Core Network Synchronisation

The purpose of core TDM network synchronisation is simple, it is to ensure that all devices are timed to a common reference source, or a number of very closely aligned reference sources which are refereed to as Primary Reference Sources (PRS).

The PRS equipment can be deployed in a number of ways dependant upon the design of a network, geographical dispersion and budget. Primary Reference Sources may be deployed centrally, widely distributed or a combination of the two methods.

The merits of each approach are discussed and explained on the Primary Reference Source page of this web site.

From the Primary Reference Source the synchronisation signal is distributed through the network. Each SDH element incorporates a System Equipment Clock (SEC) which undertakes the functions of timing generation, filtering and extraction. Between elements the timing signals is carried in the STM-N signals and then extracted by the SEC. The quality of the signal is degenerated as it transmitted through the network with jitter and wander induced by the clock recovery function of the transmission elements themselves and the transmission mediums.

In normal network operation the SEC of the SDH element is traceable to the PRS.

In addition to the SECs within the SDH elements there is a third device type dedicated to synchronisation. this is the Stand Alone Synchronisation Element (SASE). This may also be referred to as Stand Alone Synchronisation Unit (SSU), Building Integrated Timing System (BITS) or Compact Tracking Oscillator (CTO). All refer to the same type of device.

The function of the SASE is to:

Under normal conditions they provide a jitter filtering capability.
Provide distribution to multiple transmission and switching elements.
Under fault conditions they are able to automatically select alternative synchronisation sources.
Under severe fault conditions, where all input references are lost, the SASE is able to enter Holdover mode and use its own stable on-board oscillators to provide synchronisation within specification for a short time, normally days.

ITU-T G.803 defines how SASEs should be distributed in order to fulfill their role as jitter filters. A SASE must regenerate synchronisation derived from a primary reference after a maximum chain of twenty traffic elements. No more than ten SASEs should exist in a single synchronisation chain and no chain should be more than sixty traffic elements in length.

When designing and building a network the synchronisation aspect the correct planning and implementation of network synchronisation is crucial. Not only should your network be planned and implemented to provide synchronisation to all network elements within specification under normal conditions but should also be resilient to common failures. Key aspects to incorporate in the design are:-

Backup of external clock reference inputs
Backup of reference chain inputs
Backup of equipment components e.g. redundant SEC modules in SDH elements
Minimising the length and dependency of the reference chain.

The effective provisioning and distribution of network synchronisation is vitally important to the quality of services you provide over your network and can prevent degradation to service experienced by subscribers and network users such as:

Uncompressed Digitized Voice
The human ear is not usually sensitive enough to detect the loss of a few bits of digitized uncompressed voice and typically only about 5% of slips will be noticed as audible clicks.

Compressed Voice
The decompression mechanism compounds the data corruption and a slip will result in an audible click.
As the complexity of the data being transmitted increases so does the effect on the service.

Facsimile
A slip during a facsimile transmission could result in the loss of several lines of text or image.

Modem Connection
At best a slip will cause several seconds of drop out. At worst a slip will cause the connection to drop altogether.

Compressed Video
The effect of a slip on compressed video is to potentially wipe out several lines of screen. A burst of slips can cause frame freeze for several seconds.

Encrypted Data
The corruption of encrypted data due to a slip, results in the failure of the decryption routine. This in turn results in a retransmission request, amounting to a much larger volume of data than the corruption itself being re-sent - increasing decryption time and wasting network bandwidth.

OSA5548b Core Network SASE
The OSA 5548B SASE has been developed to deliver reliable performance crucial to telecommunications networks. While poor synchronisation inevitably leads to network problems, dissatisfied customers and loss of revenue, good synchronisation will improve network efficiency, thus ensuring higher quality of service, smooth operation and reduced down time. The OSA 5548B SASE is specifically designed for synchronising PDH, SDH and SONET telecom networks. It also forms the core of Oscilloquartz OSA 6500B Primary Reference Clocks.

Features:
• ETSI or 19ТТ sub-rack with dual Power converter and end-of-shelf alarms
• Integrated single or dual GPS Receiver plug-ins
• Up to 112 outputs T1, E1 and others expandable
• High quality holdover < 1x10-11/day (typical value, provides G.811 holdover for up to 24 hours)
• Input monitoring with MTIE, TDEV and frequency graphs
• In-built X.25 or Ethernet interface to SyncViewЩ network management system
• 2.048 Mbit/s and 1.544 Mbit/s SSM handling
• Conditional, programmable output squelching
• ETSI or 19ТТ sub-rack with dual Power converter and end-of-shelf alarms
• Local / remote management interface and software
• Up to 6 inputs simultaneously monitored for MTIE and TDEV

