NAVIGATIONAL INSTRUMENT WITH COMPASSES PRELIM Flashcards
It is the method of navigation used by mariners that uses landmarks as reference points, ship’s stability, fuel consumption and ship’s speed a!ong with tides and currents
TERRESTRIAL NAVIGATION
plots positions in relation to the stars and other celestial bodies
CELESTIAL NAVIGATION
is the angular distance in degrees, minutes and seconds of a point north or south of the Equator
LATITUDE (shown as a horizontal line
Lines of latitude are often referred to as
PARALLELS
is the angular distance in degrees, minutes and seconds of a point east or west of the Prime(Greenwich) meridian
LONGITUDE (shown as a vertical line
Lines of !ongitude are often referred to as
MERIDIANS
determines position by advancing a known position for courses and distances
Dead reckoning (DR)
A position so determined is called a
Dead reckoning (DR)
Correcting the DR position for leeway, current effects, and steering error result in an
estimated position (EP)
Types of navigation are
Piloting, Celestial navigation, Radio navigation, Radar navigation, Satellite navigation
involves navigating in restricted waters with frequent or constant determination of position relative to nearby geographic and hydrographic features
Piloting
involves reducing celestial measurements taken with a sextant to lines of position using calculators or computer programs, orby hand with almanacs and tables or using spherical trigonometry
Celestial navigation
uses radio waves to determine position through a variety of electronic devices
Radio navigation
uses radar to determine the distance from or bearing of objects whose position is known. This process is separate from radar’s use in collision avoidance.
Radar navigation
uses radio signals from satellites for determining position
Satellite navigation
is a tower, building or other types of structure designed to emit light from a system of lamps and lenses and to serve as a navigational aid for maritime pilots at sea or on in; and waterways
lighthouse
is a distinctively shaped and marked float, sometimes carrying a signal, anchored to mark a channel, anchorage, navigational hazard, etc or to provide a mooring place away from the shore
buoy
Ability to determine the ship’s position by use of electronic navigational aids
KUP 1
is a type of conic section. it is a curve formed by the intersection of a cone and a plane
hyperbola
three types of conic sections
parabolas, ellipses, and circles
is created when the plane intersects both halves of a double cone, creating two curves that look exactly like each other, but open in opposite directions
hyperbola
this occurs when the angle between the axis of the cone and the plane is less than the angle between aline on the side of the cone and the plane
hyperbola
the locus of points with a constant difference in distance from two reference points is a
hyperbola
A land-based, high power, hyperbolic radio navigation system which enables ships and aircraft to determine their position and speed from low frequency radio signals
LORAN
LORAN Components:
- Transmitting stations 2. LORAN receiver and antenna 3. LORAN charts
ORAN stations operations are organized into sub-groups of four to six stations called
CHAINS
LORAN UNIT
- Signal Processor 2. NavigationComputer 3. Control andDisplay
It converts time difference values to location corresponding latitude and longitude.
NAVIGATION COMPUTER
suffers from electronic effects of weather and the ionosphere effects of sunrise and sunset
LORAN
results when one LoranLOP crosses another LOP in two separate places
Fix ambiguity
would resolve the ambiguity.
third LOP
comprises advancement in receiver design and transmission characteristics which increase the accuracy and usefulness of traditional LORAN
Enhanced LORAN, also known as eLORAN or E-LORAN
includes additional pulses which can transmit auxiliary data such as GPS corrections
eLORAN
started with the launch of the U.S Department of Defense GlobalPositioning System (GPS) in the late 1970’s
GNSS (Global Navigation Satellite Systems)
GNSS systems currently include
- GPS (United States)* GLONASS (Russia)* Galileo (European Union)* BeiDou (China)
GNSS satellite systems consists of three major components or “segments:
- Space Segment* Control Segment* User Segment
comprises of a ground-based network of master control stations, data uploading stations, and monitor stations
control segment
adjust the satellites’ orbit parameters and on-board high-precision clocks when necessary to maintain accuracy
Master control stations
monitor the satellites’ signal and status, and relay this information to the master control station
Monitor stations
uploads any change in satellite status back to the satellites
Uploading stations
consists of GNSS antennas and receivers used to determine information such as position, velocity, and time
User segment
is the best known of these satellite navigation systems.
Global Position System (NAVSTARGPS)
Main elements of the satellite navigation system
-Space segment-Earth segment-Users segment
is the standard generic term for satellite navigation systems that provide autonomous geo-spatial positioning with global coverage.
Global Navigation Satellite System (GNSS)
is very important. The time it takes a GNSS signal to travel from satellites to receiver is used to determine distances (range)to satellites
Timing accuracy
1 microsecond =
300m
1 nanosecond =
30 cm
a portion of the radio spectrum between 1 and 2 GHz
L-band
transmits a navigation message, the coarse acquisition (C/A) code which is freely available to public
L1
called the P(Y) code(restricted access), is transmitted on both L1 and L2
encrypted precision (P) code
Three signals are transmitted at the moment byGPS in L1
C/A Code, P(Y) Code and M-Code.
