YSI SonTek ADVField User Manual

SonTek/YSI
8 ADVField Operation Manual (September 1, 2001)
1.2. Definitions and Terminology
This section defines terms commonly used with the SonTek ADV.
• Ping - A single estimate of water velocity.
• Sample - A sample refers to the collection of several pings to produce a mean estimate of the
water velocity. This mean value is output for storage and analysis. In addition to velocity, sig-
nal amplitude and correlation coefficient are output with each sample.
• Pinging rate - The number of pings per second in Hz. The ADV is designed to ping as quickly
as possible. The pinging rate for the ADV under normal operating conditions ranges from 80
to 500 Hz, depending on acoustic frequency and velocity range (see §1.3).
• Sampling rate - The output rate for mean velocity data. This rate is user-programmable in the
range from 0.1 to 50.0 Hz, depending on the acoustic frequency of the ADV.
• Sampling interval - The period, in seconds, over which the ADV averages data before com-
puting the mean velocity. This is the inverse of the sampling rate (a sampling rate of 25 Hz
gives a sampling interval of 0.040 second). The number of pings averaged per sample is a
function of the sampling interval and pinging rate (a sampling interval of 0.040 s and a ping-
ing rate of 250 Hz gives 10 pings for each sample). Decreasing the sampling rate (and hence
increasing the sampling interval) increases the number of pings averaged and reduces the
noise in each sample.
• Temperature - Water temperature in °C; used for sound speed calculations. It can be either a
manual input or measured automatically by the temperature sensor (option on some systems).
• Salinity - Water salinity in parts per thousand (ppt). This manual entry is used for sound speed
calculations.
• Sound speed - Speed of sound in water in m/s; calculated from temperature and salinity. This
is used to convert the Doppler shift to velocity. See the ADV Principles of Operation for in-
formation on how sound speed affects ADV velocity measurements.
• Probe configuration file - A binary file loaded by the ADV data acquisition software (and
stored in EEPROM memory by the ADVField processor) used to specify all probe-specific pa-
rameters. This includes probe geometry, sampling volume location, sampling volume size, and
velocity range settings. See the ADVField Software Manual for details.
CAUTION: If an incor-
rect probe configuration file is specified, velocity data will be invalid.
• Sampling volume - The volume of water in which the ADV makes velocity measurements.
The center of the sampling volume (in terms of its vertical extent along the axis of the acoustic
transmitter) is nominally located a fixed distance from the probe tip: 5 cm for 10-MHz and
16-MHz ADV probes; 10 cm for 10-MHz ADV probes; or 18 cm for 5-MHz ADVOcean
probes. The exact distance from the probe tip to the center of the sampling volume is encoded
in the probe configuration file. The sampling volume is cylindrical shaped, with the axis along
the axis of the acoustic transmitter. For the 10-MHz and 16-MHz ADV probes, the cylinder is
about 6 mm in diameter and 9 mm long. For the 5-MHz ADVOcean, the diameter of this cyl-
inder is about 12 mm and the height is 18 mm. See ADV Principles of Operation for details.
• Direct command interface - Direct serial communication with the ADVField processor using
a terminal or terminal emulator (e.g.,
SONTERM [DOS] or Terminal [Windows]).

YSI SonTek ADVField Specifications

General

Brand	YSI
Model	SonTek ADVField
Category	Measuring Instruments
Language	English