8/17/2019 4 Artemis Jan 2010
1/13
DP Operator Course Artemis
Training Manual
Jan. 2010 © Kongsberg Maritime AS Page 6.4.1
Rev. 07 Training
Artemis Principle
8/17/2019 4 Artemis Jan 2010
2/13
Artemis DP Operator Course
Training Manual
Page 6.4.2 © Kongsberg Maritime AS Jan. 2010
Training Rev. 07
The purpose of the Artemis positioning system is to accurately determine and locate the
position of a mobile unit, for example a vessel, with respect to a known fixed point. The
system consists of two stations, the Mobile station on the moving unit and the Fix station on
the known fixed point.
To obtain the azimuth (bearing relative to north) of the Mobile station, the Fix antenna isaimed at a reference object with known azimuth prior to locking the system. The distance of
the Mobile station to the Fix station is obtained by measuring the time elapse of coded
interruptions in the microwave signal transmitted by both stations.
The antennas of the Fix and Mobile stations automatically track each other by maintaining a
continuous microwave link. A precision shaft encoder, coupled to the Fix station’s antenna
drive shaft, measures the angle of the antenna with respect to a known reference direction,
providing the bearing of the Mobile station.
To avoid mutual interference in areas where two Artemis systems are operational, four
Fix/Mobile station frequency pairs are available. Frequency pair selection is done from the
operating panel. Automatic frequency control at the Mobile station keeps the frequencies ofthe two stations exactly 30 MHz apart.
The system is portable and easy to install and thus being ideal as a sensor for dynamic
positioning (DP). Performance is unaffected by rain, fog or haze. The minimum range is 10 m,
and maximum range when used with DP is 10 km.
System Specifications
Frequency
Frequency band : 9.2 - 9.3 GHz
Four fixed, user-selectable frequency pairs : MOBILE FIX9200 MHz 9230 MHz (pair 0)
9300 MHz 9270 MHz (pair 1)
9230 MHz 9200 MHz (pair 2)
9270 MHz 9300 MHz (pair 3)
Automatic frequency control at Mobile station.
Distance measurement
Range : 10 - 30.000 M
Display resolution : 0.01 or 0.1 m
Data update rate : 0.25 secAccuracy (short-term) : < 0.1 m standard deviation
Overall absolute accuracy accounting
for temperature effects, atmospheric
conditions and counter clock stability : 1 m standard deviation
Azimuth measurement
Range : 0 - 360 degrees
8/17/2019 4 Artemis Jan 2010
3/13
DP Operator Course Artemis
Training Manual
Jan. 2010 © Kongsberg Maritime AS Page 6.4.3
Rev. 07 Training
Display resolution : 0.001 or 0.01 degree
Data update rate : 0.25 sec
Inherent accuracy : ±0.003 degree
Overall accuracy : 0.02 degree standard deviation
Antenna
Horizontal beam width : Approx. ±2 degrees @ -3 dB
Vertical beam width : Approx. ±11 degrees @ -3 dB
Approx. 40 degrees @ -10 dB
Horizontal side lobes : < -32 dB
Gain : Approx. 28 dB
Radiated microwave energy : Approx. 100 mW
Polarisation : Vertical
Standard Artemis System - Accuracy
- Range : 10 - 30 000 m ΔR = 1.5 m
- Bearing : 360° Δθ = 0.033°
- Lateral accuracy 58 cm/1000 m
Range ± 1.5 m irrespective of distance
Bearing ± 0.033° , that is 58cm/1 km, at 10 km this gives an inaccuracy of 5.8 m.
R
Δ θ
R
Δ R
Δ θ
Δ R
R m a x .
θ
8/17/2019 4 Artemis Jan 2010
4/13
Artemis DP Operator Course
Training Manual
Page 6.4.4 © Kongsberg Maritime AS Jan. 2010
Training Rev. 07
Accurate Positioning Alignment
To get an accurate positioning alignment, the exact location of the Fix station must be known,
and a reference object (of which the bearing is known) is required.
The antenna of the Fix station is aligned with the reference object and the bearing is entered
into the system.
Relative Positioning Alignment
When using Artemis as a position reference system for DP, relative positioning is generally
used. Knowledge of the exact position of the Fix station is not required.
The Mobile and Fix stations are set in operation and the antennas locked. The bearing is taken
from the vessel and reported to the Fix station. At the Fix station 180° is added to the bearing,
and the resultant bearing is entered into the system.
8/17/2019 4 Artemis Jan 2010
5/13
DP Operator Course Artemis
Training Manual
Jan. 2010 © Kongsberg Maritime AS Page 6.4.5
Rev. 07 Training
Antenna Tracking
The Artemis antenna type A010 consists of two-slotted wave-guides of equal length, which
are joined in the centre. This is a special four port microwave device that combines the two
antenna halves to two input/output wave-guide ports, the SUM and the DIF ports. The SUM
port is used for transmitting as well as for receiving. The DIF port is used for receiving only.
The figure shows the antenna SUM and DIF pattern. The left lobe of the DIF pattern has a
phase difference of -90° and the right lobe a phase difference of +90° with respect to the phase
of the SUM pattern.
