Valeport miniSVS Operating Manual

miniSVS

Operating Manual

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This 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
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not be disclosed to any other person whatsoever without the prior written consent of the
Company.

Valeport Limited
St Peters Quay
Totnes
Devon, TQ9 5EW
United Kingdom

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.

06508141a
09 March 2017

[phone]
[e-mail]
www.valeport.co.uk

Tel:
e mail:
Web:

Table of Contents

Page 2Page 2

Table of Contents

..................................................................................................................................... 31. Introduction

..................................................................................................................................... 42. Sensors

.................................................................................................................................... 42.1. Specifications

.................................................................................................................................... 52.2. Physical Characteristics

..................................................................................................................................... 73. Communications

.................................................................................................................................... 73.1. Sampling Modes

.................................................................................................................................... 73.2. Data Formats

.................................................................................................................................... 113.3. Wiring Information

..................................................................................................................................... 184. Operations

.................................................................................................................................... 184.1. Power Up

.................................................................................................................................... 184.2. Stop Command

.................................................................................................................................... 184.3. Command Echoes

.................................................................................................................................... 184.4. Pressure Format Commands

.................................................................................................................................... 184.5. Pressure Tare Commands

.................................................................................................................................... 194.6. Other Commands

..................................................................................................................................... 205. Appendix 1: FAQ’s

Introduction

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© 2017 Valeport Ltd

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 100 dBar range transducer is used, but the miniSVS may be fitted with
a selection of different range transducers up to 6000 dBar. The pressure option also uses
a secondary PCB.

As an alternative option, the miniSVS may be fitted with a PRT temperature sensor.

Note: the miniSVS may have either a pressure or temperature sensor fitted as an

option, but not both

miniSVS

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© 2017 Valeport Ltd

2. Sensors

2.1. Specifications

2.1.1. Power

· Requires 8 – 29V DC input

· miniSVS draws approximately 17mA at 12V DC

· miniSVS with pressure draws approximately 24mA at 12V DC

· miniSVS with temperature draws approximately 20mA at 12V DC

2.1.2. Data 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).

2.1.3. Signal Frequency

Single sound pulse of 2.5MHz frequency.

2.1.4. 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

2.1.5. 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

Sensors

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© 2017 Valeport Ltd

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.

2.2. Physical Characteristics

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.

miniSVS

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© 2017 Valeport Ltd

2.2.1. Dimensions

Dependent on type supplied. See diagram below

Communications

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© 2017 Valeport Ltd

3. Communications

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)

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}