| 摘要 |
PROBLEM TO BE SOLVED: To reduce a bit error by suppressing phase noise from a local oscillator. SOLUTION: Mixers 2, 3 are in use and mix an input signal with an orthogonal 480MHz signal from a local oscillator 4 in two paths. Base band signals from I and Q paths are fed to an A/D converter 8 via the mixers 2, 3 and amplifiers 6, 7. A processor 9 modulates received data and checks errors and produces a frequency reference signal controlled by a costas loop 10 in response to the I and Q signals. The costas loop 10 applies multiple processing to the I and Q signals and an error output of the multiplier is used to make synchronization with the reference signal frequency to reduce the error. A phase error is corrected and the reference frequency signal is fed back and the frequency of the local oscillator 4 is controlled by a 2nd phase locked loop 11. |
