Valeport miniSVS User manual

© Valeport Limited
miniSVS Operating Manual Page 1 0650808J.doc
VALEPORT LIMITED
miniSVS
Sound Velocity Sensors
Operating Manual
Document Ref: 0650808
Document Version: J
Date: July 2011
This confidential document was prepared by the staff of Valeport Limited, the Company, and
is the property of the Company, which also owns the copyright therein. All rights conferred
by the law of the copyright and by virtue of international copyright conventions are reserved
to the Company. This document must not be copied, reprinted or reproduced in any material
form, either wholly or in part, and the contents of this document, and any method or
technique available therefrom, must not be disclosed to any other person whatsoever
without the prior written consent of the Company.
Valeport Limited, Tel: [phone]
St Peters Quay, Fax: [phone]
Totnes, e-mail: [email protected]
Devon, TQ9 5EW, Web: www.valeport.co.uk
UK
As part of our policy of continuous development, we reserve the right to alter, without prior
notice, all specifications, designs, prices and conditions of supply for all our equipment.
Copyright 2011

© Valeport Limited
miniSVS Operating Manual Page 2 0650808J.doc
CHAPTER DESCRIPTION PAGE
1INTRODUCTION..................................................................................3
2SPECIFICATIONS ...............................................................................4
3DATA REQUESTS AND OUTPUT FORMATS ....................................7
4WIRING INFORMATION....................................................................14
APPENDIX 1: FAQ‟S..................................................................................................18

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1 INTRODUCTION
The Valeport miniSVS Sound Velocity Sensor has been designed with the objective of
providing high resolution, high accuracy sound velocity data in the most compact
package possible. The basic principle of Valeport‟s Sound Velocity technology is “time
of flight”; that is to say, the sound velocity is calculated from the time taken for a single
pulse of sound to travel a known distance.
The miniSVS therefore consists of a single circuit board controlling all sampling,
processing and communications functions, and a sensor comprising a ceramic
transducer, a signal reflector, and spacer rods to control the path length. The two are
connected by a single coaxial cable. A titanium housing may be fitted, which provides
waterproof protection to a depth in excess of 6000m.
Optionally, a strain gauge pressure sensor may be added to the miniSVS, enabling
sound velocity profiles to be obtained. This configuration is used in the SoundBar 2
Digital Bar Checker, where a 100dBar range transducer is used, but the miniSVS may
be fitted with a selection of different range transducers up to 6000dBar. The pressure
option also uses a secondary pcb.
As an alternative option, the miniSVS may be fitted with a PRT temperature sensor.
Note that as standard the miniSVS may have either the pressure
or temperature sensor fitted as an option, but not both

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2 SPECIFICATIONS
Dimensions: Dependent on type supplied. See diagram below
Connections:
Internal Co-axial connector to sensor (J3)
5 –way Harwin (power and comms) (J1)
NB: J2 & J4 are for Valeport calibration and setup purposes –not for
use by customer.
External Standard is Subconn type MCBH6F (In titanium on titanium housings,
in brass on acetal housings)
Alternatives may be supplied on request
Wiring Information is in Section 4

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Materials:
Main housing Titanium or acetal
Main bulkhead Titanium
Space Rods Carbon Composite
Reflector Assembly Titanium
SV Transducer Ceramic transducer behind polycarbonate window.
Signal cable 3mm co-ax cable, nominal 25cm length. Push fit connector.
Pressure Transducer Stainless steel diaphragm with acetal protective cover.
Temperature sensor PRT in titanium housing with polyurethane backing.
Power:
Requires 8 –29V DC input
miniSVS draws approximately 17mA at 12vDC
miniSVS with pressure draws approximately 24mA at 12vDC
miniSVS with temperature draws approximately 20mA at 12vDC
Output:
Units are fitted with both RS232 and RS485 communications as standard. RS485 is
enabled by grounding a pin in the communications lead (refer to Section 4). Protocol
is 8 data bits, 1 stop bit, no parity, no flow control.
Baud rate is factory set to 19200. User may choose between 2400, 4800, 9600,
19200, 38400, 57600 or 115200. (Note that fast data rates may not be possible with
low baud rates).
Signal Frequency:
Single sound pulse of 2.5MHz frequency.
Update Rate:
Selected by command –Single output or continuous output at one of the following
rates: 1Hz, 2Hz, 4Hz, 8Hz ,16Hz, 32 Hz or 60Hz
.
The fastest rate possible is determined by the combination of sensors fitted:
SV only
SV + P
SV + T
Max Data Rate:
60Hz
32Hz
16Hz

