atlc(1)

📦 version 4.6.1, in debian bookworm, debian trixie, ubuntu jammy, ubuntu noble, ubuntu resolute, ubuntu stonking

🌸 NAME 🌸

Okay bestie, pull up a chair 🫶 this is atlc(1), a page from the General Commands Manual (section 1, the commands section, periodt). And atlc stands for an Arbitrary Transmission Line Calculator. That's the whole name. Iconic, honestly.

🦋 SYNOPSIS 🦋

atlc  [-C] [-s] [-S] [-v] [-c cutoff] [-d rrggbb=Er] [-i factor] [-i
prefix] [-t threads] [-r rate_multiplier] bitmapfile

Real talk: yes, the synopsis lists -i two times, and yes, -t threads appears up here even though the OPTIONS section below never says a word about it. That's just how this page is written, iykyk 😭 no cap. The -p prefix option does have its own little section further down, so keep scrolling.

⚠️ WARNING ⚠️

Not me about to say the quiet part out loud 💀 — this man page is not a complete set of documentation. The atlc project is complex enough that man pages just aren't an ideal way to document it, but out of completeness, man pages are produced anyway.

So where's the good stuff? The best documentation that was current at the time the version was produced may be found in:

/usr/share/doc/atlc/html-docs/index.html

And sometimes errors get corrected in the documentation and dropped at http://atlc.sourceforge.net/ before a new release of atlc comes out. So check there too 👀

Also, and this is the author being genuinely sweet: if you notice any problem with the documentation — even spelling errors and typos — please let him know. Yes, even typos. He said what he said 💅

💜 DESCRIPTION 💜

So atlc is a finite difference program that calculates the properties of a two-conductor electrical transmission line of arbitrary cross section ✨ You reach for it whenever there are no analytical formula known, yet you still require an answer. (Mood. That's like, the whole vibe of engineering.)

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 propagation v (m/s)
  • The velocity factor, v/c, which is dimensionless.

Here's the cute part 🎀 A bitmap file (usually with the extension .bmp or .BMP) gets drawn in a graphics package such as Gimp, available from http://www.gimp.org. That bitmap file must be saved as a 24-bit (16,777,216 colour) uncompressed file — no compression, bestie, I'm serious.

The colours in the bitmap are what tell atlc whether a region is a conductor (pure red, pure green or pure blue) or a dielectric (anything else). Pure white is assumed to be a vacuum dielectric, but other colours have different meanings. See COLOURS below for the precise definitions — don't freestyle this one 🎨

✨ OPTIONS ✨

  • -C — print copyright, licensing and copying information. (The receipts. Show me the receipts 👑)
  • -s — Skip writing the Ex, Ey, E, V, U and Er bitmap (.bmp) files
  • -S — Skip writing the Ex, Ey, E, V, U and Er binary (.bin) files
  • -v — makes the output more verbose/talkative. She will NOT stop talking 🗣️
  • -c cutoff — Sets the convergence criteria of the finite difference program. The default is 0.0001, meaning two separate iterations must be within 01% for the program to stop iterating. Setting it to a smaller positive number gives more accuracy, but takes longer. (Accuracy vs. patience, the eternal struggle 😮‍💨)
  • -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.
  • -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. Glow-up or glow-down, your call ✨
  • -r ratemultiplier — Sets the parameter 'r' used internally when computing the voltage at a point w,h. The default, which is (as of version 3.0.0) 1.95, results in what is believed to be optimal results. Setting it to 1.0 will avoid the use of the fast convergence method, which is generally not a good idea 🙅‍♀️
  • -p prefix — Adds 'prefix', which is usually a directory name, in front of the output files.

🎨 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 possible 16777216 colours can be defined precisely by 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, turquiose, sandy, brown, gray etc may mean slightly different things to different people. This is not so with atlc — the program 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).

The conductors, and what they mean, no guessing:

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 — those two are non-negotiable, bestie. The blue conductor is used to indicate a negative conductor, and is needed when the program is used to analyse directional couplers.

The following dielectrics are reconised by atlc:

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)
L. yellow 223,247,136 or 0xDFF788 as Er=3.7    (FR4 PCB)
Turquoise 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.Zocsl-docs, the documentation on your system (normally at /usr/local/share/atlc/docs/html-docs/index.html) or online at http://atlc.sourceforge.net 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, 3.7, 4.8, 6.15 or 10.2) could have been used in the bitmap, which would have been done with one of 13 different colours. white (0xFFFFFF) for Er=1.0, pink (0xFFCACA) for 1.0006 etc. No other colour (dielectric) 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 dielectric 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 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. Using -vv even more information may be produced, but this is really of only use to the developer of the project.

📁 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.

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. Consistency, she's consistent 💅

👑 SEE ALSO 👑

The whole girl squad of related pages:

And the links, because we love a source 🫶

And that's the whole page, bestie! 💖 Credit where it's due: this one was written by Dr. David Kirkby, and it's for atlc-4.4.2, dated 10th Sept 2003. Ancient wisdom, still serving looks 👑✨ Go calculate some transmission lines, you've got this 🌸🦋

📦 where this page comes from