Radio receiver apparatus of orthogonal detection type comprising local oscillator means with improved automatic frequency control arrangement
US5548619A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 19, 1995 |
| Grant date | Aug 20, 1996 |
| Priority date | — |
| Expiry date | Jan 19, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/2273
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
In a radio receiver apparatus of an orthogonal detection type, a voltage controlled first local oscillator generates a first local oscillation signal, and mixers mix an inputted reception signal with the first local oscillation signal and a 90.degree. shifted signal thereof, respectively, the mixed signals respectively being passed through first and second band-pass filters to obtain desired first intermediate frequency signals. Further, a second local oscillator generates a second local oscillation signal. Further mixers mixes the first intermediate frequency signals from the first and second band-pass filters with the second local oscillation signal and a 90.degree. shifted signal thereof, respectively. Then there is calculated either one of a sum of and a difference between the resulting mixed signals, the calculated signal being passed through a third band-pass filter to obtain a second intermediate frequency signal to be demodulated. Furthermore, an average frequency detector detects an average frequency of the second intermediate frequency signal for a predetermined time interval, and a frequency correction circuit controls the first local oscillation frequency of the first l…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.