NAVWEPS REPORT 7650 —NOTS TP 2673 COPY Fe fo AN INSTRUMENT FOR CONTINUOUS DEEP-SEA MEASUREMENT OF VELOCITY OF SOUND, TEMPERATURE, AND PRESSURE By J. R. Lovett and S. H. Sessions Research Department gongs /t we § if OA, wv OC) a Bis ot) res isan Ey aie: ut ABSTRACT. An electronic instrument for the continuous and con- current measurement in the ocean of velocity of sound, tempera- ture, and pressure has been designed and tested to depths in excess of 2,000 meters. This 70-pound transistorized instrument contains three sections: a modified NBS velocimeter for measur- ing velocity of sound, a Borg-Warner Vibrotron for pressure, and a NOTS thermistor-controlled Wien-bridge oscillator for tempera- ture. Outputs from the three sections are frequency-modulated Signals, mixed for single-conductor cable transmission to the surface. Velocity of sound is transmitted in the band 2,775- 3,225 cps, temperature in the band 5,000-8,000 eps, and pressure in the band 9,712-11,288 cps. Accuracy of measurement is sound velocity 0.3 m/sec, temperature 0.02°C, and pressure 1% in selected ranges of O-1,000 and 0-2,000 psi. U.S. NAVAL ORDNANCE TEST STATION China Lake, California 9 May 1961 | U. S. NAVAL ORDNANCE TEST STATION AN ACTIVITY OF THE BUREAU OF NAVAL WEAPONS W. W. HOLLISTER, CAPT., USN WM. B. McLEAN, PH.D. Commander Technical Director FOREWORD his report describes an instrument, developed at the U. S. Naval Ordnance Test Station, for the continuous and concurrent measurement of velocity of sound, temperature, and pressure at any ocean depth. The work was completed under the Bureau of Weapons Task Assign- ment R360FRL06-2161-RO11LOLOOL1. This report is transmitted for information purposes only. It does not represent the official views or final judgment of the U. S. Naval Ordnance Test Station, and the Station assumes no responsibility for action taken on the basis of its content. RENE L. ENGEL Head, Oceanic Research Division Released under the authority of: CHAS. E. WARING Head, Research Departmen’ sol: Technical Publication 2673 \ NAVWEPS Report 7650 svayletealieentereh sloren cre e/a thier ooeceeeee.s RESEArCh Department wee eens ces 13 leaves, abstract cards \; cise vibe senesebevguvee sie LHO numbered \ecmmee Sooddennnghnsnnntnnnn nnn nnnntnintn .. UNCLASSIFIED NAVWEPS REPORT 7650 CONTENT'S Introduction . 1 Description .. Bit). 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Block Diagram of NOTS-SVIP ieceunene cited “ainietareumeye Yevetol oes 4 3. Sound Velocity Circuit... CO URC CUnU secre CRC aR ee Tne S 5 4, End Plate With Reflected Sound mee Be Waeche oe (eirriMeve sie ofa rf Big Ae noSRenabias! Os kilehyore Chitebels Gog) 5 6 Aloo oo abo ole 6 9 ComeressunenOsedilliator (Circudct asia sos seuss eo we ee 4 74 ane eee 7. Summing Amplifier Circuit Spite sce 15 —— 8. Internal Construction of NOTS- SVIP THeERURece a ae TTY ep Ly 2 —— 9. Layout of Shipboard Readout Equipment .. a) 6 19 === 10. Sound Velocity versus Depth, Outer Santa Beeneel Channel ; 20 === ll. Temperature versus Depth, Outer Santa Barbara Channel .. eM. — = - ——— >So | so —= 4 —— == nm =S>S= © = — 3 — alotal = ‘ wa) my ae 4 a ah | hy i a 7 ett Bes 2 ba 7 eh. Bains * Sev exadyi : a) Bits diclad oe son RI A Sit I See) ry, ke 7 } “ Bi Sn ee \ i 'y, 7 ‘ r’ "e ‘ - a > i f i A‘ ‘ J s‘Oey,) , = \ : i Tie ~ r . ; J . 6! ’ e ‘ q , pee Ay. 7 4 ; i -. i 7 » “ | 0 ey A A . = vs ¥) = . ; : . im i eait 7 > £ ak) vale it t “n2NIae ears a pits NAVWEPS REPORT 7650 INTRODUCTION A sound-velocity, temperature, and pressure (SVIP ) instrument was built during 1958-1960 at the U. S. Naval Ordnance Test Station (NOTS) to satisfy the need for a continuous-reading instrument for the concurrent measurement and data transmission of three of the oceanic parameters (see Fig. 1). The NOTS-SVIP instrument contains three sections, permitting the simultane- ous measurement of velocity of sound, temperature, and pressure as the instru- ment is moved through the water. The velocimeter developed by Greenspan and Tschiegg of the National Bureau of Standards (NBS) and slightly modified by NOTS is the velocity of sound section (Ref. 1). The temperature section is a thermistor-controlled Wien-bridge oscillator developed at NOTS (Ref. 2), and the pressure section is the Vibrotron of Borg-Warner Controls, Santa Ana, California. The accuracy of