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Performance:
Sensor
Resolution
Range
Overall Accuracy
25mm
0.001m/sec
1375 –1900m/s
±0.020 m/s
50mm
0.001m/sec
1375 –1900m/s
±0.019 m/s
100mm
0.001m/sec
1375 –1900m/s
±0.017 m/s
Pressure
0.01% FS
0 to 100, 500, 1000 or 6000 dBar
±0.05%FS
(over -10°C to 40°C)
Temp.
0.001°C
-5 to +35°C
(others available)
±0.01°C
Certain features of the sensor package are designed specifically to enable high quality
data to be delivered:
Carbon
Composite
Rods:
The carbon composite material used for the sensor spacer rods has
been specifically selected to provide 3 features:
a) Excellent corrosion resistance
b) Very high strength
c) Virtually zero coefficient of thermal expansion
This last point is particularly important; accurate sound velocity
measurement relies on measuring the time taken for a pulse of sound
to travel a known distance. The material selected does not
measurably expand over the operating temperatures of the
instrument, ensuring the highest possible accuracy at all times.
Size:
The longer the path length used, the higher the accuracy that can be
achieved. It has been found that a signal stability of ±2mm/sec can
be achieved with a sensor path length of 25mm (overall 50mm path
for reflected signal), falling to ±1.7mm/sec for a 100mm path (overall
200mm path for reflected signal).
Digital
Sampling
Technique:
Enables a timing resolution of 1/100th of a nanosecond, equivalent to
about 0.5mm/sec speed of sound on a 25mm path sensor, or
0.125mm/sec on a 100mm sensor. In practice, the output is restricted
to 1mm/sec resolution.
Linear sensor performance allows easy calibration.

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3 DATA REQUESTS AND OUTPUT FORMATS
The miniSVS has 3 different sampling modes, and a selection of data output formats.
Each mode is available with each output format.
3.1 SAMPLING MODES
Single [data on request]
Multiple at defined data rates [free running]
Multiple as fast as possible [free running]
3.1.1 SAMPLING COMMANDS
S<enter> Demands a single reading to be taken and data transmitted
M<enter> Unit free runs at fastest data update rate
M1<enter> Unit free runs at 1 Hz
M2<enter> Unit free runs at 2 Hz
M4<enter> Unit free runs at 4 Hz
M8<enter> Unit free runs at 8 Hz
M16<enter> Unit free runs at 16Hz
M32<enter> Unit free runs at 32Hz
M60<enter> Unit free runs at 60Hz
3.2 DATA FORMATS
Data output is dependent on the parameters fitted to the miniSVS and the output format
selected.
Pressure data format is dependent on sensor range, and may be any of the following.
Pressure value is in dBar (abs), and leading zeroes are included, so it is a fixed length
string:
PPPP.P (e.g. 1234.5 dBar)
PPP.PP (e.g. 123.45 dBar)
PP.PPP (e.g. 12.345 dBar)

