Satellite radio vs. optical communication - Future of

                Optical communications in space have their contrasts to satellite radio that utilize frequencies in the C-Band, Ku, and Ka Band range. The most obvious advantage is speed of data transmission from orbit to and from ground based systems with speeds at up to 2 Gb with anticipation of high speed data bursts tested at 2 Tb with multi-modal laser technology. The downside currently is that rain attenuation from lasers is substantially higher than with the rain attenuation lost due from radio frequencies. Signal power generation from optical communications systems with telescope aperture could provide tens of dBs of link efficiency. Another consideration is that optical systems have a narrower beam width than RF equivalent. There is a greater interference potential with optical systems of less chance for interference from nearby satellites. There is development of the use of YAG, adaptive optics, spatial diversity, and pumped dye lasers that can have their frequencies tuned with dyes and multi-frequencies to overcome the severe effects of atmospheric impacts of weather. (OPTICAL COMMUNICATIONS AND INTERSATELLITE LINKS n.d.).

There are other systems such as Artemis which is semiconductor intersatellite link experiment (SILEX), small optical telecommunications terminal (SOTT), Solid State Laser Communications in Space (SOLACOS), Short Range Optical Intersatellite Link (SROIL).

The Transformational Satellite System (TSAT) provides orbit-to-ground laser communications. The throughput for the five-satellite constellation could top out at 10 to 40 gigabytes per second, with a total program cost of $12 billion-to-$18-billion for the entire constellation. This system will provide DoD with a very high speed data rate. This network will meet the needs of tomorrow’s high speed data transfer between ground troops and command headquarters. This is a system meant to be jam-resistant, worldwide, secure, and general purpose communication for tomorrow’s battle space. Data transmission DoD ring support will support up to 45Mbps, and laser communication user data rates into the 10-100s Gbps range. It is self-evident that a ten to hundred fold increase in data rates will greatly enhance the TSAT system with data rates connections to Space and Airborne Intelligence, Surveillance, and Reconnaissance (SISR, AISR) platforms (Anonymous 2009).

Technology being developed utilizing phased array antenna while they may be inferior to the TSAT SS, Advanced Extremely High Frequency (AEHF) Milstar III satellites will provide over 10 times the capacity and 6 times better data rate transfer than the current Milstar II satellites (staff 2009).

The future hold anything possible, German scientists have set a world record for optical communications, transmitting 26 trillion bits of data per second—enough to download hundreds of DVD’s in an instant—using just a single laser. Data streams using one transmitter instead of four encoding data into overlapping frequencies, combining four bits of data into a single wave, using the multi-modal (frequency) laser. The process for adding the extracting of the wave forms is accomplished with Fast Fourier Transform (FFT) and its inverse.  (Savage 2011).

Data communications experts foresee data rates increasing with the advent usage of grapheme as a di-electric insulator for semi-conductors, coupled with 3D-transistor design of new processor due to a 3^rd dimension added to transistor architecture. Linear technology projection of 22 nm in 2011 anticipates lithography at 10 nm levels in 2015 (Shimpi 2011).  The environment of grapheme being next to augment data and optical communication is on the horizon. Graphene creates molecular 2D bonds as strong as diamonds that have di-electric properties of diamonds with a fraction of the cost. They exhibit magnetic behavior with the need of magnetic metals. The use of grapheme is in field effect transistors. This being used in processors will great processors of 300GHz to 3000GHz or 3Terahertz.This combined with optical laser technology, ultra-high speed processors with radically increase the speed of all electronics on satellites in use today  (Ice 2010).

Works Cited

Anonymous. "Transformational SATCOM (TSAT) Transformational Communications Satellite (TSAT) Advanced Wideband System." Global Security.org. June 08, 2009. http://www.globalsecurity.org/space/systems/tsat.htm (accessed Jan 10, 2012).

Ice, Valkyrie. "Graphene is Next." Hplus Magazine. May 03, 2010. http://hplusmagazine.com/2010/05/03/graphene-next/ (accessed Jan 10, 2012).

"OPTICAL COMMUNICATIONS AND INTERSATELLITE LINKS." n.d. http://www.wtec.org/loyola/satcom2/03_06.htm (accessed 01 10, 2013).

Savage, Neil. "Fastest Single-Laser Transmission: Researchers send 26 terabits per second of data with only one lase." Spectrum. May 2011. http://spectrum.ieee.org/semiconductors/optoelectronics/fastest-singlelaser-transmission (accessed Jan 10, 2012).

Shimpi, Anand Lal. "Intel Announces first 22nm 3D Tri-Gate Transistors, Shipping in 2H 2011." Anandtech. May 04, 2011. http://www.anandtech.com/show/4313/intel-announces-first-22nm-3d-trigate-transistors-shipping-in-2h-2011 (accessed Jan 10, 2012).

staff, Defense Industry Daily. "Special Report: The USA’s Transformational Communications Satellite System (TSAT)." Defense Industry Daily. Jan 09, 2009. http://www.defenseindustrydaily.com/special-report-the-usas-transformational-communications-satellite-system-tsat-0866/ (accessed 01 10, 2013).