## NAME

         atlc - an Arbitrary Transmission Line Calculator

## SYNOPSIS

         atlc  [-v] [-c cutoff] [-d rrggbb=Er]  [-F  appendfile]  [-i
         factor] [-p threads] [-r rate_multiplier] bitmapfile

## WARNING

         This man page is not a complete set  of  documentation.  See
         the  html  files for more complete information. So far, I've
         not managed to install the html files  into  /usr/local,  so
         you  will  have  to  look into the atlc-X.Y.Z/docs/html-docs
         directory for them.

## DESCRIPTION

         atlc is a finite difference programme that is used to calcu-
         late  the properties of a two-conductor electrical transmis-
         sion line of arbitrary cross section. It  is  used  whenever
         there are no analytical formula known, yet you still require
         an answer. It can calculate:
            The impedance Zo  (in Ohms)
            The capacitance per unit length (pF/m)
            The inductance per unit length (nF/m)
            The velocity of propogation v (m/s)
            The velocity factor, v/c, which is dimensionless.

         A bitmap file (usually with the extension .bmp or  .BMP)  is
         drawn  in  a  graphics  package  such as Gimp available from
         http://www.gimp.org. The bitmap file must be saved as a  24-
         bit  (16 million colour) uncompressed file. The colours used
         in the bitmap indicate whether the  region  is  a  conductor
         (pure  red,  pure  green or pure blue) or a dielectric (any-
         thing else). Pure white is assumed to be  a  vacuum  dielec-
         tric,  but other colours have diferent meanings. See COLOURS
         below for precise definitions of the colours.

## OPTIONS

         -c cutoff
         Sets the convergence criteria of the finite difference  pro-
         gramme.  The  default is 0.0001, meaning two separate itera-
         tions must be within 01% for the programme to  stop  iterat-
         ing.  Setting  to a smaller positive number gives more accu-
         racy, but takes longer.

         -d rrggbb=Er
         is used to indicate the colour 0xrrggbb  in  the  bitmap  is
         used  to represent a material with permittivity Er. See also
         COLOURS below

         -F appendfile
         Causes the results to be  appended  to  a  file  appendfile,
         which  will  be  a text file.  If the -v option is selected,
         intermediate results will go there too.

         -i factor
         is used to lighten or darken the .bmp electric field profile
         images  produced  by  atlc.  Set  factor  >  2 to lighten or
         between 1 and 2 to darken.

         -t threads
         tells atlc to run using that number  of  threads,  to  speed
         calculation.  This option is only valid if atlc was compiled
         with the --with-mp option to configure. The Pthreads library
         ()  must  be  installed in order to compile with support for
         more than one CPU. Generally, setting the number of  threads
         to the number of cpus is a good idea, but it is worth exper-
         imenting. The number can be changed permanently  by  editing
         the parameter MAX_THREADS in definitions.h.

         -r ratemultiplier
         Sets the parameter 'r' used internally  when  computing  the
         voltage  at  a point w,h.  The default, which is (as of ver-
         sion 3.0.0) 1.95, results in what is belived to  be  optimal
         results.  Setting to 1.0 will avoid the use of the fast con-
         vergence method, which is generally not a good idea.

         -v
         makes the output more verbose/talkative.

## COLOURS

         The 24-bitmaps that  atlc  uses  have  8  bits  assigned  to
         represent  the  amount  of  red, 8 for blue and 8 for green.
         Hence there are 256 levels of red, green and blue, making  a
         total of 256*256*256=16777216 colours. Every one of the pos-
         sible i16777216 colours can  be  defined  precisely  by  the
         stating the exact amount of red, green and blue, as in:

         red         = 255,000,000 or 0xff0000
         green       = 000,255,000 or 0x00ff00
         blue        = 000,000,255 or 0x0000ff
         black       = 000,000,000 or 0x000000
         white       = 255,255,255 or 0xffffff
         Brown       = 255,000,255 or 0xff00ff
         gray        = 142,142,142 or 0x8e8e8e

         Some colours, such as pink, terquiose,  sandy,  brown,  gray
         etc  may mean slightly different things to different prople.
         This is not so with  atlc,  as  the  programme  expects  the
         colours  below  to  be exactly defined as given. Whether you
         feel the colour is sandy or yellow is up to you, but if  you
         use  it  in your bitmap, then it either needs to be a colour
         reconised by atlc, or you must define it with a command line
         option (see OPTIONS).
         red    = 255,000,000 or 0xFF0000 is the live conductor.
         green  = 000,255,000 or 0x00FF00 is the grounded conductor.
         blue   = 000,000,255 or 0x0000FF is the negative conductor

         All bitmaps must have the live (red)  and  grounded  (green)
         conductor.  The  blue  conductor is not currently supported,
         but it will be used to indicate a negative conductor,  which
         will  be  needed  if/when  the  programme  gets  extended to
         analyse directional couplers.

