US3281841A - Signal system having improved oscilloscopic display means - Google Patents

Signal system having improved oscilloscopic display means Download PDF

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US3281841A
US3281841A US413830A US41383064A US3281841A US 3281841 A US3281841 A US 3281841A US 413830 A US413830 A US 413830A US 41383064 A US41383064 A US 41383064A US 3281841 A US3281841 A US 3281841A
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keying
rate
pulse
target
pulses
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Henri G P Forestier
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Compagnie Francaise Thomson Houston SA
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/50—Systems of measurement based on relative movement of target
    • G01S13/52—Discriminating between fixed and moving objects or between objects moving at different speeds
    • G01S13/522—Discriminating between fixed and moving objects or between objects moving at different speeds using transmissions of interrupted pulse modulated waves
    • G01S13/524—Discriminating between fixed and moving objects or between objects moving at different speeds using transmissions of interrupted pulse modulated waves based upon the phase or frequency shift resulting from movement of objects, with reference to the transmitted signals, e.g. coherent MTi
    • G01S13/526—Discriminating between fixed and moving objects or between objects moving at different speeds using transmissions of interrupted pulse modulated waves based upon the phase or frequency shift resulting from movement of objects, with reference to the transmitted signals, e.g. coherent MTi performing filtering on the whole spectrum without loss of range information, e.g. using delay line cancellers or comb filters
    • G01S13/528—Discriminating between fixed and moving objects or between objects moving at different speeds using transmissions of interrupted pulse modulated waves based upon the phase or frequency shift resulting from movement of objects, with reference to the transmitted signals, e.g. coherent MTi performing filtering on the whole spectrum without loss of range information, e.g. using delay line cancellers or comb filters with elimination of blind speeds
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S1/00—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith
    • G01S1/02—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith using radio waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/06—Systems determining position data of a target
    • G01S13/08—Systems for measuring distance only
    • G01S13/10—Systems for measuring distance only using transmission of interrupted, pulse modulated waves
    • G01S13/22—Systems for measuring distance only using transmission of interrupted, pulse modulated waves using irregular pulse repetition frequency
    • G01S13/227—Systems for measuring distance only using transmission of interrupted, pulse modulated waves using irregular pulse repetition frequency with repetitive trains of uniform pulse sequences, each sequence having a different pulse repetition frequency
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/04—Display arrangements
    • G01S7/06—Cathode-ray tube displays or other two dimensional or three-dimensional displays

Definitions

  • SIGNAL SYSTEM HAVING IMPROVED OSCILLOSCOPIC DISPLAY MEANS Filed Nov. 25, 1964 5 Sheets-Sheet 2 nine pulses eLqhlf pulses nine pulses eight pulses A A A A E1 ⁇ f ⁇ f lllllll lllllll mum JL IL 1L JL 7 1 T0 T2 To 1- T0 T2 T9 LF LY Lr LY' Henri G. P Foresfier INVENTOR Oct. 25, 1966 H. G. P. FORESTIER SIGNAL SYSTEM HAVING IMPROVED OSCILLOSCOPIC DISPLAY MEANS Filed NOV- 25, 1964 5 Sheets-Sheet 5 Henri GP Foresfier I'NVENTOR.
  • an electron beam is caused to sweep the fluorescent screen of the device by applying suitable cyclically varying voltages to the deflection electrode means of the device, such as vertical and horizontal electrostatic deflection plates. Concurrently the intensity of the beam is controlled by applying to a beam control electrode, such as a Wehnelt grid, the electric pulses or signals to be displayed. These signals are then displayed on the screen as bright spots.
  • a beam control electrode such as a Wehnelt grid
  • the display may present a continuous series of spots aligned in an array on the scanning raster, and indicating a series of target distances among which the true distance is not easily seen, the display becoming ambiguous.
  • the need for such a repetitive and hence non-univocal display arises in present-day radar techniques owning to the very great range of target distances which a given radar system is required to monitor.
  • the non-univocal character of the display is of no practical consequence because the initial position of the target is known and the target may thereafter be tracked throughout its subsequent distance variations; that is, the information concerning true target distance is preserved through continuity.
