As an essential aspect of cognitive radio (CR), spectrum sensing has always been a research hotspot. In a multi-antenna scenario, the received signals from each antenna exhibit strong spatial correlation. Therefore, the covariance absolute value (CAV) detection algorithm is commonly employed, although its performance at low signal-to-noise ratio (SNR) needs improvement. This paper proposes an improved CAV detection algorithm that leverages generalized stochastic resonance (GSR) in multi-antenna scenarios. The research demonstrates that the performance of the CAV algorithm can be enhanced by introducing an appropriate direct current signal. By maximizing the probability of detection for a fixed probability of false alarm, the optimal amplitude of the additional direct current signal can be determined. Unlike previous work, this paper derives more exact formulas and considers a more general random signal model and a multi-antenna scenario. Theoretical analysis and simulation results confirm that the proposed method outperforms traditional CAV detection methods, particularly under low SNR conditions.