Telecoms, Datacoms, Wireless, IoT


Industry's first monolithic desynchronisation solution

8 May 2002 Telecoms, Datacoms, Wireless, IoT

Exar offers an integrated monolithic solution to address desynchronisation requirements when mapping/demapping from SONET/SDH (synchronous) to DS3/E3 (asynchronous) environments. This unique desynchronisation solution will be embedded in Exar's physical interface (LIU) and data aggregation devices. The first data aggregation device utilising this capability was the company's OC-12 mapper (XRT94L43) announced last October. This new LIU is a single-channel DS3/E3/STS-1 device offered in two modes: one with desynchronisation (XRT75L00D), and the other with jitter attenuation only (XRT75L00). The devices use an innovative combination of analog and digital signal processing technologies to achieve their results. Applications include access equipment, digital cross-connect systems, routers, and digital subscriber line access multiplexer (DSLAMs).

Why does the clock need desynchronisation?

The process of mapping and subsequent de-mapping of individual DS3 or E3 signals into SONET's Synchronous Payload Envelope (SPE) introduces excessive jitter and timing irregularities. Examples of jitter sources include mapping jitter, caused by bit justification, or stuffing, to match the asynchronous bit rate to a synchronous transport signal; and pointer jitter, the outcome of frequency mismatches between two networks that offset the payload and cause pointer movement.

Discrete desynchronising solutions use a combination of a very narrow-bandwidth crystal oscillator based phase locked loop (PLL) referred to as a voltage control oscillator (VCXO), and a deep FIFO for each data rate and channel. In multi-channel and multi-rate applications, external VCXOs are multiplied by the number of supported rates and channels. Exar's solution uses only one highly integrated programmable PLL so each channel can support multirate (DS3, E3 or STS-1) operations.

Here jitter/timing irregularities are removed, and then desynchronised to provide a smooth GR-253-CORE specification-compliant clock signal. Once this operation is complete the signal is suitable for retransmission and returned to the data stream.

The XRT75L00 and XRT75L00D incorporate an independent receiver, transmitter and jitter attenuator in a single 52-pin TQFP package.

For further information contact Kobus van Rooyen, ASIC Design Services, 011 315 8316, [email protected]



Credit(s)



Share this article:
Share via emailShare via LinkedInPrint this page

Further reading:

Power amps for portable radio comms systems
iCorp Technologies Telecoms, Datacoms, Wireless, IoT
CML Micro expands its SµRF product portfolio with a pair of high efficiency single- and two-stage power amplifiers that offer outstanding performance for a wide range of dual-cell lithium battery-powered wireless devices.

Read more...
RF agile transceiver
Altron Arrow Telecoms, Datacoms, Wireless, IoT
The AD9361 is a high performance, highly integrated RF Agile Transceiver designed for use in 3G and 4G base station applications.

Read more...
Choosing a GNSS receiver
RF Design Telecoms, Datacoms, Wireless, IoT
Applications requiring sub-ten-meter positioning accuracy today can choose between single-band or dual-band technology. While this decision might seem as simple as flipping a coin, it is far from that.

Read more...
Tri-Teq’s latest range of filters
RFiber Solutions Telecoms, Datacoms, Wireless, IoT
Tri-Teq recently presented its latest filter products, which included passive and co-site mitigation filters (lumped element and suspended substrate technologies) and tunable filters (bandpass and harmonic switched filters).

Read more...
Why GNSS positioning precision is enabling the next wave of IoT applications
iCorp Technologies Editor's Choice Telecoms, Datacoms, Wireless, IoT
While high-performance GNSS implementations are achievable with few limitations, most real-world applications must balance power consumption, form factor and accuracy requirements.

Read more...
The evolution of 4D imaging radar
Altron Arrow Telecoms, Datacoms, Wireless, IoT
4D imaging radar is redefining automotive sensing with unmatched precision, scalability and resilience and, as global adoption accelerates, this technology is poised to become a cornerstone of autonomous mobility.

Read more...
Links Field Networks: The perfect fit for telematics in Africa
Links Field Networks Telecoms, Datacoms, Wireless, IoT
Operating at the intersection of global SIM innovation and local market intelligence, Links Field Networks has emerged as a premier provider of telematics-oriented connectivity across Africa and beyond.

Read more...
RF direct conversion receiver
iCorp Technologies Telecoms, Datacoms, Wireless, IoT
The CMX994 series from CML Micro is a family of direct conversion receiver ICs with the ability to dynamically select power against performance modes.

Read more...
Bridging the future with RAKWireless WisNode devices
Otto Wireless Solutions Telecoms, Datacoms, Wireless, IoT
The WisNode Bridge series by RAKWireless is designed to convert traditional wired industrial protocols like RS485 and Modbus into LoRa-compatible signals.

Read more...
Mission-critical RF transceiver
Vepac Electronics Telecoms, Datacoms, Wireless, IoT
The Iris SQN9506 from Sequans Communications is a wide-band RF transceiver that operates from 220 MHz to 7,125 GHz.

Read more...









While every effort has been made to ensure the accuracy of the information contained herein, the publisher and its agents cannot be held responsible for any errors contained, or any loss incurred as a result. Articles published do not necessarily reflect the views of the publishers. The editor reserves the right to alter or cut copy. Articles submitted are deemed to have been cleared for publication. Advertisements and company contact details are published as provided by the advertiser. Technews Publishing (Pty) Ltd cannot be held responsible for the accuracy or veracity of supplied material.




© Technews Publishing (Pty) Ltd | All Rights Reserved