Movies, bowling, miniature golf – hard to find in my rural area. Dark sky – plenty of it!

A pastime of mine (and a few others around here) is to watch for satellites in the early evenings as they pass over and reflect the light of the sun. There are quite a few programs and web-sites that help in predicting the look angles (azimuth and elevation) of these objects. NORAD publishes Keplerian elements that can be "plugged into" an orbital prediction algorithm and out pop the locations of the objects (the "look" angles).

Being an amateur radio operator and having an interest in satellites led me a few years ago to design a rotor controller for satellite antennas to track the amateur satellites. This unit was 8051-based. It required a continuous stream of data from a PC to "instruct" the rotor where to point. There are numerous tracking programs and several commercial rotor controllers that perform this same task. The benefit of building my own was mainly the satisfaction of having created it myself. It also had a few bells and whistles that the others do not and could use inexpensive rotors rather than the heavy-duty commercial amateur radio versions.

As it turned out, one of the "side benefits" of the rotor controller was that I could use it to point to visible satellites to aid in locating them. I began to ponder the possibility of a portable version that could be operated independently of the computer, not requiring real-time data from the PC. Your design contest brought the incentive I needed to get to work on the project.

SatPoint is a portable satellite-tracking device with an illuminated pointer that points toward satellites under the direction of a Philips 87LPC764 controller. The user connects the unit to a PC via RS-232 to receive a download of up to 100 satellite passes. The data may span several days. The data is stored in non-volatile memory so that the unit can be turned on and off as needed without having to reload the tracking data. The PC sends the current date and time to SatPoint at the beginning of the data set. SatPoint sets its internal date and time and maintains that information automatically so that it is ready to track real-time at any time. Pushbuttons and a two line by 20 character LCD interact with the operator and allow him to select various modes of operation.

SatPoint Block Diagram