A
cordless modem comprises a radio pair interfaced to a standard data / fax modem which allows a user of a
personal computer to wirelessly connect to a
telephone line. One end of the radio pair is a
remote unit interfaced to the modem contained within the PC while the other end is a base unit connected to a standard telephone wall jack. The base unit can selectively discriminate and adjust for signals received from a telephone voice
handset or data signals received from the
cordless modem
remote unit. Upon receiving an off-hook
signal or an incoming call
signal, the base unit identifies the type of data (i.e., voice or computer modem data) and adapts accordingly by placing an FM modulator in either of a
narrow band deviation or a
wide band deviation covering the required range of the particular
signal combined with local echo. That is, when
voice data is present, a low deviation, narrow filter combination is selected. If, on the other hand, the computer data from the
cordless modem is detected, a higher deviation, wider bandwidth filter is selected. In addition, the
remote unit switches a pre-
detection filter from one mode to another depending on whether it is connected to a computer modem or to a voice
handset. Security from eavesdroppers as well as the mitigation of signal
fading is provided by overlaying a pseudo-random number (PN) code on the FM modulated signal.