measurement for the NOTS-SVIP instrument is ve- locity of sound 0.3 m/sec, temperature 0.02°c, and pressure 1% in selected ranges. The basic design of the instrument will permit its use in all ocean depths. FIG. 1. NOTS-SVTP Instrument. NAVWEPS REPORT 7650 The data are continuously transmitted as frequency-modulated signals over the supporting cable, and the three measured parameters can be displayed and recorded for detailed examination. The recorded frequency- modulated data can be readily assessed by machine data reduction techniques. Velocity of Sound. The velocity-of-sound meter is used to examine the variations in sound velocity as a function of depth in the ocean, and it provides data of greater accuracy than the bathythermograph. The bathythermograph has been of unquestioned value in providing information on the thermal structure of the ocean, in studying underwater sound trans- mission, and in making sonar predictions. However, the bathythermograph does not yield sound-velocity values directly nor does it provide imme- diate data readout. The hydrographic method of sound-velocity determination is also an indirect method requiring measurement in situ of temperature, pressure, and salinity. It does not provide either continuous or immediate readings of the velocity of sound. From 1950 to 1954 and under the Office of Naval Research sponsorship, five experimental underwater velocity-of-sound meters were developed by Springer, Cook, the University of Michigan, and the National Bureau of Standards. Two of these meters employed phase-measuring techniques, two employed the pulse-feedback principle, and one was a resonant-cavity type. Between 1954 and 1956, all five meters were reviewed by the U. S. Navy Underwater Sound Laboratory and the meters with the pulse-feedback principle were considered to be the best for measuring the velocity of sound in the ocean (Ref. 3). In 1957 Greenspan and Tschiegg of the National Bureau of Standards reported on a "sing-around" velocity measuring technique that seemed most promising for use as a continuous reading instrument for all depths in the ocean (Ref. 1). Consequently, it was decided that this circuitry should be incorporated in a NOTS field instrument that would also measure pressure and temperature. Temperature. Most observations of sea-water temperature at depths greater than 300 meters have been made with reversing thermometers. Reversing thermometers, first used in 1874, have been improved until well-made instruments are now accurate to within 0.01°C. The Hydro- graphic Office indicates that the accuracy of the reversing thermometers in the field appears to be +0.02°C (Ref. 4). The recently developed thermistor-controlled Wien-bridge oscillator at NOTS has produced a temperature accuracy of 0.02°C, and it was selected for use in the SVTP instrument (Ref. 2). NAVWEPS REPORT 7650 Pressure. Depth measurements in the ocean can be made by observing the effect of pressure on a pair of reversing thermometers, one pro- - tected and the other unprotected from pressure (Ref. 5). A great advantage of this method is its accuracy, but a serious disadvantage is that only point-depth readings are provided. The thermometers can only be read by visual inspection at the surface and only one reading taken for each depth point. The probable error of depths obtained by the unprotected thermometer is about +5 meters for depths of less than 1,000 meters, and about O. 5% of the wire depth for depths greater than 1,000 meters (Ref. 5). Other methods of reading pressure to determine ocean depth are as follows: spring-loaded bellows, Bourdon tube (a hollow spring), electrical strain gage, variable-reluctance gage, diaphragm-actuated electrical potentiometer, vibrating-wire transducer, and more recently the solid-state pressure sensitive gage. All may yield a variable voltage, current, or frequency as a function of pressure, and con- sequently are suitable for use in a continuous depth-reading meter. Accuracy of about 1% may be attained by each of these methods. The vibrating wire transducer was selected for the NOTS-SVIP instrument because of its accuracy, frequency-modulated output, and repeatability and simplicity of its associated circuitry. Pressure readings in the ocean by the SVIP instrument yield con- tinuous readings within 1% of the range of the