  We propose a new scenario for the early universe where there is a smooth
transition between an early de Sitter-like phase and a radiation dominated era.
In this model, the matter content is modelled by a new type of generalised
Chaplygin gas for the early universe, with an underlying scalar field
description. We study the gravitational waves generated by the quantum
fluctuations. In particular, we calculate the gravitational wave power
spectrum, as it would be measured today, following the method of the Bogoliubov
coefficients. We show that the high frequencies region of the spectrum depends
strongly on one of the parameters of the model. On the other hand, we use the
number of e-folds, along with the power spectra and spectral index of the
scalar perturbations, to constrain the model observationally.
