Speech transmission in cordless telephone system - uses carrier-less single sideband conversion to modulate radiation from luminance diode, with IR PIN diode for HF to LF conversion
Номер патента: DE2837907A1
Опубликовано: 06-03-1980
Автор(ы): Hans-Joachim Dr Ing Griese
Принадлежит: Sennheiser Electronic GmbH and Co KG
Опубликовано: 06-03-1980
Автор(ы): Hans-Joachim Dr Ing Griese
Принадлежит: Sennheiser Electronic GmbH and Co KG
Реферат: A low frequency signal e.g. speech is converted to higher frequencies using carrier-less single sideband techniques. It then modulates the radiation from esp. a luminescence diode working in the infra red region. At the receiver an e.g. PIN diode converts the light to electrical signals which are then changed back to the original low frequency. The intensity of radiation is controlled by the amplitude of the modulating voltage. This conserves power whilst maintaining 100% modulation depth and therefore a high signal to noise ratio. The system is suitable for e.g. cordless telephones and hearing aids. Directional receivers may be used.
Enhanced infrared-connected telephone system
Номер патента: US5241410A. Автор: Jerry R. Iggulden,Donald A. Streck. Владелец: LitePhone Systems Ltd. Дата публикации: 1993-08-31.