Vibrotron used (available in ranges from 100 to 10,000 psi). The resulting error is slightly greater than the 0.5% of protected-unprotected reversing thermometer pairs. DESCRIPTION Figure 2 is a block diagram of the NOTS-SVIP instrument. The out- puts of the velocity-of-sound, temperature, and pressure oscillators are summed and amplified to drive the cable. The individual circuits and packaging of the instrument are described in the following sections. SOUND-VELOCITY OSCILLATOR Figure 3 is a diagram of the transistorized sound-velocity circuit used in the SVIP instrument. The circuit is essentially that designed by NBS with minor modifications (Ref. 1 and 6). It has been described as a "sing around" or "an ultrasonic delay line that synchronizes a relaxation oscillator," i.e., the circuit consists of a free-running NAVWEPS REPORT 7650 annous asvo = LAdLNO avNSIS Y3AINa 37aVv2 GNv YaIdITdWY ONIWWNS 94 OS2"e ¥y3alild SSVd-MO7T ‘quownsyisuy GL AS-SLON J© wesseIg xorg °Z% “94 NOILOSS 3YNSS3IYd 9M 882'1I-zIZ'6 REIPIRET NOULONBIA VL NOILOSS 3YNLVYSAdWSL 394 8-G YOLVT1IDSO auNlveadW3l UL NOILOSS ALIDOTSA-ANNOS om S22"e -GLL2 Y3AGIAIG AINANOAYS yalsNd NV ONV YOLVYANSS 3SiNd 44= NOY LOUSIA ee et sivd ; YOLSIWNSHL J1dWvS _ N anv \ suaonasnvu. | NAVWEPS REPORT 7650 ymoatr) AyIoo]TaA-punos “Ee “Oy HLVd GNNOS NOdN SGNada3d SNIVA » wYdIOIIAL LLIWHOS = 20 Yaldiqdwy = 0 YOLVITIDSO ONINDO19 = 80 YFOOINL LLIWHOS = 70 YSMONNOS YALLIWA = “OD YAAING YOLVIMDSO ONINDO Tg = “dD yoLoaLaq="0 Yaldiddwy = ly ee ; OL rol Lv (0) wld Yor 16E ‘== Gj (== 4O6E 422 ole Yo 4S tL yrlo1 401 + jr/o1 z. 100° 2 wol i) % Yo £0 ) si ONG Cee SO ca vay ZY ZY LY) LY ZS LY Z00° 10 Z00' 10 10 j7i7lozz i710 6SONi rel we : OLb 49'S 5 8OZNI * H7losze H7/00I¢ mI 9S x Ld UGE yore Uy ob AeL- NAVWEPS REPORT 7650 blocking oscillator that is connected to a sending transducer. The resulting sound pulse is reflected twice to reduce errors due to water motion, and then picked up on a receiving transducer that is the input for a high-gain pulse-shaping amplifier (Fig. 4). The amplifier retriggers the blocking oscillator, and a repetition frequency results, which is higher than the free-running rate. Thus the water path acts as the delay Line where the variation in sound velocity through the water changes the delay and hence the "sing-around" frequency. The frequency also depends on the path length and the circuit delays. The configuration of the path length makes it impossible to measure this length to any desired degree of accuracy. Also, because of selective attenuation the received pulse rises slowly in comparison with the sent pulse; hence, an unknown time delay is introduced during which the received pulse is below the noise level. Consequently, the instrument must be calibrated in a liquid for which the velocity of sound is known accurately, and the liquid must be similar to that in which the instrument will be used. Thus, if the instrument is to be used in sea water, it may be calibrated in distilled water in which the sound velocity is known as a function of temperature. Two recent determinations of the velocity of sound in distilled water have been published by Greenspan-Tschiegg and Wilson (Ref. 7 and 8). Both determinations used similar methods. However, over the temperature range of 0-30°C, there is a difference of 0.26 m/sec in spite of claims of 0.05 m/sec and 0.093 m/sec maximum errors. The free-running frequency of the blocking oscillator is about 5 kilocycles. A "sing-around" frequency of about 6 kilocycles is achieved by increasing the path length to 24.7 cm. Negative pulses are developed across a 12-ohm resistor in the emitter lead of the blocking oscillator to switch an Eccles-Jordan circuit. This circuit produces square waves and divides the frequency in half (3 kilocycles). This frequency (3 kilocycles) is in the center of Telemetry Band 8. A small Band 8 low-pass filter is used to transmit a sine-wave output. The sound-velocity circuit may shift in frequency due to the input triggering on a precursor. To prevent shifting, NBS has found that the sending crystal should be polarized with the inner electrode made negative, and the receiving crystal should be reversed with the inner or small electrode made positive. Also adjustment of the reflectors is made with the transmitters disconnected from the rest of the