  Multi-soliton pulses, as special solutions of the Nonlinear Schroedinger
Equation (NLSE), are potential candidates for optical fiber transmission where
the information is modulated and recovered in the so-called nonlinear Fourier
domain. For data communication, the exponentially decaying tails of a
multi-soliton must be truncated. Such a windowing changes the nonlinear Fourier
spectrum of the pulse. The results of this paper are twofold: (i) we derive the
simple closed-form expressions for the nonlinear spectrum, discrete and
continuous spectrum, of a symmetrically truncated multi-soliton pulse from
tight approximation of the truncated tails. We numerically show the accuracy of
the closed-form expressions. (ii) We show how to find, in general, the
eigenvalues of the discrete spectrum from the continuous spectrum. We present
this method for the application in hand.
