US3435407A - High speed system for processing long range sonar pulses - Google Patents

High speed system for processing long range sonar pulses Download PDF

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US3435407A
US3435407A US560340A US3435407DA US3435407A US 3435407 A US3435407 A US 3435407A US 560340 A US560340 A US 560340A US 3435407D A US3435407D A US 3435407DA US 3435407 A US3435407 A US 3435407A
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signals
recording
drum
speed
high speed
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English (en)
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Jean Bertheas
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Thales SA
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CSF Compagnie Generale de Telegraphie sans Fil SA
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K5/00—Manipulating of pulses not covered by one of the other main groups of this subclass
    • H03K5/01—Shaping pulses
    • H03K5/04—Shaping pulses by increasing duration; by decreasing duration
    • H03K5/06—Shaping pulses by increasing duration; by decreasing duration by the use of delay lines or other analogue delay elements
    • H03K5/065—Shaping pulses by increasing duration; by decreasing duration by the use of delay lines or other analogue delay elements using dispersive delay lines
    • 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
    • G01S1/72—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 ultrasonic, sonic or infrasonic 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
    • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
    • G01S15/02—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems using reflection of acoustic waves
    • G01S15/06—Systems determining the position data of a target
    • G01S15/08—Systems for measuring distance only
    • G01S15/10—Systems for measuring distance only using transmission of interrupted, pulse-modulated waves
    • G01S15/102—Systems for measuring distance only using transmission of interrupted, pulse-modulated waves using transmission of pulses having some particular characteristics
    • G01S15/104—Systems for measuring distance only using transmission of interrupted, pulse-modulated waves using transmission of pulses having some particular characteristics wherein the transmitted pulses use a frequency- or phase-modulated carrier wave
    • 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
    • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
    • G01S15/02—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems using reflection of acoustic waves
    • G01S15/06—Systems determining the position data of a target
    • G01S15/42—Simultaneous measurement of distance and other co-ordinates
    • 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
    • G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
    • G01S7/523—Details of pulse systems
    • G01S7/526—Receivers

