The Cramér-Rao Bound (CRB) for direction of arrival (DOA) estimation has been extensively studied over the past four decades. with a plethora of CRB expressions reported for various parametric models. In the literature. there are different methods to derive a closed-form CRB expression. https://www.countryscenesaddleryandpetsuppliers.shop/product-category/7-5-inch-gullet-barrel/