WO1991002989A1 - Systeme topographique a sonar - Google Patents

Systeme topographique a sonar Download PDF

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Publication number
WO1991002989A1
WO1991002989A1 PCT/GB1990/001291 GB9001291W WO9102989A1 WO 1991002989 A1 WO1991002989 A1 WO 1991002989A1 GB 9001291 W GB9001291 W GB 9001291W WO 9102989 A1 WO9102989 A1 WO 9102989A1
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WO
WIPO (PCT)
Prior art keywords
sonar
elements
outputs
output signals
bank
Prior art date
Application number
PCT/GB1990/001291
Other languages
English (en)
Inventor
Peter Stanley Phillips
Original Assignee
Sea Scan Technology Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sea Scan Technology Ltd. filed Critical Sea Scan Technology Ltd.
Priority to KR1019910700370A priority Critical patent/KR920701837A/ko
Publication of WO1991002989A1 publication Critical patent/WO1991002989A1/fr
Priority to NO91911443A priority patent/NO911443L/no

Links

Classifications

    • 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
    • G01S15/88—Sonar systems specially adapted for specific applications
    • G01S15/89—Sonar systems specially adapted for specific applications for mapping or imaging
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/18—Methods or devices for transmitting, conducting or directing sound
    • G10K11/26—Sound-focusing or directing, e.g. scanning
    • G10K11/34—Sound-focusing or directing, e.g. scanning using electrical steering of transducer arrays, e.g. beam steering
    • G10K11/341—Circuits therefor
    • G10K11/346—Circuits therefor using phase variation

