Optimum local oscillator levels for coherent detection using photoconductors

1988 ◽  
Vol 27 (15) ◽  
pp. 3135 ◽  
Author(s):  
John M. Hunt ◽  
J. Fred Holmes ◽  
Farzin Amzajerdian
Keyword(s):  
Local Oscillator ◽  
Coherent Detection

Fast Optical Switch Utilizing Coherent Detection Enabled by Cooperative Filtering of Transmission Signal and Local Oscillator (LO) Wavelength Sourced from an LO Bank

2021 ◽  
Author(s):  
Ryosuke Matsumoto ◽  
Ryotaro Konoike ◽  
Hiroyuki Matsuura ◽  
Keijiro Suzuki ◽  
Takashi Inoue ◽  
...  
Keyword(s):  
Optical Switch ◽  
Local Oscillator ◽  
Coherent Detection

scholarly journals Generation and coherent detection of QPSK signal using a novel method of digital signal processing

2018 ◽  
Vol 32 (04) ◽  
pp. 1850103
Author(s):  
Yuan Zhao ◽  
Bingliang Hu ◽  
Zhen-An He ◽  
Wenjia Xie ◽  
Xiaohui Gao
Keyword(s):  
Signal Processing ◽  
Digital Signal Processing ◽  
Digital Signal ◽  
Local Oscillator ◽  
Coherent Detection ◽  
Detection Methods ◽  
Homodyne Detection ◽  
Modulation Formats ◽  
Detection Scheme ◽  
Labview Software

We demonstrate an optical quadrature phase-shift keying (QPSK) signal transmitter and an optical receiver for demodulating optical QPSK signal with homodyne detection and digital signal processing (DSP). DSP on the homodyne detection scheme is employed without locking the phase of the local oscillator (LO). In this paper, we present an extracting one-dimensional array of down-sampling method for reducing unwanted samples of constellation diagram measurement. Such a novel scheme embodies the following major advantages over the other conventional optical QPSK signal detection methods. First, this homodyne detection scheme does not need strict requirement on LO in comparison with linear optical sampling, such as having a flat spectral density and phase over the spectral support of the source under test. Second, the LabVIEW software is directly used for recovering the QPSK signal constellation without employing complex DSP circuit. Third, this scheme is applicable to multilevel modulation formats such as M-ary PSK and quadrature amplitude modulation (QAM) or higher speed signals by making minor changes.

scholarly journals A Novel Sample Based Quadrature Phase Shift Keying Demodulator

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Asraf Mohamed Moubark ◽  
Sawal Hamid Md Ali
Keyword(s):  
Phase Noise ◽  
Signal To Noise Ratio ◽  
Local Oscillator ◽  
Coherent Detection ◽  
Signal Frequency ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Incoming Signal ◽  
Shift Keying ◽  
Low Pass

This paper presents a new practical QPSK receiver that uses digitized samples of incoming QPSK analog signal to determine the phase of the QPSK symbol. The proposed technique is more robust to phase noise and consumes up to 89.6% less power for signal detection in demodulation operation. On the contrary, the conventional QPSK demodulation process where it uses coherent detection technique requires the exact incoming signal frequency; thus, any variation in the frequency of the local oscillator or incoming signal will cause phase noise. A software simulation of the proposed design was successfully carried out using MATLAB Simulink software platform. In the conventional system, at least 10 dB signal to noise ratio (SNR) is required to achieve the bit error rate (BER) of 10−6, whereas, in the proposed technique, the same BER value can be achieved with only 5 dB SNR. Since some of the power consuming elements such as voltage control oscillator (VCO), mixer, and low pass filter (LPF) are no longer needed, the proposed QPSK demodulator will consume almost 68.8% to 99.6% less operational power compared to conventional QPSK demodulator.

scholarly journals Coherent detection with an incoherent local oscillator

2018 ◽  
Vol 26 (26) ◽  
pp. 33970 ◽  
Author(s):  
Antonio Mecozzi ◽  
Mark Shtaif
Keyword(s):  
Local Oscillator ◽  
Coherent Detection

Influence of local oscillator power on sensitivity of coherent detection of space balance detector

2017 ◽  
Vol 25 (2) ◽  
pp. 334-341
Author(s):  
梁赫西 LIANG He-xi ◽  
代永红 DAI Yong-hong ◽  
艾 勇 AI Yong ◽  
单 欣 SHAN Xin ◽  
武 强 WU Qiang
Keyword(s):  
Local Oscillator ◽  
Coherent Detection
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