Back to results
US 5,402,104 AGranted
Scanning excessive separation alarm
OwnerLazaro LaRosainventor
Life of this patent
Estimating the term…
Abstract
An asset protection transponder, which may be attached to a set of keys, a car, a brief case, or even a person, transmits a response signal when queried by a transponder-pager worn by the user. The transponder-pager transmits a query signal automatically at appropriate intervals. Each asset protection transponder is on a different frequency and tone encoder setting. The transponder-pager provides both an audible and visible alarm that tells the user which asset is out of range. A test circuit lets the user poll each of the asset protection transducers to make certain that it is still within range.
Claims6
An asset protection alarm comprising;
- one or more miniature asset protection transponders that are attached to assets that are to be protected;
- and
- a transponder-pager that is in radio communication with said miniature asset protection transponders such that if the distance between any of said asset protection transponders and said transponder-pager exceeds some preset limit, said pager causes an alarm to sound, said transponder-pager comprising;
- a transmitter;
- a receiver;
- an antenna;
- a transmit/receive switch;
- a transponder logic circuit;
- and
- a scanning logic circuit and alarm means;
- such that
- when said transponder-pager initiates a query of all assets, said transmitter outputs a signal whose frequency is determined by said scanning logic circuit, wherein said transmitter output signal is conducted to said antenna via said transmit/receive switch, and wherein if a response signal from an asset protection transponder is received, said signal incident upon said antenna is directed by said transmit/receive switch to said receiver by instructions generated by said transponder logic circuit, wherein the frequency of said receiver is always the same as the frequency of said transmitter, such that if one asset protection transponder is assigned to each of said frequencies, then said receiver will receive a distinguishable signal from each of said asset protection transponders (if each of said asset protection transponders is within range).
9 more elements
Dependencies are inferred from the claim text.