Benefits:
• Full SSU/SASE/BITS functionality in a single shelf including GPS receiver(s)and management interfaces
• G.811 reference source performances for primary reference back up
• User defined IN/OUT interfaces
• Fully redundant G.812 clock regenerator for PDH, SDH, SONET
• State-of-the-art ultra stable oscillator characteristics
• Performances based input selection including majority decision
• Full remote access and management functionality
• Multi channel traffic Retiming ports
• Maintenance free plug in module concept
• User friendly GUI for local/remote access
• Simple on site upgrade of functionality primis in faucibus.
•

Horsebridge Services:
As well as supplying the OSA5548b, we also provide a host of supporting services, including:
• Installation.
• Commissioning.
• Technical support.
• Spares support.
• Product training.

If you would like to know more about the OSA5548b Core Network SASE, then why not contact us now.

OSA5548b Datasheet

OSA5581c GPS-SR Core Network SASE
Telecom networks which are out of synchronisation often suffer from bit errors and slow transmission rates. Without precise timing, transmissions can lose some information during transport, particularly in the realm of optical transport data network and broadband systems. As new standards emerge in the world of mobile telecommunications and digital broadcasting, the high quality of the synchronisation signal becomes increasingly important for cellular operators and media Centers. The OSA 5581C GPS is a GPS synchronisation receiver and distributor specially designed to eliminate these problems. All critical parts in the OSA 5581C GPS, including the GPS input & holdover unit, can be duplicated to ensure high availability. Integer rutrum.

Features:
• Fully compliant to ITU-T G.811 / Stratum 1 locked to GPS
• ETSI or 19ТТ sub-rack with dual Power converter and end-of-shelf alarms
• Single or Dual GPS for redundancy
• High quality holdover < 2x10^-10/day (OCXO)
•Rubidium holdover capability < 5 x 10^-11/month
• Wide choice of output interfaces
• Local / remote management interface and software
• Optional NTP module for Stratum 1 NTP server (RFC 1305) or IRIG-B interface
• External clock input signal filtering and processing
• E1 and T1 re-timing functionality
• certified NEBS level 3

Benefits:
• Compact multi function clock source
• Economical G.811 frequency reference for Mobile, PDH, SDH, SONET networks
• Full redundancy of critical functions
• Optimum choice of internal clock performances
• User outputs flexibility
• Adaptable user configurations
• Fully accessible for remote access
• Plug in upgradeable timing functionality
• Jitter filtering according to ITU-T G. 823
• Multi channels traffic re-synchronisation

Horsebridge Services:
As well as supplying the OSA5581c, we also provide a host of supporting services, including:
• Installation.
• Commissioning.
• Technical support.
• Spares support.
• Product training.

If you would like to know more about the OSA5581c Core Network SASE, then why not contact us now.

OSA5581c Datasheet

OSA5530b Synchronisation Distribution Unit
The Synchronisation Distribution Unit OSA 5530B SDU is designed primarily to extend the output capacity of our synchronisation systems such as OSA 6500B PRC, and OSA 5548B SASE. It can also be used in stand-alone applications where a stable reference is available. The unit provides distribution of synchronisation references to network elements, e.g. switches, cross-connects and multiplexers.

Features:
• ETSI or 19ТТ sub-rack with dual Power converter and end-of-shelf alarms
• Dual inputs for redundancy
• Up to 96 1+1 protected outputs of various types
• Local management or centralised with SyncViewЩ

Benefits:
• Ideal user output capacity expansion beyond OSA 6500B PRC or OSA 5548B SASE
• Secure Distribution of signals
• Built in Management port
• Maintenance free concept

Horsebridge Services:
As well as supplying the OSA5530b, we also provide a host of supporting services, including:
• Installation.
• Commissioning.
• Technical support.
• Spares support.
• Product training.

If you would like to know more about the OSA5530b, then why not contact us now.

OSA5530b Datasheet

OSA5533c Synchronisation Distribution Unit
The OSA 5533C SDU provides a very economic and reliable solution to the distribution of synchronisation references to network elements, such as switches, cross-connects and multiplexers. The steady expansion and growth of telecommunication services has resulted in the implementation of complex networks. These often contain a large number of network elements requiring proper synchronisation to ensure a smooth network operation with the required quality of service. Further growth results in additional output capacity being required at the network nodes to synchronise the supplementary elements and thus makes it necessary to implement expansion synchronisation equipments.The OSA 5533C SDU provides up to 64 outputs referenced to the selected input or to the Holdover Unit. A 1:1 card protection is optionally available for all output cards.

