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PA2RHB > INFO 25.08.02 22:16l 53 Lines 1866 Bytes #999 (0) @ WW
BID : BE0134PA2RHB
Read: DB0FHN GUEST
Subj: Re: Omega
Path: DB0FHN<DB0ZWI<DB0MAB<DB0FBG<DB0TUD<DB0GRL<SR6BBA<OK0PCC<OM0PBC<HA5OB<
HA3PG<GB7FCR<PI8WFL
Sent: 020825/1931Z @:PI8WFL.#NH1.NLD.EU #:945 [Enkhuizen] $:BE0134PA2RHB
From: PA2RHB@PI8WFL.#NH1.NLD.EU
To : INFO@WW
Hello again,
As regards frequencies, I have dug up my old notes to settle the matter.
Sure enough, the frequencies were
10.2 ; 11.333 ; 13.6 kHz. Later augmented with 11.05 kHz.
The lane width on the baseline was about 8 nautical miles for a single
frequency fix (measuring the phase difference between different
transmitters).
Of course, you had to know which lane you were in to begin with. That is
what the multiple frequencies were good for. Using the difference
frequencies, wider lanes were available.
The first three frequencies are multiples of 1133.33 Hz (9, 10 and 12x).
This gives a lane width (on a baseline) of 71 nautical miles.
The 11.05 kHz frequency added a raster frequency of 283.33 Hz (the four
frequencies are 36, 39, 40 and 48 times 283.33 Hz).
This corresponds to a lane width of 286 nautical miles.
Now you only had to know your qth within some 143 miles to get a fix.
The accuracy, far from being "super accurate", was something like 2 to 4
miles. Even so, you needed corrections on the phase measurements.
These corrections could be in tables in the receiver itself, or -if you
had a simple one - you had to add them manually to the meter readings
before plotting your fix on the Omega chart.
I saw the Omega system around the 80's. It was removed from the ship while
I was on service. The antenna was nice for the ham rig, though.
In 1997, long after I retired from sea, this message was sent:
P 011416Z OCT 97
FM COGARD NAVCEN ALEXANDRIA VA//NIS//
SUBJ: OMEGA STATUS AS OF 01 OCT 97
1. THE OMEGA NAVIGATION SYSTEM TERMINATED AND ALL STATIONS CEASED OMEGA
TRANSMISSIONS AT 0300Z 30 SEPTEMBER 1997 IN ACCORDANCE WITH NAVCEN
OPERATIONS ORDER DATED 141026Z AUG 97.
2.
(... more details followed )
Well, so far my old notes and a CG message.
Regards,
Rudolf
Heemskerk JO22im
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