                VectorScope - Audio Direction Finding Aid

Purpose:

This program plots the left and right components of a stereo signal as vectors
in such a way that the direction of arrival of the signal can be estimated.
This has application to direction finding, or audio phasing checks.


Installation & Usage:

Extract VectorScope.exe from the zip file to a suitable location and run it!
Part of the source code is provided in the zip download, but you do not need
the source files or Inprise's Delphi to run VectorScope.

A stereo source is required.  Note that on most sound cards, the microphone
input is mono, which displays as a vertical line.  Signals which are in phase
display as a vertical line, those which are out of phase as a horizontal line.
Left-only signals display as a line at 45 degrees anti-clockwise of vertical 
(i.e. like a more tilted version of the backslash "\" character), right-only 
signals like the "/" character.  With suitable equipment to drive the Line 
inputs of your sound card, the driection of arrival of a signal can be
estimated.


Runtime library:

If you don't already have Borland's run-time library, vcl40.bpl you will also 
need to download it.  See:

  http://www.davidtaylor.freeserve.co.uk/software/runtime.html
  http://www.user.globalnet.co.uk/~hermes02/Freeware/VCL40.zip

Extract the file VCL40.BPL from this archive and copy to your Windows System
folder (e.g. \Windows\System or \WinNT\System32).  


Options:

The program automatically attempts to keep the signal near to filling the 
display by increasing and decreasing the gain as required.  This is known as
AGC (automatic gain control).  You can change what the maximum gain will be and 
how rapidly the gain will increase with time with the options in the AGC box.
The program also has a level meter displaying a 60dB range of signal levels, 
which displays the level before the AGC is applied.


Registry entries:

VectorScope uses no registry entries.


Notes:

The program is written for Borland's Delphi 4.02, and most source is included.  
You do not need access to Delphi to run ShowMan.  The program runs on 
Windows 95, 98 and Windows NT 4.0.


Release information:

V0.1.0  1998 Nov 12  First experimental version
V0.1.2  1998 Nov 14  Add version info and ReadMe.txt


Program Status & Distribution:

This program is freeware, and remains copyright of David J Taylor, Edinburgh, 
1997-8.  This program is provided "as is", without any support.  Whilst I cannot 
answer queries relating to the use of this program, I'd value any comments or 
suggestions for improvements you may have (and there is considerable feedback 
from users in the present version of ShowMan).  Requests for distribution must 
be referred to the author, but will usually be granted if no commercial gain is 
involved.

TVersionInfoResource & TBrowseDirectoryDlg are from Brad Stowers
  http://www.pobox.com/~bstowers/delphi/
  Copyright bstowers@pobox.com (CompuServe 72733,3374)


Contacting the author:

Web site:  http://www.davidtaylor.freeserve.co.uk
E-mail:    davidtaylor@writeme.com

1998 November 14
