### ASA 124th Meeting New Orleans 1992 October

## 4aUW9. The spatial amplitude mapping method for estimation of time delay
using adaptive filtering.

**Mohammad K. Nehal
**

**
Juan A. Henriquez
**

**
Terry E. Riemer
**

**
Russell E. Trahan
**

**
**
*Dept. of Elec. Eng., Univ. of New Orleans, New Orleans, LA 70148
*

*
*
Uniform and multiple delays/advances were estimated under heavy noisy
conditions [signal-to-noise-ratio (SNR(corresponds to)signal energy/noise
energy) below 0 dB]. The technique introduced, called the spatial amplitude
mapping (SAM) method, isolates a data segment from each of the channels in a
multichannel system by using a suitable window. When two matched segments are
plotted on an x--y plane, the distribution of every pair of windowed
coordinates will remain near a straight 45(degrees) line that passes through
the origin. The distribution of two nonmatched segments or two matched segments
containing noise will scatter around this line; hence, a pair of matching
windowed segments can be found by searching for the distribution closest to the
45(degrees) line. This information is then used to estimate the segment delays.
Under very noisy conditions, however, multiple delays can be detected. A
recursive least-squares (RLS) filter is then used to adaptively estimate the
correct delay. The technique was implemented in the delay estimation of
synthetic (stationary) data and neurophysiological (nonstationary) data with
satisfying results. Compared to the window correlation technique (WCT)
[Callison et al., J. Acoust. Soc. Am. 81, 1000--1006 (1987)], SAM can estimate
delays down to a SNR of -17.1 dB while the lower bound for the WCT is -2 dB.