circuit, and the output of the amplifier is observed on an oscilloscope. This procedure is repeated until it can be seen that there is enough signal to saturate the amplifier and yet enough attenuation to remove unwanted reflections. The first signal must be clean with no precursor. NAVWEPS REPORT 7650 REFLECTOR TARGET PRESSURE PORT OUTPUT TRANSDUCER FIG. 4. End Plate With Reflected Sound Pulse. NAVWEPS REPORT 7650 TEMPERATURE OSCILLATOR A transistorized-thermistor controlled Wien-bridge oscillator was developed at this Station (Ref. 2). The circuit diagram as used in the SVIP instrument is shown in Fig. 5. Wien Bridge. In the Wien-bridge oscillator, the input is in phase with the output at the balance frequency, f5- However, the output of a balanced bridge is zero at f = f,, and hence B = O and AB = O at f = f, where B = E,/E the ratio of feedback voltage to output voltage = E/E;> ratio of output voltage to input voltage, or forward voltage gain without feedback °? > | The Barkhausen criterion for an oscillator requires at AB = ie Therefore, the bridge must be unbalanced but in such a way that the phase shift remains zero. Consider the Wien bridge in the following diagram: Ey and E, are the input and output voltage respectively of the bridge. NAVWEPS REPORT 7650 ‘yModtTy Joye] [IOSGQ sanqesiodway, *¢ “O]4 a ind LHOIT 8Z€ ‘ON 3D =* aT LV %86 NIHLIM OL GAHOLVW SYOLSIWYNSHL 9PZL XV ODAA= 1 OSZW SAINLSNGNI NOLINOD ‘IN3IDIS4309 FUNLVYAdWAL SAILVOAN 4Ytlogz == "5 aNv SSV19 DNINYOD 37/zg00°0= 9 AGOIG YSN4AZ YOS SLSNfav “yY Vy SV 3WVS NO LNSGN3dgG ‘G3LISOdad-NOSUV) Vo0s‘l = ~¥ e) oe AN "ys sv awvs NO LNSGN3d3q ‘D,/WHO/SWHO $00°0+ 2 YO ODTVa Yoor = *4 IN3ID144309 3YNLVYadWwaL YOLVITIDSO NO LNSGN3d]q ‘d3aLISOdad-Noguvd Vool = "4 "sy sv AWvS NO LNSGN3d3q ‘7y000’81 = “a Tu sv SWS NO LNSGNadaq ‘Bins’! =~ S3ANND | i] Il £9 6) U8) ra 1p Nee? SI ACES 30 April 1962 NAVWEPS REPORT 7650 = Bye 2 g where R J qh a ae ; ith E Bes = E) RT R and a is in phase wi 1 2 3 Z and at the balance frequency E), is in phase with E 2 B= k ———— 4 iL a + 45 ab where A fn ia een ay 7S Bae 1 1 al Sa a teste “oar . 1 at the balance frequency fo = Bak, C, and. 4) = (1 i J)R, (1 - 3)R, Ze oe hence BE, = i eigen Se a es Umare) If a null is desired, Ro must equal 2Rz so that Eo = Ey - Ez = 0. However, if the bridge is to be used as thé feedback network for an oscillator, the magnitude of B must not be zero although the phase shift must be kept at zero. The preceding may be done by taking the ratio of R3/ (Ro + R3) smaller than 1/3, i.e., let ae es alr where o is larger than 3. {NG ae making A f, and Bp = 1/o, the condition AB = 1 may be realized by G. As shown in the preceding, the impedance of the bridge as seen from output and input varies as a function of R. Therefore, in order to operate the oscillator over a wide frequency range, it is necessary to 10 NAVWEPS REPORT 7650 include amplitude stabilization. Stabilization is achieved by including a tungsten filament light bulb as a part of resistor R,. Thus when E, increases, Rz also increases, and AB is kept more nearly constant. To operate the oscillator over a temperature range from O to BOLCs Ro must have a small positive temperature coefficient of resistance to maintain amplitude stability. The value of this resistance and its coefficient are determined by substituting a resistance-substitution box (0.1%, if available) for Ro and adjusting it for oscillation and sinusoidal wave form. The temperature coefficient of resistance is found by temperature cycling the oscillator and noting the change in resistance over the range 0-30°C. Enough positive temperature coef- ficient wire such as Balco (Wilbur Driver Co., Newark, N. J.) is wound noninductively on two 1/10-watt, 1% carbon-deposited resistors to over- come the negative temperature coefficient of these resistors and supply the extra positive coefficient needed to stabilize the amplitude. To obtain frequency stability of the oscillator with temperature, capacitance C, must remain constant. Stability is achieved by paral- leling capacitors that have a positive temperature coefficient with capacitors having a negative coefficient. The combination used has enabled the oscillator to be temperature cycled from 0-30°C with a frequency change of less than 1 cps (Alcps = AO.01°C). Temperature stability is further improved