New Design Techniques of Variable Prescaling Counters for Spaceborne Experiments

The design techniques of prescaling counters for the automatic compression of particle measure ment data on board of spacecrafts are reviewed and new criteria are proposed, which are illustrated by examples. The standard technique of realizing logarithmic counters is criticized and alternative procedures are proposed that take into account both the effect of the statistical error, when counting events from random sources, and the efficient use of all the apriori information available about the expected counts. The resulting structure consist of a prescaling counter, where the number of stages of the prescaler that are inserted does not coincide anymore with the content of the exponent section, but is an arbitrary function of that number.     

The determination of cloud pattern motions from geosynchronous satellite image data

Cloud motion can be determined from sequential pictures obtained from the geosynchronous Applications Technology Satellites, ATS-I and ATS-III. Experiments have been conducted using two automated techniques for computing the cloud motions over the time interval between two digitized pictures. One technique is a direct application of cross-correlation using the fast Fourier Transform (fFT). In the other, a relatively simple matching technique is used in the computer to recognize binary images of cloud fields on each member of a picture pair. Results obtained from the two techniques are similar. The computed directions are in good agreement with those determined by manual methods with indications that computed speeds are more accurately resolved than those determined manually.