Xref: utzoo sci.electronics:4099 rec.ham-radio:6406
Path: utzoo!mnetor!jim
From: jim@mnetor.UUCP (Jim Stewart)
Newsgroups: sci.electronics,rec.ham-radio
Subject: Re: LORAN TI9900
Keywords: LORAN
Message-ID: <4748@mnetor.UUCP>
Date: 17 Oct 88 13:15:44 GMT
References: <1572@radio.oakhill.UUCP>
Reply-To: jim@mnetor.UUCP (Jim Stewart)
Organization: Computer X (CANADA) Ltd., Toronto, Ontario, Canada
Lines: 42

In article <1572@radio.oakhill.UUCP> charlie@oakhill.UUCP (Charlie Thompson) writes:
>I am looking for schematics for the TI model 9900 LORAN receiver.  I have
>one that is no workie.  Any clues as to where I can get schematics would
>be greatly appreciated.

I wonder if somebody could give a basic theory of operation for LORAN C.
I have read the basic theory presented in a user's manual of a friend,
but they don't get too technical.

From what I understand, around the world there are certain 'chains'
of 5 stations each.  For a given chain, one's location is determined
from the timing of a pulse from the master and the best two of 4 slave
stations.  All stations around the world operate on the same frequency
100 kHz ??

Some of the things that I don't understand:

    - the manual says a given 'chain' is determined by its repetition
      rate, but how is this actually done?  Like how does the timing
      of the various chains fit in time with respect to each other?
      How is the information for a given chain recovered, how is the
      recovery actually implemented?  Something like a slow-speed
      software PLL??

    - how is the 100 kHz selected out of all of the RF crud in the
      world?  It can't be filtered with an IF like regular signals,
      because the manual mentions something about the master producing
      5 cycles of the 100 kHz, and the receiver locks onto the third
      for accuracy, but the user can soft-select a different cycle for
      various reasons (the 5 cycles, etc could be wrong, this is from
      memory).

    - the manual mentions something about having a backup master
      station, if the first one can't be read reliably, how does
      this work??

tnx, jim
-- 
Jim Stewart, VE3SRJ
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