Dr. Muhammad Tahir

Buried life detector (BLD) is a device that is made to detect human life under the Earthquake rubble. Pakistan is one of the countries that is prone to natural disasters that cause collapse of buildings and infrastructure where it is highly probable that human life be trapped in the gaps and voids inside the debris. Such a situation requires timely and targeted rescue operation to extract the human life. Buried life detector operates at 1GHz L band frequency to target the victim trapped inside the rubble. Penetrating through 20-30ft rubble the directed signal becomes frequency modulated due to the breathing and heart beat of the human body as it gets reflected from the victim. This frequency modulation governs the phenomena of doppler frequency shift and returns back as frequency shifted doppler signal. All the multipath and surrounding reflected signal acts as unwanted signal to the system and needs to be cancelled. Clutter cancelation techniques are implemented to cancel the clutter signal for the extraction of the doppler signal. The algorithm involves the adjustment of the phase and attenuation of the reference signal so that the reflected signal cancels to its maximum. Proper demodulation techniques are executed through robust hardware modules to demodulate the captured signal and extract the doppler life signal to be processed further. The demodulation involves the use of 30MHz IF (intermediate frequency) to increase the sensitivity of the system. Once the demodulation is achieved the low frequency human signal is filtered. The filtered signal is processed to distinguish life from non life. Signal processing techniques involve the calculation of the depth of human life inside the debris. A Microcontroller board is used to implement the clutter cancelation algorithm and for the signal processing. The low SNR signal extraction involves designing of filters to extract the human life signal from the noise signal.

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