An environmentally controlled conveyor system including a sensor-instrumented conveyor belt conveying products continuously through a thermal-treatment process and a method for determining the instantaneous position of the sensors. Temperature or other sensors are embedded in the conveyor belt across its width and along its length to advance with the product through the thermal-treatment process, such as through a pasteurizer tunnel. The sensor measurements are transmitted wirelessly from the belt to a remote system controller for monitoring or controlling the system. Data from sensors measuring environmental or belt conditions are used to determine the instantaneous positions of the sensors to coordinate the sensor data with sensor position.