New Carrier Recovery Method for 16-QAM System Based on Full Constellation Points

The relationship between the data to be transmitted and the signal phase in the 16-level quadrature amplitude modulation （16-QAM） constellation is derived. Then a new carder recovery method based on this relationship is proposed, where both-the diagonal and non-diagonal signal points are used for carder recovery. The analysis and simulation results show that, the proposed method for 16-QAM has a higher acquisition speed than the times-four carrier recovery method, and has a wider acquisition bandwidth and smaller phase errors than the diagonal constellation based carrier recovery method.

VLSI Implementation of a Single-Chip DVB-C Demodulator

A single-chip DVB-C quadrature amplitude modulation（QAM） demodulator is proposed,which integrates a 3.3V 10bit 40MSPS analog-to-digital converter and a forward error correction decoder. The demodulator chip can support 4-256 QAM with variable bit rate up to 80Mbps. It features a wide carrier offset acquisition range,optimal demodulation algorithm,and small circuit area. The chip is implemented in SMIC 0.25μm 1P5M mixed-signal CMOS technology with a die size of 3.5mm×3. 5mm. The maximum power consumption is 447mW.

A method to realize NAVSOP by utilizing GNSS authorized signals

Navigation via signals of opportunity(NAVSOP)is able to realize positioning by making use of hundreds of different signals that are all around us.A method to realize NAVSOP for low earth orbit(LEO)satellites is proposed in this paper,in which the global navigation satellite system(GNSS)authorized signals are utilized as the signal of opportunity(SOP).At first,the carrier recovery technique is studied under the premise that the pseudo-code is unknown.Secondly,a method based on characteristics of Doppler frequency shift is proposed to recognize the navigation satellites.Thirdly,the extended Kalman filter(EKF)is utilized to estimate the orbital parameters by using carrier phase measurements.Finally,the proposed method is evaluated by using signals generated by a satellite navigation data simulator.The simulation results show that the proposed method can successfully realize navigation via GNSS authorized signals.

Metrology of Optical Communication Systems Using Error Vector Magnitude

Error vector magnitude (EVM) as a performance metric for M-ary quadrature amplitude modulation (QAM) formats in optical coherent systems is presented. It is shown that the calibrated BER, which would otherwise be under-estimated without the correction factor, can reliably monitor the performance of optical coherent systems near the target BER of 10-3 for quadrature phase shift keying (QPSK), 16-QAM, and 64-QAM employing carrier phase recovery with differential decoding to compensate for laser phase noise. The impact on the number of symbols used to estimate the BER from EVM analysis is also presented and compared to the BER obtained by error counting.