Definitions

  • This invention relates to a sonar surveying system for surveying an ocean bed or the like.
  • Sonar surveying systems which can map the sea floor or objects thereupon. These systems consist of basically three types, namely echo sounding sonar, side scan sonar and sector scanning sonar.
  • Echo sounding sonar systems use a single transmit/receive transducer comprising an active element which beams a pulse of sound vertically downwards. A measure of the time delay between transmission of the pulse and reception of the reflected signal from the sea floor then gives the depth of water at that point.
  • the ship is steered along a known track to scan a broad swathe of sea floor and the return signals from the sea floor are used to build up a profile of the sea bed based upon the amplitude of the returns.
  • the transducers may be deployed on a submersible or "fish" towed below the layers of water which are subject to the sudden changes.
  • Sector scanning sonar systems use similar transducer arrays as side scan systems. However by introducing time delays on the signals from the individual elements 10 of the transducer, the angle which the narrow beam pattern (in azimuth) makes to the face of the transducer can be varied. This is known as "steering" the beam pattern.
  • the output signals from the elements 10 are subjected to respective time delays before summing, producing a line of sea bed data from a predetermined angle to the transducer face; on subsequent transmissions different time delays produce lines of data from different directions.
  • a fan of sea bed data can be built up, using different time delays KI to KN for respective directions KI to KN as shown in Figure 3.
  • a sonar surveying system from which both depth and position information can be derived.
  • This system can be used in a side scanning mode or in a sector scanning mode.
  • a sonar surveying system including a receiving transducer which comprises an array of sensor elements the outputs of which are connected to a plurality of banks of delay elements, and means for summing the outputs of the delay elements of each respective bank to provide simultaneously a corresponding plurality of output signals, one from each bank, representing sonar beams received from respective directions.
  • a parallel processing system for simultaneously processing the plurality of output signals.
  • this parallel processing system comprises one or more parallel processing elements such as the transputer manufactured and sold by Inmos of Bristol, England.
  • a second transducer is mounted a predetermined distance above the first transducer and comprises a second array of sensor elements the outputs of which are connected to a second plurality of banks of delay elements, and means for summing the outputs of the delay elements of each respective bank of the second plurality to provide simultaneously a corresponding second plurality of output signals, one from each bank of the second plurality, representing sonar beams received by said second receiving transducer from said respective directions.
  • the processing system processes the output signals in pairs, one from a bank of delay elements in the first plurality and the other from a bank of delay elements in the second plurality and representing a sonar beam received from a predetermined direction, said pair of output signals being processed to determine the phase difference therebetween and to determine the amplitude of the received sonar beam.
  • FIGURE 1 shows in plan view a transducer comprising a linear array of active sensor elements the output signals from which are summed together;
  • FIGURE 2 is a side view showing a sonar pulse being transmitted from a transducer and reflected from the sea floor;
  • FIGURE 3 shows in plan view a transducer comprising a linear array of active sensor elements the outputs of which are passed through respective delay elements and then summed to represent a beam received from a direction predetermined by the delay elements;
  • FIGURE 4 shows a typical course followed by a survey vessel over an area A if regular depth soundings are necessary to determine the depth of the sea floor below the survey ship;
  • FIGURE 5 shows a transducer of a survey system in accordance with this invention
  • FIGURE 6A is a diagram to show two transducers of a side scan or sector scan sonar surveying system and a sonar return approaching them at an angle a to the vertical;
  • FIGURE 6B is a diagram to show the depth of and horizontal distance to the point of reflection
  • FIGURE 7 is a diagram to show the relation of the phase difference between the signals from the two transducers of Figure 6A, relative to the depression angle a;
  • FIGURE 8 is a diagram to illustrate the different attitude variations which can occur in a "fish" on which the transducers are mounted;
  • FIGURE 9 is a general block diagram of a sonar surveying system in accordance with this invention.
  • FIGURE 10 is a block diagram of the electronic system mounted in the fish;
  • FIGURE 11 shows a lookup table used to convert measured phase angles to depression angles
  • FIGURE 12 is a block diagram of a parallel processing system in the fish for processing the signals from the two transducers.
  • the sonar surveying system comprises two portions, one housed in a water tight pressure vessel and the other being carried onboard the ship.
  • the two portions of the system are linked by a high speed data link.
  • the pressure vessel may be mounted directly to the survey ship, or within a towed fish, or within a remotely operated submersible.
  • the ship-borne unit provides control for the overall system and includes recording facilities and also facilities to provide on ⁇ line VDU displays of attitude, sonar amplitudes and sea floor profiles.
  • a transducer of the system is shown in Figure 5 and comprises a linear array of active sensor elements 10.
  • the outputs from these sensor elements are passed through successive banks KI ... KN of delay elements, the outputs of each bank being summed to provide respective output signals SI - SN corresponding to sonar return beams received from respective directions Dl - DN.
  • the output signals SI - SN are processed simultaneously, so that a display can be generated representing a visual image of the sea floor over a broad angle of view as seen from the location of the transducer.
  • each of transducers Trl and Tr2 is as shown in Figure 5, each with its several banks of delay elements to provide pairs of output signals (one from Trl and the other from Tr2) related to a return beam received from a respective direction.
  • Transducers Trl and Tr2 are disposed one above the other, spaced apart a short distance Nowhere is the wave length of the transmitted wave).
  • a sonar pulse is transmitted from one transducer e.g. Tr2.
  • the sonar return is at a depression angle a, such that the depth D of, and horizontal distance Ds to, the point of reflection is given by R Cos a and R Sin a respectively, where R is the absolute range of the reflection.
  • the sonar return will reach the upper transducer Tr2 slightly after the lower transducer Trl, because the path length to the upper transducer is greater by the amount X.
  • the phase difference between the output signals of the two transducers is given by:
  • phase angle Q will experience a 0 to 360 degree phase shift N times for a change in depression angle a from 0 to 90.
  • N 3.
  • a first return phase detector detects the absolute time delay of the first return.
  • the two methods can be used in a complementary verification mode or in a stand alone mode, the operating mode being selected via the main shipboard operator interface.
  • the initial first return data is then used to locate a pointer in a phase-to-depression angle lookup table.
  • Subsequent phase data is then used to track phase/depression angle pairs through this lookup table, ensuring that the conversion to depression angle uses the correct phase fringe. This is explained later.
  • Phase is measured by a digital phase meter using zero crossing detectors starting and stopping high speed counters. This information is fed to an online parallel processing system which performs a running average on the phase angle values, organizes the data from port and starboard transducers, adds attitude, status, echo sounder, pressure data etc. information and outputs the result to the main ship board parallel processing system. The number of values of phase angles being used by the averager are set by the operator.
