LORAN C

Question 1

How does LORAN work?

Answer 1

Measuring time difference from a known reference point
Two towers (one master and one slave) create a hyperbolic line of position, a third tower (slave) is required for another hyperbolic line of position to create a two point fix

Question 2

What errors are there to LORAN? (4 factors)

Answer 2

Dynamic errors
1. Sky Wave Rejection
Due to atmospheric conditions, a wave from a different chain can be received. Receiver will realise this is a sky wave and reject it. It will not impose an error to position fix due to the rejection

2. Clock error
   Any errors in time will result in a poor fixed

Fixed errors
3. Land error
Slight delay in signal because the sea is a better conductor than land (signal over land)

4. Diamond error
   Poor angle of cut therefore poor fix

Question 3

Advantages of LORAN?

Answer 3

High power
Land based
Transmissions not as exposed to jamming

Question 4

Disadvantages of LORAN?

Answer 4

Not as accurate as GNSS
Another system to maintain
Largely discontinued at present

Question 5

What does LORAN stand for?

Answer 5

Long Range Navigation

Question 6

What does eLORAN stand for?

Answer 6

Enhanced Long Range Navigation

Question 7

What is eLoran?

Answer 7

eLoran is a system using LORAN-C but increases accuracy due to a GBAS

Question 8

How does the receiver tell master and slave apart?

Answer 8

Master sends out 9 pulses (so the Loran receiver knows its from the master), all slaves will send out 8 pulses

Question 9

How many chains can you use?

Answer 9

You can only always use one chain at a time, each individual chain has an unique Group Repetition interval so the LORAN-C will know which chain to use