  • the non-univocal character of the oscilloscopic display can lead to loss of information and consequent operational errors.
  • One important such case occurs in connection with radar ranging systems of the socalled dual-transmission-rate type, In these systems, means are provided for transmitting the radar signals at several different repetition rates, switch-over from one rate to another being effected whenever the target distance approaches a value which is a whole multiple of the so-called critical distance associated with said one transmission rate.
  • a signal system in which a first and a second signal train are produced at a first and a second repetition rate, respectively, said signal trains alternating for equal periods of time at a third rate which is the greatest common divisor of said first and second rates.
  • the signal trains coincide at regular intervals.
  • Said signal trains are applied to a beam-control electrode, e.g. Wehnelt grid, of a cathode-ray tube.
  • the deflection means e.g. plates, of the tube a cyclically varying voltage having a minor cycle period the reciprocal of said first repetition rate and having a major cycle period the reciprocal of said third repetition rate.
  • the electron beam of the tube is thus made to sweep out a cyclic scanning curve (or raster) on the screen of the device which cyclic curve has a line repetition frequency equaling said first rate and has a scan repetition frequency equaling said third rate.
  • the said signals will be displayed on the screen in alignment with two different loci or curves during said alternating periods of time.
  • the signals to be displayed are radar echo signals from a common target or the like, the intersection of the two curves will provide an unambiguous indication of true target distance.
  • FIG. 1 is a functional diagram of part (the so-called keying section) of a dual-rate phase-shift follow-up radar system of the general type disclosed in my co-pending application, as modified in accordance with this invention;
  • FIG. 2 is a pulse timing diagram illustrating the timing of the two alternate trains of keying pulses and the uniform coincidence pulses, produced in the system of FIG. 1;
  • FIG. 3 is a diagram showing waveforms of beamdeflection volt-ages used in the system of FIG. 1 to produce spiral scanning in accordance with the invention
  • FIG. 4 is a view of an oscilloscopic display provided in accordance with the invention when using a spiral raster
  • FIG. 5 is a functional diagram of the same system as the one shown in FIG. 1, partly illustrating the so-called follow-up section and other details thereof;
  • FIG. 6 shows an osci-lloscopic display provided in accordance with the invention when using a sinusoidal raster
  • FIG. 7 is a partial diagram showing how the system of FIG. 1 may be modified to provide the raster of FIG. 6;
  • FIG. 8 shows an oscilloscopic display provided in accordance with the invention when using a parallel-line raster.
  • the invention is applicable to a dualpulse-rate radar tracking system provided with automatic switching means whereby the radar transmitter is switched from one keying frequency to another keying frequency whenever the distance of a target being tracked enters a range in which the echo from it would be received at about the same instant a subsequent radar signal is being transmit-ted, were the transmiter to continue sending at the former keying frequency.
  • a dual-rate radar system provided with automatic switching circuitry of this type was disclosed in my earlier co-pendin-g application Ser. No. 337,352, filed January 13, 1964.
  • means are provided for for generating two trains of keying pulses E1 and E2, at different frequencies so selected in relation to each other that the pulses in the respective trains intermittently coincide at periodic intervals.
  • the pulses of only one of the two trains, Ell or E2 are applied as keying pulses to the radar transmitter at any given time in order to trigger the transmission of the radar pulses towards the target.
  • the switch-over from one to the other keying-pulse train is performed automatically whenever the target enters a distance range in which continued transmission at the former pulse rate would prove unsatisfactory owing to near-coincidence between transmitted pulses and received echoes. Furthermore, means are provided whereby the effective switching action from the former keying-pulse train (say E1) to the other pulse train (say E2), will occur precisely at an instant at which the pulses of the two trains E1 and E2 coincide.
  • the procedure just described is modified, at least during the so-called target-acquisition stage of the radar tracking procedure, which is the preliminary stage of locating a designated target and presetting the tracking follow-up section of the radar system to enable automatic tracking of the target during the subsequent, tracking stage of said process.
