Modern Possibilities of Access and Transport Networks Vladislav Skorpil
The principle of Time Division Multiplex
The Principle of Pulse Code Modulation (PCM)
The Principle of Delta Modulation (DM) and Adaptivre delta Modulation (ADM)
Adaptive Diferential PCM - ADPCM For signal with no constant midle power, samples are adapted to constant midle power
The basic block diagram for TDM system with digital modulation Older type Common codec
Transmiter part
Receiver part
The basic block diagram for TDM system with digital modulation Modern type Individual codec
Quantizing step encoder
Weighting encoder (Bit encoder)
Counting Analogue to Digital Convertor
Tracking A/D Convertor
Parallel A/D Convertor
Compenzating A/D Convertor
Shannon decoder
Shannon decoder response
Shannon Rack decoder
Shannon-Rack Decoder Response
Weighting Decoder (Bit Encoder)
Operational Amplifier
D/A Convertor with weighting resistors
D/A Convertor with cross piece structure of resistor networks
D/A Convertor with current sources
Compandors and non-linear encoders
Compression and expansion characteristics
A-low compression characteristic
Unipolar and Bipolar Signal, Signal NRZ, RZ, TPC, SPC, HDB3,AMI
Code HDB3 Maximal 3 zeroes in sequence When the sequence of 4 or more zeroes exist, then forth one is encoded as the impulse with the same polarity as the previous one This bipolarity interruption must be positive after negative and negative after possitive (zero direct current part)
Isolation impulse
Identification of impulse
Decision eye – bipolar signal
Decision eye – unipolar signal, basic noise
Influence of impulse interference
Influence of jitter
Generation of AMI signal
Quantizing distortion
Peak limiting
Time behaviour of sampling
Spectrum of sampling signal – PAM 1st sort
Ideal PAM 1st order (wide of samples approaches to zero
Spestrum of sampling signal -2nd order
Spectrum of PAM 2nd order – wide of samples equals to sampling periode
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