Features:
• ETSI or 19ТТ sub-rack with dual Power converter and end-of-shelf alarms
• Single or dual input, with holdover capability and jitter filtering function
• 16, 32 or 48 user outputs
• SSM handling on input and outputs
• Typical holdover < 5x10-10 / day
• Retiming of up to 24 E1 or T1 traffic carrying channels
• Local management or centralised with SyncViewЩ

Benefits:
• Secure distribution of synchronisation reference to network elements (switches, cross-connects, multiplexers, etcЕ)
• Multiple functionality over and above clock distribution
• Output protection for additional security
• ITU-T type III clock performances
• Compact and economical unit
•TCP/IP interface built in for remote access

Horsebridge Services:
As well as supplying the OSA5533c, we also provide a host of supporting services, including:
• Installation.
• Commissioning.
• Technical support.
• Spares support.
• Product training.

If you would like to know more about the OSA5533c, then why not contact us now.

OSA5533c Datasheet

OSA5240 GPS Receiver
The OSA 5240 GPS is specifically designed for the synchronisation of 2G, 2.5G and 3G mobile networks and SDH/SONET transport networks. DAB and DVB-T broadcasting networks and mobile location services such as E911 can also take advantage of this compact and economical synchronisation solution that provides advanced features at a fraction of the cost of other currently available solutions.

The OSA 5240 GPS is versatile: besides supplying GPS-based frequency references, it can also retime E1/DS1 traffic channels whose timing has been impaired by SDH/SONET pointer adjustments; moreover, the OSA 5240 GPS can optionally provide NTP/IRIG-B time distribution. It is therefore possible to supply frequency outputs, retiming and time distribution information without having to install separate boxes, each with its GPS antenna, cabling, management connection, etc. Reliability

Features:
• 19'' 2U high sub-rack format
• Fully compliant to ITU-T G.811 / Stratum 1 when locked to GPS
• Integrated high stability holdover functionality < 1x10^-10 / day compliant ITU-T G812 type I, V, VI or Rubidium < 5 x10^-11/month compliant G.812 type 2
• Up to 16 outputs individually configurable among 10MHz, 1PPS, 2.048MHz, E1
• 8 or 16 re-timing E1 / DS1 functionality
• Time output NTP or IRIG-B
• Roof or Wall / Windows antenna
• Full local (RS232) / remote (TCP/IP) management interface and software

Benefits:
• Synchronisation of cellular networks at BSC or MSC level
• Re-timing of traffic singals affected by SDH/SONET pointer adjustements
• Time and frequency reference for power utilities and public services
• Specialised ATM and LAN/WAN applications - UTC traceable billing applications
• Synchronisation of DVB-T transmitters in SFN (Single Frequency Networks)
• Individually selectable user output

Horsebridge Services:
As well as supplying the OSA5240, we also provide a host of supporting services, including:
• Installation.
• Commissioning.
• Technical support.
• Spares support.
• Product training.

If you would like to know more about the OSA5240, then why not contact us now.

OSA5240 Datasheet

OSA5230 GPS Receiver
The new OSA 5230 GPS Receiver conforms to G.811-/Stratum 1-quality synchronisation reference while providing 8 individually configurable outputs at a fraction of the cost of currently available solutions. The OSA 5230 GPS Receiver incorporates an integrated GPS receiver and a highly accurate oven-controlled oscillator, which filters the received signal and provides a holdover quality typical of an SSU/BITS during an eventual loss of GPS signal or antenna failure. The OSA 5230 GPS Receiver is the natural choice as a synchronisation source for UMTS, WCDMA and CdmaOne, Cdma 2000, as well as GPRS, CDMA and TDMA base station and mobile switches.

Features:
• 19ТТ 2U high sub-rack format
• Fully compliant to ITU-T G.811 / Stratum 1 when locked to GPS
• Integrated high stability holdover functionality < 2x10^-10 /day
• Holdover compliant to ITU-T G812 type I, V, VI
• 8 Outputs individually configurable among 10MHz, 1PPS, 2.048MHz, E1
• Optional BVA or Rubidium holdover for holdover compliant with G.812 type 2

Benefits:
• Cost effective, compact GPS receiver unit for Cellular networks application like UMTS, GPRS and CDMA
• Wireless and wireline telecom sync requirements
• Time and frequency reference for test equipment and instruments
• Specialised ATM and LAN/WAN applications
• DAB / DVB broadcasting systems
• Individually selectable user output

Horsebridge Services:
As well as supplying the OSA5230, we also provide a host of supporting services, including:
• Installation.
• Commissioning.
• Technical support.
• Spares support.
• Product training.

If you would like to know more about the OSA5230, then why not contact us now.

OSA5230 Datasheet

If you can't find what you are looking for then why not talk to us and we will find a solution.

Whatever your synchroisation requirements, Horsebridge has the answer.