by use of a differential amplifier, and by temperature cycling from -60 to 60°C for 8 hours before Ro is determined. The cycling "ages" the components, and minimizes changes with time in their characteristics. To avoid phase shifts through the amplifier other than in multiples of 2x, large coupling capacitors are used. Aged thermistors are used for the temperature sensing elements. The resistance curve of a thermistor with temperature approximates the re- sistance curve of a Wien-bridge oscillator with frequency. The thermistor curve can be matched to the oscillator curve with a three-point match to achieve maximum linearity with the following network: 11 NAVWEPS REPORT 7650 where Ry is given by gd os ge a ie 5 Rn + Re R, and Rp may be determined for three points and R,, R-, R- computed. A program for the solution on a IBM 709 computer is given in the Appendix. Maximum variation from the best straight line 5-20°C of +0.02°C has been achieved. Rp should be approximately 1,000 ohms at 25°C. The specifications for the temperature oscillator are as follows: Temperature range: 0-30°C Frequency range: 5,000-8,000 cps Sensitivity: 0.01°C/cps Accuracy; 0.02°C Linearity: maximum variation from best straight line; 5-20°C, +0.02°C; 0-30°C, +0.2°C Power requirement: 7.2 volts at 25 milliamperes Output voltage: 1.0 volts RMS at Z = 1,000 ohms PRESSURE OSCILLATOR The Vibrotron of Borg-Warner Controls, Santa Ana, California, is used for pressure measurements in the SVIP instrument. Pressure is sensed by displacement of a diaphragm that in turn produces a change in tension, and hence, in frequency of a vibrating wire. The advantages of the transducer are that it has a direct frequency output and requires just a simple oscillator to sustain the forced vibrations. The dis- advantages are the temperature drift, long-term frequency instability, and inherent nonlinearity. The frequency of a vibrating wire is given by the formula dL y a where f is frequency, L is length, T is tension, and » is mass per unit length. 2 NAVWEPS REPORT 7650 The nonlinearity is due to the fact that the frequency varies as the square root of the tension. For a frequency deviation of 13%, the linearity can be held to within 3% if the tension deviates about 22%. Figure 6 shows the oscillator that induces vibrations in the wire. The potentiometer in the feedback loop is adjusted for each Vibrotron, and the thermistor in the loop improves temperature-amplitude stability. The circuit operates on 24 volts and draws 4 milliamperes. The specifications for the Vibrotron are: Repeatability: short term, 0.25% Linearity: within +3% of a straight line between end points Temperature sensitivity: +0.1% of bandwidth per °c change of zero frequency SUMMING AMPLIFIER The amplifier shown in Fig. 7 combines and amplifies the sound- velocity, temperature, and pressure signals so they may be transmitted as a mixed frequency signal over the single-conductor cable. The individual signal levels are adjusted by the 50,000-ohm potentiometers. The complementary-symmetry push-pull amplifier can furnish 6 volts, peak-to-peak into an impedance of 50 ohms. MECHANICAL PACKAGING The pressure case of the SVIP instrument is made of 304 stainless steel tubing, 18 inches in length, 3-inch inside diameter, and 3/4-inch wall thickness. The end caps are l-inch thick and have O-ring seals. Sound-velocity, temperature, and pressure sensors are mounted with O-ring seals in the lower cap. A bulkhead-type 2-conductor electrical- signal output plug (No. X8LO4-57 of the Joy Manufacturing Co., St. Louis, Mo.) is compression mounted in the upper cap. The case has a computed static pressure crushing strength of 75,000 psi. All components of the SVIP instrument including transducers have been pressure tested to 10,000 psi with no evidence of leaks. The present output plug limits operation to oceanic pressures less than 10,000 psi, and a higher pressure output plug should be used for pres- sures above 5,000 psi. To permit recharging of the 7.2- and 2-volt nickel-cadmium batteries without their removal from the case, gravity-actuated mercury switches have been installed that disconnect the batteries from the electronic ) NAVWEPS REPORT 7650 “yIMIITY) Joye] IISsEC) eINSSI1q “9g “YA (1) ama 2 YSlsIId NV SNIWWAS OL (€) (Prootauera) NOYLOYBIA AG’22- O— 14 NAVWEPS REPORT 