2. Loran C
LORAN-C is a
hyperbolic
navigation system.
Operates by measuring
time distance of arrival
of signals from a pair of
synchronised
transmitters.
By using two pairs
of transmitters a
fix can be obtained.
LOPs
Transmitter 1
Extended
Baseline
Transmitter 2
3. A navigation system that was developed by the
US Coast Guard.
The system is comprised of transmission
stations located around the world.
The Loran-C signal is transmitted from these
stations at specified intervals.
By measuring the time delay between
transmissions a user can determine their
position relative to the towers.
4. The LORAN-C concept is based on groups or
“chains” of stations around the world.
Worldwide there are 28 chains.
Each chain consists of one master station and
4 – 6 secondary stations in a geographic area
The master station of each chain broadcasts a
continuous string of Low Frequency pulses
(measures in microseconds).
The unique time between the start and stop of
each pulse identifies the particular chain.
5. DIAGRAM 1.1
A and B - transmitting
stations
Curved lines- “TD” lines or
Time Difference
9. Loran C Timing
Up to three commercial cesium atomic clocks are
used to generate 5 MHz and pulse per second (or
1 Hz) signals that are used by timing equipment to
generate the various GRI-dependent drive signals
for the transmitting equipment.
11. Phase Coding
where a minus sign indicates an inverted pulse (180°
phase shift)
and a plus sign means no phase shift.
This pattern is repeated every two GRI's.
Simply stated,phase coding determines whether the
first peak in the pulse is upwardsor downwards.
12. 0
Loran C Pulses
50 100 150 200
Timings from 3rd zero-crossing (30S)
13. Unlike GPS, LORAN-C accuracy depends on
receiver location with respect to transmitters
Best on baseline between master and slave
because LOPs are closer here
LORAN accuracy is also best over water during
the day.
Conversely it is least accurate over land
masses at night (sky waves more intense at
night).
14. Types of Accuracy:
Repeatable Accuracy- ability to return to a pre-set
position for LORAN-C is .01 NM or 60ft.
Absolute Accuracy- ability of the receiver to
determine its position independently is
generally within at least 3 NM for distances up
to 2,800 NM.
15. Chayka was developed by USSR (Russia)
Similar to LORAN-C
Same frequency but different pulse shape
Russian Chayka chains also remain
operational
West Russia chain available in Eastern Europe
Some Loran-C receivers also use
Chayka signals
16. Transmitter
Designation
Emission
Delay (μS)
Location Country
Coordinates
Power
(kW)
Latitude Longitude
Lessay 6731 Chain
M Lessay France 49°08′55.224″N 01°30′17.029″W 250
X 13,000 Soustons France 43°44′23.099″N 01°22′49.584″W 250
Y 27,300 Anthorn UK 54°54′41.949″N 03°16′42.587″W 250
Z 42,100 Sylt Germany 54°48′29.975″N 08°17′36.856″E 250
Bø 7001 Chain
M Bø Norway 68°38′06.216″N 14°27′47.350″E 400
X 14,100 Jan Mayen Norway 70°54′51.478″N 08°43′56.525″W 250
Y 29,100 Berlevåg Norway 70°50′43.014″N 29°12′15.980″E 250
Eiði 9007 Chain
M Eiði Faroe 62°17′59.837″N 07°04′26.079″W 400
W 14,200 Jan Mayen Norway 70°54′51.478″N 08°43′56.525″W 250
X 28,000 Bø Norway 68°38′06.216″N 14°27′47.350″E 400
Y 41,100 Værlandet Norway 61°17′49.435″N 04°41′46.618″E 250
Sylt 7499 Chain
M Sylt Germany 54°48′29.975″N 08°17′36.856″E 250
X 14,100 Lessay France 49°08′55.224″N 01°30′17.029″W 250
Y 29,500 Værlandet Norway 68°38′06.216″N 14°27′47.350″E 250
17. Jan Mayen
Rugby
Lessay
Soustons
Berlevåg
Petrozavodsk
Former NELS & Chayka Chains
Simferopol
Slonim
Karachev
Bø
Værlandet
Eiði
Sylt
18.
19.
20. MARTHA’S VINEYARD
41 20N – 70 49W
1957 - 1962
Y
CAROLINA BEACH
1957 - Present
34 03 46.36N
77 54 46.19W
M
JUPITER INLET
1957 - Present
27 01 59.09N
80 06 52.92W
Station relocated approx 2 miles
north 1962
X
S-0/1957 – 1962
SL-0/1962 - 1965
Y
NANTUCKET
1962 - Present
41 15 11.93N
69 58 38.76W
Replaced Martha’s Vineyard
First Proven Loran System
Status “Experimental” until 1962
“Operational” 1962
CHAIN CODE NAME: CLOSE
21. SS0/1966 – 1969
SS7/1969 – 1975
9930/1975 – 1978
Y
X
W
NANTUCKET
1962 – Present
41 15 11.930N
69 58 39.090W
CAROLINA BEACH
1957 – Present
34 03 46.040N
77 54 46.760W
JUPITER INLET
1957 – Present
27 01 58.490N
80 06 53.520W
M
CAPE RACE
1966 – Present
46 46 32.180N
53 10 28.160W
NOTE:
WILDWOOD used as temp
Master or Slave “T”
CARIBOU USED as Slave S
Z
DANA
1967 – Present
39 51 07.540N
87 29 12.140W
BERMUDA
32 15 53.261N
64 52 34.270W
EGLIN
30 35 05.518N
86 36 54.470W
7930-Z