Low-power, infrared information transmission system

An infrared information transmission system comprising:

• (a) a low-power portable transmitter module including:
• (i) data input means for receiving an input signal representative of data to be transmitted;
• (ii) battery means for providing power from a battery source to power said transmitter module;
• (iii) a pulse position modulator circuit coupled to said data input means, said pulse position modulator circuit including timing means for generating pulses controllably positioned in time, within a predetermined modulation range from a reference frequency in dependence upon said input signal;
• and
• (iv) an infrared light-emitting device coupled to said pulse position modulation circuit for receiving pulses generated thereby, said light-emitting device generating infrared energy bursts in synchronism with the pulses generated by said modulator circuit;
• and
• (b) a receiver module including:
• (i) an infrared photodetector device for altering an electrical signal in accordance with received bursts of infrared energy generated by said light-emitting device to provide an electrical signal pulsed in synchronism with said bursts;
• (ii) a demodulator circuit coupled to said photodetector device for generating an output signal indicative of the deviation of the pulses of said electrical signal from said reference frequency;
• and
• (iii) means coupled to said demodulator circuit, said means being controlled by said output signal.