7650 *SqJINOJIIO aunssoud pue ‘gimje1e duiay ‘ Ay190T aA-punos WoOdT sadei[0A [eusis [enba uleiqo 04 paisnlpe oe Ny pue 6? By Oy ‘qmoiry) Jarpiduy Burwumng +) *OT4 Nel AM Ol y7tl rA| ANG » AM OI y71l Vay Wel 4711 Ne? A?) > Wee a) NAVWEPS REPORT 7650 circuits when the instrument is in the horizontal position. In this position, the batteries are connected to the two pins of the output plug in the pressure case so that charging current can be applied. When the instrument is in the vertical position, the batteries are switched to the electronic circuits and the instrument is operable. Figure 8 shows the internal construction of the instrument. An inner shell, attached to the lower plate, supports the electronic circuits, wiring, and batteries, and permits the instrument to be calibrated and tested with the pressure case removed. SHIPBOARD INSTALLATION Winch and Cable. The winch used with the SVIP instrument handles approximately 6,000 feet of 0.189-inch diameter, single-conductor poly- ethylene covered steel cable. The inner conductor of the cable is terminated electrically at the winch in a slip-ring commutator. The 6,000 feet of cable weighs 139.8 pounds in air, but because of buoyancy it weighs only 65.1 pounds in sea water. The cable has 47 strands of 30-gage and one strand of 28-gage steel wire, which are sealed with silicone paste and covered with DFD-6015 polyethylene. The breaking strength is 900 pounds. The direct-current resistance is approximately 28.3 ohms per 1,000 feet, and capacitance to sea water about 0.05 micro- farads per 1,000 feet. When the cable is on the winch, it has an inductance of 510 millihenries. With this winch and cable, the instru- ment can be lowered at a maximum rate of about 5 ft/sec and raised at about 3 ft/sec. Signals from the instrument are attenuated by resistance, capaci- tance, and inductance in the cable and winch. With 6,000 feet of the cable described above on the drum, resistance is approximately 170 ohms. The cable acts like a coaxial cable when in sea water, and therefore, has an attenuation (Ref. 9): Oy a where @ is the attenuation in nepers per unit length, and C and R are capacitance and resistance per unit length. The greatest attenuation occurs at the greatest depth. At a fre- quency of 9.8 kilocycles, the value @ becomes 0.23 nepers per 1,000 feet or a voltage attenuation of 2.0 decibels per 1,000 feet. When all the cable is wound on the drum, the capacitance to sea water is small, but inductance reaches 310 millihenries. 16 NAVWEPS REPORT 7650 BATTERIES SOUND-VELOCITY FIG. 8. Internal Construction of NOTS-SVTP Instrument. 17 NAVWEPS REPORT 7650 It can be seen that amplification must be available to overcome attenuation introduced by the cable and winch. As longer lengths of cable are used, signal-to-noise ratios and signal-amplitude variations with cable length should be carefully considered. Readout Equipment. The electrical signals transmitted over the cable are amplified, separated into their correct frequency ranges by band-pass filters, and recorded as shown in Fig. 9. The electrical signal return path is provided by the conductivity of the sea water. The received signals, after band-pass filtering, can be read on one or more digital counters, can be discriminated and re- corded on X-Y¥ plotters, or recorded on a magnetic tape recorder for playback and analysis. All three methods have been used with the SVIP instrument. When the magnetic recording method is used, frequency errors are introduced into the recorded data of a magnitude dependent upon the tape speed accuracy of the magnetic recorder. To make possible correct interpretation of the frequency data thus recorded, it is necessary to playback concurrently a stable, reference frequency re- corded at the time the instrument data are recorded. From such recorded data on magnetic tape, X-Y plots of sound velocity versus depth and temperature versus depth can be produced. Digital computer tapes can also be produced to give corrected values of sound velocity, temperature, and depth. Field Use. Since August 1959, the SVIP instrument has been used by NOTS on several cruises in the area of San Clemente Island off the coast of southern California. Figures 10 and 11 show a pair of typical, simultaneously recorded sound velocity and temperature versus depth profiles obtained. A report on the data collected on these cruises is now in preparation. CONCLUSIONS AND RECOMMENDATIONS The NOTS-SVIP instrument is a useful oceanographic research tool whose potentialities have not been fully explored. Its advantages are sensitivity; concurrent measurement of sound velocity, temperature, and pressure; visual display of information; and adaptability to modern data processing methods. A model should be developed that could be operated in medium depths of the ocean while the ship is underway. Also a free sinking and free returning model with self-contained recording should be investigated for use in great ocean depths. 