Patent ID: 6934315

Claim:
A cordless telephone on Frequency Hopping Spread Spectrum (FHSS) system comprising: a handset unit; a base unit including a main controller of said base unit, a storing unit of said base unit, and a communication unit of said base unit communicating with said handset unit; wherein said handset unit i) measures field strength on a channel for use in communication, and ii) when communicating condition of the channel is determined to be bad based on a result of the measurement, grades the channel as an inferior channel and notifies the base unit of the value of the field strength together with a channel number; and said base unit i) stores the channel number and the field strength in said storing unit of said base unit, and ii) when the number of the inferior channels has become not less than a predetermined number and when notified by said handset unit of information about a further inferior channel, compares field strength of the inferior channel with the field strength value of the stored inferior channel, determines the channel of better communicating condition as the channel to be used, and sends said handset unit a notice to switch the channel for use in communication to the channel to be used.