1. Technologies used in telecommunication networks
Sdh vs pdh
Technologies used in telecommunication networks

2. introduction PDH :-PLESIOCHRONOUS DIGITAL HIERARCHY.
A TECHNOLOGY USED IN TELECOMMUNICATIONS NETWORK TO TRANSPORT LARGE QUANTITY OF DATA OVER DIGITAL TRANSPORT EQUIPMENT SUCH AS FIBRE OPTIC AND MICROWAVE RADIO WAVE SYSTEMS.

3. Continue..
THE TERM “PLESIOCHRONOUS” IS DERIVED FROM Greek plesio which means near, and chronous, time.
IT MEANS THAT PDH NETWORKS RUN IN A STATE WHERE DIFFERENT PARTS OF THE NETWORK ARE ALMOST, BUT NOT QUITE PERFECTLY SYNCHRONISED.

4. Features of pdh
SENDING A LARGE QUANTITY OF DATA ON FIBRE OPTIC TRANSMISSION SYSTEM.
TRANSMISSION AND RECEPTION ARE SYNCHRONIZED BUT TIMING IS NOT.
THE CHANNEL CLOCKS ARE DERIVED FROM DIFFERENT MASTER CLOCKS WHOSE RANGE IS SPECIFIED TO LIE WITHIN CERTAIN LIMITS. THE MULTIPLEXED SIGNAL IS CALLED A “PLESIOCHRONOUS” SIGNAL.
PDH SIGNALS ARE NEITHER SYNCHRONOUS NOR ASYNCHRONOUS.

5. Versions of pdh THERE ARE TWO VERSIONS OF PDH NAMELY
1) THE EUROPEAN AND 2 ) THE AMERICAN.
THEY DIFER SLIGHTLY IN THE DETAIL OF THEIR WORKING BUT THE PRINCIPLES ARE THE SAME.
EUROPEAN PCM = 30 CHANNELS
NORTH AMERICAN PCM = 24 CHANNELS
JAPANESE PCM = 24 CHANNELS
IN INDIA WE FOLLOW THE EUROPEAN PCM OF 30 CHANNELS SYSTEM WORKING

6. EUROPEAN PDH HIERARCHY WITH BIT RATES
MUX
BIT RATE
PARTS PER MILLION
CHANNELS
2 Mbps
2.048 Mbps
+/- 50 ppm 30
8 Mbps
8.448 Mbps
+/- 30 ppm
120
34 Mbps
Mbps
+/- 20 ppm
480
140 Mbps
Mbps
+/- 15 ppm
1920

7. LIMITATIONS LOWER CAPACITY. ADD AND DROP DIFFICULT.
COMPLEX MULTIPLEXING AND DEMULTIPLEXING.
NO UNIVERSAL STANDARD
INTERWORKING BETWEEN HIERARCHIES COMPLEX

8. DISADVANTAGES OF PDH SYSTEM
PDH IS NO LONGER EFFICIENT TO MEET THE DEMANDS PLACED ON IT.
BANDWIDTH LIMITATIONS – MAX CAPACITY IS 566 MBPS ONLY.
NO COMMON STANDARDS AMONG VENDORS
POINT TO POINT CONFIGURATION ( LINEAR WORKING ) ONLY IS POSSIBLE.
IT DOES NOT SUPPORT HUB

9. EVOLUTION OF SDH
Because of the disadvantages in the pdh technology, sdh technology is developed which overcomes all the drawbacks of an pdh technology.
thus sdh is an advanced technology.

10. What is sdh ? SYNCHRONOUS : DIGITAL: HIERARCHY:
ONE MASTER CLOCK & ALL ELEMENTS SYNCHRONISE WITH IT.
DIGITAL:
INFORMATION IN BINARY.
HIERARCHY:
SET OF BIT RATES IN A HIERARCHIAL ORDER.

11. ADVANTAGES OF SDH SIMPLIFIED MULTIPLEXING/DEMULTIPLEXING TECHNIQUES.
DIRECT ACCESS TO LOWER ORDER TRIBUTARIES.
ACCOMMODATES EXISTING PDH SIGNALS.
CAPABLE OF TRANSPORTING BROADBAND SIGNALS.
MULTI-VENDOR, MULTI OPERATOR ENVIRONMENT.
PROTECTION SWITCHING TO TRAFFIC IS OFFERED BY RINGS.
ENHANCED BANDWIDTH.
NMS FACILITY.
UNLIMITED BANDWIDTH
GROWTH OF THE EXISTING TO THE HIGHER ORDER SYSTEM IS SIMPLE.

12. DIFFERENT SERVICES LOW/HIGH SPEED DATA VOICE INTERCONNECTION OF LAN
COMPUTER LINKS
FEATURE SERVICES LIKE HDTV
BROAD BAND ISDN TRANSPORT

13. SDH BIT RATES SDH Levels Bit rates in Kbps STM-1 155520 STM-4 622080

14. SDH NETWORK ELEMENTS The different network elements are
TERMINAL MULTIPLEXER
ADD/DROP MULTIPLEXER
REGENERATOR
SYNCHRONOUS DIGITAL CROSS CONNECT

15. ADD DROP MULTIPLEXER(ADM)

16. RING TOPOLOGY Aggregate signal Tributary signal ADM ADM ADM ADM
(STM1/STM4/STM16)
Aggregate signal
Tributary signal
(2/34/140Mbps/STM1(e)/ STM1(o))

17. conclusion Pdh is obsolete now a days and replaced by sdh technology
Sdh has many advantage over pdh technology
Sdh encompasses features like hdtv ,isdn services which pdh is incapable of
It also provides high speed data transfer

18. Thank you