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Wireless laser communication PPM polarization modulation and demodulation method

A polarization modulation and demodulation method technology, applied in the field of communication, can solve the problems of short communication distance, low rate, and easy to be affected by atmospheric random channels, so as to achieve the effect of improving code rate and transmission distance and overcoming the influence

Inactive Publication Date: 2009-12-23
XIAN UNIV OF TECH
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Problems solved by technology

[0004] The purpose of the present invention is to provide a wireless laser communication PPM polarization modulation and demodulation method to solve the problems of low code rate, short communication distance and vulnerability to atmospheric random channels in the existing wireless laser communication

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  • Wireless laser communication PPM polarization modulation and demodulation method
  • Wireless laser communication PPM polarization modulation and demodulation method
  • Wireless laser communication PPM polarization modulation and demodulation method

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Embodiment Construction

[0019] The present invention will be described in detail below with reference to the drawings and specific embodiments.

[0020] The existing pulse position modulation (PPM) method is to map a set of binary n-bit data groups into 2 n A single pulse signal at a time slot in a time period consisting of time slots, this modulation method is essentially a phase modulation.

[0021] Record the n-bit data group as M=(m 1 , M 2 ,..., m n ), this mapping relationship can be expressed by the following formula:

[0022] Φ: L=m 1 +2m 2 +......+2 n-1 m n ∈(0, 1, 2,..., 2 n-1 )

[0023] In the formula, L represents the position number of the time slot.

[0024] which is:

[0025] Where S n (t) represents the modulated signal, P C Represents pulse power, T C Represents the length of the time slot.

[0026] For example, for a 4-PPM:

[0027] If M = (0, 0), then L = 0; if M = (1, 0), then L = 1;

[0028] If M=(0,1), then L=2; if M=(1,1), then L=3;

[0029] 0, 1, 2, 3 respectively correspond to t...

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Abstract

The present invention relates to a wireless laser communication PPM polarization modulation- demodulation method, which creates one-to-one correspondence between a PPM signal of an information source and an elliptic polarizing angle. Based on the correspondence, the signal of the information source is modulated into an elliptic polarized light with a corresponding elliptic polarizing angle and emits the light in the form of an optical signal. During demodulation, the polarizing angle of the received elliptic polarized light is calculated to confirm information of the information source corresponding to the polarizing angle according to the correspondence above and then complete information demodulation. The modulation-demodulation method overcomes impact of atmospheric channel on communication and effectively eliminates lower communication code rate and short communication distance of wireless laser communication.

Description

Technical field [0001] The invention belongs to the field of communication technology, and specifically relates to a PPM polarization modulation and demodulation method for wireless laser communication. Background technique [0002] Modulation and demodulation is a key technology in wireless laser communication. At present, there are two main types of modulation and demodulation systems in wireless laser communication, one is intensity modulation / direct detection (IM / DD) system, and the other is coherent Modulation / heterodyne detection system. In the IM / DD system, the transmitting end obtains a modulated signal by directly modulating the intensity of the optical carrier, and the receiving end uses a photodetector to directly convert the optical signal into an electrical signal. The direct detection system has the advantages of small size, light weight, simple structure, low cost, and easy implementation, but its frequency band utilization rate is low, and the receiving sensitivit...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04B10/12G02F1/35H04B10/556
Inventor 柯熙政刘健
Owner XIAN UNIV OF TECH