  • the two pulse trains E1 and B2 are used in a. regular alternating sequence, the switching between the two trains being constantly effected every time the two pulse trains coincide.
  • GEl and GE2 represent the two keying-pulse generators similarly designated in my copending application.
  • Keying generator GE]. produces the keying-pulse train E1 at the first keying frequency or rate F1
  • generator GEZ produces the keying-pulse train E2 at the second keying frequency or rate F2.
  • the keying-pulse generators G131 and GEZ likewise produce, in the operation thereof, the two pulse trains Lrl and Lr2, which are at the same rates F1 and F2 as the respective keying-pulse trains E1 and E2, but are somewhat broader than they.
  • the pulse trains Lrl and Lr2 are applied to an AND- gate 9.
  • the output of this AND-gate therefore, is a pulse train Lrll, which is at the frequency F0, the greatest common divisor of F1 and F2.
  • a pulse Lrtl appears at the output of AND-gate 9 every time the two pulse trains Lrl and Lr2 (or the two .pulse trains El and E2) coincide.
  • the pulse train Lr0 from AND-gate 9 is applied (through a switch 32 closed at this time, and an OR-gate 34, which will both be later referred to in detail) to the common input of a bistable element 12, so as to switch it alternately between two states in each of which a respective one of its two outputs produces a voltage output.
  • the outputs of the bistable element 12 are applied to respective AND-gates 13 and 13 whose other inputs receive the keying-pulse trains E1 and E2 respectively.
  • the outputs from both AND-gates 13 and 13 are applied to an OR-gate 14 the output from which is applied to the keying input of radar transmitter RT.
  • the components described above are contained in a logical network generally deseignated LN.
  • bistable circuit 12 has its upper output energized the keying input to transmitter T receives E1 pulses (at repetition rate F1) from keying-pulse generator GEl, while during those alternate periods when bistable circuit 12 has its lower output energized the keying input to transmitter RT receives E2 pulses (at rate F2) from key-pulse generator GEZ. Since bistable element 12 is switched between its two states in step with the Lrt) pulses at the rate F0, which is the greatest common divisior of the pulse rates F1 and F2, it is seen that every time an LrO pulse occurs, the keying frequency applied to the radar transmitter RT is switched from value F1 to F2, or from F2 to F1, as the case may be.
  • F0 as already indicated, being the greatest common divisor of F1 and F2.
  • the lower line in FIG. 2 indicates the Lr0 pulses produced from AND-gate 9, which are separated in time by equal intervals Ti) (with T 0:1/F0).
  • the upper line in the figure indicates the keying pulses applied to radar transmitter RT.
  • the pulses applied by logic network LN to the transmitter are the E1 pulses at the rate F1.
  • the LrO pulse appearing at the end of this first T0 period acts to switch the output from the pulse train E1 to the pulse E2 at the repetition rate F2.
  • E2 pulses at repetition rate F2 are applied to the keying input of trans mitter RT.
  • the Lr0 pulse occurring at the output from AND-gate 9 acts to switch the logic-network output back from pulse train E2 to pulse train E1; and so on repeatedly. It will then be evident with the above numerical assumptions, that during one set of alternate T0 periods (herein the odd T0 periods) the radar transmitter will receive at its keying input a series of nine E1 pulses at the higher repetition frequency F1 and during the other set of alternate T0 periods (herein the even-numbered set) the transmitter will receive a series of eight E2 pulses at the lower repetition frequency F2.
  • the period T2 separating a pair of the E2 pulses is, of course 9/8 the period T1 separating a pair of the E1 pulses.
  • a cathode-ray tube CRT is schematically shown for the display of the radar signals.
  • the tube CRT includes a control electrode, e.g. a Wehnelt grid, schematically indicated at CE, a pair of vertical deflection electrodes VD and a pair of horizontal deflection electrodes HD.
  • Video signals from the radar receiver RR are applied in a conventional manner to the control electrode CE by way of connection through an amplifier EA.
  • the voltages applied to the vertical and horizontal deflection electrodes VD and CD are controlled in accordance with this invention in the manner now to be described.
