Practical realizations of the optimum closed loop structure for coherent demodulation of QPSK signals demands the approximation of the hyperbolic tangent nonlinearity (Tanh) with simpler and more easily implementable functions. This paper compares the commonly considered approximations to this nonlinearity and the practical structures which result, with an alternative in which the hyperbolic ta...

The structural diagrams of devices for the forming and processing modern amplitude-phase-manipulated signals are considered. parameters modulator demodulator have been identified, instability or inaccuracy whose setting significantly increases probability an error when receiving data. Based on results research, recommendations were made regarding necessary values to reduce a symbol reproducibil...

The study of a Digital Cartesian loop transmitter as power amplifier linearization technique is presented. It is based on Cartesian loop architecture but introducing the advantages and possibilities of using digital solutions. Stability is assured by including some adjustment elements in the loop and the digital implementation avoids modulator and demodulator impairments and provides an accurat...

The paper focuses on the design and implementation of the base-band basic receiving functions, for a binary CP-FSK demodulator pilot study, as independent modules of a complete Reconfigurable Data-Link (RDL). A model-based approach and Software Defined Radio (SDR) paradigm are used for the design. The implementation will be executed on Field-Programmable Gate Array (FPGA) based hardware.

Detailed analysis of a novel highly linear phase-locked coherent optical demodulator is presented. We investigate how loop gain, phase-modulator non-linearity and amplitude modulation influence the Signal to Interference Ratio (SIR) of the demodulated signal. ©2006 Optical Society of America OCIS codes: (060.1660) Coherent communications; (120.5060) Phase modulation

The current paper addresses the issue of estimating the sampling instant in turbo receivers. The proposed synchronizer is based on the expectation-maximization (EM) algorithm and takes benefit from the soft information delivered by the turbo system. Performance Interpolator Anti−aliasing Turbo Demodulator Matched filter a posteriori information Discrete Time 1 Ts rl r(t)

A software radio is a communication system in which most hardware is replaced by software, much in the same way as analog circuits were replaced by digital signal processors in the past 30 years. Software radios are fundamentally different from hardware radios, and new algorithmic ideas are needed to make them viable. Consider for example the IEEE 802.11b standard for wireless local area networ...