Communications: directive radio wave systems and devices (e.g. – Directive – Including a radiometer
Patent
1984-11-20
1987-08-04
Blum, Theodore M.
Communications: directive radio wave systems and devices (e.g.,
Directive
Including a radiometer
342352, 364517, 364455, G01S 302, G01S 1700, H04B 7185
Patent
active
046849556
ABSTRACT:
To measure the figure of merit (G/T) and beam radial pointing error of a satellite earth station multiple Y-factor measurement are taken using a "drift cut" procedure and then these measurements are processed using a maximum likelihood estimate (MLE) algorithm. For carrying out the "drift cut" measurement process, the earth terminal's antenna is positioned such that the antenna beam intersects the path of the apparent star motion with a predetermined declination offset and ahead of the current star position. As the star position approaches the stationary antenna beam position, power measurements uniformly spaced in time are recorded. These power measurement "samples" are then divided by the "cold sky" power measurement to obtain corresponding Y-factor measurements. To eliminate the problem of antenna pointing error and star ephemeris error, multiple drift cuts are carried out, each offset in declination by a different amount from the estimate star declination, to produce a matrix of Y-factor values. This matrix of drift cut Y-factors is then processed using a maximum likelihood estimate algorithm, to provide MLE measures of that earth terminal's figure of merit and beam radial pointing error.
REFERENCES:
patent: 4521861 (1985-06-01), Logan et al.
M. Kanda, "An Error Analysis for Absolute Flux Density Measurements of Cas-A" IEEE Trans Instrumentation Measurement, vol. 25, No. 3, Sep. 1976, pp. 173-182.
Schwartz et al., "Communication Systems and Techniques", McGraw, 1966 pp. 85-90.
Watt, "Precision Measurement of Antenna System Noise Using Radio Stars" NBS, Boulder, Colorado, pp. 1-31.
Wait et al, "A Study of the Measurement of G/T Using Cassiopeia A", NBSIR 74-382, Boulder Colorado, Jun. 1974, pp. 9-12.
Proc. of the Society of Photo-Optical Instrumentation Engineers, Wash., D.C., Apr. 17-18, 1979, SPIE vol. 178, pp. 210-216, 219, 220.
Adams, Jr. William C.
Patisaul Charles R.
Blum Theodore M.
Harris Corporation
Issing Gregory C.
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