Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Q. Explain Multiplexing Systems?
A multiplexing system is one in which two or more signals are transmitted jointly over the same transmission channel. There are two commonly used methods for signal multiplexing. In frequency-division multiplexing (FDM), various signals are translated to nonoverlapping frequency bands. The signals are demultiplexed for individual recovery by bandpass filtering at the destination. FDM may be used with either analog or discrete signal transmission. Time - division multiplexing (TDM), on the other hand, makes use of the fact that a sampled signal is off most of the time and the intervals between samples are available for the insertion of samples from other signals. TDM is usually employed in the transmission of discrete information. Let us now describe basic FDM and TDM systems.
Figure (a) shows a simple FDM system which is used in telephone communication systems. Each input is passed through a low-pass filter (LPF) so that all frequency components above 3 kHz are eliminated. It is then modulated onto individual subcarriers with 4-kHz spacing. While all subcarriers are synthesized from a master oscillator, the modulation is achieved with single sideband (SSB). The multiplexed signal, with a typical spectrum as shown in Figure (b), is formed by summing the SSB signals and a 60-kHz pilot carrier. The bandpass filters (BPFs) at the destination separate each SSB signal for product demodulation. Synchronization is achieved by obtaining the local oscillator waveforms from the pilot carrier. Telephone signals are often multiplexed in this fashion.
A basic TDM system is illustrated in Figure (a). Let us assume for simplicity that all three input signals have equal bandwidths W. A commutator or an electronic switch subsequently obtains a sample from each input every Ts seconds, thereby producing a multiplexed waveform with interleaved samples, as shown in Figure (b). Another synchronized commutator at the destination isolates and distributes the samples to a bank of low-pass filters (LPFs) for individual signal reconstruction.More sophisticated TDM systems are available inwhich the sampled values are converted to pulse modulation prior to multiplexing and carrier modulation is included after multiplexing. Integrated switching circuits have made the TDM implementation much simpler than FDM.
Define HRQ? The hold demand output requests the access of the system bus. In non- cascaded 8257 systems, this is linked with HOLD pin of CPU. In cascade mode, this pin of a sla
Depletion type MOSFET The channel is of silicon. It can be two type of channel that is an n-type or p-type channel; it is still mostly silicon. After that, we take note that
The field resistance of a dc machine is 50 ohm at 20 o C. The resistance increases to 55 ohm at 50 o C. Find the temperature coefficient of the resistance material. Ans: Sol
Types of Power Diode According to their reverse recovery characteristics of power diodes it can be classified as follows: a. General purpose diodes b. Fas
Q. What is a wave analyzer? Explain any one technique of wave analyzer giving its application also. OR Write short note on HETERODYNE Wave analyzer. OR Explai
what is a resistor?
RRC Rotate Accumulator Right Instruction This instruction also rotates the contents of the accumulator toward right by one bit. The D 7 bit moves to D 5 position a
why we rotate the armature of dc motor in anticlockwise direction
Turn off Time The time interval between the instant when the SCR current has decreased to zero after external switching of the SCR voltage circuit and the inst
Load Stack Pointer This instruction loads the stack pointer register with the 16 - bit data specified in the instruction. The 16 - bit data. When stored in sp registe
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +1-415-670-9521
Phone: +1-415-670-9521
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd