  In an axion haloscope, the weak photon signal, theoretically converted from
axions, is captured by a detection cavity. The amplification chain assists the
signal receiver to read the signal from the cavity and requires accurate
calibration. Typically, the readout line is calibrated using the Y-factor
method, involving a switch that directs the signal from either the detection
line or the calibration line. However, this switch introduces several
disadvantages. In response, we propose a calibration method that eliminates the
need for a switch. In this approach, the cavity temperature is decoupled to its
incoming noise source and can be controlled, resulting in excess or deficiency
of the noise spectrum near its resonance frequency. The experimental result
shows that the amplification chain can be calibrated directly using the
temperature-varied cavity-emitted radiation.
