### ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

## 4aUW10. Reconstruction of a periodic time-domain signal ``buried'' in
Gaussian noise.

**Stefan T. Sidahmed
**

**
Antal A. Sarkady
**

**
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*Dept. of Elec. Eng., U.S. Naval Acad., Annapolis, MD 21402
*

*
*
Power spectral analysis does a reasonably good job of signal detection but
fares poorly in characterization because the phase information is ignored in
the spectral computations. From spectral analysis, an initial or seed value for
the period of the target signal is obtained. The original digitally sampled
noisy time signal is resampled (up/down sample rate conversion) at such a rate
that precisely an integer number of time samples are obtained on each cycle of
the quasiperiodic target signal. These noisy cycles are synchronously averaged
in the time domain and an estimate for the shape of the target signal is
computed. The sample rate conversion, and the synchronous averaging is repeated
until the rms value of the result is maximized (i.e., phase cancellation is
minimized). The voltage signal-noise ratio of the reconstructed target signal
is proportional to the square root of the number of target cycles averaged.
This procedure was tested with laboratory type signals and found to have an
excellent performance at signal-to-noise voltage ratios as low as -40 dB.