ϕ
ϕ
ϕ
Antenna SUM and DIF pattern
Acting as a receiving antenna, the antenna outputs maximum SUM signal and zero DIF signal
if the incoming wave front is in parallel with the antenna. Deviations in the parallelism of the
incoming wave front result in a slowly decreasing SUM signal and a rapidly increasing DIF
signal.
8/17/2019 4 Artemis Jan 2010
6/13
Artemis DP Operator Course
Training Manual
Page 6.4.6 © Kongsberg Maritime AS Jan. 2010
Training Rev. 07
By feeding the received SUM and DIF signals to a servo detector, an error voltage is
generated.
−
The error voltage is amplified and fed to a servomotor, which drives the antenna shaft, until
the error voltage is zero, which means that the incoming wave front is in parallel with the
antenna. When the servo detector’s error voltage drives the antenna, the station is said to be
locked onto or in lock with the counter station.
Distance Measurement (Range)
The distance measurement is based on measuring the time elapse between a coded interruption
in the microwave signal transmitted by the Mobile station and the reception of a single coded
interruption in the microwave signal transmitted by the Fix station as a response to that.
8/17/2019 4 Artemis Jan 2010
7/13
DP Operator Course Artemis
Training Manual
Jan. 2010 © Kongsberg Maritime AS Page 6.4.7
Rev. 07 Training
Dip Zones
Reflection of microwave against the water surface
Although microwaves propagate
as direct waves (from antenna to
antenna), a part of the radiated
microwave energy is reflected
against the water surface and
reaches the receiving antenna
indirectly. Since the reflected
signal has to travel longer and
undergoes a 180° phase change
at the reflection point, there may
be a difference in phase between
the direct and the indirect signal
at the receiving antenna. This
may cause the direct signal to be
amplified (direct and indirect
signal in phase) or attenuated
(direct and indirect signal 180°out of phase).
The positions at which this phenomenon is experienced are generally referred to as dip zones,
range-holes, or interference zones, and are only dependent on the antenna heights and the
wavelength of the transmitted signal. The strength of the interference depends on the distance
between the transmitting and receiving antenna, and the nature of the water surface. A smooth
surface reflects the signal better than a choppy one.
PRODUCT
H1 x H2
H1 =
Mobile
antenna
height
H2 =
Fixed
antenna
height
800
700
600
500
400
300
DISTANCE (metres)
6000 10000 14000 18000 22000 26000 30000
6000 10000 14000 18000 22000 26000 30000
DIP
ZONES
8/17/2019 4 Artemis Jan 2010
8/13
Artemis DP Operator Course
Training Manual
Page 6.4.8 © Kongsberg Maritime AS Jan. 2010
Training Rev. 07
H
=
2 0 m
1 H
=
3 0 m
2
H
X H
= 6 0 0
1
2
H
=
2 m
1 H
=
3 0 m
2
H
X H
= 6 0
1
2
1
2
3
4
5
6
7
8
9
3 0
4 0
5 0
6 0
7 0
3 0
4 0
5 0
6 0
7 0
3 0
4 0
6 0
7 0 3
0 4 0
6 0
7 0 2
0 2 0
8/17/2019 4 Artemis Jan 2010
9/13
DP Operator Course Artemis
Training Manual
Jan. 2010 © Kongsberg Maritime AS Page 6.4.9
Rev. 07 Training
Artemis Mk III System
Artemis Mk IV Mobile stations can also be used together with an Artemis Mk III Fix station.
Fix Control Data Unit Mobile Control Data Unit
When using a Mk III Fix station, the frequency on which to work is selected at the Mobile
station. The frequency must lie between 9200 - 9300 MHz, and it must be defined whether the
Fix station frequency is to be 30 MHz higher or lower than the Mobile station frequency. In
addition, the transmitting power and the preamplifier have to be set manually according to the
operating range.
Artemis Mk IV System
Artemis Basic Unit (ABU)
with antenna
Basic Operating Panel (BOP)
Extended Operating Panel (EOP)
Artemis Mk IV is a microwave position
reference system of the range-bearing
type. The system comprises two identical
stations (Artemis Basic unit); one station
configured as Fix station and the other as
Mobile station. Each station consists of
an ABU, on top of which a radar-like
tracking antenna is mounted, and a BOP
if it is used as a Fix station, or an EOP if
it is used as a Mobile station.
The Fix station is set up on a known,
fixed location and the Mobile station is
installed onboard the vessel.
The antenna is specially designed and of
the slotted wave guide type. It is fitted in
a completely sealed, lightweight
aluminium structure and has a fiberglas
radome. It is suitable for exposed
conditions. For operation in polar areas,antennas with an integrated radome-
heating element are available.
