We consider the frame property of the Gabor system G(g, α, β) = {eg(t − αm) : m,n ∈ Z} for the case of rational oversampling, i.e. α, β ∈ Q. A ’rational’ analogue of the Ron-Shen Gramian is constructed, and prove that for any odd window function g the system G(g, α, β) does not generate a frame if αβ = n−1 n . Special attention is paid to the first Hermite function h1(t) = te −πt .

A (K1,3, λ)-frame of type g u is a K1,3-decomposition of a complete upartite graph with u parts of size g into partial parallel classes each of which is a partition of the vertex set except for those vertices in one of the u parts. In this paper, we completely solve the existence of a (K1,3, λ)-frame of type g .

The purpose of the paper is to analyze g-frames form \(\{\varphi T^{i} \in B(\mathcal {H},\mathcal {K})\}_{i=0}^\infty \), where \(T\in {H})\) and \(\varphi {K})\), discuss properties operator T. We consider stability g-Riesz sequences \). Finally, a weighted representation g frame introduced some its are presented. provide sufficient condition for given g-frame \(\Lambda =\{\Lambda _{i}\in {B(...

for all f ∈ H . The constant A (respectively, B) is a lower (resp. upper) frame bound for the frame. One of the most important frames for applications, especially signal processing, are the Weyl-Heisenberg frames. For g ∈ L(R) we define the translation parameter a > 0 and the modulation parameter b > 0 by: Embg(t) = e , Tnag(t) = g(t− na). For g ∈ L(R) and a, b > 0, we say for short that (g, a,...

Let A ⊂ L2(R) be at most countable, and p, q ∈ N. We characterize various frame-properties for Gabor systems of the form G(1, p/q,A)= {e2 g(x − np/q) : m, n ∈ Z, g ∈ A} in terms of the corresponding frame properties for the row vectors in the Zibulski–Zeevi matrix. This extends work by [Ron and Shen, Weyl–Heisenberg systems and Riesz bases in L2(R d). Duke Math. J. 89 (1997) 237–282], who consi...

This work presents a quantitative framework for describing the overcompleteness of a large class of frames. It introduces notions of localization and approximation between two frames F = {f i } i∈I and E = {e j } j∈G (G a discrete abelian group), relating the decay of the expansion of the elements of F in terms of the elements of E via a map a : I → G. A fundamental set of equalities are shown ...

An independent set S of a connected graph G is called a frame if G − S is connected. If |S| = k, then S is called a k-frame. We prove the following theorem. Let k ≥ 2 be an integer, G be a connected graph with V (G) = {v1, v2, . . . , vn}, and degG(u) denote the degree of a vertex u. Suppose that for every 3-frame S = {va, vb, vc} such that 1 ≤ a < b < c ≤ n, degG(va) ≤ a, degG(vb) ≤ b − 1 and ...

We investigate shift invariant subspaces of $L^2(G)$, where $G$ is a locally compact abelian group. We show that every shift invariant space can be decomposed as an orthogonal sum of spaces each of which is generated by a single function whose shifts form a Parseval frame. For a second countable locally compact abelian group $G$ we prove a useful Hilbert space isomorphism, introduce range funct...

In the study of Weyl-Heisenberg frames the assumption of having a finite frame upper bound appears recurrently. In this note it is shown that it actually depends critically on the timefrequency lattice used. Indeed, for any irrational > 0 we can construct a smooth g 2 L2(R) such that for any two rationals a > 0 and b > 0 the collection (gna;mb)n;m2Zof time-frequency translates of g has a finite...

Nomenclature β,γ(∈ S) = The gimbal and wheel angles. (rad) Rβ(∈ SO(3)) = Transformation from gimbal frame G to the spacecraft body frame B. Is = Spacecraft inertia without the CMG gimbal and wheel inertia. (kg.m) Ig, Ir = Gimbal frame inertia, wheel inertia about own centre of mass represented in gimbal frame. (kg.m) (Igr)β = Combined inertia of gimbal frame and wheel in the spacecraft frame. R...