To receive additional copies of this publication, order the Northstar Sensors Technical Reference Manual (Part No. GM8900).
Limited warranty policy
Northstar 8700, 8800 series, and 8900 series sensors
Northstar Technologies, a division of CMC Electronics, Inc., warrants its family of 8700, 8800 series, and 8900 series sensors 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.
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 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. The warranty 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 Northstar’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 Northstar 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 or the unit from a
vehicle, inspection, packaging, handling, reinstallation, and the
like.
Northstar 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.
* Certain Northstar control heads are warranty-protected against
damage due to water leakage, provided the head has not been
tampered with.
To use this manual effectively, please read this entire two-page section
first. This document doesn’t contain basic installation information. If
you’re looking for instructions about mounting the sensors and antennas,
connecting the cables, or other details on interfacing the Northstar sensors to other Northstar receivers, please refer to the corresponding North-star Installation Manual.
1.1 Scope of this manual
Section 1 - About this manual
1.1.1 Audience
1.1.2 Contents
The Northstar Sensors Technical Reference Manual is intended for readers
with a good technical knowledge of the components of GPS consumer
navigational instruments. This audience includes engineers and other
technical product-development persons in original equipment manufacturer (OEM) environments; experienced dealers of marine, land-based, or
other navigational equipment; and small start-up companies, all looking
for ways to interface their products with Northstar sensors.
This manual presents this technical information in a logical, easy-to-use
format; each section is organized for access to specific information. In this
way, you can go directly to the source of that information without sifting
through unnecessary levels to find what you need.
The manual covers the following products:
•Northstar 8700 GPS Position Sensor
•Northstar 8800 Series Beacon Sensors
•Northstar 8900 Series GPS/DGPS Position Sensors
Additional high-level information about antennas, pinouts and configurations, NMEA protocol, beacon binary protocol, RS-422 and RS-232 interfaces, and the 8X00 ALLSTAR Engine Monitor Program is all contained
within this manual. In fact, if you own this Northstar Sensors Technical Reference Manual, you should have received a copy of the Northstar
8X00 ALLSTAR Engine Monitor Program. (If you didn’t receive this program, call the Northstar sales department and order Northstar Part Number GS8900, shipped on a 3-½ inch diskette at no charge.)
This document supersedes the Northstar Installation and Operation Man-ual (Northstar Part Number GM8900, Revision G).
1.1.3 Conventions
05/01/97 REV H PAGE 1
The conventions listed below are used throughout the manual to consistently refer to certain information, as follows:
and
NOTE
reader information. Be sure to read the information in these note and
caution boxes.
NMEA command is the bold typeface used when the text refers to a com-
mand given to, or output by, the sensors;
(without bold) used when a table refers to a command given to, or output
by, the sensors.
CAUTION
are the headings for text boxes containing important
NMEA command is the typeface
Section 1 - About this manual
1.1.4 Glossary and
acronyms
1.1.5 Registration
card
1.1.6 Service and
repair
This manual contains two separate sections to clarify technical terms,
abbreviations, acronyms, and initialisms. Each new term is defined when
it first appears; however, a term once defined is not redefined each time it
appears. Consequently, you may want to refer to the back of this manual
if you find a term you don’t understand.
Make sure you fill out the owner’s registration card included with the
sensor and return it to Northstar Technologies. We must have your complete mailing address (not just a company name) so we can send you any
future product information.
In case of an operating problem with a Northstar sensor, you may contact
your dealer or return the sensor to the Northstar factory for diagnosis
and repair. Be as complete and accurate as possible when you describe an
operating problem. If you need immediate assistance, feel free to call
Northstar service at (508) 897-7251.
Each sensor is covered by a two-year limited warranty, which, in summary, states that if a sensor is returned to the factory by the owner 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
sensor has been properly installed and hasn’t been abused. The only cost
to the owner will be the one-way shipping charges that might be imposed
by the dealer.
Shipments to Northstar Technologies should be made to the following
address:
Northstar Technologies, 30 Sudbury Road, Acton, MA 01720
If you have special overnight or two-day shipping requirements (UPS or
Federal Express), please call the Northstar factory for turnaround time
and freight costs before shipping your sensor.
