LORAN A and C - Back in the day

Only while studying in Maritime Academy:) but stations still available, nobody have to worry about the reorganization. Dollar, dollar bill you’all😤

the last version worked as well as GPS, wait it cant be spoofed ( not very easily) so safer than
the UK once they found out how vulnerable GPS is started work on E-loran but…
yes in typical EU form, we need our own GPS no matter the cost…( in airbus 380 style)

I applied for a job related to avionics once and it turned out the job entailed selling Omega sets for airplanes. I actually almost laughed out loud, I think I said “I could make more money REMOVING them than adding them”. GPS was starting to be a thing at that point.
Wasn’t Omega the system on about 10 or 20 KHz that had “lanes” and if it lost track of which lanes you had crossed you were SOL?

The Omega receiver must “know” or keep track of the number of whole lanes. This was normally achieved by accurately initialising the position of the receiver at the point of departure. In the beginning the systems was plagued by random lane jumps which made it impossible to use in an aircraft.

Well before the decommissioning of the Omega system in 1997, advances in digital navigation computers had automated the fix determination process and the processor used all available transmitted signals to maximise the accuracy of the displayed position. Also lane ambiguity could be avoided at the same time.

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Lane count can be lost due to power interruptions, operator error, atmospheric disturbance or inability to detect lane crossings during or aircraft maneuvers. It often occurred with a weak signal of the Norway transmitter. To reset the lane count, using only the 10.2 kHz OMEGA signal, requires a knowledge of the receiver position within 4 nm. Most other kind of fixes on board are not that accurate, especially not on an aircraft.

Where position information of this accuracy is not available, it is possible to use the 10.2 kHz signal with the 13.6 kHz signal to establish the lane count. This method of combining phase information, on the two OMEGA frequencies plus the difference frequency, has the effect of providing significantly wider lanes. This process is called heterodyning. In an aircraft there often is no time to resort to this method of re establishing the lane count. On a ship time isn’t in most cases a problem although the operator has to be familiar with the procedure.

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I wonder if “Loran D” with the same setup as C but with Omega frequency and power would work? Is there some math or geometry issue that prevents that?

It could work, I think but who am I, but it probably would be less accurate compared to the system of phase measurement as used in the Omega system.

Wartime development of the Loran-A system had been rushed. Even in ground wave range, it was never a very accurate system. LORAN-D was a short range, high accuracy, low power, tactical system designed for use as a bombing aid by the United States Air Force. It used “portable” transmitters and much shorter baselines than Loran- C, plus a sixteen pulse transmission instead of eight. Loran-D modified the Loran-C pulse pattern by interleaving an additional 8 pulses after each pulse of the current Loran-C pulse pattern.

LORAN-B was better suited because it basically was a phase comparison variation of Loran-A and an attempt to re-design the system properly plus add some new features.

It was handy for fisherman. I was on a Clammer that had a large Loran pen plotter set up. The skipper would fish along a specific X or Y TD line, when he hit a lucrative bed of clams he would start the plotter. He could then top her about and repeat-dredge the exact line with the pen plotter within yards of the previous. I reckon it didnt leave much in the way of clams on the bottom, but Fisheries kept an eye on us and for every hour on a lucrative bed we had to dedicate some period of time on an unknown bottom. The work was bust ass hard, but the pay was more than I had ever made, and the deckhands got to keep the Monkfish that got hung up in the dredge. Still one of my favorite eating fish,

In the very early ‘70s I was a newbie Ensign on an amphibious flagship, leading a major landing wave during an exercise onto a beach in NC. As we approached, there was a LOT of discussion on the bridge, then the signals for the formation to reverse course. Yes, we were one lane off and missed the landing beach by eight (8) nm. RADM and BG shit on the 0-6 CO, and the ex-navigator (LT) left the ship on a hello shortly thereafter.

That was my first exposure to Omega. :grinning::grinning:

Loran-C could be WAY off as far as lat-lon, but the error was always the same, so fishermen loved it because it would get you back to a saved waypoint within a boat-length unless you had a really short boat.

cut my teeth in 1965 with a WW2 APN9

Cut my teeth with a giant loran c unit in the back of the wheelhouse as an AB. The Captain took the time with me and trusted my lining up the lines to navigate for our single screw rig with no autopilot. We shared 1 hour on, 1 hour off wheel watches… Thank you Capt Sam Evans for encouraging me to go forward. I never forgot where I came from and the people who helped me get there to retirement. Forever grateful for those oldtimers that gave me a shot. I did pay it forward with more than a few. No regrets.