  • a vertical deflection modulator VM the output from which is applied by way of an amplifier VA to the vertical-deflection plates VD; and there is provided a horizontal-deflection modulator HM the output from which is applied by way of an amplifier HA to the horizontal-deflection plates HD.
  • the deflection modulators VM and HM each have a carrier input 16 and 17 respectively, which are both connected to receive the E1 pulses from keying generator GE1. It is noted however that the carrier input 16 to vertical-deflection modulator VM has a delay circuit 18 interposed therein which imparts a 90 delay to the E1 pulses applied to that modulator with respect to the E1 pulses applied to horizontal modulator HM.
  • Each of the deflection modulators VM, HM further has a modulating input connected to the output of a sawtooth generator SG.
  • Generator SG has a control input 20 connected to receive Lr0 pulses from the output of AND- gate 9, so as to emit a linear sawtooth wave at each occurrence of an Lr0 pulse.
  • the voltages applied by amplifiers VA and HA to the vertical and horizontal deflection plates VD and HD of the cathode-ray tube will have the waveforms shown at UV and UH respectively in FIG. 3.
  • the vertical deflection voltage UV (lower curve) is a waveform of identical shape but displaced in time one fourth the minor period T1 with respect to the horizontal deflection voltage UH.
  • the spiral scanning pattern just described wherein the scanning cycle frequency is F0 and the line repetition or pitch frequency is F1 is used according to the invention both when the radar system is transmitting at the repetition rate F1 (keying pulses E1) and when transmitting at the repetition rate F2 (keying pulses E2).
  • keying pulses E1 keying pulses E1
  • keying pulses E2 keying pulses E2
  • T0 periods the odd-numbered T0 periods in FIG. 2
  • successive echo signals received from the target (assumed to be stationary) will appear as luminous spots a, a, a" etc. on the spiral raster S displayed on the radar screen, all aligned along a common radius such as 0R. This is evident when one considers that as each spot on the screen is produced by a video signal applied to control electrode CE over an amplifier EA connected to the receiver output 15, when the target is stationary these video signals occur with the same repetition frequency as the transmission repetition frequency F1.
  • the video signals are applied through amplifier EA with this same repetition rate F2, different from the scanning frequency which is still F1, so that the spots b, b, b etc. indicative of successive echoes from the target will now line up along a spiral are 2, which differs from the scanning spiral S.
  • Equation 4 is the equation of an Archimedean spiral S in which the spiral pitch, i.e. the radial distance between corresponding points of adjacent turns such as the points a, (1, etc. marked out on radius OR in FIG. 3, is (T 1/TO)H.
  • Equation 6 becomes H P' (s o) (7) Such is the equation of this spiral 2 shown in FIG. 4.
  • the echo signals from the stationary target all line up on a spiral diiferent from (and radially expanded with respect to) the scanning spiral at the intersections of said second spiral with the successive turns of the first, or scanning, spiral.
  • the position of the spot formed by the echo from the common target must necessarily be the same whether given by the one or the other keying frequency.
  • the echo spot is positioned at the intersection of radius OR (the locus of spots given by the keying frequency F1) and spiral Z (the locus of spots as given by keying frequency F2).
  • This partic ular spot therefore, appears as a double spot, i.e. a spot of enlarged diameter, as indicated at A, and is thus readily distinguishable from the neighboring spots.
  • the target distance is x, or xi260.4, or xi520.8, or xi78l.2 km., etc.
  • the above uncertainty is, usually, of no consequence, because once the automatic tracking follow-up section of the radar system has been set manually to track a designated target (e.g. by the phase-shift follow-up method described in the copending application referred to above), it will continue automatically to keep track, there being no reason for the system to lose track of the target at any time.
  • the automatic tracking section of the system would tend to lose track of the target at the instant of switchover from one particular keying-pulse train i.e. the one used at the time of the manual setting of said tracking section, to the other keying-pulse train should the target enter a distance range requiring such switchover as explained in the copending application.
  • the display system described herein was primarily designed to overcome this difliculty.
