Radio communication system
US5555453A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 20, 1995 |
| Grant date | Sep 10, 1996 |
| Priority date | — |
| Expiry date | Mar 20, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B1/28
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A CW (Continuous Wave) radio frequency signal converted to an IF (Intermediate Frequency) signal is mixed with a local oscillator signal by an IF mixer, and the obtained signal is converted to a digital signal by an ADC (Analog-to-Digital Converter). A digital bandpass filter passes only the target component in the output of the ADC. The passed IF signal is demodulated by a digital demodulator, and the demodulated signal is converted to an analog signal before being output as a sound. When pitch control to increase the reception pitch by .DELTA.f is instructed, an MPU (Microprocessor Unit) alters the frequency of the local oscillator signal by .DELTA.f as well as the center frequency of the digital bandpass filter by .DELTA.f, so that the center frequency of the input signal to a narrow-band filter coincides with the center frequency of the digital bandpass filter.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.