Satel Az-EL, Instruction Manual, Page: 6 / 16

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serial cable, of a length appropriate to your situation, is required, and this can be bought at any
computer or electronics store.
This completes the cabling connections.
III. Installing the Software on your computer
Introduction to the software
The accompanying CD-ROM contains the Sat EL rotor control program, this instruction
manual, a freeware copy of the well-known terminal program, Kermit , and several freeware
programs for synchronizing your computer’s clock to an atomic standard. Before discussing
the installation of these programs, it is useful to describe the overall way the Sat
EL controller
interacts with your computer.
The
Sat EL rotor system is an improved version of the azimuth-elevation system
described in the Dec, 1999, QST article by Jim Koehler, VE5FP entitled “An Inexpensive Az-El
Rotator System”. Like that system, the Sat
EL rotors are controlled by a dedicated
microprocessor which keeps track of time, stores future desired pointing angles and moves the
rotors to point to these positions at the appropriate times. All communication between the
Sat
EL system and your computer is via a serial RS-232 port, as it was in the earlier VE5FP
system,
This improved version of the system is backward compatible with the original system.
This means that you can, if you choose, control the Az-El just by running a “terminal” program
such as
Kermit ; one which makes your computer act like a terminal to talk to the Sat EL
system. In this way you can change the microprocessor date and time, move the two rotors in
all directions: the elevation rotor up or down, the azimuth rotor clockwise or counter-clockwise,
etc. You can also type in a list of future desired positions and the time that you want the
system to point there. You can disable future automatic motion, enable it, clear the memory
and interrogate the system to determine its status. A full set of the commands to the system
and its response are described in the original article. A summary of these commands is found
in Appendix A.
However, this way of controlling the rotor system is tedious and prone to error. The
original controller was very memory limited and so had very limited input checking. It was,
therefore, prone to locking up if commands were mistyped. The new controller has more
sophisticated command parsing, but using a plain terminal and typing desired future positions
is still tedious and error-prone.
To simplify things, Sat EL provides a program to facilitate control of the rotors. This
program is named AzElControl.exe and can be installed from the accompanying CD-ROM.
AzElControl.exe will allow you to quickly upload data from ephemeris files produced by either
the InstantTrack or Nova for Windows

satellite prediction programs. You can enable or
disable motion, clear the memory, synchronize the controller clock to your computer clock, etc,
all using the Sat
EL Windows

-resident AzElControl.exe program.
Most computer clocks are very inaccurate and so it is advisable to reset them correctly
once a day or so. The time synchronizing programs will do that via the Internet.