8/17/2019 4 Artemis Jan 2010
10/13
Artemis DP Operator Course
Training Manual
Page 6.4.10 © Kongsberg Maritime AS Jan. 2010
Training Rev. 07
Antenna Indicator Display
The antenna indicator display shows:
a) The ANTENNA DIRECTION marker, which indicates the direction of the antenna
with respect to the chosen reference direction. When the EOP is connected to the
Mobile station, the marker indicates the relative antenna bearing. When connected to
the Fix station, the marker indicates the azimuth.
b) The MAIN BEAM marker, if signal containing the correct address code is received
and the antenna is locked to the counter station.
c) The AUTOSEARCH SCAN SECTOR marker, if the autosearch operating mode is
selected and an autosearch scan sector is set. The unshaded area indicates the actual
scan sector.
8/17/2019 4 Artemis Jan 2010
11/13
DP Operator Course Artemis
Training Manual
Jan. 2010 © Kongsberg Maritime AS Page 6.4.11
Rev. 07 Training
Operation
The Mobile and Fix stations are operated via the keyboard and display of the operating panels.
Once a link has been established between the two stations, the complete system can be
controlled from one station, generally the Mobile station.
Operator interaction between the keyboard and the display of the operating panel is via a
menu structure. This is basically the same for both the Mobile and Fix station.
OPERATE
MODIFY
MONITOR
WAKE-UP
FIX
CONFIG
1
2
3
4
5
6
MOB
Main menu Mobile station
OPERATE
MODIFY
MONITOR
WAKE-UP
MOBILE
CONFIG
1
2
3
4
5
6
FIX
Main Menu Fix station
From the main menu a selection can be made from the six categories by keying in the number
adjacent to the category.
- OPERATE
is selected to display the position parameters distance and azimuth.
- MODIFY
is selected to read and/or change station parameters, location parameters, autosearch
scan angles, clock, operating mode, communication parameters and voice channel
volume.
- MONITORis selected to monitor supply voltages, mixer crystal currents, Automatic Gain Control,
tuning and servo signal readings, temperature of wave guide and distance measuring
circuit.
- WAKE-UP
is selected to define the time and date the station is to switch itself on, this function is
normally not used.
- FIX (if Mobile station)
is selected at the Mobile station to remotely access the Fix menu structure to read
and/or modify Fix station parameters.
- MOBILE (if Fix station)
is selected at the Fix station to remotely access the Mobile menu structure to readand/or modify Mobile station parameters.
- CONFIG
is selected to configure an ABU before it is put into operation for the first time.
8/17/2019 4 Artemis Jan 2010
12/13
Artemis DP Operator Course
Training Manual
Page 6.4.12 © Kongsberg Maritime AS Jan. 2010
Training Rev. 07
Artemis Mk IV Beacon
For short range positioning the Artemis Mk IV Beacon is a good alternative to the Artemis
Mk III or Mk IV Fix station. Typical applications are Floating Storage Tankers and Loading
Buoys.
The beacon provides only the distance to the Artemis Mobile station. The bearing is obtained
by combining the Mobile antenna bearing with the heading of the vessel as measured by the
vessel’s gyro compass.
There are three different antennas available:
Omni-directional antenna for range 10 - 2500 m
Semi-omni-directional antenna for range 10 - 5000 m
Horn antenna for range 15 - 1000 m
The horn antenna is specially intended for applications where the beacon is mounted in a
substantially higher position than the Mobile station and the system is operated at very short
ranges.
ARTEMIS BEACONBASE
POSITION
ARTEMIS
BEACON
ARTEMIS MICROWAVELINK
THE BEACON IS SIMPLY A TRANSPONDER. NO
BEARING DATA TRANSMITTED
ARTEMIS
MOBILE
ANTENNA
SHUTTLE TANKER
DURING APPROACH
OFFSHORE LOADING
TERMINAL WITH
BEARING MEASURED
AT MOBILE ANTENNA
TELEMETRY LINK ALLOWS TURNTABLE AZIMUTH TO BE
TRANSMITTED TO THE VESSEL SUCH THAT BEACON OFFSET
CAN BE COMPENSATED FOR, CORRECTING THE RANGE TO
THE BASE LOCATION
8/17/2019 4 Artemis Jan 2010
13/13
DP Operator Course Artemis
Training Manual
Jan. 2010 © Kongsberg Maritime AS Page 6.4.13
Rev. 07 Training
Operation of two Systems
Given the available Artemis frequency band of 9200-9300 MHz, two Artemis systems can be
operated simultaneously in the same area by choosing frequency pair 0 or 2 for one system
and frequency pair 1 or 3 respectively for the other system. Whether more than two systems
can be operated simultaneously depends on the relative position of the vessels’ work areas.
Two Vessels using Artemis in different Sectors
Normally no interference will occur if a
spatial beam separation of at least 10° is
maintained. If, for instance, the vessels
are working at different faces of a
platform, i.e. have their Fix station
installed on different sides of the
platform, there is no interference to beexpected as long as the two beams do not
come within 10° of each other.
Vessels working in the same Direction
In the above figure the direction of the
microwave beams of Fix 1 - Mobile 1and Fix 2 - Mobile 2 differs less than
10°, so mutual interference can be
expected. This is especially the case at
larger working distances where the
beams converge. The solution is to
choose different frequency pairs.