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1.
David Harris Robert K. Cessaro Fred K. Duennebier David A. Byrne 《Marine Geophysical Researches》1987,9(1):67-94
The Hawaii Institute of Geophysics began development of the Ocean Subbottom Seisometer (OSS) system in 1978, and OSS systems were installed in four locations between 1979 and 1982. The OSS system is a permanent, deep ocean borehole seismic recording system composed of a borehole sensor package (tool), an electromechanical cable, recorder package, and recovery system. Installed near the bottom of a borehole (drilled by the D/V Glomar Challenger), the tool contains three orthogonal, 4.5-Hz geophones, two orthogonal tilt meters; and a temperature sensor. Signals from these sensors are multiplexed, digitized (with a floating point technique), and telemetered through approximately 10 km of electromechanical cable to a recorder package located near the ocean bottom. Electrical power for the tool is supplied from the recorder package. The digital seismic signals are demultiplexed, converted back to analog form, processed through an automatic gain control (AGC) circuit, and recorded along with a time code on magnetic tape cassettes in the recorder package. Data may be recorded continuously for up to two months in the self-contained recorder package. Data may also be recorded in real time (digital formal) during the installation and subsequent recorder package servicing. The recorder package is connected to a submerged recovery buoy by a length of bouyant polypropylene rope. The anchor on the recovery buoy is released by activating either of the acoustical command releases. The polypropylene rope may also be seized with a grappling hook to effect recovery. The recorder package may be repeatedly serviced as long as the tool remains functionalA wide range of data has been recovered from the OSS system. Recovered analog records include signals from natural seismic sources such as earthquakes (teleseismic and local), man-made seismic sources such as refraction seismic shooting (explosives and air cannons), and nuclear tests. Lengthy continuous recording has permitted analysis of wideband noise levels, and the slowly varying parameters, temperature and tilt.Hawaii Institute of Geophysics Contribution 1909. 相似文献
2.
R. Herber 《Marine Geophysical Researches》1979,4(2):247-253
The ocean bottom seismograph (OBS) of the Institut für Geophysik, Hamburg (IfG) is designed for refraction seismic experiments and for recording microseismic noise. Hydrophone signals are recorded directly on a casette tape recorder with a band width of 3–60 Hz. Signals from three component 1 Hz seismometers are recorded on a 2nd casette tape recorder in FM for a frequency range of 0.1–1 Hz. A telemetering buoy at the surface is connected with the OBS by a polypropylene rope. 相似文献
3.
T. J. G. Francis I. T. Porter R. D. Lane P. J. Osborne J. E. Pooley P. K. Tomkins 《Marine Geophysical Researches》1975,2(3):195-213
The ocean bottom seismograph described in this paper has been developed primarily for recording earthquakes on the mid-oceanic ridges. The instrument is suitable for dropping onto the most rugged areas of the ocean floor. Acoustic tracking with the ship's precision echo sounder enables it to be located there relative to both the topography of the sea bed and the ship. The outputs of a 3-component seismometer and a hydrophone are recorded in FM form on a low-power magnetic tape recorder designed specifically for the instrument. 相似文献
4.
An inexpensive Pull-Up Shallow Water Seismometer (PUSS) has been designed and built to conduct long range seismic refraction experiments in the North Sea and the continental shelf around Britain, with the particular goal of studying the crustal and lithospheric structure under the epeirogenic basin of the North Sea. Signals from a gimbal-mounted 3-component geophone and a hydrophone are frequency modulated and mixed with clock and flutter correction signals before being recorded on a standard speed cassette tape recorder, with one hour of recording time. A 100 hour programmable timer allows the interval between the time of reset of the clock and each shot window of optional 5 or 10 min duration, to be preselected. The PUSS is launched and recovered using a pull-up technique originally developed for current meters. The replay system is also described.In May 1976 sea trials of 5 PUSSes were conducted along a 200 km refraction line in the North Sea. The encouraging performance of the equipment resulted in the decision to build a further 10 units and to proceed with a 400 km refraction line planned for the summer of 1977. 相似文献
5.