Refer to the Limited Warranty Policy at the beginning of this manual for
further details on warranty and service policies and procedures.
PAGE 205/01/97 REV H
2.1 Overview
Section 2 - Introduction
Section 2 - Introduction
Northstar’s family of position sensors, comprised of models 8700, the
8800 series, and the 8900 series, features self-contained, 12-channel GPS
modules with two-channel, automatic, medium-frequency radio-beacon
receivers, packaged in rugged “black box” aluminum enclosures.
These high-performance units provide reliable GPS and/or DGPS positioning for the following applications:
•Custom OEM systems requiring superior, “all-in-view” GPS perfor-
mance
•Automatic vehicle location (AVL) and monitoring systems, including
railroads, highways, emergency, public transportation, and trucking
•Mobile ground information systems (GIS) data acquisition, including
asset management and mapping
•Precision agriculture, including yield mapping, yield monitoring, and
sampling
•Forestry, including aerial spraying, planting, and forest mapping
•Surveying/mapping, including aerial, highway, and legal surveys;
utility mapping
•Marine navigation
2.1.1 Northstar
8700
2.1.2 Northstar
8800 series
2.1.3 Northstar
8900 series
The Northstar 8700 is a 12-parallel-channel, DGPS-ready, fast-acquisition
GPS receiver that continuously tracks all available satellites. The 8700
accepts DGPS corrections from any source of Radio Technical Commission for Maritime Services (RTCM) SC-104 data. See Section 4, “GPS
Receivers,” for complete information about the Northstar 8700.
The Northstar 8800 series (comprised of either the 8800 or the 8801, an
8800 bundled for agricultural applications) is a two-channel, auto-tuning,
Minimum Shift Keying (MSK) radio-beacon receiver, also known as a beacon demodulator, or BDM, which supplies fully automatic differential
corrections for an external DGPS-ready receiver. While the 8800 series’
Channel 1 processes real-time corrections, Channel 2 automatically
searches for alternates. The 8800 series works worldwide with beacons
that conform to the SC-104 specification.
See Section 5, “Beacon Receivers” for complete information about the
Northstar 8800 series.
Northstar combines the 8700 and the 8800 to form the Northstar 8900
series of sensors, which provide optimum performance in self-contained,
fully automatic DGPS units. See Section 6, “GPS/Beacon Combination
Receivers” for complete information about the Northstar 8900 series.
05/01/97 REV H PAGE 3
Section 2 - Introduction
(A
l dimensions in inches
)
2.1.4 Sensor
dimensions
The sensors share common dimensions as outlined below.
•Height = 2.0 inches
•Width = 4.6 inches
•Depth = 8.9 inches
•Weight < 2 pounds
2.1.5 Power
l
FIGURE 1 - 8700/8800 series/8900 series dimensions
Each sensor is easy to use: Just connect the antenna and supply the
power.
CAUTION!
Before you apply power to the system, double-check
all wiring. A small, but significant number of units
sustain damage because of incorrectly wired connections. This damage isn’t covered under warranty. Be
sure you don’t apply primary voltage directly to any
of the signal input/output wires of the GPS sensor;
this may vaporize circuit-board conductors within
the sensor.
Status indicator light
NOTE:
The information below only applies to the Northstar
8800 series and 8900 series sensors; NOT to the
Northstar 8700 sensor.
PAGE 405/01/97 REV H
Section 2 - Introduction
The status indicator light illuminates when the unit’s power is turned on.
When you first turn power on, the light turns green for just a few seconds. The light then turns red, and stays red as long as the sensor is
searching for a beacon. Once the sensor has locked onto a beacon, the
light will then turn green.
Another function of the status indicator light is flashing red/green. The
light will only flash red/green if the beacon antenna (not GPS) is open or
shorted. Check your antenna or antenna wiring to determine the problem, if you see the flashing red/green light. Once the problem has been
fixed, the light will turn red for as long as several minutes, while the sensor searches for a beacon. The light will return to green once it has locked
onto a beacon.
The status indicator light in the 8800 and 8900 sensors refers to beacon
status, not GPS status.
