Absolute Calibration

After setting up the external cold target as described in the operating manual, chapter 4.1.2, an absolute calibration can be initiated.
When the absolute calibration menu is entered the frequency list is loaded from the connected radiometer and displayed in Calibrated Frequencies. The list contains the frequencies of both receivers that will be calibrated assuming the related receivers are checked (Receiver 1, Receiver 2) in Receiver Selection. The integration time Ti is selectable between 5 Seconds and 60 Seconds (Integration Time group box) and defines the integration time period for each calibrated channel. The total integration time is given by Ttotal = 4 * Ti + 10 because four integration cycles have to be passed according to section 4.1.3.1 (four point method) and calibration mirror movements take about 10 seconds. 
Start Calibration starts the absolute calibration procedure. During calibration, the current activity is displayed in the message line. When the integration cycles have completed, the message Calibration successful! Save? is displayed and the user has to confirm to save the calibration with Continue. The absolute calibration parameters are then stored on the radiometer PC. With See Results, the calibration parameters of the current calibration are displayed. Leave the calibration menu by pressing Finished.
 If the error message No response to cold load. Calibration terminated! appears, the cold target was probably not filled with liquid nitrogen or was not installed at all.
No noise diode response. Calibration terminated! indicates a malfunction of one of the noise sources. Contact RPG for help in this case.