David A. Byrne George H. Sutton J. Grant Blackinton Frederick K. Duennebier 《Marine Geophysical Researches》1983,5(4):437-449
In most of the Ocean Bottom Seisometers (OBS) used today, the sensors, electronics, recorders, flotation, and ballast are contained in one rigid package. Usually this configuration requires a large mass, a large vertical cross section in the water, and relatively small bearing surface area in contact with the bottom, resulting in poor seismic characteristics and increased noise sensitivity. An OBS recently developed at the Hawaii Institute of Geophysics (HIG) minimizes these problems by physically separating the sensor from the main OBS package. Direct comparison between signals recorded by a standard HIG configuration Pop-up Ocean Bottom Seismometer (POBS) and signals from the new Isolated Sensor Ocean Bottom Seismometer (ISOBS), deployed near each other in deep water, clearly demonstrates the advantages of the isolated sensor configuration. Although the ISOBS is superior to older OBS designs, recent testing suggests that further improvements can be made. 相似文献
6.
A pop-up bottom seismic recorder designed for seismic refraction experiments was built by the Institute of Oceanographic Sciences in 1968. The device is housed within a 71 cm diameter sphere weighing 270 kg when launched. signals picked up by a hydrophone are recorded in analogue form on magnetic tape in the band 2–100 Hz. The total continuous recording period is 12 hr but the lifetime of the system can be effectively extended by cycling the tape-recorders to allow shooting to go on for up to 3 days. Ballast release is by acoustic command or by pre-set clock. The instruments have been used in water depths from 150 to 4820 m making a total of 63 deployments with a 95% recovery rate. A new version with three-component geophones is being built. 相似文献
7.
W. G. McDonald A. C. Hubbard R. G. Bookbinder K. McCamy 《Marine Geophysical Researches》1977,3(2):179-196
Ocean bottom seismographs designed to meet the requirements of both seismicity and refraction experiments have been operated extensively on twelve cruises (72 deployments). Signals from a hydrophone, and two geophones (horizontal and vertical) are direct recorded on a modified commercial tape recorder providing 10 day continuous recording at 1/40 ips and a 2–80 Hz band width. The free-fall deployment technique with timed ballast release has yielded a 93% recovery rate (96% over the most recent 24 deployments) despite frequently difficult weather and sea conditions. Emphasis on reliability and operational simplicity has produced an instrument that can be operated in arrays by a single shipboard technician.Lamont-Doherty Geological Observatory Contribution Number 2535. 相似文献
8.
William A. Prothero Jr. 《Marine Geophysical Researches》1977,3(1):119-141
The ocean bottom seismometer capsule contains a 1 Hz. vertical seismometer and triggerable or programmable digital recording system. The output of the seismometer is continuously digitized at a preselected rate of 64, 128, or 256 samples/sec. The digital data words are mixed with a time code and synchronization characters, serialized and passed through a 1536 sample shift register which acts as a delay line. The serial output bits are then encoded and recorded on a SONY TC800B tape recorder which is turned on when a seismic event occurs. The event trigger occurs when the seismic signal jumps to 8 times the time averaged input signal. A memory may be programmed to run the recorder on a schedule so that small amplitude signals from refraction shots are sure to be recorded. Data are recovered using the same recorder for playback and a decoder which provides an analog output for field data interpretation or a digital output for computer analysis. An acoustic transponder allows precise ranges between the capsule and ship to be determined. In addition, commands for the capsule to release or to transmit diagnostic data may be given from the surface ship. The capsule falls freely to the ocean bottom. After a predetermined time or when a release command is received, it is released from a 68 kg steel tripod and floats to the surface. A dual timer and explosive bolt system is used to increase recovery reliability.The first capsules were designed and constructed between October 1972 and October 1973. Good results were obtained from 38 out of 43 launchings made on six expeditions in 1974, 1975, and 1976. Four capsules have been lost. 相似文献
9.
A new and inexpensive pop-up ocean-bottom hydrophone recorder has been developed for use in seismic refraction experiments. It is capable of operating in water depths of up to 4000 m and in very rugged topography, and uses an acoustic command system built by the U.K. Institute of Oceanographic Sciences for recovery. The instrument is mounted in an inexpensive cylindrical pressure case based on commercially available extruded aluminium alloy tubing, and uses glass spheres and syntactic foam for buoyancy. Hydrophone and clock signals are frequency modulated and recorded on tape cassettes, with a recording duration of three hours allowing up to 18 programmed shot windows. The prototype has made seven free descents on the Mid-Atlantic ridge and in the Gulf of Oman, and successfully recorded shots under operational conditions for the first time in September 1979. The total component cost of the prototype was £2740 (1979 prices).(Department of Earth Sciences, University of Cambridge Contribution No. ES135). 相似文献
10.
