Method and apparatus for cordless infrared communication

An infrared receiver/transmitter (RT) module for use in a communication system using a time division multiple access communication protocol for enabling a central control unit connected to telephone lines to communicate with a plurality of portable infrared devices located within a building through a signal processing unit which produces a repetitive frame signal having time spaced transmission and receiving segments each of which includes a plurality of time spaced respective transmission and receiving slots, comprising:

• an infrared, receiver and transmitter (RT) module, said RT module including means for sending signals received from a base unit within transmission slots at an infrared carrier frequency to portable infrared devices and means for sending signals received in the form of infrared signals from portable devices within receiving slots to the base unit;
• said RT module including a signal strength detector to produce characteristic signals indicative of the strength of infrared signals occurring during respective receiving slots and incident at the RT module from infrared portable devices communicating during said respective receiving slots with the base unit;
• means for producing a reference signal indicative of a high quality infrared signal level incident on the RT module;
• and means responsive to the reference signal and a signal representative of the infrared signal incident on the RT module for producing said characteristic signals when said infrared signals incident on the RT module exceed the reference signal level.

An infrared receiver/transmitter (RT) module for use in a communication system using a time division multiple access communication protocol for enabling a central control unit connected to telephone lines to communicate with a plurality of portable infrared devices located within a building through a signal processing unit which produces a repetitive frame signal having time spaced transmission and receiving segments each of which includes a plurality of time spaced respective transmission and receiving slots, comprising:

• an infrared, receiver and transmitter (RT) module, said RT module including first means for sending signals received from a base unit within transmission slots at an infrared carrier frequency to portable infrared devices and second means for sending signals received in the form of infrared signals from portable devices within receiving slots to the base unit;
• said RT module including a signal generator, which produces characteristic signals indicative of a quality of infrared signals occurring during respective receiving slots and incident at the RT module from infrared portable devices communicating during said respective receiving slots with the base unit;
• means for producing a reference signal indicative of an acceptable quality infrared signal level incident on the RT module;
• means responsive to the reference signal and a signal representative of the infrared signal incident on the RT module for producing an enabling signal when said infrared signals incident on the RT module exceed the reference signal level;
• and
• means responsive to the enabling signal and an electrical form of the infrared signals incident upon the RT module for activating the second sending means.

An infrared receiver/transmitter (RT) module for use in a communication system using a time division multiple access communication protocol for enabling a central control unit connected to telephone lines to communicate with a plurality of portable infrared devices located within a building through a signal processing unit which produces a repetitive frame signal having time spaced transmission and receiving segments each of which includes a plurality of time spaced respective transmission and receiving slots, comprising:

• an infrared, receiver and transmitter (RT) module, said RT module including means for sending signals received from a base unit within transmission slots at an infrared carrier frequency to portable infrared devices and means for sending signals received in the form of infrared signals from portable devices within receiving slots to the base unit;
• said RT module including a signal strength detector to produce characteristic signals indicative of the strength of infrared signals occurring during respective receiving slots and incident at the RT module from infrared portable devices communicating during said respective receiving slots with the base unit;
• and means for sensing a calibration mode and means responsive to the sensed calibration mode for returning signals to a base unit for a measurement of the length of a cable coupling the RT module to the base unit.

An infrared digital and analog communication system using a time division multiple access communication protocol for enabling a central control unit connected to telephone lines to communicate with a plurality of portable infrared devices located within a building through a signal processing unit which produces a repetitive frame signal having time spaced transmission and receiving segments each of which includes a plurality of time spaced respective transmission and receiving slots, a respective pair of which is, when needed to establish communication, designated to transmit and receive signals between a portable infrared device and a base unit, comprising:

• a base unit operatively located between the signal processing unit and the portable devices for enabling communication therebetween;
• a plurality of spaced apart stationary infrared receiver and transmitter (RT) modules, interposed between the base unit and said portable devices, for transmitting and receiving infrared signals at a desired carrier frequency to and from said portable devices;
• said RT modules each including a signal processor, which produces a characteristic signal representative that the intensity or the signal-to-noise ratio of IR carrier signals from portable devices incident on the respective RT module for each receiving slot exceeds a minimum threshold level;
• a receiving signal selector in the base unit, responsive to said characteristic signals from RT modules, to select a received signal from one of several RT modules which respond to an infrared portable device transmission for transfer of the selected received signal to said signal processing unit, whereby the system's IR connection to a portable infrared device can be effectively, automatically and instantly handed off from an RT module experiencing an unacceptable infrared input signal to an RT module having an acceptable infrared input signal.