Software-defined radio system and method for detecting packets

A software-defined radio system for detecting packets is disclosed, including: a transmitting end configured for assigning a preamble and a postamble to a start position and an end position of a packet of a signal, respectively, before transmitting the signal; and a receiving end configured for detecting if a packet exists in the air or in a channel based on the preamble and the postamble, wherein the receiving end stores the signal in memory when detecting the preamble, and stops storing the signal in the memory and transmits the signal to a computing device when detecting the postamble. A packet detection method for a software-defined radio system is also provided.