Portable security system using communicating cards

A portable security system comprising a series of cards, a first one of the cards adapted for wireless communication with the other cards, each card being sized sufficiently small as to be capable of being accommodated within a card compartment Of a wallet and having a plastic body housing:

• (a) a memory holding one or more digital identification codes for identifying the card;
• (b) a carrier signal generator;
• (c) modulation means for modulating the carrier signal with the one or more identification codes in the memory;
• (d) an antenna;
• (e) a transmitter connected to the antenna for intermittently transmitting the modulated carrier signal;
• (f) a receiver connected to the antenna for intermittently receiving a modulated carrier signal;
• (g) demodulation means for demodulating the carrier signal to obtain a digital code carried in that signal;
• and,
• (h) a comparator means for determining if a correspondence exists between one of the one or more identification codes in the memory and the digital code carried in the received modulated carrier signal;
• the first card also housing an alarm means;
• whereby, within a defined communication range, a modulated carrier signal intermittently transmitted by the first card is adapted to create a correspondence in the comparator means on each of the other cards, whereby on creation of such correspondence on each other card that other card is adapted to transmit a return modulated carrier signal to the first card, whereby each of the return modulated carrier signals is adapted to create a correspondence in the comparator means on the first card, and whereby the alarm means on the first card is actuated if such correspondence is not created in the comparator means on the first card by each of the return modulated carrier signals after a defined number of transmissions of the modulated carrier signal by the first card.

A portable security system comprising a series of cards, a first one of the cards adapted for wireless communication with the other cards, each card being sized sufficiently small as to be capable of being accommodated within a card compartment of a wallet and having a plastic body housing:

• (a) a memory holding one or more digital identification codes for identifying the card;
• (b) a carrier signal generator;
• (c) modulation means for modulating the carrier signal with the one or more identification codes in the memory;
• (d) an antenna;
• (e) a transmitter connected to the antenna for intermittently transmitting the modulated carrier signal;
• (f) a receiver connected to the antenna for intermittently receiving a modulated carrier signal;
• (g) demodulation means for demodulating the carrier signal to obtain a digital code carried in that signal;
• and,
• (h) a comparator means for determining if a correspondence exists between one of the one or more identification codes in the memory and the digital code carried in the received modulated carrier signal;
• the first card also housing an alarm means;
• each of the other cards also housing an activation switch and not being in communication with the first card until the activation switch on the particular other card is activated, the first card being adapted to be made aware of which of the other cards have been so activated;
• whereby, within a defined communication range, a modulated carrier signal intermittently transmitted by the first card is adapted to create a correspondence in the comparator means on each of those other cards which are activated, whereby on creation of such correspondence on each of those activated other cards each such activated other card is adapted to transmit a return modulated carrier signal to the first card, whereby each of the return modulated carrier signals is adapted to create a correspondence in the comparator means on the first card, and whereby the alarm means on the first card is actuated if such correspondence is not created in the comparator means on the first card by each of the return modulated carrier signals after a defined number of transmissions of the modulated carrier signal by the first card.