Description: For this mission, a UAF built solar sensor system is being used. The main parts of the system include four Army Research Lab SLIT solar sensors provided by NSROC and a Solar Measurement Unit (SMU). The four solar sensors will be evenly spaced on the same horizontal plane to produce data representing the rocket's relative position to the sun and the rocket's spin rate. The SMU is an embedded system board. The SMU needs to gather and process the data produced by the sun sensors, and then pass this data on to the Telemetry Stack (TM) (see Figure 1). The firmware to carry out the responsibilities of the SMU needs to be written, loaded into the SMU microprocessor, and pre-flight tested.SMU Firmware

Descripton: The microprocessor on the SMU must sample the signals being sent to the SMU board from the sun sensors as often as possible, preferably every 50 microseconds. Executing the section of the program which performs calculations on the data can wait until after rocket launch, but data transmissions occur regularly from program startup, thereby showing the program is working, even if no sensor data is received. The status of sensors needs to be tracked and sent along with each transmission. The status needs to indicate whether a sensor was read and used in the current calculation, or if there was a perceived error in the sensor transmission. The calculated data should be sent in a packet to the TM after each calculation is completed. Three LEDs are available for use as status indicators.

Sun Sensors: The four solar sensors (SLITS), developed by Army Research Labs (ARL), will be provided by NSROC. The sensors will be mounted on the skin of the rocket in the same plane at 0˚, 90˚, 180˚, and 270˚, starting from an arbitrary point in the plane. As the rocket spins, the sun will move over each sensor, producing an electrical pulse. This pulse is sent out of the sensors in digital form.The sensors at 0˚ and 180˚ are set perfectly perpendicular to the horizontal plane, while the sensors at 90˚ and 270˚ are set 15˚ off the perpendicular. If spin rate is constant, the pulse from the 0˚ and 180˚ sensors will be received at a constant rate, while the pulse from the other two sensors will be received at a rate which will vary with the angle of the sun.

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Each solar sensor detects directed sunlight.  Four sensors are mounted equidistant on the horizontal plane of the rocket.  Data collected from the sensors as the rocket rotates are used by the Solar Measurement Unit.