  • the control electrode CE of the cathode ray tube CRT has applied to it over a connection 22a socalled marker pulse which is a pulse recurring at the repetition frequency F0, the same as the repetition frequency of the Lri) pulses mentioned above.
  • marker pulses however are derived not from the AND gate 9 producing said Lrtl pulses, but from a similar AND gate (not shown) forming part of the selector logic network L in the follow-up section of the system, here schematically shown.
  • the said logic network L produces a train of pulses called L'c in said application, which repeat at the repetition rate F0, i.e.
  • the said delayed pulses L'c at the repetition rate F are used to provide marker pulses for the display, and are for this purpose passed through a marker-pulse amplifier MA and through an elongator-and-splitter circuit PS, of any suitable conventional design, such that the output of the circuit PS, when applied by line 22 through amplifier MA to the control electrode CE of the cathode-ray tube, will appear on the screen as a split, elongated streak or marker index shown at MI in FIG. 4. Since the marker pulse recurs at repetition rate Ft), the resulting marker index MI is displayed at a particular position along the spiral S and this particular position is determined by the variable delay imparted to the L'c pulses by the variable phase shifter g5.
  • the radar operator through selective adjustment of the phase shifter 4 is able to shift the marker index MI along the sweep spiral S until it frames or straddles the spot A indicative of true target distance, as indicated in dotted lines at MI in FIG. 4.
  • the tracking follow-up servo-motor M (FIG.
  • a reverser switch 26 is interposed in the connection 24- from comparator C to motor M.
  • the switch 26 when moved from its full-line position (the normal position during automatic tracking mode of operation of the system) to its dotted-line position during the initial acquisition mode of system operation, connects the motor input to an auxiliary voltage source AS through a potentiometer 28.
  • manual operation of the potentiometer control knob 39 will actuate motor M to modify, through gearbox B, the mechanical setting of phase shifter 1; and thereby shift the marker index MI along the spiral scan curve S on the radar screen.
  • the switch 26 After the operator has rotated knob 36 so that the marker index MI has framed the true-distance spot A as shown at MI, he moves the switch 26 to its automatic-tracking position shown in full lines. At this time the phase shift imparted by the phase shifter to the L'c pulses, and simultaneously imparted thereby to the follow-up pulse trains P1 and P2 generated by the follow-up pulse generators GP1 and GPZ, exactly equals the time required by the radar signals to travel from transmitter RT to the target and for the echo (or response) signals to travel back from the target to receiver RR.
  • the follow-up pulses P or P as the case may be, applied by follow-up logic L to comparator C coincide in time with the echo signals applied to the comparator from receiver RR, and so long as this condition obtains the follow-up servomotor M remains stationary.
  • the comparator applies an output voltage to motor M causing the motor to readjust the setting of phase shifter until a new equilibrium position has been reached. Automatic tracking of the target thus proceeds generally as described in the copending application.
  • keying-pulse trains at one rate would continue to be applied by network LN to the keying input of transmitter RT (and follow-up pulse trains P1 at the same rate would continue to be applied by follow-up network L to comparator C) for as long as the target does not approach a distance which is an integral multiple of the critical distance c/2F1, at which time the readings would become unreliable.
  • the keying frequency is switched to the other of the two available values, F2, both in the keying section and in the follow-up section of the system, all as explained in the copending application.
  • the binary circuit 12 is shown in FIG. 1 as having its input alternatively controllable, by way of OR-gate 34 earlier referred to, through the pair of automatic-control connections 36, 38 which may be regarded as connected to the outputs of the respective AND gates called 11 and H in FIG. 4 of the copending application.
  • OR-gate 34 earlier referred to
  • the logic network LN operates, in the manner described above in detail, to cause regular alternation between the two states of binary circuit 12, and hence between the two pulse trains E1 and E2 applied to the keying input of transmitter RT, at the rate of the L0 pulses.
  • switch 32 When on the other hand switch 32 is open and switches 40 are closed, the binary circuit 12 is switched between its two states in dependency on target distance, and the switching between the two keying-pulse trains E1 and E2 is similarly made dependent on target distance, in accordance with the operating mode described in the co-pending application.
