Qunying Zhang

Design of modulated m-sequence ultrawideband radar for life detection

In life detection with ultrawideband (UWB) radar, the high signal-to-noise ratio (SNR) is very important for good performance. In this paper, the m-sequence with a carrier is applied to life detection, and SNR can be improved by pulse compression and linear average. The hybrid sampling technique is used to improve the sampling resolution and reduce the cost. The peak-to-sidelobel ratio after pulse compression would be degraded when the delay resolution of the delay line drifts in different temperature, thus the actual delay resolution of the delay line should be measured before hybrid sampling. Experiments show that the proposed modulated m-sequence UWB radar has good detection performance.

A novel handheld pseudo random coded UWB radar for human sensing applications

A novel handheld pseudo random coded ultra-wideband (UWB) radar for human sensing applications is presented in this paper. In order to reduce the size of the radar and obtain good penetrability, the center frequency of the m-sequence is assigned to about 1.1GHz. The peak voltage of the m-sequence is 4.5Vpp, while the length of the m-sequence can be chosen to obtain different signal-to-noise ratio (SNR). The digital transmitter, the dual-channel receiver and the clock synchronization are discussed in detail. The experimental results show that the proposed handheld pseudo random UWB radar has good detection performance for human sensing applications in complex environment.

A Novel Generator of Ultra-wideband Pulse

A novel Ultra-Wideband (UWB) picoseconds pulse generator is described in this paper. The basis of the generator is an avalanche transistor and a unique pulse forming circuit, which forms ultra-wideband balanced Gaussian pulses. The unique pulse forming circuit utilizes the performance of the SRD effectively to generate a couple of balanced narrow pulses with high pulse repetition frequency (PRF) up to 1MHz. A simple avalanche transistor driver is also described, which transforms a trigger signal to a driving pulse with the timing and amplitude parameters required by the SRD. After optimizing the circuit parameters and the bias conditions of the pulse generator, the design can generate a couple of balanced ultra-short electrical pulses with the peak output voltages of approximately 30V at 100 kHz PRF and the output pulse width FWHM (Full-Width at Half-Maximum) of approximately 250 ps. As the power dissipation of this generator is very low that it is used for application in near-field UWB radar sensors.

Design and testing of a pseudo random coded GPR for deep investigation

The sounding depth is one of the most important parameters of Ground Penetrating Radar (GPR), and it is also the main limitation of GPRs applications. A pseudo random coded GPR for deep investigation is described in this paper. It could achieve a sounding depth more than 130 meters. A long Golay sequences and TGA (time-gain amplifier) technology are utilized to increase the SNR of faint echoes from deep layer underground, and enhance the sounding depth. The platform could be either a vehicle or a large airship. Field tests were carried out on Kubuqi desert located in Inner Mongolia, north-west of china, to verify the detection ability of this GPR system. The sounding results agree well with the results from the drilling and resistivity logging.

A coded pulse UWB radar system design for life sign detection

UWB radar can be well used as life sign detection since it has great penetrating ability and high resolution. Pseudo random coded radar can increase transmitting power without decreasing resolution and penetrating ability, so it is suitable for the life sign detection. In this paper, a coded pulse signal generating method based on FPGA will be introduced. In order to decrease the cost and complexity of receiver design, hybrid sampling method will be used in this system design. At last, the experiment result will be given.

Design of wireless automatic synchronization for the low-frequency coded ground penetrating radar

Low-frequency coded ground penetrating radar (GPR) with a pair of wire dipole antennas has some advantages for deep detection. Due to the large distance between the two antennas, the synchronization design is a major challenge of implementing the GPR system. This paper proposes a simple and stable wireless automatic synchronization method based on our developed GPR system, which does not need any synchronization chips or modules and reduces the cost of the hardware system. The transmitter omits the synchronization preamble and pseudorandom binary sequence (PRBS) at an appropriate time interval, while receiver automatically estimates the synchronization time and receives the returned signal from the underground targets. All the processes are performed in a single FPGA. The performance of the proposed synchronization method is validated with experiment.