
Air Traffic Control (ATC) v1.0 for Windows 95 and Windows NT

Overview
--------

ATC is screen saver module that runs under Windows 95 and Windows NT.
The module simulates the movement of airplanes through an airspace as 
might be shown on an air traffic controller's radar screen.

System Requirements
-------------------

To run ATC you must have Windows 95 or Windows NT. This module will
not run under Windows 3.1. This module will work in most screen 
resolutions and color bit depths; however, it looks best with 16-bit
color modes (or higher).

Installation
------------

Place the .scr file for ATC in your windows folder (usually c:\windows or 
c:\winnt). The file name is "Air Traffic Control.scr" or 'airtra~1.scr' 
from an MSDOS command prompt. 

Operation
---------

To access the settings for the ATC module, use the Display control found
within the Control Panels list. Open the Display control panel and click
on the 'Screen Saver' tab. Select 'Air Traffic Control' from the list of 
modules and click on 'Settings...'.  

There are two settings that may be adjusted: 'Planes' and 'Audio'. The 
Planes slider controls the number of airplane blips which move through 
the region scanned by the radar. To adjust the number of planes, you 
may click on the slider to the left or right of its current setting. 
You may also adjust the planes setting by clicking and holding the 
slider until you reach the desired setting. Note that this module is a
CPU hog! If you have a 486, you will probably want to adjust the Planes 
slider to generate few planes in the airspace.

Digitized pilot speech can be enabled and disabled using the 'Audio' 
check box. An check appears in the box when speech is enabled. 

Once you have adjusted your settings, click 'OK' to save them. Click
'Apply' on the display control panel to set Air Traffic Control as
your default screen saver.

About the Simulation
--------------------

This screen saver module was developed for the 1994 After Dark Contest.
I came up with the idea to do the simulation after I realized that I 
don't have any artistic talent -- meaning I needed something for the 
contest that was interesting but wouldn't require any free-form 
drawing on my part. An air traffic control radar simulation seemed to 
fit the bill.

I began construction of the module with the hope that the end result 
would be a display that looked almost real. So, I started off by 
constructing the static part of the screen using digitized photos of 
a speaker, some switches, and a dark metal console. The photos are of
actual components of a 1950s-era shortwave radio. The photos were 
scanned in and manipulated using Adobe PhotoShop.

To add to the effect of the module, I thought some good sounds would
help. For this, I used a cheap VHF radio to record some aircraft 
communications going on in my area. The sounds were sampled into a Mac
using Apple's HyperCard at a 6-to-1 compression ratio. There are nine 
sound clips in the present version of the module.

For the dynamic part of the simulation (the plane movement), I took a 
look at old books that had pictures of some FAA air traffic radar 
consoles. These consoles are quite large and have additional details 
associated with each plane, such as airplane altitude and direction. I 
decided not to display this information because the resulting display 
is a bit too cluttered and performance suffers quite a bit. I settled 
on displaying only the aircraft identifier. For each airplane, a random 
speed, direction, and altitude are generated when the plane first 
appears. This information is then used to update the plane position 
every time the radar sweep band comes around. As the sweep band moves 
through an airplane's position, the radar echo is shown by the plane 
brightening. The plane blip then dims slightly as the sweep band moves 
away from it.

The airports shown on the display are from the San Francisco Bay 
region in California (the airports are Oakland, San Francisco, and 
San Jose). The airports are only there to spice up the display 
slightly -- you won't see any airplanes taking off or landing at 
any of them.

Those of you who watch the simulation closely will note that planes 
always travel at the same speed across the region and that they never
land, takeoff, or do any of that nasty mid-air collision business. I
may add to the realism/entertainment value of the simulation by 
adding these features in the future.

Oh, and in case your wondering, no, I did not win the contest.

Source Code
-----------

If you would like to have the documented source code for ATC, send
US$10 to the address listed at the end of this document. The source 
code is available for both the Apple Macintosh (Symantec Think C/C++ 
compiler) and Windows 95/NT (Microsoft Visual C++). If you are 
requesting source code, keep in mind that derivative works based on 
the source may not be distributed without the written consent of 
Jeff Budzinski and Black Cat Software.
Distribution

Distribution
------------

You may freely distribute this software provided no fee is charged 
except that which covers reasonable duplication costs for the 
distribution media.

Warranty
--------

This software is free, so please don't send your lawyers chasing after me.

Contacting the Author
---------------------

Comments, complaints, suggestions, etc. can be sent to:

   Jeff Budzinski
   Black Cat Software
   4546 B-10 El Camino Real
   Suite 358
   Los Altos, CA 94022
   415.596.8728
   Email: jeff@furball.com

Trademarks
----------
   
HyperCard is a trademark of Apple Computer, Inc. Symantec C++ and Think C 
are trademarks of Symantec Corporation. Windows 95, Windows NT, and 
Visual C++ are trademarks of Microsoft, Inc.