  • Figure 9 shows the main components of the survey system, these being the fish electronics FE, operator interface (control and analysis parallel processing system) PE, high resolution graphic displays GD, digital mass storage medium ST and position fixing equipment PF (which includes systems for measuring any offset of the fish from the main ship's position fixing equipment).
  • Data from the fish is sent over a high speed bidirectional data link LN to the ship-borne unit SU. This stores all incoming data from both the fish and position fixing equipment onto the digital recording media.
  • Some online analysis of the data is also performed to give samples of the sea floor profiles hence enabling the qualty of the survey data to be monitored.
  • the system PE is also used to communicate with the parallel processing system housed in the fish thus enabling online changes to be made to the operating parameters of the overall surveying system.
  • Figure 10 shows the fish electronics in block diagram form, comprising pre-amplifiers PREl and PRE2, Automatic Gain control Amplifiers AGC1 and AGC2, parallel processing signal acquisition element P2, sonar pulse generator SP, data acquisition system DA, digital phase meter DP, first return phase meter FD, system status and alarms circuit SSA, parallel processing control and communications elements Pi and envelope detector ED.
  • the system shown in Figure 10 is simplified in that it assumes only one signal from each of Trl and Tr2: the manner in which the multiple signals SI to SN from each transducer are handled will be explained with reference to Figure 12.
  • the power, duration and repetition rate of the sonar pulse is set by PI via a set- pulse board SP, a Power amplifier PA generating the necessary power to drive the transducer Tr2.
  • a precision clock is also initiated at transmission time.
  • the data acquisition system DA under the control of PI multiplexes the attitude data to the surface, and data from a status and water alarms circuit SSA is also transmitted at this time.
  • the system then awaits the detection of the first return, whereupon the absolute phase is determined by the first-return phase meter FD, this data being stored for later reference.
  • the time, as determined by the precision clock is also recorded at the detection of the first return.
  • Both the clock and absolute phase data are transmitted to the surface for use in the later analysis.
  • the first return detector FD also enables the digital phase meter DP allowing phase data to be transmitted to the element P2 for processing.
  • the digital phase meter DP uses zero crossing detectors to start and stop digital counters - these counters being fed from the Automatic gain control amplifiers AGC1, AGC2 which maintain their signal outputs at a constant level.
  • the zero crossing detectors connected to transducer Trl via PREl and AGCl are used to enable the other detectors connected to TR2 in sequence so that the measurement is always of the phase on Tr2 with respect to Trl. Phase differences are measured between zero crossing detections occurring as the signal level passes from a negative to a positive voltage (positive-going detection) and for signals passing from a positive to a negative voltage (negative-going detection) .
  • Phase values for both positive- and negative- going detections are then transmitted to the parallel processing element P2 (one digital sample consisting of a pair of these phase values).
  • P2 then performs a running average on these digital samples, the number of values used in this averaging processing being preset by the operator. This eliminates DC drift in the preamplifiers and AGC's.
  • An envelope detector consisting of an A to D converter ED ( Figure 10) feeds amplitude data to the parallel processing element P2. Here it is combined with the averaged phase angle data, for transmission to the surface unit. This enables traditional side scan sonar plots to be produced from the equipment to assist in the analysis of survey data. This data is also used to detect areas of poor signal return.
  • the final signal processing is performed by the shipborne parallel processing system PE which uses a series of algorithms to process the data.
  • the raw data is firstly stored on the digital mass storage media ST for later analysis.
  • the phase data is then converted to a depression angle by use of the lookup tables shown in Figure 11.
  • the value of the first return enables the pointer P to be positioned in the correct place in this table; subsequent values of phase are then used to search in the search window W around pointer P for a conversion value to depression angle pointer P is then updated to a new position by the last phase value converted.
  • the conversion is inhibited when the signal level falls below a predetermined minimum, set by the number of values in the averaging process whose amplitude falls below a set level (as detected by the envelope detector) exceeding a predetermined minimum. This eliminates errors that can occur due to shadow areas where signal levels fall below the general noise level.
  • a value of depression angle equal to that extracted from the last piece of acceptable data, is then used as the current value and a flag is attached to this data which is used to indicate poor data areas on the ship-board displays. Roll errors are then corrected.
  • a conversion is then made from depression angle range R to a depth/distance matrix.
  • the absolute range R is determined by measuring the speed of sound in the sea at the survey site, then using the data from the clock to determine the range of the first return. Subsequent ranges to this are then predetermined by the digitizing rate of the system. Position data is then added - with corrections for yaw, pitch, heave, surge, sway and any offset of the fish from the main ship's position - to produce the depth/position matrix. Finally this data is displayed on the graphics display GD in different formats as required by the operator. Hard copies can be obtained on a proprietary graphics plotter GP as required.
  • the characteristics of this processing can be altered in the field, by the ship-board main computer.
  • the range of values of the averaging algorithm may be changed to suit the particular type of sea floor being surveyed, the digitizing rate of the system changed, and/or the separation of the transducers altered and new lookup tables down-loaded from the ship.
  • Other alterations such as fine tuning of the power, duration and repetition of the transmit pulse are also available.
  • the transducers may be changed so that different sonar transmission frequencies can be used and the system parameters altered accordingly.
  • the system performance can be opti zed with regard to sea floor profiles, fish flying height above sea floor, overall range required, and accuracy of measurement required.
  • the above surveying system may be implemented at differing transmission frequencies and digitizing rates. Further the number of beams formed may be varied up to 20 or more. The system may then be used to obtain data either side of the direction of travel using one or more beam patterns or looking in the direction of travel using one or more beam patterns.
  • a first group of parallel processing elements is provided, each element of the group receiving a pair of signals, one from Trl and the other from Tr2.
  • Element Til for example receives the summed output SI from the first delay bank KI of Trl and the corresponding summed output from the first delay bank or Tr2, and so on. Til determines the phase difference between Trl and Tr2 for the respective return beam direction, also the amplitude of this return beam.
  • This data is passed to a parallel processing element T12 of a second group of such elements, together wth the corresponding data from two other elements T21 and T31 in the first group.
  • the outputs of each set of three elements in the second group is passed to a further parallel processing element, and so on.
  • the detection of the time delay between reception of the same signal on Tr2 after reception by Trl may also be varied by using correlation techniques.
  • the sonar transmission signal for the correlation technique could be a single frequency, a chirp, a pseudo random binary sequence, a frequency modulated sweep - linear or non linear, etc.

