The RF Temperature Transmitter
This component is positioned permanently inside the trailer, ideally adjacent to the return air inlet of the refrigeration unit. It consists of an environmentally hardened temperature sensor, a 3.7 volt lithium battery, a low power FM digital transmitter and an antenna, all encased in a completely sealed food safe polypropylene housing.
The transmitter carrier frequency is 434MHz with an operating range of one hundred metres. A unique four digit identity number and the current temperature in degrees Celsius, at half-degree resolution, are transmitted at intervals of approximately one minute. The identity number is also printed onto the housing, together with its bar code version. Under normal operating conditions, the battery has a life of approximately four years. |