| 摘要 |
A decision directed frequency detector and method for a quadrature amplitude modulated signal (QAM) demodulator. The demodulator interacts with a voltage controlled oscillator (VCO) that generates a carrier signal to demodulate the QAM signal into a baseband signal. The frequency detector determines the direction of rotation of the baseband signal by sampling the baseband signal relative to predetermined points in the phase plane. For example, if one sample has a negative phase offset with respect to a predetermined point and the next one has a positive phase offset, it detects that the rotation is clockwise, and vice-versa. |