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Multimedia (AREA)
  • Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
  • Transducers For Ultrasonic Waves (AREA)

Abstract

Un système topographique à sonar comporte un transducteur de réception lequel comprend un réseau d'éléments de détection (10), dont les sorties sont connectées à une pluralité de banques KI à KN d'éléments de temporisation, ainsi qu'un moyen destiné à additionner les sorties des éléments de temporisation de chaque banque respective afin de produire simultanément une pluralité correspondante de signaux de sortie SI à SN, un de chaque banque, représentant des faisceaux de sonar reçus de sens respectifs D à DN. On a prévu un système de traitement parallèle destiné à traiter simultanément la pluralité de signaux de sortie SI à SN.
PCT/GB1990/001291 1989-08-15 1990-08-15 Systeme topographique a sonar WO1991002989A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
KR1019910700370A KR920701837A (ko) 1989-08-15 1990-08-15 소나탐사시스템
NO91911443A NO911443L (no) 1989-08-15 1991-04-12 Sonar-undersoekelsessystem.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB898918577A GB8918577D0 (en) 1989-08-15 1989-08-15 Sonar survey system
GB8918577.1 1989-08-15

Publications (1)

Publication Number Publication Date
WO1991002989A1 true WO1991002989A1 (fr) 1991-03-07

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ID=10661638

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Application Number Title Priority Date Filing Date
PCT/GB1990/001291 WO1991002989A1 (fr) 1989-08-15 1990-08-15 Systeme topographique a sonar

Country Status (7)

