Hyperbolic navigation systems

Andre Kesteloot andre.kesteloot@ieee.org
Mon, 10 Feb 2003 09:30:07 -0500

-------- Original Message --------
Subject: Re: LF: Loran
Date: Mon, 10 Feb 2003 11:39:34 +0000
From: James Moritz <j.r.moritz@herts.ac.uk>
Reply-To: rsgb_lf_group@blacksheep.org
To: rsgb_lf_group@blacksheep.org

Dear Hugh, LF Group,

For an explanation of Loran C and other hyperbolic radio navigtion systems,
take a look at


The Loran transmitters all operate on 100kHz, and transmit short pulses -
this leads to the sidebands extending into the 136kHz bands. Usually, in SE
England, you should be able to hear the rhythmic chattering sound under
quiet band conditions at 136kHz - if not, you need to look into your RX
sensitivity! The nearest TX is at Lessay on the french coast. Each Loran
chain has a different pulse repetition frequency (GRI), so different parts
of the world have different Loran lines. Because of the pulsed signal, the
duty cycle is quite small, and the mean power is much less than the PEP.

Cheers, Jim Moritz
73 de M0BMU