Exhibit 10.82

January 6, 2004

Mr. David L.E. Jones
President
SDR Metro
27367 Tungsten Road
Euclid, OH 44132


Dear David:

This is to confirm our agreement to extend the $600,000 payment due described in
the Note between Radio Metrix Inc. and SDR Metro Inc. dated January 8, 2002 (the
"Note"). Payment in full of the $600,000 will now be due on February 9, 2004.

This change in the required date of payment does not alter or extend our 180 day
period for right of redemption  (described in the Remedy Upon Default  Agreement
dated  January 8th,  2002) -- in other words the "clock  starts  ticking" on the
right of redemption period on January 9, 2004.

However,  if SDR  Metro  receives  $250,000  from us by  February  8th,  2004 or
earlier, you will accept that as full and final payment of the Note.

As  mentioned  to you last night,  we invite Brent Simon to visit us in the next
few weeks here in Sarasota so that we can have a  "brainstorming"  session  with
our team (on our nickel).  Based upon my dinner  discussion  with Brent, I think
that he could help to significantly  accelerate and expand Invisa's  development
efforts.  While we did not have the chance to delve into specifics,  I hope that
Brent  would  want to work  with us as a paid  consultant.  We  should  finalize
compensation arrangements in our first meeting.


Agreed and Accepted,


By: /s/ Herb M. Lustig                        By: /s/ David L.E. Jones
    --------------------------                    -------------------------
    Herb M. Lustig                               David L.E. Jones
    President and CEO                            President
    Invisa, Inc. (parent company of              SDR Metro, Inc.
    Radio Metrix)



/s/ Barbara J. Baker       1-07-04            /s/ Pamela S. Brooking
Barbara J. Baker                              Hendricks County
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April 30, 2006
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