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EP (1) EP0438562A1 (fr)
JP (1) JPH04501316A (fr)
KR (1) KR920701837A (fr)
AU (1) AU6155390A (fr)
CA (1) CA2039157A1 (fr)
GB (1) GB8918577D0 (fr)
WO (1) WO1991002989A1 (fr)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20020088094A (ko) * 2001-05-17 2002-11-27 위즈정보기술주식회사 컴퓨터 클러스터링 및 개방형 컴퓨터 네트워크 기반의실시간 수중 감시 시스템
WO2011048224A1 (fr) 2009-10-23 2011-04-28 Thales Procede de localisation et de cartographie simultanees par filtrage non lineaire elastique
US9142206B2 (en) 2011-07-14 2015-09-22 Navico Holding As System for interchangeable mounting options for a sonar transducer
US9182486B2 (en) 2011-12-07 2015-11-10 Navico Holding As Sonar rendering systems and associated methods
US9223022B2 (en) 2009-07-14 2015-12-29 Navico Holding As Linear and circular downscan imaging sonar
US9244168B2 (en) 2012-07-06 2016-01-26 Navico Holding As Sonar system using frequency bursts
US9268020B2 (en) 2012-02-10 2016-02-23 Navico Holding As Sonar assembly for reduced interference
US9541643B2 (en) 2009-07-14 2017-01-10 Navico Holding As Downscan imaging sonar
US10151829B2 (en) 2016-02-23 2018-12-11 Navico Holding As Systems and associated methods for producing sonar image overlay
US11367425B2 (en) 2017-09-21 2022-06-21 Navico Holding As Sonar transducer with multiple mounting options

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5678626B2 (ja) * 2010-12-06 2015-03-04 株式会社Ihi 水底下物体の探査類別方法
JP2012225934A (ja) * 2012-06-25 2012-11-15 Mitsubishi Heavy Ind Ltd 水中航走体および障害物探知装置

Citations (3)

* 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
EP0070494A1 (fr) * 1981-07-17 1983-01-26 SINTRA-ALCATEL Société Anonyme dite: Sonar sous-marin
US4679176A (en) * 1983-11-24 1987-07-07 Hitachi, Ltd. Ultrasonic receiving apparatus

Patent Citations (3)

* 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
EP0070494A1 (fr) * 1981-07-17 1983-01-26 SINTRA-ALCATEL Société Anonyme dite: Sonar sous-marin
US4679176A (en) * 1983-11-24 1987-07-07 Hitachi, Ltd. Ultrasonic receiving apparatus

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
The Radio and Electronic Engineer, Volume 53, No. 7/8, July/August 1983, IERE, (London, GB), M.H. YASSAIE et al.: "Application of Time-Delay-and Integrate c.c.d.s. in Sector Scanning Sonars", pages 295, 300 see page 299, right-hand column - page 300 *

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20020088094A (ko) * 2001-05-17 2002-11-27 위즈정보기술주식회사 컴퓨터 클러스터링 및 개방형 컴퓨터 네트워크 기반의실시간 수중 감시 시스템
US9541643B2 (en) 2009-07-14 2017-01-10 Navico Holding As Downscan imaging sonar
US9223022B2 (en) 2009-07-14 2015-12-29 Navico Holding As Linear and circular downscan imaging sonar
US10024961B2 (en) 2009-07-14 2018-07-17 Navico Holding As Sonar imaging techniques for objects in an underwater environment
WO2011048224A1 (fr) 2009-10-23 2011-04-28 Thales Procede de localisation et de cartographie simultanees par filtrage non lineaire elastique
US9142206B2 (en) 2011-07-14 2015-09-22 Navico Holding As System for interchangeable mounting options for a sonar transducer
US9182486B2 (en) 2011-12-07 2015-11-10 Navico Holding As Sonar rendering systems and associated methods
US10247823B2 (en) 2011-12-07 2019-04-02 Navico Holding As Sonar rendering systems and associated methods
US9268020B2 (en) 2012-02-10 2016-02-23 Navico Holding As Sonar assembly for reduced interference
US9354312B2 (en) 2012-07-06 2016-05-31 Navico Holding As Sonar system using frequency bursts
US9244168B2 (en) 2012-07-06 2016-01-26 Navico Holding As Sonar system using frequency bursts
US10151829B2 (en) 2016-02-23 2018-12-11 Navico Holding As Systems and associated methods for producing sonar image overlay
US11367425B2 (en) 2017-09-21 2022-06-21 Navico Holding As Sonar transducer with multiple mounting options

Also Published As

Publication number Publication date
JPH04501316A (ja) 1992-03-05
GB8918577D0 (en) 1989-09-27
CA2039157A1 (fr) 1991-02-16
AU6155390A (en) 1991-04-03
KR920701837A (ko) 1992-08-12
EP0438562A1 (fr) 1991-07-31

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