Answer / p jayakumar

PDH is Plesiochronous Digital Hierarchy and SDH is
Synchronous Digital Hierarchy.Both are used in PCM
transmission systems. Both use TDM principles for PCM
frames.
The difference is In PDH the clock used is not the
same throughout the transmission network. But in SDH a
synchronous clock is used in the entire Transmission system.
PDH is the old system used for only point to point
communication and interconnectivity between the sytem is
difficult.Whereas SDH is the lattest system used in any
kind of transmission configuration and interconnectivity
between different systems is very easy.PDH used in
2Mb,8Mb,34Mb and 140 Mb systems only.But SDH used in STM-1
(155.52Mbps,STM-4(622.08Mbps),STM-16(2.5Gbps) and STM-64
(10G BPS) transmission systems.
There are many merits in SDH

Easy for Add Drop multiplexing/Demultiplexing is easy.

Very useful for Ring configuration in optical
communications.

Easy growth to high bit rates in steps with evolution of
transmission technology.

Capable of transporting ATM(Asynchronous Transfer Mode)
channels,DLC(Digital Loop Carrier) is working on SDH.

SDH is the Indian sytem which is equivalent to American
SONET(Synchronous Optical Network)

Answer / mughis

SDH is cost effective and easy traffic cross capacity. but PDH has not ..

Answer / shankar

SDH - Synchronous Digtal heighrarchy & PDH - Plesiochronous

http://telecom-transmission.blogspot.in/2013/03/pdh-basics-pdh-interview-questions.html

What do you mean by a grounded load?

0 Answers  

---

How to Create the Cross connection with RRI & E1T1.

0 Answers   NSN,

---

What is meant by radix (or base) of a number system?

0 Answers  

---

When transmitting digital signals is it necessary to transmit some harmonics in addition to fundamental frequency?

2 Answers  

---

WHEN +VE VOLTAGE ON THE GATE P-CHANNEL JFET IS INCRESED DRAN CRICUT WILL BE WHAT CONDITION

0 Answers   Bosch,

---

how to find the fault in smps if i am not getting the output

0 Answers   Philips,

---

15. Ater interface is between transcoder and MSC – True/False 16. SS7 signaling is used in Abis interface – True/False 17. FlexiEdge BTS has RRI card – True/False 18. From Transcoder to MSC, data rate for each call is 64Kbps – True/false

2 Answers   NSN,

---

In our body current flow. In which form it is??? AC or DC

1 Answers   Ecil, Fairchild, TCS,

---

which is preferred in ckts for x-or operation a) 1 x-or gate b) 4 nand gates

1 Answers  

---

what is standared for leakage voltage(not current)in electronics industries who are manufacturare of vcd, dvd and controll cards.

0 Answers  

---

What is the frequency range of satellite communication?

0 Answers  

---

AT INPUT OF ups ,n-e is 2 volt ,at out of ups n-e is 15volt why?

1 Answers   Quantum,

---