  • switches 32 and 49 here shown for clarity as separate, ganged switches may in actual practice be replaced by a single switch performing an equivalent function.
  • the operation of the switching means 32-40 is preferably ganged with the operation of the manual switch 26 (FIG.
  • FIG. 5 the deflection-voltage control means shown in detail in FIG. 1 and described in connection with that figure are schematically shown as the block DC.
  • the echo spot indicative of the true distance of a target appears in the form of an enlarged-diameter spot A by virtue of being the geometric intersection of the two echo loci OR and 2. While such an enlarged-diameter double spot will generally be found sufficient to permit the radar operator to pick out the true echo without any hesitation from among the neighboring spots of lesser diameter and/ or lesser brightness, the invention contemplates the provision of means for rendering such recognition even easier and more positive.
  • the lower output of binary element 12 i.e., that output thereof which is energized during those alternate Ti ⁇ periods when E2 keying pulses are being utilized, is applied to the input of a ringing oscillator Rt).
  • oscillator R0 When energized, oscillator R0 produces a small-amplitude output wave at a frequency which preferably is approximately the reciprocal of the pulse width of the radar pulses used in the system.
  • the output from oscillator R0 is connected to the output of vertical-deflection amplifier VA through a 90-ph ase shifter or delay device, and is applied to the output of horizontal-deflection amplifier I-IA directly.
  • the improved radar scanning and display system of the invention is susceptible of a number of embodiments and modifications other than those disclosed.
  • One especially important class of modifications involves the type of scanning raster used, which may be other than the spiral ras-ters heretofore considered.
  • FIG. 6 illustrates the type of display obtained with the system of the invention when using a sinusoidal rather than a spiral raster.
  • the cyclic sweeping or scanning curve 5 instead of being an Archimedean spiral as the similarly designated curve in FIG. 4, is a sine-curve.
  • the repetition frequency of this curve i.e.
  • the frequency at which the entire curve S is repeatedly swept out by the electron beam across the cathode-ray screen is F0, the greatest common divisor of the two keying pulse rates F1 and F2, while the dine repetition frequency, i.e., the frequency at which corresponding points such as a, a, a" of consecutive sine cycles are scanned by the beam, in one of the two keying frequencies used, herein F1.
  • a sinusoidal scanning raster of this kind can be obtained by the means shown in the partial diagram of FIG. 7 in which components corresponding to components presentin FIG. 1 are similarly designated. As shown,
  • the horizontal-deflection amplifier HA is fed with a sinewave voltage at the frequency Fl, supplied by sine-wave generator SW whose input receives the E1 pulses from keying-pulse generator GEll.
  • the vertical-deflection amplifier VA is fed with a linear sawtooth wave having the cycle repetition frequency F0, the greatest common divisor of the keying frequencies F1 and F2, as derived from sawtooth generator SG having its input connected to the output of AND-gate 9.
  • Equations 8 are the parametric Cartesian equations for the scanning curve S.
  • the quantities x and y are constants of the sawtooth generator SG and sinewave generator SW and define the boundaries of the scanning raster as shown in FIG. 6.
  • the echo spots a, a, a, a' are all aligned on a common line RR parallel to the y axis as shown.
  • the echo spots b, b, b", b' are all arrayed on a sine curve 2 the Cartesian equation of which can be written 2 l 5 x sin 1r(a b)y (9) where a and b have the meanings .precedingly given and no is determined by the actual target distance.
  • the sine curve 2 is bodily displaced parallel to the y coordinate axis, just as in FIG. 4 the spiral E was in the same circumstances bodily rotated.
  • the echo signals from a stationary target all line up on a common line parallel to one coordinate (the repetitive coordinate) axis of the scanning raster; while (2) During those alternate periods when the other keying frequency (F2) is being used, the echo signals are all arrayed upon a differential curve of similar nature to that of the scanning curve, but expanded with respect to the scanning curve in a direction parallel to the aforementioned repetitive coordinate axis, at the intersections of said second curve with the firs-t, i.e. scanning curve; and consequently (3) The unique, or quasi-unique, intersection of the expanded differential curve with the said common line parallel to the repetitive coordinate taxis will provide an unambiguous indication of the ture target distance.
