| 摘要 |
A full duplex infrared communication system suitable for use in connection with a telephone system is disclosed. The communication system includes a base station and a remote wireless set. High quality audio is provided through use of an FM sinusoidal current driven signal transmission between the base station and the remote wireless set. Further, transmission is made over bands which do not harmonically overlap. For example, the base station may transmit at 250-430 1 KHz and the remote wireless set may transmit at 1.45-1.63 MHz. Further, adverse effects of cross-talk and signal reflection are reduced by using transmission carrier signals for the base station and the remote wireless set having different wavelengths. For example, the base station may use LEDs which emit signals at a wavelength of 940 nm while the remote wireless set may use LEDs which emit signals at a wavelength of 880 nm. LEDs with slow turn-on and turn-off times, e.g., approximately 1 microsecond, are used in the Base TX to minimize harmonic radiation and Base RX desensitization. The remote TX LEDs are current driven, and have much faster turn-on and turn-off times than the Base TX LEDs, however its radiated fundamental and harmonics are much higher in frequency than the remote RX frequency and do not effect it during normal operating conditions. Further, the system does not require optical gain (lens, parabolic reflectors) and is omnidirectional.
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