Abstract: The altitude of an aircraft is determined by measuring the output of a pressure transducer on the aircraft because the altitude is defined by the atmospheric pressure at that point. In this altitude measurement, the relationship between the altitude and the atmospheric pressure is nonlinear, and most pressure transducers exhibit some nonlinearity. High accuracy altitude measurement, correcting those nonlinearities, have been disclosed in the prior art utilizing a quasi-exponential function generator (QEFG). A quasi-exponential function is an exponential function with a time constant which varies with time. However, the characteristics of the pressure transducer and QEFG are affected by temperature, and there have been no appropriate means other than the use of a thermostat to maintain the accuracy of measurement when the temperature varies.

Abstract: Apparatus for obtaining a numerical value of a polynomial function of a variable. The method of cascade accumulation is used in which memories M0, M1, M2, . . . , Mn are involved, and under one cycle of manipulation, the content of memory M1 is added to the content of M0, the content of M2 is added to the content of M1, and so on until the content of Mn is added to the content of Mn-1. By loading a digital value determined by the coefficients of the polynomial a.sub.0, a.sub.1, a.sub.2, . . . , a.sub.n in each of the memories as its initial value, and repeating x cycles of the above mentioned manipulations, the digital value of the functionw = a.sub.0 + a.sub.1 x + a.sub.2 x.sup.2 + . . . + a.sub.n x.sup.nis obtained in the memory M0.

Abstract: This invention relates to apparatus for obtaining the numerical value of a function of a single or plural number of variables. The method of cascade accumulation is used in which memories M0, M1, M2, . . . , Mn are involved and under one cycle of manipulation the contents of memories M1, M2, . . . , Mn are added to the contents of M0, M1, M2, . . . , Mn-1 respectively. By loading a digital value determined by a.sub.0, a.sub.1, a.sub.2, . . . , a.sub.n into each of the memories as its initial value and repeating x cycles of the above mentioned manipulations, the digital value of the functionw = a.sub.0 + a.sub.1 x + a.sub.2 x.sup.2 + . . . + a.sub.n x.sup.n 1.is obtained at the memory M0.By extending the above principle to two dimensional operations, a digital function of two variables expressed byw = a.sub.00 + a.sub.10 x.sub.1 + a.sub.20 x.sub.1.sup.2 + a.sub.30 x.sub.1.sup.3 + . . . + a.sub.01 x.sub.2 + a.sub.11 x.sub.1 x.sub.2 + a.sub.21 x.sub.1.sup.2 x.sub.2 + a.sub.31 x.sub.1.sup.3 x.sub.2 + . . . + a.

Abstract: This invention discloses apparatus for linearizing the relation between altitude and an output signal of a sensor which represents the n th power of atmospheric pressure by means of generating a basically exponential signal of a parameter and obtaining the corresponding value of the parameter at which the exponential signal coincides with the output signal of the pressure sensor. This invention also includes means for measuring an accurate altitude by correcting the above linearized value according to the standard atmosphere adopted by the ICAO by means of generating a function for compensating the effect of temperature distribution of the standard atmosphere.

Abstract: This invention discloses apparatus to obtain altitude measurement in digital value by linearizing the relation between the actual altitude and the output signal of a pressure sensor, by means of a digital function generator. An accurate measurement is made possible under the standard atmosphere, adopted by International Civil Aviation Organization (ICAO), where the relations between the altitude, static pressure and temperature are given. The digital function generator of the invention generates a function represented by a polynomial in the form of a power series of a variable. Because of the versatility of the above function, a variety of pressure sensors having different response characteristics may be used for this invention.