Modulated signal transmitting apparatus
US5301355A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 12, 1990 |
| Grant date | Apr 5, 1994 |
| Priority date | — |
| Expiry date | Jul 12, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B10/11
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An infrared remote control signal is entered into a receiving circuit where it is converted into an electrical, modulated signal made up of a carrier and a command signal. The modulated input signal is sent to a control signal output circuit where it is filtered to send only the carrier of the remote input signal to a frequency-voltage conversion circuit. The frequency-voltage conversion circuit generates a control DC voltage according to the carrier frequency. The control DC voltage changes the pass band characteristic of a voltage-controlled filter in such a manner that the voltage-controlled filter selectively passes the desired fundamental frequency component and harmonic components of the carrier signal. The voltage-controlled filter also passes the command signal component. Thus, at the output of the voltage-controlled filter is obtained a modulated output signal whose carrier frequency is varied from that of the modulated input signal. With the carrier frequency changed, the resulting infrared remote control signal sent out from a transmitting circuit can be prevented from being affected or interfered with by external noise from fluorescent lamps.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.