[Milsurplus] Re: Loran C

[Brooke Clarke]

Hi John:

The LORAN-C system is a totally redundant system when compared to GPS and this is part of the requirement needed for WAAS, which is an FAA program for aircraft blind landing.  It's my understanding this is the reason that LORAN-C is not being shut down.  Note that classical LORAN-C receivers (pre DSP chip) only tracked the stations in one chain (3 or 4 stations), but there is a new LORAN-C receiver that's DSP based and tracks "all in view" stations.  This is similar to a 12 channel GPS receiver, except that there are about 40 LORAN-C stations in the US.

As to the question about which receiver type to get for precision frequency & time applications, the answer is GPS.  You can get on the order of +/- 30 ns from a GPS receiver designed for time transfer, like the Motorola units.  Prior time transfer systems were:  LORAN-C, WWVB, WWV.  There are a number of disciplined frequency sources on the market that take in the 1 Pulse Per Second output of a GPS receiver and use that to remove the drift from a 10.0 MHz oscillator.  Kind of like automatically adjusting the fine frequency knob on an HP 105 oscillator on a continuous basis.

73,

Brooke Clarke, N6GCE

-- 
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>Date: Sat, 04 Sep 2004 13:10:45 -0400
>From: "J. Forster" <jfor at quik.com>
>Subject: [Milsurplus] Loran C
>To: Test Equipment List <test-equipment at mailman.qth.net>
>Cc: Milsurplus <milsurplus at mailman.qth.net>
>Message-ID: <4139F714.3BC77E45 at quik.com>
>Content-Type: text/plain; charset=us-ascii
>
>A week or two, someone was asking about the anticipated life of the Loran system
>in the context of whether to buy a Loran or a GPS receiver as a standard of
>frequency (time interval). While not scholarly, here are a couple of articles I
>just came across:
>
>http://www.nutsvolts.com/toc_Pages/aug04toc.htm
>http://www.nutsvolts.com/toc_Pages/sep04toc.htm
>
>Of course, spending $100 million does not mean the system will not be shut down
>on October 2nd, but it seems unlikely.  FWIW,
>-John
>
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