Effects of spectral amplitude and phase errors on image reconstruction

2004 ◽  
Author(s):  
Wen-Hsin Hsiao ◽  
Rick P. Millane
Keyword(s):  
Image Reconstruction ◽  
Spectral Amplitude ◽  
Phase Errors ◽  
Amplitude And Phase Errors

Amplitude and Phase Errors Calibration of the Satellite-Borne DBF Transmitting RF Channel

2011 ◽  
Vol 30 (9) ◽  
pp. 2182-2184 ◽  
Author(s):  
Hong-mei Zhao ◽  
Hua-li Wang ◽  
Shan-xiang Mu ◽  
Zhong-chuan Zhang ◽  
Cheng-guo Li
Keyword(s):  
Phase Errors ◽  
Amplitude And Phase Errors

Improved Calibration Method of Amplitude and Phase Errors Based on Diagonal Loading

2013 ◽  
Vol 717 ◽  
pp. 359-364 ◽  
Author(s):  
M. Rizwan Anjum ◽  
Pi Lei Yin ◽  
Peng Fei Shi ◽  
F. Ismail
Keyword(s):  
Calibration Method ◽  
Adaptive Antenna ◽  
Sidelobe Level ◽  
Phased Array Antenna ◽  
Diagonal Loading ◽  
Level Characteristic ◽  
Phase Errors ◽  
Low Sidelobe ◽  
The Impact ◽  
Amplitude And Phase Errors

The amplitude and phase errors deteriorate the low-sidelobe level characteristic of phased array antenna, which degrades radar performance seriously. Therefore an improved calibration method of amplitude and phase errors based on diagonal loading is proposed to address the problem of amplitude and phase errors in this paper. Initially, the mathematical models of amplitude and phase errors are developed and the impact of amplitude and phase errors is analyzed. It is found that although the interference can be suppressed when there is amplitude and phase errors in the array, the low-sidelobe level characteristic of adaptive antenna is badly deteriorated. An improved calibration method of amplitude and phase errors based on diagonal loading is proposed. Compared with traditional calibration method, proposed method can reduce the sidelobe level efficiently. At last simulations were carried out to verify the effectiveness of proposed method.

scholarly journals Influence of amplitude and phase imbalance of quadratures on the noise immunity of coherent reception of signals with quadrature amplitude modulation

2021 ◽  
Vol 9 (1) ◽  
pp. 29-37
Author(s):  
G. V. Kulikov ◽  
A. A. Lelyukh
Keyword(s):  
Amplitude Modulation ◽  
High Speed ◽  
Noise Immunity ◽  
Signal To Noise Ratio ◽  
Phase Error ◽  
Quadrature Amplitude Modulation ◽  
Phase Errors ◽  
Wide Range ◽  
Signal Demodulation ◽  
Amplitude And Phase Errors

Quadrature amplitude modulation (QAM) is used for high-speed information transmission in many radio systems and, in particular, in DVB-S and DVB-S2/S2X digital satellite television systems. A receiver included as a part of the transmitting equipment of such systems has a block for the formation of quadrature oscillations used as a reference for signal demodulation. Due to hardware instabilities, amplitude and phase errors may occur, which leads to quadratures imbalance. These inaccuracies cause additional errors in the received signal demodulation. This can significantly degrade the noise immunity of the reception. The paper investigates the influence of amplitude and phase errors in the formation of quadrature oscillations (imbalance of quadratures) on the noise immunity of coherent reception of QAM signals. Using the methods of statistical radio engineering the parameters of the distributions of processes in the receiver are obtained, and the probability of a bit error is estimated. The dependences of the bit error probability on the amplitude unbalance factor, on the phase error of quadrature formation and on signal-to-noise ratio are obtained. It is shown that the amplitude imbalance of the quadratures leads to a significant decrease in the noise immunity of QAM signals reception  at M ≥  16. The acceptable amplitude deviation in this case can be considered to be equal to 5%. At M= 4, the amplitude imbalance in a wide range of values practically does not affect the noise immunity. The phase imbalance of  quadratures  markedly affects the noise immunity of coherent reception of QAM signals. The permissible phase error is no more than 0.05 rad (3 degrees). As the signals positionality increases, this influence also increases.

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