Zhang Qishan

Concatenated prime codes and quadratic prime codes

From both construct formula view and finite field model view, the relationship between concatenated prime codes and quadratic prime codes has been studied in this paper. As a result, two new methods of constructing frequency hopping (FH) sequences are derived, designated as exchange and time shift, which are still generalized and combined. Finally, one application of the novel methods to the general quadratic prime codes is presented and more new families of FH sequences are generated with properties unchanged.

Large frequency offset carrier synchronization in segmented matched filter DS/BPSK receiver

This paper investigates the effects of significant frequency offset on the performance of a digital segmented matched filter (SMF) DS/BPSK receiver. A new carrier frequency discriminator for carrier acquisition in this structure of high dynamic DS/BPSK receiver is presented. The proposed algorithms employs segmented correlator and whole length correlator outputs to form a frequency discriminator (CFD) which has a tracking range of the symbol rate, and the tracking range is independent of the spreading code length. A frequency synchronization scheme is also explored, which extending the range of frequency acquisition and shorting the time of acquisition. At mean time the paper presents the best discriminator selection between CFD and four-quadrant frequency discriminator(FQFD) during the process of acquisition.

Design of delay mapping receiver for GPS remote sensing

Backgrounds and advantages of sea surface wind remote sensing technique based on GPS and the ocean scattered signal measure technique are introduced. Five main techniques are discussed as improving the signal noise ratio, dual front-end receiver design, calculating the specular point code delay, working modes configuration and the embedded firmware function. Inshore flight tests were done in Tianjin with the receiver mounted on an airplane. Results show that the delay mapping receiver (DMR) can receive direct and ocean scattered GPS signal simultaneously which achieves the performance specifications

Estimation of Doppler-Shift Based on Correlation-Peak Waveform

In DS/SS receiver, correlation peak power is square of sine-function of Doppler shift. By taking this priori knowledge into account, the paper put forward a Doppler shift estimation algorithm using nonlinear least squares estimation method. Estimation performance was evaluated by computer simulation and compared with four-quadrant frequency discriminator algorithm (FQFD) used in GPS receivers.

A novel method used for the performance analyzing of channel estimation in time-varying fast fading channel-equivalent channel analysis method

In a time-varying fast fading channel, due to the influence of amplitude fading and fast phase changing, the performance of QAM system was deteriorated seriously, it is also the main reason that restrains high-dimension modulation from use in fast mobile communications. In order to solve this problem, many estimation methods were presented previously. As is known, the process of channel estimation is practically that of compensation of the channel characteristic. So, in analyzing the performance of various channel estimation methods one also analyzes the equivalent channel after compensation. The characteristics of the equivalent channel after compensation is examined in the course of equivalent channel estimation. This method named the equivalent channel analysis method is introduced. By using this method, the system performance after using channel estimation is only a function of the Doppler shift and correlative coefficient of channel, and depends on the channel estimation method. We only need to calculate the correlative coefficient of two neighbouring symbol, we can obtain the relation formula between the error probability and Doppler shift using channel estimation, so it simplifies the analysis of the system performance.

The gibbs derivatives of generalized Bridge functions

The logical derivatives of p-adic copy-shift and shift-copy generalized Bridge functions are given in this paper. When p equals 2, they are exactly the logical derivatives of natural ordering copy-shift and copy-shift Bridge functions.

Design of distributed hardware preprocessor for realtime processing of telemetry data

Even though minicomputers and microcomputers are larger and faster than ever before, they have not kept pace with the demands of telemetry users. Hardware preprocessor of telemetry data has been used in distributed telemetry computer system for processing all data at extremely high rates. According to the requirements and characteristics of telemetry data processing, a distributed multiple data stream hardware preprocessor with multiplex microcomputers of telemetry data is introduced in the paper. Each data stream is processed by three microcomputer models coupled in multi-computation architecture. The microcomputer models consist of TMS320C25 in the preprocessor. The preprocessor owns the features of wavefront array processors. A time-wait procedure can be done in pipeline processing and large data processing can be derived in parallel processing and pipeline processing.<<ETX>>