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Quadratic phase memory

  • US 3,898,446 A
  • Filed: 09/06/1974
  • Issued: 08/05/1975
  • Est. Priority Date: 09/06/1974
  • Status: Expired due to Term
First Claim
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1. A system for producing sine and cosine values of a rotating vector comprising memory means containing magnitude values for a rotating vector stepped in discrete steps over a 90* range;

  • selector means connected to said memory means whereby said magnitude values will be presented at outputs of the memory means in the proper step sequence of the rotating vector;

    sign generating means connected to the outputs of said memory means so as to provide the magnitude values with a proper sign in accordance with the quadrant in which the rotating vector is located;

    outputs of said selector means being so related to the rotating vector as to provide signals indicating the quadrant said rotating vector is in;

    outputs of said selector meanS being connected to said sign generating means so as to control the sign said sign generating means will apply to the magnitude values;

    said memory means is divided into first and second sections;

    said first section containing the magnitude values stepped in discrete steps of the sine of the angles from 0* to 45*;

    said second section containing the magnitude values of the sine of 90* to 45* in discrete steps;

    first and second outputs of said first and second sections;

    said selector means being connected to the first and second sections of said memory means so as to cause the first section to read out the magnitude values at its output sequentially from 0* to 45*, and said second section to read the magnitude values sequentially from 90* to 45* at its output whereby one section presents the sine magnitude value and the other section presents the cosine magnitude value;

    said sign generating means comprising first and second sign generating means each having an input and an output;

    switching means connected between the outputs of the first and second sections of the memory means and the inputs of said first and second sign generating means so as to connect the output of the section having the sine magnitude value to the first signal generating means input and to connect the output of the section having the cosine magnitude value to the input of the second signal generating means; and

    said selector means being connected to said switching means so as to control the operation thereof in accordance to which half of a particular quadrant the rotating vector is located.

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