Empirical determination of the frequencies of an almost periodic sequence

This note is concerned with the problem of determination of the countable set Λ={λ₁, λ₂, ...} of frequencies belonging to an almost periodic sequence by methods in which a finite number of frequencies {λ₁⁽ⁿ⁾, λ₂⁽ⁿ⁾, ..., L(K_n)⁽ⁿ⁾}=Λ_n are produced at each stage n. We seek algorithms for which Λ_n converges to Λ but yet each Λ_n is not too big