  In this paper, we introduce and characterize a subspace of bandlimited
signals. The subspace consists of all $\Omega$ bandlimited signals such that
the non-zero parts of their Fourier transforms are pieces of some $T$
bandlimited signals. The signals in the subspace are called BT-limited signals
and the subspace is named as BT-limited signal space. For BT-limited signals, a
signal extrapolation with an analytic error estimate exists outside the
interval [-T, T] of given signal values with errors. Some new properties about
and applying BT-limited signals are also presented.
