Pulse Coded Modulation (PCM)

In this section we will look at the process of converting an analog signal to be digitally
transmitted into a digital format.
To transmit digitally we only have a discrete set of symbols that can be sent at a fixed
rate. Hence before we can send the signal we need to quantize it in time and amplitude.
A process of achieving this quantization is PCM.
A general criterion is that the digitally modulated transmitted signal can be demodulated
and converted back into an analog form with a tolerable amount of distortion. Generally
the specification of“tolerable” is very subjective.For example consider voice quality
requirements of a wireless phone.
Given distortion tolerance, the objective is generally to optimize the encoding such that a
minimum bit rate is consumed with the application.

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Armature Winding ,Pole Pitch, Coil Span, Commutator Pitch

Now we are going to discuss about armature winding in details. Before going through this section, we should understand some basic terms related to armature winding of dc generator . Pole Pitch Definition of Pole Pitch The pole pitch is defined as peripheral distance between center of two adjacent poles in dc machine. This distance is measured in term of armature slots or armature conductor come between two adjacent pole centers. This is naturally equal to the total number of armature slots divided by number of poles in the machine. If there are 96 slots on the armature periphery and 4 numbers of poles in the machine, the numbers of armature slots come between two adjacent poles centers would be 96/4 = 24. Hence, the pole pitch of that dc machine would be 24. As it is seen that, pole pitch is equal to total numbers of armature slots divided by total numbers of poles, this can alternatively referred as armature slots per pole . Coil Span or Coil Pitch Coil of ...

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