Wavelet processing for wideband spreading function estimation Free

The statistic used to quantify the amount of environmental spreading a signal undergoes as it traverses through a channel is called a spreading function, and it includes the effects of moving, distributed scattering objects, multipath, boundary effects, etc., on the signal. Traditionally, narrow‐band signals have been transmitted, and the spreading functions were estimated by calculating the outputs of narrow‐band‐matched filters. Now that wideband processing has become more accessible, we need a solid concept of estimating wideband spreading functions. This paper shows that a wideband spreading function can be estimated by computing the wavelet transform of the received signal while using the transmitted signal as the mother wavelet. The paper then computes the second‐order statistic, called the wideband scattering function, associated with the wideband spreading function. To assess the total scattering, several scattering functions are convolved to yield an overall representation of the environment. This representation can then be incorporated into a detection processor. The payoff is that if any portion of the scattering environment is known a priori, this information can be exploited in the detector. As knowledge of the scattering process is acquired, it is combined via the cascaded scattering function formulation.