| 摘要 |
PROBLEM TO BE SOLVED: To inexpensively build a message transmission system and to secure a wide communication area, and then, to convey messages in utmost secrecy. SOLUTION: A low-speed frequency hopping private radio system is constituted of radio zones ZA, ZB, and ZC composed of master radio equipment A0, B0, and C0 connected to a host computer and (n) sets of slave radio equipment A1-An, B1-Bn, and C1-Cn connected to POS terminal equipment TA1-TAn, TB1-TBn, and TC1-TCn. By using radio cards CD1-CDm provided with displays and buzzers, a specific hopping frequency f0 is assigned to the cards CD1-CDm and a message is transmitted to the cards CD1-CDm from the master and slave radio equipment by using the hopping frequency f0. When the cards CD1-CDm receive the message, the cards CD1-CDm inform their users of the reception of the message by actuating their buzzers and, at the same time, display the message on their displays. |
