Automatic satellite tracking system for the NASA Satellite Photometric Observatory
The development of an Automatic TV Tracking System for NASA's mobile 61 cm aperture Satellite Photometric Observatory is described. The analysis techniques used to match the FOV and resolutions to changing seeing conditions are covered in details. Theoretical reasons for such matching of general interest are discussed. It is shown that the energy density in a satellite image is 11 times greater during good seeing conditions than during typical seeing conditions. The Z7987 image tube is shown to be able to detect 16th magnitude objects under ideal seeing conditions using only 8 percent of the light collected by the main telescope. Experimental results show that the SPO equipped with a Z7987 camera can track a satellite at any orbital velocity with less than 0.14 mr accuracy using the DBA Series 606 TV Tracker. The manual system used prior to the installation of the Automatic TV Tracking System could maintain track at 1.1 mr accuracy for comparison.
Television System Optimization For Astronomy And Special Applications
The predominance of television systems which operate at standard broadcast rates tend to mask several system optimization techniques which can improve performance of nonstandard systems. Astronomical systems, in particular, benefit by use of nonstandard frame rates, line numbers, and a proper balance between exposure time and sensor gain. Resolution and signal-to-noise from a given sensor can be maximized by proper selection of the number of TV lines and the frame time. In addition, the signal-to-video noise for a given TV resolution has a peak value for the video bandwidth picked from sensor and system parameters.
On the Signal-to-Noise Ratio in Television Storage Tubes
Publisher Summary This chapter discusses the optimum scanning conditions, especially for those cases where the scanning speed is not, as in normal television broadcast technique, prescribed by standards. There are two main processes in the operation of television image storage tubes: the development of the charge pattern and the evaluation of the stored charge by a scanning process. One of the important parameters in the performance of these tubes is the signal-to-noise ratio, which depends primarily on the inherent statistical fluctuations of the electron charge per picture element—that is, on the noise pattern in the charge itself. It is quite possible to get good signal-to-noise ratio in electron storage tubes without a multiplier if optimum conditions are reached. The advantage of electron multiplication in the tube is more pronounced for smaller amounts of charge and for higher numbers of picture elements. The results presented in the chapter are good approximations, though they could be improved by considering various effects on the signal-to-noise ratio. The numerical results of such an analysis may differ from the simpler calculation to a certain extent; the relations given in this chapter are close enough in practice to serve as a guide for optimum construction and operation of a storage tube.