| 摘要 |
A warning system is provided to enable an owner to find out a stolen article easily by generating a warning sound. A first warning unit transmits a radio signal with a first frequency and receives a radio signal with a second frequency, and generates a warning sound when the radio signal with the second frequency is not received. A second warning unit transmits the radio signal with the second frequency and receives the radio signal with the first frequency, and generates a warning sound when the radio signal with the first frequency is not received. |
