초록 ▼

The IFF system uses basic identification codes which are transmitted between an interrogator and a responder. The basic codes are chosen in dependence upon the time and position of the interrogator or responder at the time of choice. In one version of the system, the lifetime of a code is less than

The IFF system uses basic identification codes which are transmitted between an interrogator and a responder. The basic codes are chosen in dependence upon the time and position of the interrogator or responder at the time of choice. In one version of the system, the lifetime of a code is less than or equal to the propagation time of a radio signal for a given maximum range between the interrogator or responder. Interactive interrogation may also take place using codes chosen in the same way as the basic codes. Local information may also be transmitted between the interrogator and transponder. An example of apparatus for performing these operations transmits basic or other codes together with a time code defining the time of production of the basic or other codes. It is not essential to transmit a time code in some circumstances. Position and time information may be gained from an external communications system.

대표청구항 ▼

An IFF apparatus for transmitting a first code to and receiving a second code from another IFF apparatus, comprising a transmitter for transmitting the first code, a receiver for receiving the second code, means for producing the first code either in dependence upon the time of its production and up

An IFF apparatus for transmitting a first code to and receiving a second code from another IFF apparatus, comprising a transmitter for transmitting the first code, a receiver for receiving the second code, means for producing the first code either in dependence upon the time of its production and upon the position of the apparatus or in dependence upon the time of production of the second code and upon the position of the another apparatus at the time of production of the second code, an input for receiving positional information relating to at least the direction of the another IFF apparatus relative to the apparatus, reference code producing means responsive to the positional information and to the time of production of the received code to produce at least one reference code, and means for comparing the at least one reference code with the received code.