
11. Installation Considerations
The DART 300 CDPD modem is designed for stationary applications, not
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
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
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(minutes) | 80 |
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Time | 40 |
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| 25 | 30 | 35 | 40 | 45 | 50 | 55 |
Ambient Temperature (C)
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.
2110212 Rev 1.0 | Page 93 |