Definitions

  • the pulse compressing technique meets with many difficulties, because the dispersive lines actually used as compression networks do not permit, as is known, of the desirable compression rates at frequencies of some kc./s.
  • the listening period between two successive transmissions may be of several tenths of second.
  • This time interval is wasted if the received signals are treated separately in a plurality of decoding channels.
  • the problem is of dealing rapidly with compressed pulse sonar signals with a duration of some hundred milliseconds, a recurrence period of some tenths of seconds and a center frequency of some kilocycles.
  • This processing can be made with a dispersive line of reasonable size and operating at higher frequencies with pulses whose length cannot normally exceed ten milliseconds.
  • an information processing system for time multiplexing a plurality of simultaneously available variable sequences of N information items, said sequences being periodically repeated, said system comprising: means for recording said items at a first speed and playing them back at a second speed, said second speed being at least N times higher than said first speed; means for sequentially operating said recording and playing-back means in respective synchronism with said sequences; said recording means having at least N inputs for respectively collecting said N information items; said playing-back means having at least N outputs for reading said information items; switching means having at least N inputs, respectively connected to said playing-back means outputs, and one output; and means for sequentially connecting said switching means output to said switching means inputs for sequentially providing said information items at said switching means outputs.
  • FIG. 1 is a diagram of a long-range sonar system using frequency compression
  • FIG. 2 shows the oscillograms of frequency modulated wave pulses at the input and at the output of a dispersive network
  • FIG. 3 is a diagram of a system according to the invention.
  • FIG. 4 is a diagram explaining the operation of the system according to the invention.
  • FIG. 1 shows a simplified diagram of a long range sonar. It comprises a transmitter-receiver 1 supplying a hydrophone array 2.
  • Array 2 transmits ultrasound waves which are frequency modulated and are radiated according to a broad radiation lobe, such as that traced in dotted lines.
  • a hydrophone receiver array 3 is coupled to the transmitter-receiver 1 by a plurality of channels to which correspond respectively the reception lobes 4, 5, 6, 7, 8, 9 and 10 arranged in fan shape.
  • the lobes are shown as clearly separated from each other, although in actual practice they are very close to each other.
  • Targets 11 and 12 are assumed to lie in the zone explored by the sonar and reflect wave trains towards the hydrophone group 3.
  • the latter transducer converts them into reception signals which propagate along the corresponding channels towards the transmitter-receiver 1.
  • Each of these signals is applied, after amplification, to a dispersive network 13, which compresses it and supplies compressed pulses by means of which the targets can be displayed in an azimuth-distance presentation, on an indicator 14.
  • the group 2 radiates a frequency modulated wave pulse which is propagated towards the targets 11 and 12 from which it is reflected towards the group 3.
  • the channels corresponding to the lobes 5 and 8 are the seat of reception signals which, after amplification, are available at the input of the dispersive network 13.
  • the invention provides a device for multiplexing in time the reception signals so as to process them successively in a single compression channel. This also results in a much better utilization of the listening time and of the compressing system.
  • FIG. 3 shows a diagram of a long-range sonar according to the invention. It comprises a transmission hydrophone array unit 2 and a reception hydrophone array unit 3 with m aligned transducer elements. These elements are connected to a pre-amplifier unit 15 whose outputs supply m inputs of a receiving channel formation matrix 16.
  • This matrix which is of a known type, comprises phase-shifters and an interconnection which makes it possible to obtain at its N outputs the decoupled reception signals respectively incoming from N directions, to which correspond the lobes 4, 5, I O of FIG. 1.
  • Amplifiers 17 assure the further amplification of these signals which are made available at the N outputs 4 to 10.
  • a set of twoposition change-over contacts 18 switches the preformed channels either to a first assembly 19 of N-magnetic recording heads, or to a second similar assembly 20.
  • the said recording heads 19 and 20 are, respectively associated with magnetic drums 21 and 22 carrying N erasable tracks and at least one prerecorded track on which the acoustic pulse to be radiated has been recorded once for all.
  • the drums 21 and 22 are driven in uniform rotation by high speed motors 27 and 28 and low speed motors 29 and 30.
  • Electromechanical clutches 23, 24, 25 and 26 permit the selection of one or the other rotational speed for each drum.
  • the reading out of the tracks recorded on the drums is made by means of reading heads 31 and 32 with regard to the pre-recorded track, and head groups 33 and 34 with regard to the other tracks.
  • the reading system is completed by a set of rotating switches 36, 37 and 38, whose respective sliders are driven by a common reducer 35 at half the slow rotational speed of the drums.
  • the switch 38 has two fixed contacts which are respectively connected to the outputs of the reading heads 31 and 32 associated with the pre-recorded tracks.
  • the slider of the switch 38 supplies the amplifier 39 connected to the power stage 43 of the sonar transmitter.
  • the slider of the rotary switch 37 supplies the receiver amplifier 40.
  • the switch 37 has two groups of N contacts. The contacts of each group are respectively connected to the reading heads of groups 33 and 34.
  • the switch 36 has its slider permanently connected to a supply (not shown) and has two contacts. Through its contact A it controls the clutches 23 and 26 and contacts 18 to bring them into position A. Through its contact B it controls the clutches 24 and 25 and contacts 18 to bring them into position B.
  • a mixer 41 receives the signals coming from a local oscillator 42 and from the amplifier 40. The resulting signal is applied to the dispersive network 13 which compresses it. After detection by the detector 44, the compressed signal is applied to the indicator 14 whose angular and radial sweeps are synchronized with the rotation of the switch 37 by means of a control input 45.
  • FIG. 4(a) shows diagrammatically the two states A and B which are successively provided according to whether the slider of switch 36 engages its contacts A or B.
  • the switch 38 connects for a time interval the reading head 31 to amplifier 39.
  • the drum 21 rotates at high speed, and the pre-recorded track supplies a linearly frequency modulated signal which is applied to the transmitter, comprising the amplifiers 39 and 43 and the hydrophone array 2.
  • An ultrasonic wave train is radiated as shown at (b) in all directions of the zone covered by the sonar.
  • the drum 22 rotates at slow speed and the recording heads 20 are connected to the receiver hydrophone array 3, through the pre-amplifiers 15, the matrix 16, the amplifiers 17 and the contacts 18 which are in position A.
  • the transmitted radiation is reflected by the targets 11 and 12, located, for example, in the lobes and 8 of FIG. 1, and one obtains in the receiving channels 5 and 8 signals delayed by A and A, respectively. These signals are shown in FIG. 4 at (c) and (d) respectively. Obviously, their delay with respect to the starting of the radiated pulses measures the distance between the targets and the sonar system. Their position among the receiving channels corresponds to the direction of the reception. These signals are recorded on the drum 22, whose tracks pass at low speed past the heads 20.
  • the succession of the channels corresponds to a sweep or scan of the space by the lobes of the hydrophonic unit 3 and this scanning is repeated in the indicator 14 in synchronization with the switching action of the switch 37
  • the succession of the channel signals is equivalent to a signal received from a unique lobe in azimuthal scanning with a transmitted pulse whose frequency and duration are respectively multiplied and divided by N, and which propagates in a medium whose sound velocity is N times the sound velocity inlwater.
