US3751712A — Digital differential analyzer spiral scan generat…

Claim 1

Independent Claim 267 words

A system for generating pulses representing increments Delta x and Delta y in digital pulse trains to be used for positioning an object along a spiral path in a rectangular Cartesian coordinate system comprising: means for generating first and second clock pulses representing respective constant azimuth increments Delta theta of said spiral path, and constant range increments Delta r of distance R of said spiral path from the center of said coordinate system; means responsive to said first clock pulses for generating values of sin theta and cos theta , and for generating a first pulse train representing constant increments Delta u of successive changes in the value sin theta and a second pulse train representing constant increments Delta v of successive changes in the value cos theta ; including first and second cross-coupled digital differential analyzers wherein sin theta is developed as an integrand by a counter in said second analyzer in response to increments Delta u from said first analyzer, and cos theta is developed as an integrand by a counter in said first analyzer in response to increments Delta v from said second analyzer, and said increments Delta u and Delta v are produced in said first and second analyzers in response to said increments Delta theta ; means responsive to said second clock pulses for generating a continuously increasing value of said distancE R; and means responsive to said value R for varying the pulse rate of said first and second pulse trains as a function of said value R to produce said trains of pulse increments Delta y and Delta x, respectively.

Claim 2

Independent Claim 267 words

A system for generating pulses representing increments Delta x and Delta y in digital pulse trains to be used for positioning an object along a spiral path in a rectangular Cartesian coordinate system comprising: means for generating first and second clock pulses representing respective constant azimuth increments Delta theta of said spiral path, and constant range increments Delta r of distance R of said spiral path from the center of said coordinate system; means responsive to said first clock pulses for generating values of sin theta and cos theta , and for generating a first pulse train representing constant increments Delta u of successive changes in the value sin theta and a second pulse train representing constant increments Delta v of successive changes in the value cos theta ; including first and second cross-coupled digital differential analyzers wherein sin theta is developed as an integrand by a counter in said second analyzer in response to increments Delta u from said first analyzer, and cos theta is developed as an integrand by a counter in said first analyzer in response to increments Delta v from said second analyzer, and said increments Delta u and Delta v are produced in said first and second analyzers in response to said increments Delta theta ; means responsive to said second clock pulses for generating a continuously increasing value of said distancE R; and means responsive to said value R for varying the pulse rate of said first and second pulse trains as a function of said value R to produce said trains of pulse increments Delta y and Delta x, respectively.

Claim 3

Dependent Claim 109 words

A system as defined in claim 1 wherein said means for generating values of sin theta and cos theta , and said first and second pulse trains comprises first and second cross-coupled digital differential analyzers wherein sin theta is developed as an integrand by a counter in said second analyzer in response to increments Delta u from said first analyzer, and cos theta is developed as an integrand by a counter in said first analyzer in response to increments Delta v from said second analyzer, and said increments Delta u and Delta v are produced in said first and second analyzers in response to said increments Delta theta .

Claim 4

Dependent Claim 67 words

A system as defined in claim 2 including third and fourth digital differential analyzers for producing third and fourth pulse trains as a function of respective integrands in said first and second analyzers and increments Delta r of said distance, and means for adding said third and fourth pulse trains to said first and second pulse trains, respectively, to produce said increments Delta y and Delta x.

Claim 5

Independent Claim 221 words

A system for generating pulses representing increments Delta x and Delta y as digital pulse trains for positioning an object along a spiral path in rectangular Cartesian coordinate system in synchronism with an azimuth sinusoidal signal representing sin theta as the distance of said spiral path from the center of said coordinate system varies comprising: means for generating first and second clock pulses of independent frequencies representing respective increments Delta theta of successive changes in azimuth of said spiral path and increments Delta r of successive changes in said distance; means responsive to said first clock pulses for generating absolute sin theta and cos theta values, and a first pulse train representing changes in constant increments Delta u of sin theta and a second pulse train representing changes in constant increments Delta v of cos theta ; means for counting said second clock pulses to generate a increasing varying value R of said distance; means responsive to said value R for varying the pulse rate of said first and second pulse trains as a function of said value R whereby the rate of said first and second pulse trains represent absolute values of sin theta and cos theta ; and means responsive to said sinusoidal signal for determining the signs of said absolute values of sin theta and cos theta .

Claim 6

Independent Claim 221 words

A system for generating pulses representing increments Delta x and Delta y as digital pulse trains for positioning an object along a spiral path in rectangular Cartesian coordinate system in synchronism with an azimuth sinusoidal signal representing sin theta as the distance of said spiral path from the center of said coordinate system varies comprising: means for generating first and second clock pulses of independent frequencies representing respective increments Delta theta of successive changes in azimuth of said spiral path and increments Delta r of successive changes in said distance; means responsive to said first clock pulses for generating absolute sin theta and cos theta values, and a first pulse train representing changes in constant increments Delta u of sin theta and a second pulse train representing changes in constant increments Delta v of cos theta ; means for counting said second clock pulses to generate a increasing varying value R of said distance; means responsive to said value R for varying the pulse rate of said first and second pulse trains as a function of said value R whereby the rate of said first and second pulse trains represent absolute values of sin theta and cos theta ; and means responsive to said sinusoidal signal for determining the signs of said absolute values of sin theta and cos theta .

