Communication

Maximum high load communication on today's date is done by optical fibers. Because they can wear a very high load and provide a high duty period. Since optical frequency is very high so they provides a very high bandwidth and can easily sustain very high load.

This can be done by using two methods 

• By single laser and detector 
• By dual laser and detector

Single laser

This is done with the help of mirrors, since mirrors are passive element so they do not provides any time dependent noise.

This site provides an overview of new 4th generation Free Space Optics wireless bridges used to connect buildings and towers with Gigabit capacity, license-free, interference-free data transmission capability.

In the news: NASA launching Earth-to-Moon/Satellite Free Space Optics link (video below). For more information on NASA laser communications,

The Lunar Laser Communication Demonstration (LLCD) is NASA's first high-rate, two-way, space laser communication demonstration.

What is LLCD? 

NASA is venturing into a new era of space communications using laser communications technology and it's starting with the LLCD mission. For decades NASA has launched and operated satellites in order to expand our understanding of earth and space science. In order to sustain this vision, satellites have increased their observation capabilities, transmitting data over greater distances, with a corresponding increase in data downlink rate and data volume. In an effort to address these challenges and enhance the Agency's communications capability, NASA has directed the Goddard Space Flight Center (GSFC) to lead the Lunar Laser Communication Demonstration (LLCD).

LLCD will be NASA's first-step in creating a high performance space-based laser communications system. The LLCD mission consists of a space terminal that will reach lunar orbit as a payload aboard the LADEE spacecraft; and a robust ground segment that consists of three ground terminals in optimal locations around the globe.

Laser communications set for Moon mission

An advanced laser system offering vastly faster data speeds is now ready for linking with spacecraft beyond our planet following a series of crucial ground tests. Later this year, ESA’s observatory in Spain will use the laser to communicate with a NASA Moon orbiter.

The laboratory testing paves the way for a live space demonstration in October, once NASA’s Lunar Atmosphere and Dust Environment Explorer – LADEE – begins orbiting the Moon.

LADEE carries a terminal that can transmit and receive pulses of laser light. ESA’s Optical Ground Station on Tenerife will be upgraded with a complementary unit and, together with two US ground terminals, will relay data at unprecedented rates using infrared light beams at a wavelength similar to that used in fiber-optic cables on Earth.


Optic fiber line to give China access to Pak military networks

BEIJING: Work on lying a fiber optic cable line linking China to Pakistan is set to begin soon. 

Sources said that the link will give China access to Pakistani military's communication networks. Radio Pakistan reported that a team of exports have visited parts of the area to be covered by the line and plan to begin work soon. 

Telecom experts recently carried out inspection in Sost and Khunjarab in the upper Hunza area of Gilgit Baltistan, Radio Pakistan said quoting officials of the communication department in the area. 

The new lines will also connect Rawalpindi, the military headquarters of Pakistan and Gilgit Baltistan including areas in Pakistan Occupied Kashmir, sources said. 

Pakistani experts have talked about the security challenges faced by the project including the possibility of the communication lines being monitored and disrupted by Taliban militants but they have not expressed any worry about the access it would give to Chinese authorities, observers said. This may be because Pakistan regards China as an all-weather and trusted friend, they said. 

China and Pakistan signed an agreement for the optic fiber project by the Chinese company Huawei during the visit of Prime Minister Nawaz Sharif to Beijing in July. 

The fiber cable connecting Rawalpindi and Khunjarab on the Pakistan-China border will be 820 km long and will cost $44 million. 

Both neighbors have opted for additional measures to mitigate security challenges because voice and data traffic along the militant infested border could be monitored and disturbed, sources said. Erratic climatic conditions in the area also pose a challenge. 

The project planners have provided for an alternative link between Pakistan and Trans-Asia Europe cable in China to ensure connectivity with the international telecom traffic in case of disruption, APP, the Pakistani news agency reported.