ISSN:1124-318X    

DOI:10.1002/ett.4460040102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

ISSN:1124-318X    

DOI:10.1002/ett.4460040103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

ISSN:1124-318X    

DOI:10.1002/ett.4460040104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

ISSN:1124-318X    

DOI:10.1002/ett.4460040105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

ISSN:1124-318X    

DOI:10.1002/ett.4460040106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

ISSN:1124-318X    

DOI:10.1002/ett.4460040107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractSource coding techniques for reducing the bit rates of TV and HDTV signals are presented and discussed with respect to satellite broadcasting applications. The source coding techniques require transmission bit rates of 9 Mbit/s for a TV and 45 Mbit/s for an HDTV signal in order to provide distribution quality as required for broadcasting. Also three scalable coding schemes are outlined which allow graceful degradations at the boundary of the broadcasting service area by a transition from a HDTV to TV picture resolution. VLSI implementations of TV and HDTV decoders have been investigated in order to achieve compact and low cost realization. It is shown that the silicon area of VLSI devices can be kept small by choosing algorithms with small signal processing requirements and by taking advantage of a priori known features. VLSI architectures for the implementation of subband filters and DCT are discussed as key components.

ISSN:1124-318X    

DOI:10.1002/ett.4460040108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractSpread Spectrum Code Division Multiplex is an attractive scheme for the transmission of multiple signals over a satellite transponder. By using orthogonal or quasi‐orthogonal spreading codes the interference between the users can be virtually eliminated. However, the acquisition and tracking of the spreading code phase can not take advantage of the code orthogonality since sequential acquisition and Delay‐Locked loop tracking depend on correlation with code phases other than the optimal despreading phase. Hence, synchronization is a critical issue in such a system.A demonstration hardware for the verification of the orthogonal CDM synchronization and data transmission concept is being designed and implemented. The system concept, the synchronization scheme, and the implementation are described. The performance of the system is discussed based on computer simulati

ISSN:1124-318X    

DOI:10.1002/ett.4460040109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe ESA Data‐Relay System (DRS) is a space‐borne communications system which provides communications between ground stations and satellites in low Earth orbits (LEOs) with inter‐orbit links giving a data‐relay facility. The system requires a ground based receiver and modem and this paper describes the implementation of such a receiver relying heavily on Digital Signal Processing Techniques. The spread spectrum receiver and modem is presently under development by Satellites International Limited under contract to the European Space Agency (ESA). The specification requirement for the demodulator is severe, with low signal‐to‐noise ratios and high Doppler shifts. The demodulator is very flexible in terms of the types of signal it can receive, which include spread spectrum signals. The demodulator is implemented almost completely using digital techniques. Such an approach leads to potentially low implementation losses and allows the use of novel techniques in the receiver's

ISSN:1124-318X    

DOI:10.1002/ett.4460040110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper describes the design of a BPSK/QPSK demodulator implemented using multi‐rate digital signal processing in a CMOS ASIC. The demodulator is fully programmable via serial and parallel interfaces and handles symbol rates from 125 sym/s to 4 Msym/s. It performs at less than 0.5dB degradation from ideal BER vs.EhINcharacteristic. The system design considerations lead to the choice of a complex IF scheme with sampling at four times the intermediate frequency and a combined analog and digital matched filtering based on the pulselet concept. Signal processing algorithms include Costas carrier phase error detector, Zero‐Crossing Detector for timing error and algorithms for lock detection and loop filtering. Simulations of the entire demodulator including the ASIC part is accomplished by proprietary software. The ASIC is manufactured in a radiation tolerant 1 μm CMOS gate array process using 34085 gates. The main application area is spaceborne coherent TT&C transponders. The ASIC will fly on SPOT‐4 in 1994 as a part of the Experimental 5‐Band Tra

ISSN:1124-318X    

DOI:10.1002/ett.4460040111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY