The efficiency optimization of a feedforward low distortion power amplifier is presented. Based on the principle of distortion compensation, the main amplifier output power, that of subamplifier, and amplifier efficiency have been accurately derived. In the present analysis, the coupling coefficient of main signal and distortion paths is selected as the optimization parameter because it may ess...

The inftuence of bandpass non-linear distortion on an OFDM signal is investigated. The spectrum of the distorted sig@ and tbe resulting detection errors are detsrndned. Non-linear distortion of OFDM signals CaU sigdcantly increase the reeeiver BER. Previous S@WS rSIy on simulation, or apply to specific non-linearities only. He% an analysk is presented which is applicable to any weakly non-linea...

The evolution from the second generation of mobile communication technology (GSM) to the third generation (UMTS) requires a change of the modulation format. Due to the fact, that in UMTS the information is also packed into the envelope of the transmission signal, a linear amplification without distortions becomes essential. Power amplifiers operate at saturation with the highest efficiency. The...

Inspired by a recently proposed constructive framework for the distributed source coding problem, 1 we propose a powerful constructive approach to the watermarking problem, emphasizing the dual roles of "source codes" and "channel codes." In our framework, we explore various source and channel codes to achieve watermarks that are robust to attackers in terms of maximizing the distortion between...

The paper describes solutions, how to improve a quality of basic testing methods to be possible to use them for dynamic testing high-resolution / middle speed AD converters and AD modules. The following methods are described: an application of low-distortion band pass filters, a digital correction of a known distortion of a testing signal, an application of a two-tone (or multitone) signal, an ...

Abstract In order to achieve optimum service availability, Ka-band gateways must deliver very large effective isotropic radiated power (EIRP) per signal. For most signal types, and for all multicarrier uplinks, uplink power is limited by distortion in the final amplifier. Such distortion may be defined by a number of metrics, including adjacent-channel power ratio (ACPR), noise power ratio (NPR...

Digital signals are complex-valued functions on Zn. Signal sets with certain properties are required in various communication systems. Traditional signal sets consider only the time distortion during transmission. Recently, signal sets against both the time and phase distortion have been studied, and are called time-phase signal sets. Several constructions of time-phase signal sets are availabl...

Traveling Wave Tube (TWT) amplifiers are high power, often broadband microwave amplifiers used extensively in satellite communications and electronic countermeasures. While the high-power outputs and wide gain-bandwidths make TWTs ideally suited for these purposes, the nonlinearity of these devices results in amplitude, phase and spectral distortion. Nonlinear distortion products appear as harm...

In this paper, a novel channel–optimized multistage vector quantization (COMSVQ) codec is presented in which the stage codebooks are jointly designed. The proposed codec uses a signal source and channel–dependent distortion measure to encode line spectral frequencies derived from segments of a speech signal. Simulation results are provided to demonstrate the consistent reduction in the spectral...