| 摘要 |
<p>An analogue modem circuit (224) and carrier recovery method for use between an RF receiver and a digital modem circuit; comprising :receiving a baseband RF input signal;an up-converter (506) with frequency supplied by an up-converter voltage controlled oscillator, VCO (522);a down-converter (510) with frequency supplied by a down-converter VCO (520);a Costas loop sub- module (518); and outputting baseband outputs from the down-converter (520) to a digital modem circuit; wherein :the up-converter (522) feeds the down- converter (510), and the Costas loop module (518) performs Costas loop functionality on the output of the down-converter (510) to control the up- converter VCO (522) frequency output to thereby control modification of the rotation of the symbols of the baseband signal. One or both VCOs may be controlled dependent upon a residual frequency difference between the VCOs when the Costas loop functionality is being started.</p> |
