Frequency modulation and demodulation of a 10.6‐μm CO2laser

1980 ◽  
Vol 36 (1) ◽  
pp. 29-30
Author(s):  
Y. Yasuoka ◽  
T. Takahashi ◽  
T. K. Gustafson
2014 ◽  
Vol 624 ◽  
pp. 561-566
Author(s):  
Jun Wang ◽  
Shuo Feng

The paper introduces a system using PLL frequency modulation and demodulation technique, and using infrared as the carrier to realize wireless communication. CD4046 is a common CMOS low-frequency phase locked loopintegrated circuit, and it has the characteristics of high VCOlinearity, tunable center frequency and acquisition frequency range, low power consumption and simple for use. The paper introduces the design scheme using the technique for infrared communication, and proposes a method using sing-chip microcontroller to control single channel to realize the simultaneous transmission of acoustic signal and digital signal, which has great practicability.


Author(s):  
Renuka Kajur ◽  
K. V. Prasad

The Gaussian minimum shift keying (GMSK) is one of the best suited digital modulation schemes in the global system for mobile communication (GSM) because of its constant envelop and spectral efficiency characteristics. Most of the conventional GMSK approaches failed to balance the digital modulation with efficient usage of spectrum. In this article, the hardware architecture of the optimized CORDIC-based GMSK system is designed, which includes GMSK Modulation with the channel and GMSK Demodulation. The modulation consists of non-return zero (NRZ) encoder, an integrator followed by Gaussian filtering and frequency modulation (FM). The GMSK demodulation consists of FM demodulator, followed by differentiation and NRZ decoder. The FM Modulation and demodulation use the optimized CORDIC model for an In-phase (I) and quadrature (Q) phase generation. The optimized CORDIC is designed by using quadrant mapping and pipelined structure to improve the hardware and computational complexity in GMSK systems. The GMSK system is designed on the Xilinx platform and implemented on Artix-7 and Spartan-3EFPGA. The hardware constraints like area, power, and timing utilization are summarized. The comparison of the optimized CORDIC model with similar CORDIC approaches is tabulated with improvements.


2014 ◽  
Vol 543-547 ◽  
pp. 2426-2430
Author(s):  
Zhang Cheng Yang ◽  
Xiang Lin Wang

The popularity of internet technology has brought the change very big to the life and production of modern humans, the current Internet technology application has penetrated into people in every aspect of modern life, has become an indispensable part of people's life. Firstly, system model of the current network communication to dissect, analyzes the architecture of network communication system, modulation and demodulation principle is applied to design the FM communication signal modulation system network communication in the Internet technology, the non coherent demodulation method to build FM demodulation system, realize the demodulation process through differential device, the anti noise performance of the method of frequency modulation system of MATLAB simulation experiments, the experimental results show that the method of anti noise performance significantly, to a certain extent, provide theoretical basis and technical support for the research in this field.


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