Improvement of Real Time f0F2 Prediction for OTH Radars.
PHILLIPS LAB HANSCOM AFB MA
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Dandekar and Buchau 1986 presented an empirical algorithm for improving the f0F2 predictions for the sunrise transition period. The algorithm uses an average hourly gradient obtained from the previous four days f0F2 observations and the present f0F2, to predict f0F2 for the next hour. A further improvement was achieved by adding a second order correction term to the averaged slope. The second order correction takes into account 1 the change in now f0F2 with respect to the previous four days average f0F2 and 2 the increasingdecreasing gradient of f0F2. In the algorithm the sign of the second order term is selected so as to set a converging trend for the correction term. The algorithm is applied to a 24-hour period by dividing the time interval in two sections 04-16 and 16-04 LT and reversing the sign of the second order correction for these two intervals, to assure the use of the converging trend from the algorithm for the 24 hour cycle. The scheme reduces the standard error in prediction from 0.9 MHz using the lONCAP method to 0.4 MHz at high solar activity and from 0.5 MHz using IONCAP to 0.9 MHz at low solar activity. The algorithm proposed here improves the f0F2 prediction by 50 at high solar activity and by 40 at low solar activity. The method provides a minimum of 25 improvement in the real time prediction of f0F2 for 80 of the time. This level of reduction in the error of prediction of f0F2 is useful to the OTH radar frequency management, becuse every 6 change in M ratio of radar frequency to f0F2 at midpoint of the radar range requires an adjustment of the radar operation frequency.
- Computer Programming and Software
- Active and Passive Radar Detection and Equipment