Specifications

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The Em50R operates on five AA b atteries for a duration of five to six months. Its sensor
interface is limited to SE 12-bit analog. A stereo head-phone jack with excitation, signal,
and ground is the standard hardware interface for sensors. This requires that the Em50R
use Decagon’s sensors only. The cost of the system is anywhere from $400 to $600 making
it a very reasonable solution cost-wise.
The Em50R d oes appear to be an excellent solution for multi-site monitoring. As seen
above, the logger satisfies the low-power, cost, ruggedness, and radio requirements. It does
not satisfy the n ecessary interface capability because it does not support SDI-12 or digital
sensors. It also does not allow for any other sensors to be u sed with this sy s tem. Lastly,
it does not support any data-basing features like automatic data routing and storage. A
significant effort in design is required to make centralized storage possible.
2.6 Summary of Product Reviews
Various products from several manufactures th at specialize in the collection of agri-
cultural data have been evaluated. All systems were compared to the list of s pecified
requirements. Every one of the pr oducts discussed in sections 2.5.1-2.5.4 satisfies the power
requirements and all can interface to a type of radio. However, none of these products
deliver a complete networked system with all the features expressed in section 1.3. All of
these loggers work well and have their place in providing services to their respective target
commu nities. However, no currently available product supports all the required set of fea-
tures f or distribu ted networking at the desired cost point. Although all the products offer
various forms of wireless communication, none of them establish a network, create data
routing paths, or store data in a central location automatically. Therefore, a need exists to
develop a system that has been targeted to distributed networking.