18 NAVWEPS REPORT 7650 oy O1 AONANDAYS ERR EREPEL 4¥304093y AdVL JILANSVA Y3SLNNOD TVLISIG ‘yuowdinby ynopeoy psvoqdryg jo ynokeT °6 “OY oy 882 1l-2126 ySaLis 3SYNSSAYd 94 9-S yas AunLvuadWwal YalslId WV SINVLIOA WN GZ2"e-S222 yas A.LIN013A-GNNOS LNAWNYLSNI HONIM [_] (\d) dLAS 19 *[euue yy) eieqieg eyUeG 131009 ‘uidoqg snsi9A A}ID0[9A pUNOg ‘QT “OI a | 43 1 | is 4 ba | 3s 3 a | poo oe ae NAVWEPS REPORT 7650 NAVWEPS REPORT 7650 } } j j H t } i i j i t i ; i i i / fore cere nen nt inn ene nme nite cn 2 *jeuuey’) Bieqiegd Byues i i qoing ‘yidaq snsso,A oinjesiodway, *{][ “OIA I { ¥ | i i es eee a seston BE j i | | 4 4 i Zs ss es i 2 i i i } 196! HOUWIN Iz ce ceaatsaselr dices nc cance acoder ee, Bis so mene a sii srnipntannaepeceoes a - Cilia tA i i : | | M 2b, 6208 HL N u2S,6S0ze i | i i | : ; | i i : i { i j I ser aniai tate tate er a marcas ‘es Wie ee es av ee eee eres ee me eer i / 900! i e i. —— - | | et I: OR IE ALLO DOR GIT mer ancensrt CRUE LEER. CB BERR TIID ree siesta ssshabaneoennis shot ts oni ess cam auee teen ets ei Ae ssi — sans +——- 39v4uns — 21 NAVWEPS REPORT 7650 APPENDIX PROBLEM NO. 080-07, THREE Rist Purpose The purpose of this problem is to solve three equations of the following type for R> R5> R 30 tee ee, i Rah BR Bo BER 5) pe ea L Chia DR 4 Bah eae ss 2 * DR 5) Tea ay epee Ez FR . 2 * FR 3 Method The problem is converted to one of least squares. Equality in the above equations is replaced by difference and the sum of squares is formed. Through the use of subroutine no LSQ, the original estimates for R,> Ry» R, are adjusted in an attempt to minimize the sum of squares. Procedure To successfully implement the program, an estimate must be made for R,, Ro, Rz and something must be known about the accuracy of the esti- mate. A quantity DR is input to the program and is the basic increment for adjusting R,, Ro, Ra. DR should be about 10% of the expected accuracy of the estimate. If the results of the first entry of the program are not satisfactorily accurate, re-enter the program using as an estimate for Rj, Ro, Ra the values that produced the least sum of squares and a DR, which is 10% of the original. For best results scale Ri, Ro, Ra, and DR to avoid making the sum of squares too small. s This problem was originated by J. R. Lovett and programmed by R. D. Dancey of this Station. - Subroutine Np LSQ was written by R. S. Gardner of this Station. (ae NAVWEPS REPORT 7650 The input deck is assembled as follows: Card Columns 1. FORTRAN Job Card i FouO 16=51) 33-66 68 70 72 Opeth OuanC ala al ee) 3. Program Deck 4h. "DATA" Card J. 7-10 5. Data Card 1-3 4-6 Entry x FJQB 08007, J. O., A. J. O. The numbers should be separated with commas and no blanks should appear Identification (name, phone number) 9 O 5 XEQ * DATA Number of iterations (about 15 or 20) Maximum number of entries (normally 100) These two numbers should be blocked to the right with no decimal point punched. The following numbers can appear anywhere in the field but must have a decimal point punched. 7-18 19-30 31-4e 43-54 DR Rs 6. Data card. These numbers can appear anywhere in the field but must have a decimal point punched. Se 13-24 25-36 37-48 49-60 61-72 YAo0aAaWd SYS The data is output after every iteration in floating point decimal. The output includes the new R,, Ro, R33 the three deviations, and the sum of the squares. 