After selecting the desired calculator mode, press the 'Change Mode' button.
1) RMS expected in given time: enter your desired integration time (in minutes) and the central frequency of your expected line (in GHz) to determine the sensitivity in the selected units (mK or mJy).
2) Time required for target RMS: enter your desired sensitivity (in mK or mJy) and the central frequency of your expected line (in GHz) to determine the integration time required to perform the requested observation.