From: Ed Switalski <E.Switalski@bnr.co.uk>
Date: Thu, 17 Mar 94 01:16:04 PST
To: Matthew J Ghio <mg5n+@andrew.cmu.edu>
Subject: Re: Radio Networking
In-Reply-To: <YhVvlky00awO45VkcL@andrew.cmu.edu>
Message-ID: <199403170915.5154@bnsgs200.bnr.co.uk>
MIME-Version: 1.0
Content-Type: text/plain




    >About how far can one transmit with 250mw?
 
*** Quite Far !

    With coherent CW you can key morse Japan/US i.e cross the Pacific
    on a few watts.

    CCW involves getting the Tx master oscillator and the receivers
    local oscillator phase-locked (by using the local time/frequency 
    standard transmitter (e.g. WWV MSF etc  -one can also get nifty little
    rubidium standard clocks quite cheaply these days).

    US readers might care to look in the ARRL handbook for 1982 or thereabouts.

    CCW implies  slow signalling speeds- a few baud, very narrow detection
    bandwidth few hertz (to match signalling) and coherent TX and RX.
 
    The ultimate limit is probably phase shift in the ionosphere.

    Use a frequency that a bit off Big Brother's scanner channel
    spacing and your emmission may not be detected  -unless the spook
    is right on top of you. Which is just as well given it might 
    take DAYS to download a .ps document ;-(

    Note this is a slow and gentle way of doing things, as opposed 
    to a  high-bandwidth, time-compressed (fairlyly high-power) "screech"
    transmission  with somthing like meteorscatter.


			Regards,
                                               __o        __o
                           Ed                  \<,        \<,
    _________________________________________()/ ()_____()/ ()_____________

    Ed Switalski			      email: eswitals@bnr.co.uk
    Dept GM21,              
    BNR Europe Ltd, Oakleigh Rd South,         tel: +44 (0)81 945-2924
    New Southgate,			       fax: +44 (0)81 945-3116
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