Claim 7

Dependent Claim 105 words

A system as defined in claim 4 including: control means responsive to said sinusoidal signal for determining when said absolute values of sin theta and cos theta start increasing from 0 to substantially 1, and start decreasing from substantially 1 to 0; a first up-down counter for counting said first pulse train up and down in response to said control means in synchronism with said absolute values of sin theta increasing and decreasing; and a second up-down counter for counting said second pulse train up and down in response to said control means in synchronism with said absolute values of cos theta increasing and decreasing.

Claim 8

Dependent Claim 211 words

A system as defined in claim 5 wherein said means for generating absolute values of sin theta and cos theta , and said first and second pulse trains comprises first and second cross-coupled digital differential analyzers wherein sin theta is developed as an integrand by a counter in said second analyzer in response to increments Delta u from said first analyzer, and cos theta is developed as an integrand by a counter in said first analyzer in response to increments Delta v from said second analyzer, and said increments Delta v and Delta u are produced in said first and second counters in response to said increments Delta theta , and wherein said integrand counter for developing the absolute values of sin theta is set to zero when said control means determines the absolute value of sin theta is to start increasing, and to substantially one when said control means determines the absolute value of sin theta is to start decreasing, and said integrand counter for developing the absolute values of cos theta is set to zero when said control means determines the absolute value of sin theta is to start increasing, and to substantially one when said control means determines the absolute value of cos theta is to start decreasing.

Claim 9

Dependent Claim 36 words

A system as defined in claim 6 wherein each of said analyzers includes a residual accumulator, and said accumulator is reset by said control means each time said integrand counters are caused to change counting direction.

Claim 10

Dependent Claim 67 words

The combination of claim 7 including third and fourth digital differential analyzers for producing third and fourth pulse trains as a function of respective integrands in said first and second analyzers and increments Delta r of said distance, and means for adding said third and fourth pulse trains to said first and second pulse trains, respectively, to produce said pulses representing increments Delta y and Delta x.

Claim 11

Dependent Claim 210 words

Apparatus for generating digital spiral sweep pulse trains to permit PPI display in a sonar system using rectangular Cortesian coordinates X and Y comprising: a source of azimuth clock pulses representing d theta in incremental form where theta is an azimuth angle; a first pair of digital differential analyzers cross-coupled to form two integrators responsive to said clock pulses to form derivatives of sin theta and cos theta as respective pulse increments Delta u and Delta v; a source of range clock pulses representing dr in incremental form, where the sum of clock pulses at any given time during a spiral sweep cycle represents range R; a counter for adding said range clock pulses; and a second pair of digital differential analyzers coupled to said first pair of digital differential analyzers, one digital differential analyzer of said second pair being responsive to derivatives of sin theta and the numerical content of said range counter for forming derivatives of X, and the other of said digital differential analyzer of said second pair being responsive to derivatives of cos theta and the numerical content of said range counter for forming derivatives of Y, said derivatives of X and Y being in the form of pulses representing increments Delta x and Delta y.

Claim 12

Dependent Claim 210 words

Apparatus for generating digital spiral sweep pulse trains to permit PPI display in a sonar system using rectangular Cortesian coordinates X and Y comprising: a source of azimuth clock pulses representing d theta in incremental form where theta is an azimuth angle; a first pair of digital differential analyzers cross-coupled to form two integrators responsive to said clock pulses to form derivatives of sin theta and cos theta as respective pulse increments Delta u and Delta v; a source of range clock pulses representing dr in incremental form, where the sum of clock pulses at any given time during a spiral sweep cycle represents range R; a counter for adding said range clock pulses; and a second pair of digital differential analyzers coupled to said first pair of digital differential analyzers, one digital differential analyzer of said second pair being responsive to derivatives of sin theta and the numerical content of said range counter for forming derivatives of X, and the other of said digital differential analyzer of said second pair being responsive to derivatives of cos theta and the numerical content of said range counter for forming derivatives of Y, said derivatives of X and Y being in the form of pulses representing increments Delta x and Delta y.

Claim 13

Dependent Claim 239 words

Apparatus as defined in claim 9 wherein integrand counters of said first pair of digital differential analyzers form as integrands the absolute values of sin theta and cos theta in response to counting up and down said increments Delta u and Delta v, respectively, and including: a source of synchronizing sinusoidal azimuth sweep signal; synchronizing means responsive to said sweep signal for determining when said sweep signal passes through cardinal points of 0*, 90*, 180* and 270* ; control means responsive to said sweep signal for causing said integrand counter for sin theta to count up during first and third quadrants of said sweep signal cycle, and down during second and fourth quadrants of said sweep signal cycle, and for causing said integrand counter for cos theta to count down during said first and third quadrants, and count up during said second and third quadrants; and preset means responsive to said sweep signal for causing one of said integrand counters to be preset to zero at cardinal points where said control means initiates an upward counting operation for said one counter, and to preset the other of said integrand counters to substantially one at the same time, and to preset the other of said counters to zero at cardinal points where said control means initiates an upward counting operation for said one counter, and to preset the one of said integrand counters to substantially zero at the same time.

