05453748 is referenced by 23 patents and cites 19 patents.

A transponder receives a stable reference frequency transmitted from an interrogator and compares the stable reference frequency to a local oscillator frequency that has short term stability. A comparison signal is provided to a synchronous oscillator for providing a locked signal that briefly locks onto the comparison signal and "remembers" its phase and frequency characteristics. The locked signal, which is inherently locked to the stable reference signal of the interrogator, is then combined with the short-term stable local oscillator frequency, and the combined signal is used in the up-converted reply back to the interrogator.

Title
Method and apparatus for responding to an interrogation signal
Application Number
8/152800
Publication Number
5453748
Application Date
November 15, 1993
Publication Date
September 26, 1995
Inventor
Kevin W Lindell
Trumbull
CT, US
Agent
Christopher O Edwards
Assignee
Westinghouse Norden Systems
CT, US
IPC
G01S 13/79
View Original Source