1. A portable heating chamber system for pyrometric proficiency testing, comprising: an enclosing structure defining an interior zone and an exterior zone; within the interior zone, one or more air circulating means and one or more heat sources; a data acquisition device located in the exterior zone; multiple temperature sensors uniformly distributed within the interior zone, wherein each temperature sensor transmits sensor temperature data to the data acquisition device through a wired or wireless connection; a control sensor located at or near the center of the interior zone; in the exterior zone, a temperature controller which receives control temperature data from the control sensor and responds to the control temperature data by transmitting temperature control signals to the heat sources through one or more wired or wireless connections; wherein the temperature control signals are adapted and configured to achieve and maintain a constant and uniform control temperature in the interior zone; wherein the data acquisition device is adapted and configured to receive and record the sensor temperature data from each temperature sensor at regular intervals for a set test duration and to record a high and low temperature for each temperature sensor for the test duration; wherein the data acquisition device has multiple input channels, each of which is adapted and configured to receive the sensor temperature data from one of the temperature sensors; and wherein associated with each of the temperature sensors is a sensor correction factor, and wherein associated with each of the input channels is a channel correction factor.