BROAD-BAND SOURCE LOCALIZATION AND SIGNATURE ESTIMATION

The temporal signature and source location of a broadband impulse prop agating in an ocean waveguide are estimated using matched mode process ing and illustrated using simulated data in an Arctic sound channel. M atched mode processing provides a simple method for broadband signal d etection and localization; the peak-to-sidelobe ratio is significantly improved using broadband data compared with the narrow-band case. The range and depth ambiguity function evaluated at the source location y ields directly the source spectrum, which is inverse Fourier transform ed to estimate the original signal waveform. For the simulated data, t he reconstructed signal, compensated for spreading loss and array sign al gain, agrees rather well with the original waveform. The estimated spectrum/waveform is weaker than the original spectrum/waveform due pr edominantly to the fact that the Arctic wave guide is lossy. A method for coherent broadband processing is proposed to improve signal locali zation and detection when the original source spectrum is known. Multi plying (correlating) the original spectrum with the range and depth am biguity function, the product can be coherently summed over the freque ncy band of the signal. Near theoretical processing gain is achieved f or the simulated data. Broadband signal detection is proposed using a frequency versus depth plot in addition to the commonly used frequency versus bearing plot.