  • FIG. 8 shows a parallel-line scanning curve or raster.
  • the scanning curve swept out by the electron beam at the scan recurrence rate F6 is a family of parallel lines S, inclined to the x-axis of the oscilloscope screen.
  • the line repetition frequency is the keying rate F1.
  • the echo spots are aligned as at a, a, a along a line R'R parallel to the y axis.
  • the pulse rate F2 is used, the echo spots are aligned as at b, b, b" along a line 2.
  • the intersection A of 2 with R-R provides the unique indication of true target distance.
  • the means for developing deflection voltages capable of providing a display of the type shown in FIG. 8 will be readily conceived by those familiar with the art from the explanations previously given herein.
  • wobble.- voltage means similar to those described in connection with the first embodiment may be provided in order to display circles around the spots of one of the arrays, if this is desired.
  • novel method of oscilloscopic display provided in accordance with the invention, while being of considerable value when applied to dual-rate radar systems such as the automatic dual-rate, phase-shift follow-up system specifically described herein as an exemplary embodiment of the invention, is susceptible of many other applications, such as in monitoring a chain of separate radar stations transmitting at different frequencies, as well as in other cases where repetitive signals are to be displayed.
  • pulse rates F1 and F2 were inherently available in the signal system with which the oscilloscopic display systems is associated, it should be understood that in other applications of the invention only one such pulse rate (say F1) may be present in the signal system, in which case the companion pulse rate (F2), as well as the coincidence pulse rate (F0) would be developed especially for the purposes of the invention.
  • a signal system comprising means for producing a first signal train at a first repetition rate
  • an oscilloscopic display device including electron-beamproducing means, deflection electrode means, beamcontrol electrode means and a screen; means for applying said first and second signal trains to the control electrode means of the display device;
  • first signals will be displayed on a linear first locus composed of the corresponding points of successive cycles of said cycle scanning curve while said second signals will be displayed on a second locus comprising another curve intersecting said linear locus.
  • a signal system comprising means for producing a first signal train at a first repetition rate
  • an oscilloscopic display device including electron-beamproducing means, deflection electrode means, beamcontrol electrode means and a screen; means for applying said first and second signal trains to the control electrode means of the display device;
  • said cyclically varying voltage includes a vertical and a horizontal deflection-voltage component, said voltage components being cyclically varying in accordance with said minor and major cycles respectively, where-by said scanning curve is a curve cyclically repetitive along one Cartesian coordinate, said first locus is a line parallel to said one repetitive coordinate and said second locus comprises another curve generally similar to said scanning curve but expanded with respect thereto in a direction parallel to said one coordinate.
  • a signal system comprising means for generating a first train of control signals at a first repetition rate
  • an oscilloscopic display device including electron-beamproducing means, deflection electrode means, control electrode means and a screen;
  • said resulting signals will be displayed on the screen at the intersections of said scanning curve with a line indicative of said time displacement during periods when said first signal trains is enabled and at the intersections of said scanning curve with another curve during periods when said second signal train is enabled and the intersection between said line and said other curve will provide an unambiguous identification of said time displacement.
