Ask Electrical & Electronics Expert

An underwater optical communications system that implements forward error correction is demonstrated. The system uses a 405 nm diode laser to transmit on-off-keying (OOK) return-to-zero modulated data at a rate of 500 kbps to a photodiode receiver using a (255,129) Reed-Solomon code. The signal is digitized at the receiver and sent to a PC for post-processing. Experimental measurements collected in an indoor water tank suggest that the coded system can reduce the power required to achieve a bit-error-rate of 10-4 by approximately 8
dB relative to an uncoded OOK system.

As scientific progress demands more and varied data from the earth's oceans, and the military requires greater scrutiny of undersea traffic and threats, the need for reliable underwater communication links increases. The mobility requirements of submarines and autonomous underwater vehicles make tethered links infeasible, and radio frequency electromagnetic waves are highly attenuated in ocean water, preventing their widespread use. As sound waves undergo very little attenuation in the underwater channel, underwater acoustic
communications has been a topic of research for some time. However, due to issues of multipath interference and lack of bandwidth, acoustic data rates are limited. Acoustic links also exhibit very long propagation delays. 

One potential solution for high bandwidth and low latency underwater wireless communications is the use of optical communication systems. Such systems have grown more popular in recent years with the creation of reliable, low-cost light sources, like LEDs and diode lasers that take advantage of the comparatively low attenuation of light in the 400 nm - 550 nm range in seawater. Communication links have been demonstrated at rates of 10 Mbps and 1 Gbps. Researchers have also investigated the benefits of different modulation techniques on underwater optical communication systems.

While researchers have examined the use of forward-error- correction (FEC) codes to improve acoustic underwater communication systems , these techniques have not been applied to an underwater optical communication system. In principle, the use of such coding should allow the system to operate at a lower signal-to-noise ratio (SNR) for a given bit-error-rate (BER). Since the received signal power directly corresponds to the amount of detected photons, absorption and scattering of photons is the main source of signal attenuation.

This paper describes the application of a Reed-Solomon (RS) FEC code to an underwater optical communication link, in order to reduce the power requirements and/or extend the range of such a link over a varying degree of water conditions.

Electrical & Electronics, Engineering

  • Category:- Electrical & Electronics
  • Reference No.:- M9292612

Have any Question?


Related Questions in Electrical & Electronics

Question 1for the ce amplifier in figure 1 given the

Question 1 For the CE amplifier in Figure (1), given the following component parameters: Parameter Value β DC , β AC 150 V BE 0 . 7 V V CC 12 V R C 820 ? R E 1 100 ? R E 2 220 ? R 1 20 k? R 2 5 . 2 k? R L 100 k? C 1 , C ...

Question -i a star-connected three-phase synchronous

Question - (i) A star-connected, three-phase synchronous induction motor takes a current of 10 amps from a 415 volt supply at unity power factor when supplying a steady load. If the synchronous reactance is 5 ohms/phase ...

1 a name the three major groups of contamination and

1. (a) Name the three major groups of contamination and briefly describe their physical characteristics. (b) Where do the above contamination types come from? Give one example of each. 2. Name two processes metrics which ...

Question 1 in the voltage regulator circuit in figure p221

Question 1: In the voltage regulator circuit in Figure P2.21, V 1 = 20 V, V Z = 10 V, R i = 222Ω and P z (max) = 400 mW. (a) Determine I L, I z , and I L , if R L = 380Ω. (b) Determine the value of R L , that will establ ...

Summative assessmentin 2017 sej101 assessment will consist

Summative Assessment In 2017 SEJ101 assessment will consist of nine tasks that will develop a portfolio of your assessed work. Throughout the trimester you will have the opportunity for feedback on all nine tasks before ...

1 a name the three major groups of contamination and

1. (a) Name the three major groups of contamination and briefly describe their physical characteristics. (b) Where do the above contamination types come from? Give one example of each. 2. Name two processes metrics which ...

1 a name the three major groups of contamination and

1. (a) Name the three major groups of contamination and briefly describe their physical characteristics. (b) Where do the above contamination types come from? Give one example of each. 2. Name two processes metrics which ...

Case studythis assignment consists of a written report of

CASE STUDY This assignment consists of a written report of approximately 1000 words and any diagrams in which you are asked to critically compare different process methods used to achieve the same result and show an awar ...

Problem 1 a two-phase servomotor has rated voltage applied

Problem 1: A two-phase servomotor has rated voltage applied to its excitation winding. The torque speed characteristic of the motor with Vc = 220 V, 60 Hz applied to its control phase winding is shown in Fig.1. The momen ...

Electrical engineering questions -q1 two ideal voltage

Electrical Engineering Questions - Q1. Two ideal voltage sources designated as machines 1 and 2 are connected, as shown in the figure below. Given E 1 = 65∠0 o V, E 2 = 65∠30 o V, Z = 3Ω. Determine if Machine 1 is genera ...

  • 4,153,160 Questions Asked
  • 13,132 Experts
  • 2,558,936 Questions Answered

Ask Experts for help!!

Looking for Assignment Help?

Start excelling in your Courses, Get help with Assignment

Write us your full requirement for evaluation and you will receive response within 20 minutes turnaround time.

Ask Now Help with Problems, Get a Best Answer

Why might a bank avoid the use of interest rate swaps even

Why might a bank avoid the use of interest rate swaps, even when the institution is exposed to significant interest rate

Describe the difference between zero coupon bonds and

Describe the difference between zero coupon bonds and coupon bonds. Under what conditions will a coupon bond sell at a p

Compute the present value of an annuity of 880 per year

Compute the present value of an annuity of $ 880 per year for 16 years, given a discount rate of 6 percent per annum. As

Compute the present value of an 1150 payment made in ten

Compute the present value of an $1,150 payment made in ten years when the discount rate is 12 percent. (Do not round int

Compute the present value of an annuity of 699 per year

Compute the present value of an annuity of $ 699 per year for 19 years, given a discount rate of 6 percent per annum. As