Since the computed range contains errors and is not exactly equal to the actual range, we refer to it as a
“pseudorange”
The ionosphere contributes to most of the atmospheric error. It resides at _ above the earth’s surface
70 to 1000 km
Free electrons resides in the ionosphere, influencing
electromagnetic wave propagation
are frequency dependent. It can be virtually eliminated by calculating the range using bothL1 and L2
Ionospheric delay
the lowest layer of the Earth’s atmosphere, contributes to delays due to local temperature, pressure and relative humidity
troposphere
Receivers need at least _ to obtain a position.
4 satellites
are modulated by a unique pseudorandom digital sequence, or code. Each satellite uses a different pseudorandom code
GNSS signals
means that the signal appears random, but actually repeats itself after a period of time
Pseudorandom
For each satellite tracked, the receiver determines the
propagation time
a term used to describe the strength of a satellite configuration on the accuracy of data collected with GPS receivers. W
DOP (dilution of precision) is
The orbital period of each satellite is approximately
12 hours
At any point in time, a GPS receiver will have at least _ in view at any point on Earth under open sky conditions
6satellites
Each satellite is identified by their _
Space Vehicle Number(SVN) and theirPseudoRandom codeNumber (PRN
GPS signals are based on
CDMA technology
tracks the satellite broadcast sign a land pass them on to the master control station where the ephemerides are recalculated
monitor stations
used to calculate the position of each satellite in orbit, and information about the time and status of the entire satellite constellation, called the almanac
ephemeris data
is responsible for doing everything from performing calculations, to providing the analog circuitry for the antenna, to power control, to the user interface
GPS chipset
is a specific type ofGPS receiver. DGPS receivers have additional antenna that receive signals not only from satellites but directly from ground stations.
DGPS - Differential GPS or DGPS
GPS receivers send serial data out of a transmit pin (TX) at a specific bit rate. The most common is 9600bps for 1Hz receivers but 57600bps is becoming more common
Baud Rate
When a GPS receiver has a lock or fix, there are at least 4 satellites in good view and you can get accurate position and time
Lock or Fix
The mathematical method used to calculate position using multiple reference points
Trilateration
The time it takes, after power-on ,to accurately compute your position and time using atleast 4 satellites.
TTFF - Time to first fix
is how often it calculates and reports its position. The standard for most devices is 1Hz (once per second
Update Rate
is a network of ground based stations (in North America)that transmit correction data back to the satellites
WAAS, or wide area augmentation system
which is freely available to the public
coarse/acquisition (C/A) code
usually reserved for military application
restricted precision (P)code
is one of the signals broadcast on the L1 carrier. This code is only broadcast on the L1 carrier.
Coarse Acquisition Code, or C/A code
The other signals on the L1carrier are the
Precise Code, or P code
is used by civilian receivers to locate position
C/A code
is the distance from the receiver to the satellite
range
This is the error in the offset of the GPS measurement of the pseudorandom code and the time recorded by the satellite for the data
Receiver Clock Error
is an Earth-centered, Earth-fixed terrestrial reference system and geodetic datum
WGS84
is the datum used by the Global Positioning System (GPS)
World Geodetic System 1984 (WGS84)
Most of the admiralty chart referred to a local data but position obtained from the GPS system refers t
WGS 84 data.
basically consist of any number of base stations that are distributed over a large area on the ground and generate with the help of master stations correction data for each region
Space-Based-Augmentation-Systems (SBAS)
is a Japanese satellite based augmentation system (SBAS), i.e. a satellite navigation system which supports differential GPS (DGPS) to supplement the GPS system by reporting (then improving) on the reliability and accuracy of those signals
MTSAT orMSAS
is an enhancement to Global Positioning System that provides improved location accuracy, from the 15-meter nominal GPS accuracy to about 10 cm in case of the best implementations
Differential Global Positioning System (DGPS
These ground stations may be up to_ from the receiver, and it is important to note that accuracy deteriorates the further you are from the ground station
200 nautical miles
send their measurements to master stations which send the corrections to WAAS satellites every 5 seconds or quicker
ground stations
Europe’s global navigation system
GALILEO
The Galileo navigation signals will provide good coverage even at latitudes up to -, which corresponds to the North Cape, and beyond
75 degrees north
Galileo will have 5 main services
- Open access navigation 2. Commercial navigation 3. Safety of life navigation4. Public regulated navigation 5. . Search and rescue- system
is an international tracking and identification system incorporated by the IMO under its SOLAS convention to ensure a thorough tracking system for ships across the world.
Long RangeTracking andIdentification (LRIT
has always the right to access the information for ships in its own registeR
Flag state
has the right to access when a ship has declared its intention to go to a port in that state - but not if the ship is in the territorial waters of another state
Port state
has the right to access for ships within 1000 Nm from its coast - but not if the ship is in the the territorial waters of another state
Coastal state
sends a signal to the pulse generator which triggers a pulse and simultaneously starts the recorder trace
recorder
is a type of SONAR (originally an acronym for SOund Navigation And Ranging) used to determine the depth of water by transmitting sound pulses into wate
Echo Sounder
converts the electric energy into sound energy producing a pulse.