23 NAVWEPS REPORT 7650 ine) 2h REFERENCES Greenspan, Martin, and Carroll E. Tschiegg. '"Sing-Around Ultrasonic Velocimeter for Liquids," REV SCI INSTRUMENTS, Vol. 28, No. 11 (November 1957), pp. 891-901. U. S. Naval Ordnance Test Station. Deep-Sea Temperature Meter, by Hugh B. Martin III, and George R. Lewis. China Lake, Calif., NOTS, 8 September 1959. (NAVORD Report 6589, NOTS TP 2321.) U. S. Navy Underwater Sound Laboratory. Study and Evaluation of ONR-Sponsored Sound Velocity Meters, by Harry Sussman. New London, Conn., NUSL, 1 March 1956. (USL Research Report 299.) U. S. Navy Hydrographic Office. Final Report of the Committee on Instrumentation. Oceanographic Instrumentation, 2nd ed. Part III. Sea Water Temperature Measurement, by Murray H. Scheffer. Washington, HO, September 1960. (Special Publication-41.) Sverdrup, H. U., Martin W. Johnson, and Richard H. Fleming. The Oceans, Their Physics, Chemistry, and General Biology. New York, Prentice-Hall, 1942. P. 351. Tschiegg, C. E., and E. E. Hays. '"Transistorized Velocimeter for Measuring the Speed of Sound in the Sea," ACOUS SOC AM, J, Vol. 31, No. 7 (July 1959), pp. 1038-1039. .- Greenspan, M., and C. E. Tschiegg. "Speed of Sound in Water by a Direct Method," NATL BUR STANDARDS, J RES, Vol. 59, No. 4 (1957), pp. 249-254. Wilson, Wayne D. “Speed of Sound in Distilled Water as a Function of Temperature and Pressure," ACOUS SOC AM, J, Vol. 31, No. 8 (August 1959), pp. 1067-1072. Everitt, William Littell. Communication Engineering, 2nd ed. New York, McGraw-Hill, 1937. 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Taylor Model Basin Naval Air Development Center, Johnsville Naval Civil Engineering Research and Evaluation Laboratory, Port Hueneme Naval Ordnance Laboratory, White Oak Naval Postgraduate School, Monterey (Library, Technical Reports Section) Naval Radiological Defense Laboratory, San Francisco Naval Research Laboratory Naval Torpedo Station, Keyport (Quality Evaluation Laboratory, Technical Library) Naval Underwater Ordnance Station, Newport Naval Weapons Plant (Code 752) Navy Electronics Laboratory, San Diego Navy Hydrographic Office (Oceanographic Division) Navy Mine Defense Laboratory, Panama City Navy Underwater Sound Laboratory, Fort Trumbull Navy Underwater Sound Reference Laboratory, Orlando Office of Naval Research Branch Office, London (Oceanography ) Office of the Naval Attache, Paris, via BuWeps (DSC) USRO/DEF6, (U. S. Mission to NATO, Navy Section), via BuWeps (DSc) Armed Services Teenne eal taea lon Agency (TIPCR) The Supreme Allied Commander Atlantic, ASW Research Center, La Spezia, Italy, vie BuWeps (DSC), via Secretariat, S-DMICC Coast and Geodetic Survey Head, Current and Tides Branch (1) Head, Operations Branch (1) PRP FP PRPRPRPRP PREP PRPRRPRP PRP PRRREP PRPeEH Coast and Geodetic Survey, Los Angeles Committee on Oceanography Committee on Undersea Warfare National Bureau of Standards (C. E. Tschiegg) Office of Technical Services Fisheries Research Board of Canada, Nanaimo, British Columbia (Pacific Oceanographic Group, John P. Tully), via BuWeps (DSC) Pacific Naval Laboratory, Esquimalt, British Columbia, via BuWeps (Dsc) Agricultural and Mechanical College of Texas, College Station (Head, Department of Oceanography and Meteorology) Applied Physics Laboratory, University of Washington, Seattle Bulova Watch Company, Woodside, N. Y. (Electronics Division) Chesapeake Bay Institute, JHU, Baltimore Daystrom Inc., Poughkeepsie, N. Y. (Electric Division) General Motors Underwater Laboratory, Goleta, Calif. (Sea Operations Department ) General Precision, Inc., Librascope Division, Glendale, Calif. Hudson Laboratories, Columbia University, Dobbs Ferry, N. Y. Hughes Aircraft Company, Fullerton, Calif. (Underseas Warfare De- partment ) Lamont Geological Observatory, Columbia University, Palisades, N. Y. Lockheed Aircraft Corporation, Burbank (Antisubmarine Warfare Systems) Marine Acoustical Services, Inc., Miami Marine Physical Laboratory, University of California, San Diego a Honeywell Regulator Company, Seattle (Deep Ocean Research Unit Ordnance Research Laboratory, Pennsylvania State University (Development Contract Administrator) Oregon State College, Corvallis (Department of Oceanography ) Ramsay Engineering Company, Anaheim, Calif. Scripps Institution of Oceanography, University of California, La Jolla Southwest Research Institute, San Antonio (Oceanography and Meteorology Division) University of Miami, Marine Laboratory, Miami University of Washington, Seattle (Department of Oceanography ) Vought Aeronautics, Dallas (Underwater Instrument Group) Woods Hole Oceanographic Institution, Woods Hole, Mass. NOTS CL 1098 (6/61) 140