2.1.6 Interfacing
You can interface Northstar position sensors to a wide variety of external
devices, such as navigators, computers, yield monitors, and so on. These
external devices, or host systems, receive and process the data from the
sensor, and in some applications, may control the sensor.
Each sensor has two, full-duplex serial I/O ports that may be connected to
a host system in a variety of ways and for different applications. The function of each I/O port is determined by a Programmed Array Logic (PAL)
chip that acts as a matrix switch, which can configure the I/O port to several configurations.
All three sensors use identical I/O hardware and circuitry, configured for
specific applications by jumper options controlling the PAL chip. Any one
of the eight standard configurations (see Section 8, “Input/Output Configurations” for a complete list of standard configurations) is selectable from
combinations of three jumper pins located on the 25-pin data/power connector.
The standard, recommended configuration for each sensor described in
this manual is further described in its corresponding NorthstarInstalla-tion Manual. Custom configurations also may be available for large quantities of sensors as special orders.
05/01/97 REV H PAGE 5
Section 2 - Introduction
PAGE 605/01/97 REV H
3.1 Housing
Section 3 - Packaging
Section 3 - Packaging
The sensor is housed in a rugged aluminum enclosure with a mounting
flange.
NOTE:
The housing isn’t completely waterproof, so keep the
sensor away from direct contact with water spray or
splash.
The sensor enclosure includes keyhole slots, located at the rear of the
sensors, which aid in installations of limited access. You can mount the
sensors either horizontally or vertically; see Figure 1 in Section 2, “Introduction,” for case and mounting dimensions.
Northstar ships each sensor system with the following parts; check with
Northstar if these parts aren’t included with your sensor.
8902-CAOptional interfacing cable for connecting to North-
star 800 series GPS-ready Lorans (only supplied with
units for connection to 800-GPS or 800X-GPS, if
specified at time of order.
Table 5: 8901 parts
Part #Description
8901-A8901 integrated GPS/DGPS position sensor with
internal splitter
AN200Combination antenna with 20 feet of RG-59U coaxial
cable
GM-625Northstar 8901/8901AL Ag DGPS Sensors Field Instal-
lation Manual
8901-CAOptional interfacing cable for agricultural applica-
tions
8903-CAOptional interfacing cable for AgLeader applications
(included with Northstar 8901AL sensor)
05/01/97 REV H PAGE 9
Section 3 - Packaging
PAGE 1005/01/97 REV H
Section 4 - GPS receivers
4.1 Northstar 8700
The Northstar 8700 GPS position sensor decodes satellite radio signals,
and provides three-dimensional position, velocity, time, and other status
information at a maximum rate of once per second.
Each of the 12 parallel channels continuously tracks a GPS satellite signal.
To support faster acquisition of GPS signals, the sensor makes provisions
for external initialization of data. Further, the sensor can use externally-provided differential corrections to reduce inherent GPS inaccuracies; WGS-84 (World Geodetic System) is used as its reference datum.
Section 4 - GPS receivers
4.1.1 Features
4.1.2 Technical
specifications
•12-channel correlator for “all-in-view” reception
•External antenna
•Code and carrier tracking of L1 GPS frequency (1,574.42 MHz) for
increased accuracy
•Very fast signal reacquisition after signal obscuration
•Two serial input/output data ports: One to transmit navigation data,
another for differential data input or other needs. Either one can be
used for maintenance (reprogramming mode).
Power requirements
•10 to 40 VDC
•6 watts power consumption
•0°C to +55°C temperature range of operation
•Internal, two-amp fuse
Electrical requirements
The 8700’s power supply is protected against reverse-polarity power
inputs, and features a remote turn-on ability. The 8700 turns on whenever power is applied to pin 25, ground to pin 13, and remote-on pin 12 is
connected to a source of +5 to +40 VDC.
