design of human body scanner based on uwb

TSSA 2011, Denpasar Bali

Design of Human Body Scanner Based on 4-11 GHz Ultrawideband Technique

for Airport Security Applications

Dr.Ir.Joko Suryana Ir.Ade Siregar

School of Electrical Engineering and Informatics

Institut Teknologi Bandung, Indonesia


Abstract

• Currently, the airport became one of the very vital and should have a very high level of security. – The main problem that arises is how to optimize airport security

systems that already exist so as to improve the safety and comfort of passengers planes.

• In this study we propose an ultrawideband imaging for scanning the human body to detect the presence of weapons and weapons concealment locations by prospective passengers in the body. – Ultrawideband technique has advantages compared to metal detector

in terms of its ability to produce images sharp weapons, and its size, shape and exact position of the sharp weapon.

• From the initial study conducted shows that the candidate body scanner system on this plane capable of detecting hazardous metal beneath the cloth with an acceptable error rate


Human Body Scanner

• The human body scanner is a whole–body imaging device used for detecting objects concealed underneath a person’s clothing.

• Typical uses :– detection of items

for commercial loss prevention,

– screening at government buildings and airport security checkpoints


Block Diagram of HBS

• A block diagram of the microwave imaging system for scanning the human body :– A pair of Tx and Rx antennas can be moved

along the rail from top to bottom using a motor to perform vertical scanning on the human body and also can be shifted horizontally to perform straight left-to right scanning .

– A transceiver creates the wideband illumination and measures the magnitude and phase of the scattered wavefront.

– An interface board controls the timing and the synchronization of the system with the computer. Data from the transceiver is digitized using an A/D converter and transferred to the computer.

– After a full aperture of data is collected, the computer reconstruction algorithm is used to focus the data into a 3-D image. The 3-D data set is then collapsed into a single 2-D fully-focused image which is displayed on the computer.


4-11 GHz HBS

• In this paper, we uses Stepped Frequency Radar technique for human body scanner for airport security applications.

• This system is consist of :– 4-11 GHz antennas

– microwave sensors with 4 – 11 GHz working frequency

– data acquisition subsystem

– computer with signal processing software for target imaging.


Stepped Frequency Radar Principle

• Signal with bandwidth B, lowest frequency fr, and highest frequency ft is discretized into N frequencies separated by frequency space Df. Scanning process is done by transmitting signal with initial frequency fr from t0 until t0+Dt. At t0+Dt, transmitter re-transmit signal with new frequency fr+Df.

• This process continues until the highest frequency fr is transmitted. Total time to complete the scanning process at this N frequencies is NDt. If the signal from fr until ft touches the linear material such as soil and plastic, the reflected signal will have the same frequency but the phase and the amplitude have changed.


Test Setup

• We have developed our human body model equipped with weapon object such as gun model as well as knife models. – The human body model is represented by plywood, on the

other hand for representing the weapon we use metal plate material.

• In the S21 measurement for microwave imaging process, determining the size of the scale and the distance between the antenna and the object is affecting the image quality. In this experiment, we perform 2 different scenarios :– First scenario is using 80 cm distance between the human body

model with our Tx and Rx antennas– Second scenario is using 40 cm distance between the human

body model with our Tx and Rx antenna


Test Setup

• Human Body and Weapon Models

• Proposed Human Body Scanner Aparattus


Test Setup

• In both of the scenarios :

– We have performed 60 x 60 points of scanning in horizontal and vertical directions.

– Each point of measurement we have 201 frequency domain samples of 4-11 GHz bandwidth.

– For obtaining the human body images, we need to process the 60 x 60 x 201 matrix data in a such way to detect the presence of weapons and weapons concealment locations by prospective passengers in the body.


Test Results :First scenario is using 80 cm distance

• From 60x60 samples observation of first measurement obtained then S21 compared with the second measurement.

• Data is taken 33x38 matrix of the first 60x60 matrix, with the imaging processing matlab.


Test Results :First scenario is using 40 cm distance

• The second measurement is done after getting experience from the first measurement. In this measurement object is placed far above the floor at a height of 40 cm and zoomed is done at 16 x 16 pixels.

• While the distance between the transmitter and receiver antenna to the object also observed at 40 cm distance.


Conclusions

• The results of human body scanner testing shows us that the proposed ultrawideband imaging work well to detect and identify the weapon models for airport security applications.

• Raw data processing software also has important role in eliminating clutter and enhancing S/N that improves the performance of imaging.

• In the S21 measurement for ultrawideband imaging process, determining the size of the scale and the distance between the antenna and the object is affecting the image quality. – In this experiment, a distance of 40 cm between the antenna and the

object can produce high resolution of weapon model images.

• Therefore, from the initial study conducted shows that the candidate body scanner system on this plane capable of detecting hazardous metal beneath the cloth with an acceptable error rate.


Thank You

design of human body scanner based on uwb

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