-test is completed, the 2505 reports the test
results on its host port through another NMEA message, and
then proceeds either to initialization mode if the test was
passed or to fault mode if a problem was detected.
Initialization mode
The 2505 automatically enters initialization mode when power
is applied or after completion of self-test mode. While in
initialization mode, the 2505 retrieves satellite orbital data
(ephemeris or almanac) stored in its EEPROM memory.
Integrity checking is performed on all data retrieved from the

SECTION ONE Introducing the 2505
2505 INSTALLATION MANUAL, Revision A Page 7
EEPROM to ensure accuracy. After initialization, the 2505
enters acquisition mode.
Acquisition mode
The 2505 enters acquisition mode whenever sufficient
real-time satellite data is available to produce an initial
navigation solution. Acquisition mode can be entered from
initialization, navigation or dead-reckoning mode. The 2505
exits either to navigation mode when satellites have been
acquired or to fault mode if a problem is detected.
After each satellite-in-view is acquired, the 2505 collects new
ephemeris data by decoding the satellite downlink data
message. When a sufficient number of satellites are being
tracked, then position, velocity and time are computed, and the
2505 enters navigation mode. If the 2505 can’t acquire signals
normally due to an absence of valid almanac data, it initiates a
“Search the Sky” acquisition, attempting to acquire any and all
satellites in the GPS constellation. After a satellite has been
acquired, ephemeris data is decoded from the satellite
down-link message. In “Search the Sky,” the Time-To-First-Fix
(TTFF) is typically less than two minutes. After a sufficient
number of satellites have been acquired, the 2505 enters
navigation mode. For TTFF details, see Table 4, “2505 technical
specifications,” on page 19.
Navigation mode
The 2505 operates in Navigation mode whenever sufficient
satellite information and measurement data are available to
produce a GPS fix. Navigation mode is entered from either
acquisition or dead-reckoning mode, and exits to
dead-reckoning or fault mode.
Navigation mode has three sub-modes: differential 3-D,
differential 2-D, and 3-D nav:
•differential 3-D
•differential 2-D
•3-D nav
The 2505 automatically chooses the highest-performance
sub-mode available for the satellite data currently being
received, and reports to its host port the current navigation
sub-mode.

SECTION ONE Introducing the 2505
Page 8 2505 INSTALLATION MANUAL, Revision A
Differential 3-D
The 2505 operates in differential 3-D mode when it receives
data from at least four satellites with adequate geometry and
differential corrections, from either WAAS satellites or
radiobeacons. This is the navigation mode with the highest
performance.
Differential 2-D
The 2505 operates in differential 2-D mode when it receives
data from only three satellites with adequate geometry and
differential corrections, from either WAAS satellites or
radiobeacons. This is the navigation mode with the highest
performance when differential 3-D mode can’t be used.
3-D nav
The 2505 operates in 3-D nav mode when it receives data from
at least four satellites with adequate geometry, but no
differential corrections. This is the preferred navigation mode
when sufficient WAAS or radiobeacon corrections aren’t
available.
WAAS/beacon differential mode
While beacon and GPS acquisition is occurring, the 2505’s GPS
receiver is simultaneously searching for and acquiring the
WAAS differential signal from a geostationary satellite that
operates in the same frequency band as the GPS satellites. (To
avoid conflict, WAAS uses special PRN satellite identification
numbers.) Once the WAAS signal has been acquired and
settled, and provided that the GPS has entered navigation
mode, the 2505 can now enter WAAS or beacon differential
mode. WAAS and beacon modes are selected with a switch on
the connector panel. The switch functions are as follows:
•In the “WAAS/beacon” position, WAAS will be used, but
will revert to beacon if WAAS is lost or unavailable.
•In the “WAAS only” position, only WAAS differential
corrections will be used, if they’re available.
Dead-reckoning mode
The 2505 enters dead-reckoning mode when navigation mode
can’t be maintained. The speed and direction are assumed
constant, based on the last known data, to allow the 2505 to
provide an estimated position.

SECTION ONE Introducing the 2505
2505 INSTALLATION MANUAL, Revision A Page 9
Fault mode
The 2505 enters fault mode if it determines that its outputs are
affected by one or more critical system faults. This mode
supersedes all others and remains active until the next
power-down/power-up cycle. Fault mode can be entered from
any other mode, except initialization, whenever an
unrecoverable fault is detected. Fault mode protects against the
transmission of inaccurate data.
Automatic beacon
operation
The 2505 enters automatic beacon operations at power-up, and
requires no further supervision from the host GPS receiver.
Automatic operation is achieved by the use of two independent
receiver channels:
•Channel 1 tracks the best available beacon signal (the one
with the lowest data error rate), and sends the
demodulated DGPS corrections to the GPS receiver.
•Channel 2 continuously scans the entire beacon frequency
band (283.5 to 325 kHz) locating and measuring received
DGPS beacon signals. The 2505 then stores this
information as a DGPS beacon “directory” in
battery-powered memory.
If the signal received and monitored by Channel 1 degrades for
any reason, the 2505 selects a better frequency from its beacon
“memory.” This lets the 2505 switch to the best beacon signal
before your GPS accuracy is affected. Automatic beacon
operation can be used for all except the most specialized
applications, and is supported by most commercially available
GPS receivers.
At any time, the host device can override automatic station
selection by issuing NMEA tuning commands on the serial
interface. In this manual mode, the 2505 will output DGPS
corrections from the selected station. Automatic operation will
be restored at the next power-down/power-up cycle, or when
the host device issues a tune command frequency of “0” (zero).
For further details about manual mode, see “Appendix C NMEA
output protocol” on page 23.

SECTION ONE Introducing the 2505
Page 10 2505 INSTALLATION MANUAL, Revision A