Communications: directive radio wave systems and devices (e.g. – Determining distance – With remote cooperating station
Patent
1983-05-26
1987-02-24
Tubbesing, T. H.
Communications: directive radio wave systems and devices (e.g.,
Determining distance
With remote cooperating station
342127, G01S 1384
Patent
active
046460926
ABSTRACT:
In a continuous wave electromagnetic positioning or distance measuring system of the Wadley type (see U.S. Pat. No. 2,907,999) a number of secondary phase measurements are obtained from a number of successively produced primary phase measurements in such a manner that any instrumental errors incorporated in the primary phase measurements are eliminated. Each secondary phase measurement represents the fractional part of the phase delay that would be experienced by a signal of accurately known measuring frequency when propagated electromagnetically along a propagation path corresponding in length to the distance to be measured. The measuring frequency is determined by the frequencies of pattern and auxiliary pattern signals used in obtaining the primary phase measurements. By suitable choice of the measuring frequencies, the distance can then be derived from the phase measurements, the result being unambiguous to the wavelength of the lowest measuring frequency and being accurate to a fraction of the wavelength of the highest measuring frequency. The system is ideal under static conditions where the distance does not change during the measuring sequence. Under dynamic conditions, where the distance changes during the measuring sequence, problems arise. Heretofore, the multiplying factor .beta. which relates one measuring frequency to the next higher measuring frequency was chosen to be as small as possible with what were considered to be reasonable averaging times for the individual primary phase measurements, and the problems arising under dynamic conditions were dealt with by decreasing the highest measuring frequency. The resultant loss in accuracy was accepted as inevitable. In the present invention the factor is increased so as to be in the range 1>.beta.>1/8. This reduces the accuracy requirement for the phase measurements, permitting a reduction in the averaging times, and consequently reducing the effect of distance changes during the measuring operation. The superiority of this approach stems from the quadratic relationship between the reduction in averaging times and the loss in accuracy, noise conditions being equal.
REFERENCES:
patent: 3315257 (1967-04-01), Sauberlich
patent: 4307397 (1978-11-01), Holscher
Cubic Corporation; Model CR-100 Series Precision Range/Range Rate Measurement System; Aug. 1978.
Cubic Corporation; Ku-Band Precision Distance Measuring Equipment.
Deck Article--Mecanique, Materiaux, Electricite, vol. 55, No. 279, Mar. 1973, pp. 18-22.
Cubic Corporation Brochure--Precision Ranging System.
European Search Report issued on European Patent Appln. 83303224.
Barron Jr. Gilberto
Plessey South Africa Limited
Tubbesing T. H.
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