  • the multiplexed signals delivered by the switch 37 are amplified by the amplifier 40; they are mixed in the mixer 41 with the signal of the local oscillator 42 before reaching the dispersive network 13 where they are successively compressed.
  • the operation introduces a time delay T which is shown at (f) in FIG. 4, showing the compressed signals after having been detected by the detector 44. These signals are applied to the indicator 14 and modulate the scanning beam in accordance with the angular and distance location of the targets.
  • the invention may be applied to a sonar with a range of 10 km., a transmission frequency of 5 kc./s. and 20 receiver channels
  • the listening period is 113.3 seconds and the transmitted pulses will be linearly frequency modulated in a 500 c./s. band with a duration of 200 ms.; a compression rate of 100 is provided.
  • the recording speed will correspond to one revolution in 13.3 seconds and the reading speed will amount to 20 revolutions during the same time.
  • the read out signal will therefore have a center frequency of 100 kc./s., a duration of 10 ms. and a modulation band of 10 kc/s.; it will be located in an interval T/N equal to 0.66 second.
  • the compression of the said signal will be effected by means of an acoustic line having a center frequency of 25 kc./s., which requires a frequency change by means of a kc./s. oscillator.
  • the line described in a copending application for a Dispersive Acoustic Lines, Ser. No. 554,785 filed Apr. 25, 1966 by P.
  • Tournois and assigned to the same assignee, can be used.
  • the signal compressed by such a line has a duration of ,uS. and undergoes an envelope detection, before it is applied to a visual display system which traces in polar coordinates 20 lines in 13.3 seconds.
  • the information may also be processed by means of a single magnetic drum, used alternately for recording and reading. However, with two drums and the alternating of the functions of recording and reading, no information is lost.
  • the system of the invention has also other advantages: the decoding and the processing of the signals are effected by means of a single receiving channel whatever the number of reception channels; the manufacture of the dispersive network is made easier, due to the use of an accelerated time scale; the presentation of the information on a cathode ray tube indicator and their subsequent transmission at a distance are simplified, due to multiplexing.
  • FIGURE 3 Another modification of the system according to the invention consists in providing an additional track wherein a local oscillation is recorded.
  • This arrangement shown in FIGURE 3 in dashed lines permits a substantial compensation of any flutter, i.e. fluctuations in the speed of the drums.
  • the arrangement comprises a stable oscillator 46, recording heads 47 and play-back heads 48 which are alternately coupled to the input of mixer 41 by means of a switch 49.
  • This track can receive the recording of the stable oscillator 46 during the slow passage in order to supply from the heads 48 a correctly multiplied frequency during the fast passage phase.
  • the improvement obtained by the use of the above mentioned additional track is a substantial reduction of the flutter arising in the frequency supplied by mixer 41; this reduction results from the fact that mixer 41 supplies the difference between two frequencies which are subjected to the same amount of flutter.
  • An information processing system for the time multiplexing a plurality of simultaneously available N variable sequences of information items, said sequences being periodically repeated, said system comprising: means for recording said items at a first speed and playing them back at a second speed, said second speed being at least N times higher than said first speed; means for sequentially operating said recording and playing-back means in respective synchronism with said sequences; said recording means having at least N inputs for respectively collecting said N sequences of information items; said playing-back means having at least N outputs for reading said information items; switching means having at least N inputs respectively connected to said playing-back means outputs and one output; means for sequentially connecting said switching means output to said switching means inputs for sequentially providing said information items at said switching means output; said information items being frequency modulated signals and pulse compression means being coupled to said switching means output for compressing said signals.
  • a system as claimed in claim 1 further comprising display indicator means connected to the output of said pulse compression means; said indicator means having a scanning means and means for operating said scanning means in synchronism with said sequentially connecting means.
  • said recording and playing-back means comprise at least one magnetic drum having at least N erasable tracks; driving means for rotating said drum at either said first or said second speeds; clutch means controlled by said sequentially operating means for coupling said driving means to said drum; said recording means comprising at least N first recording heads respectively associated with said tracks and respectively coupled to said recording means inputs; said playing-back means comprising at least N first play-back heads respectively associated with said tracks and coupled to said playing-back means outputs; said drum effecting a revolution at said first speed within the duration of one of said sequences and at least N revolutions at said second speed within the duration of the next of said sequences.
  • said recording and playing-back means further comprise a second magnetic drum having at least N tracks; at least N second recording heads respectively associated with said tracks of said second drum; at least N second play back heads respectively associated with said tracks of said second drum; change-over means controlled by said sequentially operating means for alternately coupling said first and said second recording head to said recording means inputs; said switching means comprising at least N further inputs respectively connected to said second playback heads; said clutch means including means for further coupling said driving means to said second drum for alternately rotating said drums at said first and said second speeds.
  • a system as claimed in claim 3 incorporated in a long range sonar system comprising a further track on said drum; a further play-back head facing said last mentioned track for supplying a frequency modulated pulse at regular intervals of time; means for radiating said pulse connected to said further play-back head; means for receiving in response to said pulse a plurality of echo signals forming said variable sequences of N information items available in N respective channels corresponding to a plurality of reception directions; display indicator means connected to the output of said pulse compression means for displaying said echo signals in said respective reception directions, said indicator means having a scanning means and means for operating said scanning means in sychronism with said sequentially connecting means.
  • pulse compression means comprise a mixer having a signal input, a local oscillator input and an output; dispersive delaying means having an input connected to the output of said mixer and an output.
  • a system as claimed in claim 6, further comprising a reference track on said first drum; a further play-back head facing said track, said further play-back head being connected to said local oscillator input and said reference track being pre-recorded.
  • a system as claimed in claim 6, further comprising a reference track on said first drum, further recording and play-back heads facing said reference track; said further play-back head being connected to said local oscillator input and said further recording head being coupled to a constant frequency generator.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Nonlinear Science (AREA)
  • Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
US560340A 1965-06-29 1966-06-24 High speed system for processing long range sonar pulses Expired - Lifetime US3435407A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR22670A FR1448949A (fr) 1965-06-29 1965-06-29 Perfectionnements aux sonars à grande portée

