Patent ID: 6154663
Filing Date: 2000-11-28
Classification: H04M

Abstract:
A portable telephone communications system having a portable telephone terminal and a repeater unit, and a remote receiver unit, wherein:the repeater unit includes a main power supply control device which includes detection means triggered by a signal from the telephone terminal arising on receipt of an incoming call, frequency modulating means for receiving signals representative of a remote caller's voice from the telephone terminal, and converting them into a frequency modulated signal, and including infra-red transmission means for transmitting said frequency-modulated signal to the remote receiver unit;the remote receiver unit includes an infra-red receptor, demodulation means and means for outputting the demodulated signals as audible voice signals, and further comprises a noise level comparator which compares the voltage of noise generated when no infra-red signals are received with a predetermined level and delivers an output signal when said voltage exceeds the predetermined level, and a time counter which outputs a reset signal when the output from the noise comparator has been generated for a predetermined time interval, and a second power supply control device which controls the power supply to the remote receiver unit, and is arranged to switch off the power on output of a reset signal from the time counter.