Signal processing apparatus, system and method for automatic gain control using the same

The present invention relates to a signal processing apparatus, and a system and a method for automatic gain control using the same. The signal processing apparatus comprises: a frequency sweeping unit for outputting a signal (S) to sweep each channel frequency within a given range by a receiver; a signal level detecting unit for detecting a signal level of each channel by reading, from the receiver, a gain value determined when each channel frequency is swept; and a take over point (TOP) adjusting unit for changing a TOP value of the receiver according to the detected signal level of each channel. The signal processing apparatus and the system and the method for automatic gain control according to the present invention are able to improve operational characteristics of a receiver in a strong electric field or a weak electric field. [Reference numerals] (110) Frequency sweeping unit;(120) Signal level detecting unit;(130) TOP adjusting unit