1. Find the coordinates of a suitable Communications Satellite
2. Confirm the coordinates of both desired Ground Stations
3. Connect to the Origin Ground Station
4. Calculate the Azimuth and Elevation to the Satellite
5. Adjust the Ground Station to acquire the Satellite
6. Connect to the Satellite
7. Calculate the Azimuth and Elevation to the Target Ground Station
8. Adjust the Satellite to acquire the Target Ground Station
9. A link should automatically establish and can be used normaly
=== [ Subject 1: Finding a Ground Station ] ===
Satellite communication relays allow users to create their own links between
hosts. These links are one way and can be made between any two Hosts equiped
with Ground Stations. The following Hosts are equiped with ground stations:
hosts with 'NASA' or 'university' in their descriptions, and military hosts
with the '.af' suffix in their name. A special program will be needed to
connnect to and operate the dish itself.
=== [ Figure 2: Ground to Orbit Communication ] ===
Any satellite dishes' physical location can be described with a 3 component
coordinate ( x, y, z ). Ground Station dishes point at the sky, Satellite
dishes point at the ground. To acquire a Satellite utilizing a Ground
Station, the correct azmiuth and elevation must be known. The elevation and
azimuth can be calculated with the coordinates of both dishes. The azimuth
and elevation are expresed in degrees utilizing a floating point variable.
Both the azimuth and the elevation must be accurate to within 0.5 degrees.
=== [ Subject 3: Calculating Azimuth ] ===
The Azimuth (in degrees) can be found by utilizing the following formula:
Let the coordiantes of the Origin Dish be: ( Ax, Ay, Az )
Let the coordinates of the Target Dish be: ( Bx, By, Bz )
NOTE: This will be in radians
Let K equal: atan2( Bx - Ax, By - Ay )
If K contains a value less than zero, increase the value by: 2 * [PI]
Let the Azimuth equal K * 180 / [PI]
=== [ Subject 4: Calculating Elevation ] ===
The Elevation (in degrees) can be found by utilizing the following formula:
Let the coordiantes of the Origin Dish be: ( Ax, Ay, Az )
Let the coordinates of the Target Dish be: ( Bx, By, Bz )
Let K equal: sqrt( ( Bx - Ax ) ^ 2 + ( By - Ay ) ^ 2 )
Let the Elevation equal: atan( ( Bz - Az ) / K ) * 180 / [PI]
NOTE: The Elevation for a Ground Station must always be positive
NOTE: The Elevation for a Satellite is typically negative
=== [ Subject 5: Communicating with a Satellite ] ===
The computer systems embeded in Communication Satellites are rudimentary at
best. As such, Satellites accept command strings in the form of two byte
hexadecimal followed by an optional four byte parameter, usually in the form
of a hex-encoded floating point variable. A Satellite's response typically
takes the form of a short hex-encoded ASCII string or a hex-encoded floating
point variable.
=== [ Figure 4: Example Established Link ] ===
NOTE: The & symbol denotates that this link is a Satellite connection
mimsy$ netstat
host organization location
---- ------------ --------
& ames NASA Ames Research Center Moffett Field, CA
anagld Analytics, Inc. Columbia, MD
aplcen Johns Hopkins University, APL Center Laurel, MD
arinc Aeronautical Radio, Inc. Annapolis, MD
black-silicon Black Silicon, Fortress Of Computati McLean Virginia
=== [ Documentation 1: Example Satellite Command String ] ===
The following commands are generic to all Communications Satellites.
NOTE: The * denotates that this command must be followed by a four byte
parameter, usually a floating point variable.
NOTE: The contents of "" are hex-encoded ASCII literal strings.
NOTE: Entering an invalid command returns the error: "BAD_CMD"
NOTE: Failing to supply a parameter returns the error: "NO_PARAM"
NOTE: Unnecessary parameters are ignored
00 :
Request: The name of the Satellite
Response: Hex-encoded ASCII string
01 :
Request: The X Coordinate of the Satellite
Response: Hex-encoded floating point variable
02 :
Request: The Y Coordinate of the Satellite
Response: Hex-encoded floating point variable
03 :
Request: The Z Coordinate of the Satellite
Response: Hex-encoded floating point variable
04 :
Request: The Azimuth of the Satellite's dish
Response: Hex-encoded floating point variable
05 :
Request: The Elevation of the Satellite's dish
Response: Hex-encoded floating point variable
06 :
Request: The name of the Host the Satellite's dish is pointed at
Error, the Satellite failed to detect a host: "NO_RESPONSE"
Response: Hex-encoded ASCII string
07 :
Request: Close the connection to the Satellite
Response: "DISCONNECT"
08* :
Request: Change the Azimuth of the Satellite's dish
Error, parameter is less than 0 degrees or greater than 360 : "BAD_ANGLE"
Error, parameter was not a floating point variable: "NOT_FLOAT"
Response: "SUCCESS"
09* :
Request: Change the Elevation of the Satellite's dish
Error, parameter is less than -90 degrees or greater than 90 : "BAD_ANGLE"
Error, parameter was not a floating point variable: "NOT_FLOAT"
Response: "SUCCESS"
99* :
Reserved for Satellite broadcast and administration.
