A receiver for receiving a target signal complying with a specific communication specification comprising a specific spectrum characteristic includes a detecting module for detecting a packet of an input signal, a transforming unit for transforming the packet from a time domain to a frequency domain to derive a spectrum characteristic of the input signal, and a determining unit for determining whether the input signal is the target signal according to the spectrum characteristic of the input signal. Therefore, the proposed receiver is able to reduce packet miss rate and false alarm rate while robust to a severe channel condition, and achieve fast and accurate signal quality detection.