Transducer
Which sends a powerful electric pulse to the Transducer
Transmitter
converts the received sound energy of the echo into an electric pulse and sends it to the receiver
Transducer
which has been at a speed proportional to the speed of sound, creates a physical mark on a paper or a visual blip or a digital signal for the recorder.
stylus
The determination of position by advancing a known previously fixed position for courses and distances
dead reckoning
Navigation that involves frequent and/or constant determination of position in relation to geographic & hydro-graphic features in the vicinity
piloting
A conic section is formed by the intersection of a cone and a plane, which of the following is NOT a conic section?
sphere
Where a vessel’s position has been determined by the application of leeway, current, wind & wave effects on it’s track, it is termed as:
dead reckoning
The act of directing a ship, aircraft, etc. from one place to another, or the science of finding a way from one place to another
navigation
The angular distance in degrees, minutes and seconds of a point north or south of the Equator and they are also referred to as parallels
latitude
It involves reduction of measurements done on heavenly bodies to lines of position:
celestial navigation
A tall structure equipped with lighting systems that serve to aid mariners in navigation at sea:
lighthouse
A type of clock which provides high positional accuracy for transmitted LORAN-C signals
atomic clock
The angular distance in degrees, minutes and seconds of a point east or west of the Prime (Greenwich) meridian:
longitude
The Arctic & Antarctic Circles are located where?
66 degree 34’ N & S of the Equator
The Earth’s coordinates: these lines are often referred to as meridians.
longitude
Transmitted radio energies in the form of waves that follow the curvature of the earth are called
ground waves
Navigational method where landmarks are used as reference points in the determination of the vessel’s position along it’s intended track:
terrestrial navigation
The use of electronic wave transmissions to determine position using various devices:
radio navigation
GALILEO Satellites will have an operating lifespan of how many years?
12
The GLONASS System use 24 satellites that use ‘antipodal’ orbits, which means that each satellite is on the same orbital plane but is separated by how many degrees?
180 degrees
Differential GPS (DGPS) uses the difference between the satellite reading and the reading from the
ground location station
Satellite Navigation Systems comprise the following components EXCEPT Choose the correct answer.
land segment
GALILEO Satellites have 3 orbital planes, and will have how many degrees of inclination
56 degrees
Galileo satellites will operate at an orbit altitude of 23,222 kilometers. This height is classified as
Medium Earth Orbit (MEO)
The Wide Area Augmentation System (WAAS) can provide an accuracy of:
1.5 m vertical, 1 m lateral
A distinctively shaped and marked float, sometimes carrying a signal, anchored to mark a channel, anchorage, navigational hazard, etc or to provide a mooring place away from the shore
buoy
The GALILEO System is designed to give good coverage up to how many degrees latitude North?
75 degrees
A unique number having 9 digits which is assigned to radio stations including ship stations
MMSI number
An echo sounder utilizes which frequency type from the below choices?
Low Frequency
Satellites now have augmentation systems which are primarily designed to provide
accuracy & precision
shown as horizontal line
latitude
vertical line
longitude
Measurement of constant time-differences and, hence, constant distance difference places the receiver
HYPERBOLIC LINE-OF-POSITION
class of navigation systems based on the difference timing between the reception of two signals, without reference to a common clock (this timing reveals the difference in distance from the receiver to the two stations)
HYPERBOLIC NAVIGATION
Plotting all of the potential locations of the receiver for the measured delay
hyperbolic lines
1989, there were _ Loran-C chains comprising 67 stations and transmitting on 100 kHz; year 2000 this had grown to 28 chains
16
operates in the 90 to 110 kHz frequency band
LORAN (LONG RANGE NAVIGATION)
became operational in 1958 and has been in service since then primarily serving the maritime
community
LORAN (LONG RANGE NAVIGATION
first developed at the Massachusetts Institute of Technology during World War II for military ships and aircraft located within 600 miles of the American coast
Loran
loran was first developed at the _ during World War II for military ships and aircraft located within 600 miles of the American coast
Massachusetts Institute of Technology
was extended to cover most of the continental United States and, in cooperation with
Canada and Russia, Canadian waters and the Bering sea; numerous other countries have deployed loran-like systems as well.
loran c
LORAN COMPONENTS
- Transmitting stations
- LORAN receiver & antenna
- LORAN charts
One station in the chain is designated the
master
is to calculate the time between reception of the signals from the MASTER and SLAVE stations, which are emitted at different frequencies, at low or very low bands 90 kHz-110 kHz in pulse group and has power of 400-1600 kilowatts*
theory
LORAN UNIT
navigation computer, signal processor, control and display
a. Preset Position in Latitude-Longitude and/or relative to a destination, waypoint or check
point
b. Bearing and distance to your destination
c. Ground speed and estimated time en route
control and display
receives the signals and measures the difference between the time of arrival of each
secondary station pulse group and the master station pulse group; time difference depend on the location of the receiver on the aircraft/ship in relation to the three or more transmitters; each time difference value is measured to a precision of about 0.1 microsecond
signal processor
have serious effects as with any radio based system
magnetic storms