Dynamics
•Velocity: 1800 km/h
•Acceleration: 4 g
•Jerk: 2 m/sec
3
Position accuracy
•3 m horizontal, with DGPS, 95 percent confidence
•30 m horizontal, without Selective Availability (SA) imposed, 95 per-
cent confidence
•100 m horizontal, with SA imposed, 95 percent confidence
05/01/97 REV H PAGE 11
Section 4 - GPS receivers
Acquisition time
•60 seconds typical Time-To-First-Fix (TTFF) with current almanac
Reacquisition time
•< 1 second typical to re-acquire (5-second obscuration)
•< 3 seconds typical to re-acquire (60-second obscuration)
The 8700 automatically switches between six operating modes:
•Self-test
•Initialization
•Acquisition
•Navigation (includes four sub-modes: differential 3-D, differential
2-D, 3-D nav, and 2-D altitude-hold)
•Dead reckoning
•Fault
FIGURE 2 - 8700 ALLSTAR engine operating modes
The six modes are described in detail below.
PAGE 1205/01/97 REV H
Section 4 - GPS receivers
Self-test
Upon request from an external source via the GPS primary port, using
either RS-232 or RS-422, the 8700 enters self-test mode. This test requires
no more than 15 seconds. Upon completion, the 8700 reports the test
results on its primary port through an NMEA message that’s displayed on
the host PC, if available. Then, the 8700 proceeds either to initialization
mode if it passes the test, or to fault mode if it detects a problem.
Initialization
When either power is applied or the self-test mode is complete, the 8700
enters initialization mode. While in this mode, the 8700 retrieves satellite-orbit data stored in its EEPROM memory. To ensure accuracy, the
8700 performs integrity checks on all data retrieved from the EEPROM.
After initialization, the sensor enters acquisition mode.
Acquisition mode
Whenever sufficient real-time satellite data is available to produce an initial navigation solution, the 8700 enters acquisition mode. Acquisition
mode can be entered from initialization, navigation, or dead-reckoning
modes (see below for separate descriptions of navigation and dead-reckoning modes).
The 8700 uses almanac data (stored in EEPROM memory) that describes
the satellite orbits, which helps quickly acquire signals from the GPS satellites. After each satellite in view is acquired, the 8700 collects its ephemeris data by decoding the satellite down-link data message. When enough
satellites are being tracked, the unit computes position, velocity, and
time, then enters navigation mode.
If valid almanac data is absent, and the 8700 can’t acquire signals normally, it initiates a “search the sky” acquisition, attempting to acquire all
satellites in the GPS constellation. In search the sky, the TTFF typically is
less than five minutes. After it acquires each satellite, ephemeris data is
decoded from the satellite down-link message. When enough satellites
are being tracked, the 8700 enters navigation mode—although it exits to
fault mode if it detects a problem.
Navigation mode
The 8700 enters navigation mode whenever sufficient satellite information and measurement data is available to produce a GPS fix. The unit
enters navigation mode from acquisition or dead-reckoning modes, and
exits to dead-reckoning or fault mode.
Navigation mode consists of four sub-modes. The 8700 automatically
chooses the highest-performance sub-mode available for the satellite data
that it currently receives. On its primary port, it reports the current navigation sub-mode:
•3-D Differential
This navigation mode has the highest performance. The 8700
operates in this mode when it receives data from at least four
satellites with adequate geometry and differential corrections.
Differential SC-104 corrections can be taken in the auxiliary data
port using either RS-232 or RS-422.
05/01/97 REV H PAGE 13
Section 4 - GPS receivers
•2-D Differential
When 3-D differential mode can’t be used, this is the
highest-performance navigation mode. The 8700 operates in this
mode when it receives data from only three satellites with adequate
geometry and differential corrections. SC-104 differential corrections
can be taken in on the auxiliary data port using either RS-232 or
RS-422.
•3-D Nav
When sufficient differential corrections aren’t available, this is the
preferred navigation mode. The 8700 operates in this mode when it
receives data from at least four satellites with adequate geometry,
but no differential corrections.
•Altitude-Hold (2-D Nav)
This is the least-preferred navigation mode. If satellite
measurements are insufficient to produce a 3-D navigation solution,
but sufficient when altitude information is available, the 8700
operates in this mode, where the altitude is assumed constant.
Dead-reckoning mode
The 8700 enters dead-reckoning mode when it can’t remain in navigation
mode. The speed and direction of the vehicle are assumed constant to
allow the 8700 to provide an estimated position.
