Correlation imaging is attracting more and more attention as a novel imaging technique taking advantage of the high-order coherence of light fields. To reconstruct an image of the object, many frames of different speckle patterns are required. Therefore, the speed of imaging is strongly limited by the speed of the refreshing rate of the light field. We propose a coprime-frequencied sinusoidal modulation method for speckle pattern creation using a spatial light modulator in a computational ghost imaging system to increase the speed of imaging. The performance of the proposed method is discussed as well.