Claim 14

Dependent Claim 27 words

Apparatus as defined in claim 10 including means responsive to said sweep signal for continually determining the signs of said integrands sin theta and cos theta .

Claim 15

Dependent Claim 87 words

Apparatus as defined in claim 11 including a third pair of digital differential analyzers, one of said analyzers of said third pair being responsive to said integrand sin theta and to said range clock pulses for forming derivatives of X, and the other of said analyzers of said fourth pair being responsive to said integrand cos theta and to said range clock pulses for forming derivatives of Y, and means for adding respective derivatives of X and Y formed by said third and fourth pairs of analyzers.

Claim 16

Independent Claim 255 words

A system for converting an azimuth sweep signal and a range sweep enable signal into digital pulse trains Delta x and Delta y for positioning an electron beam on a cathode ray tube for PPI display of video signals, the combination comprising: a source of pulses representing increments Delta theta of azimuth sweep angle gated on by said range sweep enable signal; a source of pulses representing increments Delta r of range sweep gated on by said range sweep enable signal; means comprising digital differential analyzers for computing absolute sine and cosine values of sweep angle theta as integrands and pulses representing increments Delta u and Delta v of sin theta and cos theta , respectively, in response to said pulses representing increments Delta theta in accordance with the following equations: Delta u V Delta theta Delta v U Delta theta where V is the absolute value of sin theta , and U is the absolute value of cos theta ; means comprising digital differential analyzers for computing said pulse trains Delta x and Delta y in response to said pulses representing increments Delta r and said pulses representing increments Delta u and Delta v in accordance with the following equations: Delta x1 R Delta u Delta y1 Rdv where x1 and y1 are equal to Delta x and Delta y, respectively, R is an integrand value of range continuously determined by counting said pulses representing increments Delta r of range sweep from a preset value at the beginning of said range sweep enable signal.

Claim 17

Independent Claim 255 words

A system for converting an azimuth sweep signal and a range sweep enable signal into digital pulse trains Delta x and Delta y for positioning an electron beam on a cathode ray tube for PPI display of video signals, the combination comprising: a source of pulses representing increments Delta theta of azimuth sweep angle gated on by said range sweep enable signal; a source of pulses representing increments Delta r of range sweep gated on by said range sweep enable signal; means comprising digital differential analyzers for computing absolute sine and cosine values of sweep angle theta as integrands and pulses representing increments Delta u and Delta v of sin theta and cos theta , respectively, in response to said pulses representing increments Delta theta in accordance with the following equations: Delta u V Delta theta Delta v U Delta theta where V is the absolute value of sin theta , and U is the absolute value of cos theta ; means comprising digital differential analyzers for computing said pulse trains Delta x and Delta y in response to said pulses representing increments Delta r and said pulses representing increments Delta u and Delta v in accordance with the following equations: Delta x1 R Delta u Delta y1 Rdv where x1 and y1 are equal to Delta x and Delta y, respectively, R is an integrand value of range continuously determined by counting said pulses representing increments Delta r of range sweep from a preset value at the beginning of said range sweep enable signal.

Claim 18

Dependent Claim 102 words

A system as defined in claim 13 further comprising: a pair of counters for counting up and down pulses of said trains Delta x1 and Delta y1 to form the absolute values of X and Y; means responsive to said azimuth sweep signal for controlling said pair of counters to count up said pulses of said train Delta x1, during said first and third quadrants of azimuth angle theta , and to count down the balance of the time, and to count pulses of said train Delta y1 in a direction always opposite to counting said pulses of said train Delta y1.

Claim 19

Dependent Claim 105 words

A system as defined in claim 13 wherein said last named means further comprises digital differential analyzers for computing additional pulse trains Delta x2 and Delta y2 in response to said pulses representing increments Delta u and Delta v in accordance with the following equations: Delta x2 U Delta r Delta y2 V Delta r and means for combining said pulse trains Delta x1 and Delta x 2 into a single train Delta x equal to Delta x1 + Delta x2 and for combining said pulse trains Delta y1 and Delta y2 into a single train Delta y equal to Delta y1 + Delta y2.

Claim 20

Dependent Claim 102 words

A system as defined in claim 15 further comprising: a pair of counters for counting up and down pulses of said trains Delta x and Delta y to form the absolute values of X and Y; means responsive to said azimuth sweep signal for controlling said pair of counters to count up said pulses of said train Delta x, during said first and third quadrants of azimuth angle theta , and to count down the balance of the time, and to count pulses of said train Delta y in a direction always opposite to counting said pulses of said train Delta y.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1976-08-06	1977-02-05	1977-08-07	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1980-08-06	1981-02-05	1981-08-07	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1984-08-06	1985-02-05	1985-08-07	$7700.00	Window Closed / Lapsed

Digital differential analyzer spiral scan generator

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag