YSI SonTek ADVField, Technical Documentation Manual

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SonTek/YSI
16 ADVField Operation Manual (September 1, 2001)
2.4. ADVField Autonomous Data Collection Setup
An autonomous (i.e., stand-alone or remote) deployment requires more forethought than a real-
time deployment. For example, during real-time operation, you can change your data collection
parameters “on-the-fly”, operate 24 hours per day, and collect a virtually unlimited amount of
data. However, when you deploy your system for autonomous data collection, you will not be
able to change your data collection parameters (in most cases) without first retrieving your sys-
tem. Additionally, in an autonomous deployment, you have a limited amount of battery power
and data-storage memory.
The following sections explain how to calculate power and memory requirements, and how to
prepare, set up, and deploy an ADVField for an autonomous deployment.
2.4.1. Calculating Power Requirements
During data collection, the ADV has a mean power consumption ranging from 3.5 to 5 W, de-
pending on the velocity range setting. Table 3 lists the approximate power consumption for each
velocity range.
Table 3. Approximate Power Consumption vs. Velocity Range
16/10-MHz ADV
Velocity Range
5-MHz ADVOcean
Velocity Range Power Consumption
±
3 cm/s
±
5 cm/s
3.5 W
±
10 cm/s
±
20 cm/s
3.8 W
±
30 cm/s
±
50 cm/s
4.0 W
±
100 cm/s
±
200 cm/s
4.5 W
±
250 cm/s
±
500 cm/s
5.0 W
The standard alkaline battery packs supply 18 V with a nominal capacity of 42 Ah. Lithium
packs supply 21.6 V with a nominal capacity of 84 Ah. When calculating battery life, we recom-
mend using 80% of the nominal capacity. This allows for temperature variations (nominal ca-
pacities are at 20
°
C) and a reasonable safety margin. Thus, alkaline and lithium packs have work-
ing capacities of (0.8 * 18 * 42 = 600 Wh) and (0.8 * 21.6 V * 84 Ah = 1450 Wh) respectively.
The standard system configuration uses either two alkaline or two lithium battery packs wired in
parallel. Two alkaline packs have sufficient power for 10-14 days of continuous operation; two
lithium packs have sufficient power for 24-34 days of continuous operation (both depending on
the velocity range setting).
For most applications, the ADVField uses a reduced duty cycle to conserve battery power and ex-
tend deployment length. See §1.3 for a description of how to calculate the duty cycle. When not
actively collecting data, the ADV consumes less than 1 mW of power. The battery life increases
proportionally with the duty cycle. A 50% duty cycle will double the battery life; a 10% duty cy-
cle increases battery life by a factor of 10.
2.4.2. Calculating Memory Requirements
The ADV records between 8 and 22 bytes of data per sample. See §3.7 for a description of the
recording options and to help determine the number of bytes that will be stored with each sample.
Computing the amount of memory required for a deployment is done in three steps.