Communication apparatus, communication system, and key opening/closing controlling method

A non-transitory computer readable medium storing a program for operating a communication apparatus, the program being executable by at least one processor to perform operations comprising:

• measuring a phase characteristic of a frequency of a propagation channel to and from another communication apparatus;
• generating a time response characteristic from the phase characteristic, the time response characteristic including a waveform component;
• and
• performing a determination on whether or not an obstacle is interposed between the communication apparatus and the another communication apparatus on a basis of the waveform component of the time response characteristic, wherein
• the waveform component is one of a plurality of waveform components including a preceding wave component and a delayed wave component, and
• the determination is performed on a basis of a component ratio between the preceding wave component and the delayed wave component in the time response characteristic.

A method for controlling a communication apparatus, the method comprising:

• measuring a phase characteristic of a frequency of a propagation channel to and from another communication apparatus;
• generating a time response characteristic from the phase characteristic, the time response characteristic including a waveform component;
• and
• performing a determination on whether or not an obstacle is interposed between the communication apparatus and the another communication apparatus on a basis of the waveform component of the time response characteristic, wherein
• the waveform component is one of a plurality of waveform components including a preceding wave component and a delayed wave component, and
• the determination is performed on a basis of a component ratio between the preceding wave component and the delayed wave component in the time response characteristic.