National Science Council

Chung Shan Institute of Science and Technology

Yuh-Maiw Jong

Chia-Chi Huang

Shin-Yuan Wang

Jian-Hui Shen

A vector network analyzer using sliding correlator techniques and multi-user detection techniques. The sliding correlator technique is based on the time domain sliding effect caused by a small clock frequency offset in the pseudo random code generators of a transmitter and a receiver. A time scaled version of the impulse response of the device under test can be obtained from the time domain slided pseudo random code signals by using a correlator. A multi-user detection method is introduced using two uncorrelated pseudo random codes. One of the uncorrelated pseudo random codes measures the D.U.T. and another code is a reference channel. These codes can be demodulated and despread with one receiver module. A Fast Fourier Transform of the measured impulse response is the frequency response of the measured signal. By using multi-user techniques and calculating the frequency domain despreaded test signal and the frequency domain despreaded reference signal repeatedly, the test device frequency responses is obtained and disturbances of resulting signals caused by the receiver chaining characteristics and multi-user PN code effects are eliminated. The measurement time is also reduced as a single measurement generates output data for a wide frequency band instead of for a single frequency.

Vector network analyzer architecture based on sliding correlator techniques

A method and an architecture for correcting carrier frequency offset and spreading code timing offset in a direct sequence spread spectrum communication system are disclosed. In the present invention, the carrier frequency offset is divided into an integer part and a fractional part, wherein the integer part is defined as integer multiples of the reciprocal of the period of a spreading code. The integer part of the carrier frequency offset can be obtained by matching received signals with a spreading code whose central frequency is located at integer multiples of the reciprocal of the period of the spreading code and searching the one, of the matched results, with the largest amplitude. Besides, a direction flag can be obtained by comparing the amplitude of the searched one with that of the matched results neighboring the searched one. After correcting the integer part carrier frequency offset, the difference between the phase angles of two successive matched results can be calculated and used to calculate the fractional part of the carrier frequency offset according to the direction sag. After the carrier frequency offset is corrected, the correction of the timing offset of the spreading code can be made by searching for the first path of the channel impulse response which produces the minimum delay spread.

Method and architecture for correcting carrier frequency offset and spreading code timing offset in a direct sequence spread spectrum communication system

Growing community of inventors

Taoyuan, Taiwan

Yuh-Maiw Jong