# US 4,852,026 A · Method and apparatus for the evaluation of an angle over an extended range > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,852,026 A - Document ID: US4852026A - Status: Granted - Kind: A - Application number: 06/879,196 - Filed: 1986-06-25 - Granted: 1989-07-25 - Earliest claimed: 1986-06-25 - Assignees: Enertec - Inventors: Michel Berard - Web page: https://patentgrep.com/patent/US4852026A ## CPC - G01R 15/247: {Details of the circuitry or construction of devices covered by G01R15/241 - G01R15/246} - G06F 7/548: Trigonometric functions; Co-ordinate transformations - G06F 7/62: Performing operations exclusively by counting total number of pulses {; Multiplication, division or derived operations using combined denominational and incremental processing by counters, i.e. without column shift (G06F7/68 takes precedence)} - G06J 1/00: Hybrid computing arrangements - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - G06J: HYBRID COMPUTING ARRANGEMENTS (optical hybrid computing devices G06E3/00) ## Abstract A method and device for evaluating an angle A known by at least two trigonometric functions and capable of varying over a range greater than 360.degree.. Two counter integers N.sub.0, N.sub.1 are stored and up-dated, each with respect to the other, as a function of even and odd indicator signals FC.sub.2, FS.sub.2. The value of the angle A, expressed in quarter turns, is given by the first or the second counter number as a function of the value of the even indicator signal FC.sub.2. ## Claims ### Claim 1 A method for evaluating the variation, from an initial instant, of an angle A capable of varying over a range greater than 90.degree., by using instantaneous values of at least an even indicator signal FC.sub.2 and an odd indicator FS.sub.2, respectively related to the signs of the cosine and the sine of a double angle 2A, comprising the steps of: (a) putting and storing in memory, at an initial instant, two counter numbers, N.sub.0, N.sub.1 ; (b) defining a localization parameter X by assigning to it, as a function of the instantaneous value of the even indicator signal, the value of one of the counter numbers N.sub.0, N.sub.1 ; (c) reading out the other of the counter numbers N.sub.0, N.sub.1, by assigning it as a new value that of the localization parameter X increased or decreased by one in dependence upon the instantaneous value of the product of the two indicator signals; (d) selectively repeating the previous steps (b) and (c) in the course of time; and (e) producing at least a first output signal related to the localization parameter X, variation of which, expressed in multiples of quarter turns, represents the variation of the angle A since the initial instant in corresponding multiples of 90.degree.. ### Claim 2 (depends on 1) A method according to claim 1, wherein: the even and the odd indicator signals are respective direct representations of the signs of the cosine and the sine of the double angle 2A. ### Claim 3 (depends on 1) A method according to claim 1, wherein: the counter number reset during step (c) takes the value of the localization parameter X increased by one if the product of the indicator signals is positive and decreased by one if said product is negative. ### Claim 4 (depends on 1) A method according to claim 1, further comprising the steps of: receiving a cosine tracking signal C proportional to the cosine of the angle A and a sine tracking signal S proportional to the sine of the angle A; choosing a measurement signal M respectively proportional to the cosine and sine tracking signals when the even indicator signal is respectively negative and positive; and improving the evaluation of the angle A by assigning to this angle the value represented by the algebraic sum of the first output signal and a second output signal equal to an inverse trigonometrical function of the measurement signal M. ### Claim 5 (depends on 4) A method according to claim 4, wherein: the angle A is evaluated from the expression X.multidot.90.degree.+(FC.sub.2).multidot.(FS.sub.2) Arc sin M, wherein X is the localization parameter, (FC.sub.2) and (FS.sub.2) are respectively the even and odd indicator signals taking the values +1 or -1 following the positive or negative sign of the cosine and the sine of the double angle 2A respectively, and where M designates the absolute value of the measurement signal. ### Claim 6 (depends on 4) A method according to claim 4, wherein: the angle A is evaluated from the expression X=90.degree.+FD.multidot.Arc sin M, where X is the localization parameter, FD is an out-of-phase indicator signal, taking the values +1 or -1 according to the sign of the difference C-S of the cosine and sine tracking signals, and where M is the measurement signal. ### Claim 7 Apparatus for evaluating the variation, from an initial instant, of an angle A that can vary over a range greater than 90.degree., by using at least an even indicator signal FC.sub.2 and an odd indicator signal FS.sub.2 respectively related to the cosine and sine of the double angle 2A, comprising: two read/write memories; memory reading address means responsive to the even indicator signal and adapted to deliver as a first output of the apparatus a duplication signal X representative of the contents of one of the two memories, selected according to the value of the even indicator signal (FC.sub.2); an operator circuit adapted, according to the value of the product of the indicator signals, to increment or decrement the value of the duplication signal X; and memory writing address means adapted to write in that one of the two memories which was not selected the value of the duplication signal X as modified by the operator circuit. ### Claim 8 (depends on 7) A device according to claim 7, further comprising: an inverse trigonometric function conversion circuit receiving a measurement signal M related, as a function of the value of the even indicator signal, either to the cosine of the angle A or the sine of the angle A, and supplying at a second output of the apparatus a signal representative of an inverse trigonometrical function of the measurement signal M.