  • a radio ranging system comprising a transmitter having a keying input for controlling the repetition rate of signals transmitted thereby toward a target;
  • a receiver for receiving response signals from the tarmeans for generating a first train of keying pulses at a first rate
  • coincidence means deriving from said first and second pulse trains a third pulse train at a third rate the greatest common divisor of said first and second rates;
  • selector logic means having inputs connected to said keying-pulse-generating means and output connected to said keying input of the transmitter;
  • said logic means further having a controlling input connected to said coincidence means whereby to apply said first and second keying-pulse trains to said keying input for respective periods regularly alternating in accordance with said third rate;
  • an oscillographic dispsay device including ele:tron-beamproducing means, deflection electrode means, beamcontrol electrode means and a screen;
  • voltage-developing means having inputs connected to said first keying-pulse generating means and said coincidence means for developing at least one cyclically varying voltage having a minor cycle period the reciprocal of said first repetition rate and a major cycle period the reciprocal of said third rate;
  • said voltage-developing means having a voltage output connected to said deflection electrode means of the display device whereby said electron beam will sweep out on the screen a cyclic scanning curve having a line repetition frequency equaling said first rate and a scan repetition frequency equaling said third rate, and
  • said response signals will be displayed on the screen at the intersections of said scanning curve with a line indicative of target distance during periods when said first keying pulses are applied and at the intersections of said scanning curve with a different curve during periods when said second keying pulse train is applied, and the intersection between said line and said different curve will provide an unambiguous identification of target distance.
  • control means connected to said receiver responsive to target distance, and said logic means having a second controlling input connectable to said control means for selectively applying said first and second keying-pulse trains to the keying input of the transmitter in dependency on target distance, and operator-controlled switching means displaceable between a first position in which said first controlling input is connected to the logic means and a second position in which said second controlling input is connected to said logic means.
  • the system claimed in claim 10 including means for applying to said deflection electrode means a marker pulse train at a repetition rate equaling said third rate, thereby to display said marker pulse train as a marker index on the screen of the device, and means for adjusting the time relationship of said marker pulse train with respect to said first and second pulse trains whereby said marker index may be brought into coincidence with said intersection.

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Radar Systems Or Details Thereof (AREA)
US413830A 1963-11-26 1964-11-25 Signal system having improved oscilloscopic display means Expired - Lifetime US3281841A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR955024A FR1387128A (fr) 1963-11-26 1963-11-26 Perfectionnements aux dispositifs de représentation associés aux radars

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US3281841A true US3281841A (en) 1966-10-25

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US413830A Expired - Lifetime US3281841A (en) 1963-11-26 1964-11-25 Signal system having improved oscilloscopic display means

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Country Link
US (1) US3281841A (enrdf_load_stackoverflow)
CH (1) CH439419A (enrdf_load_stackoverflow)
DE (1) DE1272401B (enrdf_load_stackoverflow)
FR (1) FR1387128A (enrdf_load_stackoverflow)
GB (1) GB1084034A (enrdf_load_stackoverflow)
NL (1) NL144737B (enrdf_load_stackoverflow)
SE (1) SE343147B (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2192313A1 (enrdf_load_stackoverflow) * 1972-07-07 1974-02-08 Thomson Csf
US3937879A (en) * 1965-07-29 1976-02-10 The United States Of America As Represented By The Secretary Of The Navy Information display system having main and auxiliary sweeps
US4005422A (en) * 1974-03-02 1977-01-25 Mitsubishi Denki Kabushiki Kaisha Radar with sampling gate circuit for video signal

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3020541A (en) * 1953-10-27 1962-02-06 Gen Electric Electrical signal indicator
DE1033281B (de) * 1957-03-09 1958-07-03 Telefunken Gmbh Verfahren zur Festzeichenunterdrueckung in einem Impulsrueckstrahlgeraet mit Sichtanzeige
DE1250896B (enrdf_load_stackoverflow) * 1963-01-16

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3937879A (en) * 1965-07-29 1976-02-10 The United States Of America As Represented By The Secretary Of The Navy Information display system having main and auxiliary sweeps
FR2192313A1 (enrdf_load_stackoverflow) * 1972-07-07 1974-02-08 Thomson Csf
US4005422A (en) * 1974-03-02 1977-01-25 Mitsubishi Denki Kabushiki Kaisha Radar with sampling gate circuit for video signal

Also Published As

Publication number Publication date
GB1084034A (enrdf_load_stackoverflow)
FR1387128A (fr) 1965-01-29
NL144737B (nl) 1975-01-15
NL6413768A (enrdf_load_stackoverflow) 1965-05-27
CH439419A (fr) 1967-07-15
DE1272401B (de) 1968-07-11
SE343147B (enrdf_load_stackoverflow) 1972-02-28

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