         The following dielectrics are recognised by atlc and so  are
         produced by rect_cen_in_rect.

         white     255,255,255 or 0xFFFFFF as Er=1.0    (vacuum)
         pink      255,202,202 or 0xFFCACA as Er=1.0006 (air)
         L. blue   130,052,255 or 0x8235EF as Er=2.1    (PTFE)
         Mid gray  142,242,142 or 0x8E8E8E as Er=2.2    (duroid 5880)
         mauve     255.000,255 or 0xFF00FF as Er=2.33  (polyethylene)
         yellow    255,255,000 or 0xFFFF00 as Er=2.5    (polystyrene)
         sandy     239,203,027 or 0xEFCC1A as Er=3.3    (PVC)
         brown     188,127,096 or 0xBC7F60 as Er=3.335  (epoxy resin)
         Terquoise 026,239,179 or 0x1AEFB3 as Er=4.8    (glass PCB)
         Dark gray 142,142,142 or 0x696969 as Er=6.15   (duroid 6006)
         L. gray   240,240,240 or 0xDCDCDC as Er=10.2  (duroid 6010)
         D. orange 213,160,067 or 0xD5A04D as  Er=100.0  (mainly  for
         test purposes)

## EXAMPLES

         Here are a few examples of the use of atlc. Again,  see  the
         html documentation in atlc-X.Y.Z9ocsl-docs for for examples.

         ex_1 % atlc coax2.bmp
         This is a simple example (ex_1), in which the geometry of  a
         transmission  line is defined in coax2.bmp. In this example,
         only the predefined dielectrics (Er =1.0, 1.0006, 2.1,  2.2,
         2.33,  2.5,  3.3,  3.335, 4.8, 6.15 or 10.2) could have been
         used in the bitmap, which would have been done with  one  of
         10  different  colours  (white  (0xFFFFFF)  for Er=1.0, pink
         (0xFFCACA) for 1.0006 etcin the  bitmap  file  coax2.bmp  No
         other  colour(dilectric)  could have been used, since it was
         not specified with the -d option.

         ex_2 % atlc -d f9e77d=2.43 somefile.bmp
         In ex_2, a dielectic with Er=2.43 was wanted. A colour  with
         the  RGB  values  of  0xF9E7&d was used. The -d option tells
         atlc what Er this colour refers to.

         ex_3 % atlc -v .bmp coax2.bmp
         In ex_3, atlc has been instructed to print  the  results  of
         intermediate  calculations  to  stdout.   Normally, only the
         final result is printed.

## FILES

         bitmapfile.bmp
            Original bitmap file. Must be 24-bit colour uncompressed.
         bitmapfile.Ex.bmp
            X-component of E-field as a bitmap. Red=+dV/dx,  blue  =-
         dV/dx
         bitmapfile.Ey.bmp
            y-component of E-field as a bitmap. Red=+y, blue =-y
         bitmapfile.E.bmp
            E-field, as E=sqrt(Ex^2+Ey^2).
         bitmapfile.V.bin
            Voltage as a bitmap, red= positive, blue =negative.
         bitmapfile.Er.bin
            Bitmap showing the permittivity as a  grayscale.  Lighter
         is a higher
            permittivity.
         bitmapfile.U.bmp
            Energy.
         bitmapfile.txt Results, in a text file for easy reading.

         In addition to the bitmaps, the data is also saved in binary
         files.

         All the saved binary files (.bin's) are saved  as  a  double
         precision number for each of the pixels. The first double is
         the top left, the last the bottom  right.  If  the  original
         image  has width W and height H, the saved binary files will
         be W-1 by H-1.

         All the saved bitmap files  are  24-bit  uncompressed,  just
         like the input files.

## SEE ALSO

         rect_cen_in_rect(1),    circ_in_circ(1).    rect_in_rect(1),
         circ_in_rect(1).      rect_in_circ(1),     readbin(1)    and
         sym_strip(1).

         http://atlc.sourceforge.net                - Home page
         http://sourceforge.net/projects/atlc       - Download area
         atlc-X.Y.Z/docs/html-docs/index.html       - HTML docs
         atlc-X.Y.Z/docs/qex-december-1996/atlc.pdf - theory paper
         atlc-X.Y.Z/examples                        - examples
         http://www.david-kirkby.co.uk              - my home page
         http://www.david-kirkby.co.uk/ham          - ham radio pages