Fault mode
The 8700 enters fault mode from any mode—except initialization—when
and if the 8700 determines that one or more critical system faults are
affecting its outputs. Fault mode supersedes all others, and remains active
until the next power-down/power-up cycle.
PAGE 1405/01/97 REV H
Section 5 - Beacon receivers
5.1 Northstar 8800 series
The Northstar 8800 series DGPS beacon sensor system receives corrections broadcast by land-based marine radio beacons situated along most
of the U.S. coastline and inland waterways (see Figure 3 below). GPS
receivers can use these corrections to improve their GPS accuracy to 10
meters or better, with three-meter accuracy 95 percent of the time commonly available.
The 8800 can significantly enhance the accuracy and performance of all
differential-capable GPS receivers that support the standard RTCM
SC-104 DGPS corrections format. DGPS corrections remove the errors
caused by atmospheric variations and Selective Availability, or SA. SA is
the intentional degradation of satellite signals by the U.S. Department of
Defense.
Section 5 - Beacon receivers
WA
OR
NV
CA
Approximate limit of
µV signal strength
75
Additional probable
coverage area for
µV sensitivity
20
MT
ID
UT
AZ
WY
NM
CO
ND
SD
TX
NE
KS
OK
MN
WI
MI
IA
MO
AR
LA
IL
MS
IN
TN
AL
KY
OH
GA
WV
PA
VA
NC
SC
FL
FIGURE 3 - Radio-beacon coverage map
NOTE:
Figure 3 is current as of 03/01/97. For the absolute latest in radio-beacon coverage information, please visit
the Northstar web site at http://www.north-starcmc.com. Then, follow the “What’s new” link,
click on “Interesting web links,” and select the USCG
Navigation Center.
NY
ME
VT
NH
MA
CT
N
J
5.1.1 About the
Northstar 8801
The 8800 and 8801 sensors are functionally identical; the only difference
is their configuration. The 8800 can be used with either the Northstar
8410 ACU or the Northstar AN195 H-field antenna, and is intended primarily for marine applications. The 8801 is a bundled system intended
05/01/97 REV H PAGE 15
Section 5 - Beacon receivers
primarily for agricultural and other land-based applications. It includes
the AN195 H-field antenna and the Northstar 8801-CA cable assembly,
which provides a standard nine-pin connector to interface the 8800 to a
personal computer or other equipment designed to receive differential
corrections.
Because the two units are functionally identical, this section uses the
common term 8800 to refer to both models.
5.1.2 Features
5.1.3 Technical
specifications
•Two channels
•Automatic evaluation of available radio-beacon signals
•Automatic selection of best stations
•Superior channel performance and impulse blanking techniques
Wiring diagrams on connecting the 8800 to Northstar GPS receivers are
provided in the Northstar 8800 and 8801 Beacon Receivers Installation Manual (Northstar Part Number GM635); these receivers include the
Northstar 806, 806X, and Europa GPS navigators; and the Northstar 8000,
8100, 8300, 8700, and 9300 DGPS sensors used with the Northstar 800
and 9000 series navigators. For other receivers, use the Northstar diagrams as a guide, and consult the interfacing diagrams supplied with
your receiver. You can use the 8800 with any brand of GPS receiver that
supports the standard RTCM SC-104 DGPS corrections format.
NOTE:
Some Northstar units may require a software upgrade
for use with the 8800.
Power requirements
•10 to 40 VDC input voltage
•5 watts power consumption
•Remote turn-on ability
•2-amp input fuse
Signal processing
•Two channels
•283.5 - 325.0 kHz frequency range
•< 2 Hz tuning resolution
•Minimum signal strength: < 5 µV/m @ 100 bps
•> 100 dB dynamic range
•> 50 dB at 1 kHz adjacent channel rejection
•Acquisition time: Five seconds, manual command; 15 seconds, auto-
matic warm start; 15 minutes, automatic cold start (only at first turn
on after installation—time varies, depending on local beacon frequencies)
•Predictive variable-length noise blanker
PAGE 1605/01/97 REV H
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