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US3435407A true US3435407A (en) 1969-03-25

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US (1) US3435407A (enrdf_load_stackoverflow)
FR (1) FR1448949A (enrdf_load_stackoverflow)
GB (1) GB1149017A (enrdf_load_stackoverflow)
NL (1) NL6609075A (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2109443A6 (enrdf_load_stackoverflow) * 1970-10-16 1972-05-26 Thomson Csf
US3790925A (en) * 1969-06-26 1974-02-05 Electroacustic Gmbh Echo-sounding apparatus having a digital intermediate store
US4199246A (en) * 1976-10-04 1980-04-22 Polaroid Corporation Ultrasonic ranging system for a camera
US4693940A (en) * 1983-02-14 1987-09-15 Raychem Corporation Laminate and method of preparing same
US6046962A (en) * 1997-05-27 2000-04-04 Thomson Marconi Sonar Sas Electrodynamic transducer for underwater acoustics
US6144342A (en) * 1996-02-13 2000-11-07 Thomson-Csf Method for controlling the navigation of a towed linear acoustic antenna, and devices therefor

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3742436A (en) * 1971-03-24 1973-06-26 Westinghouse Electric Corp Side looking sonar apparatus
US3937066A (en) * 1973-11-01 1976-02-10 Stanford Research Institute Ultrasonic camera system and method

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2995725A (en) * 1955-06-10 1961-08-08 Honeywell Regulator Co High speed sonar scanning apparatus

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2995725A (en) * 1955-06-10 1961-08-08 Honeywell Regulator Co High speed sonar scanning apparatus

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3790925A (en) * 1969-06-26 1974-02-05 Electroacustic Gmbh Echo-sounding apparatus having a digital intermediate store
FR2109443A6 (enrdf_load_stackoverflow) * 1970-10-16 1972-05-26 Thomson Csf
US4199246A (en) * 1976-10-04 1980-04-22 Polaroid Corporation Ultrasonic ranging system for a camera
US4693940A (en) * 1983-02-14 1987-09-15 Raychem Corporation Laminate and method of preparing same
US6144342A (en) * 1996-02-13 2000-11-07 Thomson-Csf Method for controlling the navigation of a towed linear acoustic antenna, and devices therefor
US6046962A (en) * 1997-05-27 2000-04-04 Thomson Marconi Sonar Sas Electrodynamic transducer for underwater acoustics

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NL6609075A (enrdf_load_stackoverflow) 1966-12-30
GB1149017A (en) 1969-04-16
FR1448949A (fr) 1966-08-12

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