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Explain FDM and show how CCITT standards help in building the base band?
Frequency Division Multiplexing: This is the process of combining some information channels through shifting their signals to various frequency groups in the spectrum therefore they can be transmitted simultaneously over common transmission service.
The bandwidth of a telephone speech signal is quite less than 4 kHz. Where, the available bandwidth on unloaded cables pair is fine above 100 kHz. Therefore this is possible, by using modulation techniques, for divide up the cable bandwidth then a number of telephone speech paths can be carried at the same time along a single cable pair. The normal arrangement contains 24 telephone channels per cable pair, the modulation in 24 channels being carried out within the two stages. In the primary stage, 12 channels are multiplexed together to form that is commonly termed as a basic group. This basic group arrangement is demonstrated in figure. Each of the 12 telephone signals are single side-band amplitude modulated on to carriers spaced at 4 kHz intervals 64 kHz to 108 kHz. The lower side-band (LSB) is utilized in every case. The 12 base-band signals are thus translated in the frequency band from 60 kHz 108 kHz as demonstrated. The block diagram for the channel translating equipment is specified in figure. To form a 24-channel system, to basic groups are occupied together. One basic group (B) is transmitted directly as this stands. Another basic group (A) is amplitude modulated on to a carrier are 120 kHz and the lower side-band is occupied such as to take the frequency range from 12 kHz to 60 kHz as demonstrated in figure. by using two stages of modulation for basic group A, this is possible to decrease the physical size of the component needed for the LSB filters of the figure, because the lowest cut- off frequency needed is at 64 kHz quite than 12 kHz when the whole block of 24 channels were assembled together in one stage of modulation.
FIG - Basic Group Arrangement
FIG - Channel Translating Equipment
The standards are for all testers using the IDE of Rational Robot to make their automated test scripts. The mission is to decrease maintenance costs when it comes to changes.
Which interface controls what is shown on the p.c.? Presentation Interface controls what is shown on the p.c
what it is mean
Error handling in Hard disk in computer architecture : Modern drives also make widespread use of Error Correcting Codes (ECCs), specifically Reed-Solomon error correction.
How can we declare a table control in the ABAP/4 program? Using the syntax controls type tableview using screen .
Converter is an application that converts distance measurements among metric and U.S units.
Design a circuit which computes the square of a number? This should not make use of any multiplier circuits. This should use Multiplexers and some other logic as: 1^2=0+1=1
Discuss the applications of thermodynamics in field of energy technology Sol: Thermodynamics has wide applications as basis of thermal engineering. Nearly all process and engi
Q. Interrupt - Driven Input-output? Problem with programmed I/O is that processor has to wait a long time for I/O interface to see whether a device is free or waits until compl
What is the difference between field-group header and other field groups? The header field group is a particular field group for the sort criteria. The system automatically p
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