Patent ID: 7606144

Claim:
A real-time surveillance network system, with a backup mechanism and able to switch communication transmission direction in real-time, comprising: a plurality of surveillance stations, further comprising a network card, said network card having a clock reconstitution module for providing clocks and using Ethernet physical layer for transmitting a carry frame and a monitor frame, both said carry frame and said monitor frame having a data field for clock synchronization adjustment in physical layer; and a plurality of transmission segments, each said segment connecting two said stations, each said segment further comprising two independent transmission lines, and all said segments forming a double-ring loop; wherein each said surveillance station being assigned an identification (ID) during initialization of said system, and said station with the smallest ID being assigned as a master station of said system and remaining said stations being assigned as slave stations, said carry frame containing media data and control data, said monitor frame containing data regarding state of each said segment, said station switching transmission direction upon detecting said monitor frame indicating a disconnection in said segment, wherein said carry frame further comprises: a preamble (PRE) field, for clock synchronization adjustment in said physical layer; a start of frame delimiter (SFD) field for the starting of said frame; a type/length (T/L) field for the type and the length of said frame excluding the PRE, SFD and CRC fields; a unit control data (UCD) field for system control data; a media data (MD) for media data; and a cyclic redundant code (CRC) for the CRC value of entire said frame ranging from said T/L field to said MD field.