Tests of a new Ocean Bottom Hydrophone (obh) instrument have recently been completed at Woods Hole Oceanographic Institution. This instrument is designed to float 3 m above the seafloor at depths of up to 6100 m for periods of up to 10 days and continuously records the output of a single hydrophone on a four-channel 0.064 cm/s (1/40 in./s) analog magnetic tape recorder. This instrument has an acoustic transponder and release system and is designed primarily for multiple deployments as a fixed ocean bottom receiver for seismic refraction work.Contribution No. 4174 of the Woods Hole Oceanographic Institution. 相似文献
11.
Adrian N. Bowen 《Marine Geophysical Researches》1984,6(3):275-293
A seismic reflection profiling system utilising a surface air gun source and a deep-towed horizontal hydrophone streamer has been developed for high resolution studies in the deep ocean. The instrument is deployed on a conventional armoured single conductor cable at depths of up to 6 km. Seismic data from the 30 m long streamer is wide-band frequency modulated up the towing cable to the ship together with a high frequency monitor from a 3.5 kHz echo-sounder mounted on the instrument package. The geometry of the system allows an order of magnitude improvement in spatial resolution compared with that obtained from standard surface source/receiver configurations. The summed hydrophones of the streamer attenuate cable-generated mechanical noise, and the 3.5 kHz sea-surface and bottom reflected returns provide receiver positioning information. The system has been successfully deployed at depths of 5 km in the Vema Fracture Zone in the North Atlantic, and although initially difficulties were experienced in balancing the streamer, subsequent profiles across the transform fault show details of sub-bottom structure which on conventional surface records are generally masked by diffraction hyperbolae. 相似文献
12.
Irish J.D. Morey K.E. Needell G.J. Wood J.D. 《Oceanic Engineering, IEEE Journal of》1991,16(4):319-328
To measure oceanographic parameters such as currents, temperature, conductivity, pressure, and suspended sediment concentrations, two film-recording current meters were upgraded with microprocessor-controlled data recorders and additional sensors. Two telemetry links relay data and allow the in situ operation of the remote instrument to be checked. In one configuration, the bottom-mounted current meter communicated by a 35-m-long wire to a small surface spar buoy, and then by a packet radio link to a nearby ship. In another development, the current meter relays data to a controller and buoyant data capsule on the bottom instrument package. The controller collects and processes the data from the current meter and periodically transfers these processed data to a data capsule and releases it. When released, the capsule rises to the surface and transmits its data to shore via the ARGOS satellite, while acting as a satellite tracked drifter 相似文献
13.
We describe recent mechanical andeelectronic modifications to the Cambridge Ocean Bottom Hydrophone system, enabling it to record in addition three geophone channels from a deployed, disposable geophone package. Examples of data from seismic refraction experiments show good correspondence between records of ground motion detected by the hydrophone and the vertical geophone. Seismic signals are undistorted by noise from instrument related sources. Clear examples of P to S conversions just below the receiver are observed. Improved recording conditions are achieved by deploying the geophones in a small pressure vessel as far away as possible from the main instrument package. 相似文献
14.
A simple shaker table for seismometer calibration 总被引：1，自引：0，他引：1
Frederick K. Duennebier George H. Sutton David Harris David A. Byrne 《Marine Geophysical Researches》1984,6(3):311-328
A unique and simple shaker table (shake table or shaking table), designed, constructed, and installed at the Hawaii Institute of Geophysics, has proven to be a valuable aid in testing and calibrating short period seismometers, as well as ocean bottom and ocean sub-bottom seismometer/tilt meter packages. It consists of a platform suspended in a stairwell by a single elastic cord (10 m extended length) driven by GeoSpace HS-10 geophones. Platform motion is monitored by orthogonal reference geophones and tilt meters. The relatively low natural periods of the platform, about 1.9 sec vertical and 6.5 sec horizontal, provide sufficient isolation from local vibrations that calibration can be made near operational amplitudes. Vertical or horizontal driver geophones can be driven by a commercial signal generator or white noise generator, or from magnetic tape output. The table can also be tilted with respect to the drivers to determine tilt tolerances and to calibrate tilt meters. A Hewlett-Packard 3582-A spectrum analyzer, used to analyze both reference and output signals, provides near real-time system cabibration and is an efficient means for investigating parasitic system resonances. The analyzer can also provide a white noise signal source to the driver geophones.Hawaii Institute of Geophysics Contribution 1443. 相似文献
15.
