Table 3. The absolute value of phase noise covariance between every two directions for balanced encoding strategies and simple encoding strategies and the corresponding ratios.

		Theoretical values	Experimental values
			|cov(x, y)|	|cov(x, z)|	|cov(y, z)|	$$\overline{\left|\mathbf{\text{cov}}\right|}$$
Three-point	Balanced	0	0.00033	–	–	0.00033
	Simple	$${\sigma }_{\phi }^2$$	0.04361	–	–	0.04361
	Bal/Sim	0	0.8%	–	–	0.8%
Four-point	Balanced	0	0.00044	0.00014	0.00034	0.00031
	Simple	$${\sigma }_{\phi }^2$$	0.04644	0.04753	0.04609	0.04669
	Bal/Sim	0	0.9%	0.3%	0.7%	0.7%