Synchronization Technique Used in Analog FDM

 Frequency division multiplexing (FDM) is an analog modulation technique that combines analog signals. In FDM several frequencies bandwidths are carried through a single line. Then it is transmitted to the receiver. In this case, in FDM we use guard bands within two bandwidths. Using guard band is a technique that use in FDM for synchronization. We can see it in this figure.

 

When we transmit these 10 kHz bandwidths (signals) to receiver without guard (5 kHz) bands, the receiver cant identity what is the 1^st, 2^nd, 3^rd signal. It hasn’t any understand about the bandwidth of the signal.

               We can see in this figure, if we use a guard band between them the receiver can identify the signals. It can know the bandwidth of the signal.

               That’s how synchronization technique used in analog FDM.

Throughout this article I hope you may get some thing. This provides very basic explanation and future will cover more. Comments are well come. Thank you.

Benefits of Modulation in Telecommunication

Modulation for efficient transmission

                                                         

                      Signal transmitting over appreciable distance always involves a traveling electromagnetic wave. The efficiency of any particular transmission method depends upon the frequency of the signal being transmitted. By exploit in the frequency translation property of modulation the message can be inserted into carrier which has the frequency selected for the desired transmission method.

Modulation to overcome hardware limitation

                                             

                      The design of the communication may be constrict by the cost availability of the hardware, performance of the hardware often depends on the frequencies involved. Modulation permits that designer to place a signal in some frequency range that avoids the hardware limitation.

Modulation to reduce noise and interferences

                      A method for overcoming noise and interferences is to increase signal power until it overcomes the contamination. But increasing power is costly and may damage the equipments. Fortunately FM and certain other types of modulations have a valuable property of suppressing both noise and interferences.

Modulation for frequency assignment

                      When we tune a radio or television, particular station we are selecting one of the many signals being received at that time. Since each station has a different assigned carried frequency that desired signal can be separated from the others by filtering.

    Throughout this article I hope you may get some thing. This provides very basic explanation and future will cover more. Comments are well come. Thank you.

ATM technology in SDH

By using ATM technology, variable bit traffic is transport over SDH Network. In hybrid ATM, payload of SDH frame are filled with ATM cells by using ATM cells. The bit rates are depends on the number of ATM cells. In this system SDH traffic and ATM traffic are combined in to same SDH bearer, Nodes have the visibility of ATM cells. Therefore they separate the SDH traffic from ATMJ. And they route each one to their respective switching fabric. After they have been swathed, they may recombine in a hybrid payload, network element requires both SDH & ATM traffic management. ATM cells are mapped in conceded STS-N payload. 

SDH frames with ATM cells

Voice traffic ATM over SDH

ATM is a core protocol used over the sonnet/SDH backbone of the ISDN. All the data packets in the link always encounter full size under normal quinine conditions so that experience maximum quinine delays, so that we need some technique to avoid this. It is ATM. Reduction of this end to end delay is very much important when carrying voice traffic, because the conversion of digitized voice in to an analog audio signal is a hesitantly real time process. When there is a stream of data and in they stream there is a space and patently they data is not available. If it is valid able delayed due to quinine then we face a problem to overcome that we uses ATM over SDH.

    Throughout this article I hope you may get some thing. This provides basic explanation and future will cover more. Comments are well come. Thank you.