Abstract

We propose the Allan Variance method to identify spurious signals with sensitive detectability. With this method, detection level of -56 dB with respect to the system noise can be achieved within the integration time less than 10 min. Detected spurious signals can be mitigated by masking these channels before spectral bunching to required spectral resolution. We will present the principle of the method and the performance taken through the ALMA system verification activity. This method can be applied for universal single-dish spectroscopy.