U.S. Wireless Data USWD500, Руководство пользователя

Страница: 36 / 58

USWD500 User’s Manual Version 3.0 - 32 -
Chapter 4
Integration Considerations
This chapter provides OEMs (Original Equipment Manufacturers) with discussions
of critical research and development (R&D) issues that must be considered to
ensure successful integration of the USWD500 CDPD Modem into their host
platforms. This overview identifies your areas of responsibility and U.S. Wireless
Data’s level of support required to resolve each issue. The following list
summarizes the R&D procedures, including many tasks that you need to perform
when integrating the USWD500 Modem.
Determining End Product Use
Because all design considerations are driven by an effort to meet the needs of the
final user, it is important to have a clear understanding of how the end product will
be used. For example, design issues related to a mobile device (e.g. POS
terminal), such as the EMI (electromagnetic interference) generated by a vehicle’s
engine and vibration, are completely different from considerations required for a
fixed telemetry application device. Knowing what is and what is not important to
the end user helps make engineering decisions in every product design.
It is your responsibility to develop the usage model. U.S. Wireless Data is
available to provide assistance and answer questions related to the USWD500
CDPD Modem, but is not directly involved in this phase.
Amount and Frequency of Messages Sent/Received
It is important to determine how much and how often data will be sent in each of
the uplink (terminal to network) and downlink (network to terminal) directions.
Does the end user turn the terminal on and run for a long time (e.g. 8 hours a
day)? Does the user turn on the unit only when making a query to the host
system? This information has a critical influence on the requirement for battery
capacity and the values of sleep mode.
You are responsible for developing the message model. A helpful approach for
creating this model is to define the peak and average throughput requirements
based on input from the user.
Hardware Design Considerations
The process of integrating the USWD500 CDPD Modem into a hardware design
requires many considerations, such as power requirements, heat dissipation, and
physical mounting of the unit to ensure proper grounding.