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2110212 Rev 1.0 Page 93
11. Installation Considerations
The DART 300 CDPD modem is designed for stationary applications, not in-vehicle installations.
Due to the varied applications of the DART modem, there is no single correct way to install the
product. What follows are guidelines for making appropriate installation decisions.
Use the previous section on Device Attachment for information on making the actual connections
to the antenna, serial data, and power.
11.1. Environment
The standalone DART 300 is ruggedly constructed. However, it is not waterproof, so do not
locate the modem where it can get wet. Also, refer to the humidity specification in Section 14.3
below. If installing the DART 300 in a wet environment, enclose it in a proper National Electrical
Manufacturer’s Association (NEMA) enclosure.
11.1.1. Temperature and Auto Shutdown
The modem has a temperature sensor at the radio within the unit. If the radio reaches 75°C the
modem will shutdown automatically to prevent the radio from deviating from specifications.
When the modem has cooled, it will reset as though there had been a power-cycle.
Always install the unit where there is adequate ventilation to prevent possible overheating. If the
modem is transmitting on a high duty cycle, it can become quite hot inside the case. The section
below includes suggestions on allowable duty cycle for given ambient temperatures.
11.1.2. Temperature vs. Duty Cycle
The temperature within the modem is highly dependent on the duty cycle of the transmitter. If the
modem is transmitting in short bursts (3 seconds or less) at intervals of a minute or more (~5%),
there should be little problem within the nominal temperature range of the modem (-30 to +55°C).
For higher duty cycle operation, consult the chart below.
0
20
40
60
80
100
120
25 30 35 40 45 50 55
Ambient Temperature (C)
Time (minutes)
5%
10%
25%
50%
100%
This chart shows the time taken (y axis) to reach the modem’s Auto Shutdown at a given ambient
temperature (x axis) for each of the transmitter duty cycles shown in the legend. A 5% duty cycle
is sustainable at all temperatures. Higher duty cycles can be sustained for periods less than two
hours.