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Temperature data format is fixed to a 5 digit string with 3 decimal places. Temperature
value is in °C and leading zeroes are included; it is signed only if negative. Examples:
21.456
02.769
-01.174
In the examples below, pressure data is expressed as {pressure} and the temperature
data is expressed as {temperature}
3.2.1 VALEPORT STANDARD FORMAT
#082;off Sets data format to standard Valeport mode (SV in mm/s)
SV only
<space>1234567<cr><lf>
where 1234567 is the speed of sound in mm/sec [i.e. 1234.567 m/sec]
P + SV
<space>{pressure}<space>1234567<cr><lf>
where 1234567 is the speed of sound in mm/sec [i.e. 1234.567 m/sec]
T + SV
<space>{temperature}<space>1234567<cr><lf>
where 1234567 is the speed of sound in mm/sec [i.e. 1234.567 m/sec]
P + T + SV
<space>{pressure}<space>{temperature}<space>1234567<cr><lf>
where 1234567 is the speed of sound in mm/sec [i.e. 1234.567 m/sec]
3.2.2 ALTERNATIVE FORMAT #2:
#082;2 Sets SV data format to metres per second to 2 decimal places.
SV only
<space>1234.56<cr><lf>
where 1234.56 is the speed of sound in m/s
P + SV
<space>{pressure}<space>1234.56<cr><lf>
where 1234.56 is the speed of sound in m/s

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T + SV
<space>{temperature}<space>1234.56<cr><lf>
where 1234.56 is the speed of sound in m/s
P + T + SV
<space>{pressure}<space>{temperature}<space>1234.56<cr><lf>
where 1234.56 is the speed of sound in m/s
3.2.3 ALTERNATIVE FORMAT #3:
#082;3 Sets SV data format to metres per second to 3 decimal places.
SV only
<space>1234.567<cr><lf>
where 1234.567 is the speed of sound in m/s
P + SV
<space>{pressure}<space>1234.567<cr><lf>
where 1234.567 is the speed of sound in m/s
T + SV
<space>{temperature}<space>1234.567<cr><lf>
where 1234.567 is the speed of sound in m/s
P + T + SV
<space>{pressure}<space>{temperature}<space>1234.567<cr><lf>
where 1234.567# is the speed of sound in m/s
3.2.4 CSV FORMAT (SBE CT FORMAT)
#082;csv Sets the miniSVS to output in CSV/SBE CT mimic mode
TTT.TTTT,CC.CCCCC,SSSS.SSSS,VVVVV.VVV <cr><lf>
This format mimics the SBE output format, where:-
TTT.TTTT is temperature value
CC.CCCCC is conductivity value
SSSS.SSSS is salinity value
VVVVV.VVV is sound velocity in m/s
In this format, the miniSVS will substitute zeroes for parameters it cannot
measure.

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3.2.5 SEABIRD CTD FORMAT
#082;SEABIRD Sets the miniSVS to output in Seabird CTD mimic mode
TTT.TTTT,CC.CCCCC,PPPPP.PPPP, SSSS.SSSS,VVVVV.VVV <cr><lf>
This format mimics the Seabird CTD output format, where:-
TTT.TTTT is temperature value
CC.CCCCC is conductivity value
PPPPP.PPPP is the pressure value
SSSS.SSSS is salinity value
VVVVV.VVV is sound velocity in m/s
In this format, the miniSVS will substitute zeroes for parameters it cannot
measure. Leading zeroes are replaced with spaces
NB. This output format is only available from firmware version 0650713B5
3.2.6 AML SVT FORMAT
#082;AML_SVT Sets the miniSVS to AML SVT mimic mode
<space>{temperature}<space><space>1234.567<space><space><cr><lf>
where 1234.56 is the speed of sound in m/s
In this format, the miniSVS will substitute zeroes for parameters it cannot
measure.
3.2.7 MVP FORMAT
#082;MVP Sets the miniSVS to MVP mode
<space>pppp.p<space><space>ssss.ss<space><space>tt.ttt<space><cr><lf>
Where
pppp.p denotes pressure/depth
ssss.ss denotes speed of sound
tt.ttt denotes temperature
In this format, the miniSVS will substitute zeroes for parameters it cannot
measure.