基于潜标测量的海洋环境噪声谱特性分析 总被引：3，自引：1，他引：2
利用海洋环境噪声测量潜标系统对南海典型海域开展了为期3个月的海洋环境噪声测量,16通道海洋环境噪声测量系统每小时测量两分钟噪声信号。数据处理结果表明,800~5 000Hz范围内,噪声谱与风速相关性最好,且风速越大相关性越好,噪声谱与风速的相关性好于与浪高的相关性。风关噪声谱级在海水中部基本不随接收深度发生变化,但由于测量水听器阵长度未能覆盖整个水深,因此未给出海面和海底处谱级变化规律。在400Hz以上的高频段整个风速范围内噪声谱级都随风速发生变化,且噪声谱级与对数风速具有很好的线性关系。 相似文献
16.
H. -W. Kebe 《Marine Geophysical Researches》1981,5(2):207-220
Moored sonobuoys are used for refraction seismic measurements at sea, although the range of operation is limited by the self noise caused by the hydrophone suspension.In this paper the main causes of self noise are discussed and a useful deployment scheme of a moored sonobuoy with suspended hydrophone is described.Some design criteria, in particular an equation for calculation of the optimal length of the expandable rubber band-which is situated between the surface float and the damping-body-are discussed.Finally, it is shown from noise measurements during the F. S. Valdivia cruise in 1975, that self noise level in the band 2 Hz to 20 Hz is 180 mPa to 280 mPa at a fully developed windsea with a characteristic wave height of more than 4 meters and a waterstream velocity about 0.5 m s1.During these measurements the hydrophone was attached to the cable without rubber band. It is concluded that at a normal seastate the self noise level can be reduced to the order of ocean floor noise. 相似文献
17.
Hae-Hoon Park 《Ocean Engineering》1993,20(2)
An indirect tension measurement method of a towing cable in midwater or a buoy cable is proposed using underwater acoustic positioning systems, etc., to give the in-water cable tension. The most simple and traditional cable tension measurement method is to apply a mechanical tension meter at the one end of the cable, but the method has limits in the aspects of continuous monitoring and manual operation. However, the technique in this study is to apply the Pode's analysis of the equilibrium configuration and tension of a flexible twine, in which the cable tension is given as a function of the geometric positions of both ends of the cable. A set of nonlinear integral equations is formulated and solved numerically by the Newton-Raphson method. Then the inclination angles and the tensions at the lower and the upper ends of the cable could be obtained. The derived method enables us to track a towed object, to measure the tension of a towing cable or a buoy cable and is also applicable to the remotely operated vehicle (ROV) tethered to a mother ship. 相似文献
18.
Echert D.C. Morison J.H. White G.B. Geller E.W. 《Oceanic Engineering, IEEE Journal of》1989,14(2):195-202
The development and initial field test results of the Autonomous Ocean Profiler (AOP) are described. The profiler uses a hydrodynamic lift device to fly the instrument package up and down the water column along a taut vertical cable. Because the local currents drive the platform's vertical motion, power requirements are low, and therefore long, unattached deployments are possible. By using ARGOS or GOES satellite retrieval networks, the system can supply near-real-time data. The system provides profile data at very high vertical resolution in contrast to conventional buoys, which gather data only at fixed sensor depths. Because only a single set of sensors is required to cover the vertical range desired, the system is low cost and, for many applications, expendable. The initial deployment configuration is as an Arctic drifting buoy 相似文献
19.
To perform geophysical and multidisciplinary real-time measurements on the ocean floor, it has been attempted to reuse decommissioned submarine cables. The VENUS project reuses the TPC-2, which is one of these systems and runs across the entire Philippine Sea Plate between Guam Island and Okinawa Island. The VENUS system comprises an ocean floor observatory, a submarine cable, and a land system. The major components of the ocean floor observatory are geophysical instruments and a telemetry system. There are seven scientific instrument units including broadband seismometers and a hydrophone array. Digital telemetry using the old analog telephone cable obtains high data accuracy and real-time accessibility to data from a laboratory on land. The bottom-telemetry system and a part of sensor units were installed at a depth of 2157 m on the landward slope of the Ryukyu (Nansei-Syoto) Trench on August 29, 1999. The data from the hydrophone array and tsunami gauge have been correctly transmitted to the data center. The rest of the scientific instruments will be deployed by deep-tow equipment and a remotely operated vehicle. Using a decommissioned submarine cable will greatly reduce construction costs compared to using a new cable system 相似文献