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Acousonde™ Tips & Tricks

Updated 9 April 2013

Following some rules of thumb can improve your experience with the Acousonde. Here are a few less-than-obvious techniques.



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Preparation

Break in batteries that have been on the shelf
Lithium primary cells that have been in storage for months or longer, particularly in warm temperatures and especially if used before storage, may have accumulated a form of internal resistance known as a passivation layer. Using the battery will gradually break down this layer, but not without initial risk of premature failure due to this temporary resistance. To "break in" a battery suspected of passivation we recommend placing the battery in the Acousonde backwards, thereby operating the reverse-battery warning light, for 5 to 10 minutes before use. This should not be necessary for fresh, newly manufactured batteries.
Ensure battery surface is clean and dry
Contaminants on the battery surface, particularly when combined with condensation due to excessive moisture inside the battery compartment, may increase power leakage from the battery and shorten deployment life. If the battery has not been kept clean and dry, it may be necessary to wipe the entire battery surface with an alcohol-moistened tissue.
Insert battery under driest conditions possible
When inserting the battery and sealing the housing, do so under the driest conditions possible, especially for deployments in cold water. This will limit the risk of condensation inside the housing.
Clean the battery contacts
Dirty contacts in the Acousonde battery compartment or on the battery itself can introduce resistance that will shorten deployment life. Clean all Acousonde and battery contacts before deployment by lightly swabbing with isopropyl alcohol.
Use high-purity alcohol for cleaning
Isopropyl alcohol, while a fine cleaning agent for battery contacts, is often found in solutions including up to 30% water. The water may take much longer to evaporate than the alcohol, leading to the risk of excess humidity and condensation within the battery compartment and consequently shorter deployment life. Use the highest-purity isopropyl alcohol available to clean contacts.
Grease the threads
Bare aluminum oxidizes immediately on contact with air, leaving a microscopic insulating layer. To discourage the formation of this insulation on the threads of the battery housing and battery cap, do not clean the threads without regreasing them with silicone grease. If in doubt, screw the battery cap all the way in a few times after greasing, while at the same time pulling on the battery cap, to mechanically wear off any existing oxidation.
Use a compliant spacer to secure the battery
The battery housing is designed to accommodate batteries whose length is at the upper limit of manufacturer tolerance. Most batteries are shorter than this and will be able to move within the housing. To minimize battery movement, place a compliant spacer -- such as a nylon washer, or an o-ring selected or cut to fit -- in the bottom of the battery cap. This will help restrict movement of the battery during deployment.
Tighten the battery cap very securely
A secure ground connection depends on tight electrical connection through the battery housing threads. Motion combined with changes in pressure and temperature may cause the threads to loosen slightly, creating a power-failure risk. To discourage this, tighten the battery cap well. To tighten the "dome" battery caps that come with the Acousonde 3B, we recommend using a jumbo flat screwdriver to get sufficient leverage. For the cylindrical caps that come with the Acousonde 3A, we recommend using a rubber mitt, or wrapping the cap in self-vulcanizing rubber tape, to allow you to grip it tightly without slipping. We are planning to add flats to new 3A battery caps to allow use of a wrench.
Check float-retention tabs on the 3B
The glue used to secure the Acousonde 3B float-retention tabs has survived over a month of seawater soaking as well as freeze-thaw cycling. We believe it to be a permanent attachment. However it does not hurt to verify that the tabs are secure before deploying the instrument. If by chance a tab attachment point is loose, use a swab soaked in isopropyl alcohol to clean the contact areas of the tab and the urethane, wait for them to dry, and insert a small amount of superglue to reattach.
Consider a grip-retention lanyard
If the deployment grip you are using could separate from your attachment pole, the weight of the grip would overcome the flotation attached to the tag and the entire assembly could be lost at sea. If there seems any chance of the deployment grip separating, use a lanyard to tie the grip to a secure location on the deployment pole.
Serial numbers B003A003-4 and B003A007-12: tape front end
These eight Acousonde 3A units contain a component that is sensitive to very bright sunlight and incandescent light. If the component is exposed to this kind of light when the instrument is first powered up or when sampling is started -- including an unattended delayed start -- the hardware may fail to operate, the operating system will shut down, and full removal and reapplication of power may be necessary (an ordinary magnetic-switch reset may not be enough). The problem is avoided by wrapping black tape circumferentially around the 3A in the region of the component, located on the same side of the instrument as the pressure transducer about 4.2 cm (1 5/8") back from the hemispherical leading edge of the urethane encapsulant. About 4 cm (1 1/2") width of tape coverage, centered on the component's position, should suffice to shade it; it is not necessary to wrap the entire unit. This is only recommended for the specific units stated! The issue has been fixed in later units.

Operation

Verify correct clock setting
The Control page of the PalmOS command application shows the Acousonde's time-of-day setting after every infrared interaction with the Acousonde. Use this indication to check if the Acousonde has been successfully set to the correct time.
Verify operation using top-of-minute LED flash
The Acousonde produces a visual indication of status at the top of every minute. Do not deploy the Acousonde without waiting for at least one top-of-minute indication to verify correct operation (as well as correct alignment of the Acousonde's clock).

Offloading data

Offload one volume at a time
It is possible to ask a USB host Mac OS X or Windows computer to offload data from multiple volumes of a given Acousonde simultaneously; however, we strongly discourage this. Simultaneous offloading can take much longer than offloading one volume at a time and may wear out the storage cards prematurely.

This is because an Acousonde is not able to power or communicate with more than one of its storage cards at a time. Multiple storage volumes do appear to be mounted on the USB host computer but this is a kind of illusion. In reality all but one of the underlying storage cards are turned off.

If asked to offload data from multiple volumes simultaneously via USB, the Acousonde must frenetically power its storage cards on and off to maintain the illusion. Each time a card is turned on, data transfer must be suspended until the lengthy card-restart process completes. Thus, if asked to transfer data from multiple volumes simultaneously, the Acousonde may spend more time waiting for card-restart to complete than it does actually reading card data.

Data transfer from a given Acousonde is much faster, not to mention easier on the equipment, when done one volume at a time.


Identifying a suitable spare or replacement MicroUSB-to-USB cable

Use a MicroUSB-to-USB cable that is fully wired for data
Some MicroUSB cables for mobile phones and related appliances provide only power, not data. These cables may look usable, and indeed may fit in the Acousonde and allow it to boot normally; however, the contents of the Acousonde will not be accessible from your personal computer.
Get a MicroUSB-to-USB cable that fits in the battery housing
The Acousonde battery housing cannot accommodate all MicroUSB-to-USB cables. Some cables' finger-grip section, molded around the MicroUSB plug, is too large to fit in the housing while still allowing the plug itself to mate with the MicroUSB socket at the housing's deep end. Such cables cannot be used with the Acousonde.

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