Simplicity GTH Series User manual

Simplicity GTH Series User manual
Product introduction
Corelatus develops a range of products where the common denominator is that
they are connected to the telephone network via E1 or T1 links (2 or 1.5Mbit/s)
and are controlled over ethernet.
The product range consists of: E1/T1 network probes, Gateways, IVR functions
and Voice mail functions.
Our customers are system builders who add their own application software on a
server and market the complete package. The end customers are normally
telecom operators.
A typical installation consists of an application server (processor) and one or
several Corelatus chassis. Both the chassis and the server are normally mounted
in a 19" rack and are interconnected via ethernet. Corelatus products handle all
telecom specific and time critical operations. Higher protocol levels and
application software are handled by the server.
All products are designed to provide telecom grade reliability. Reliability is
achieved on all levels: hardware, software and system level.
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Product range
E1/T1 Network Probes
Probes non-intrusively extract information from E1/T1 links. The probe filters and
forwards signalling information or voice to an external application over TCP/IP.
• SS7 MTP-2 (ITU Q.703)
• Frame Relay (ITU Q.922)
• ATM over E1/T1
Gateways are used to transfer signalling and media streams between E1/T1
PCM links and IP.
LAPD, MTP-2 and Frame Relay are available for signalling. Voice streams can
be forwarded over either RTP (for real-time voice applications) or TCP (for
logging and analysis applications).
IVR functions
The Interactive Voice Response (IVR) functions provides the timing-sensitive
parts of IVR applications:
• Voice prompt playback
• DTMF detection
• Timeslot switching
• Conferencing, 3 party or multi-party
Voice mail functions
Voice mail functions provide a possibility to play and record voice messages
from/to the harddrive of an application host.
• Recording: incoming speech on a time slot is forwarded to a TCP socket.
• Playing: speech on a TCP socket is forwarded to a time slot.
Signalling gateways, IVR and Voice mail functions can often be combined in the
same physical equipment. It is thus possible to create a compact and cost
efficient solution. An example is where an MTP-2 signalling gateway and IVR
functions are combined for a mobile prepaid system.
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Carrier-grade hardware
All products are based on a common hardware module, the Generic Telecom
Hardware (GTH). A GTH module is completely self-sufficient and distinguishes
itself from PCI or cPCI boards by being physically, electrically and functionally
isolated. Well defined interfaces and clear responsibilities simplify the system
builder's job.
Common system features:
Module features:
• 19" rack mount (1U high)
• No moving parts
• Dual 48VDC power inputs
• Up to 3 modules in a chassis
• 8 duplex or 16 RX E1/T1 G.703 interfaces
• Dual ethernet
• Low power consumption (8 - 10W)
• +/- 1ppm frequency source
• An XML-based API
Generic Telecom Hardware
A GTH module is generic in the sense that it is equipped with E1/T1 interfaces,
two ethernet interfaces and the hardware resources to process the data to and
from the telecom interfaces in almost any way. Up to 3 modules can be mounted
in a 1U high 19" chassis.
Three GTH modules in their 19" chassis
The GTH module is extremely "soft". Functionality is, to a large degree,
determined by software in the processor, the DSP and in the programmable logic.
The GTH, unlike more traditional designs, is not functionally constrained by
ASICs: the software and the "soft" hardware of the GTH module allow
functionality to be added without hardware modifications.
Module 1
DC power
E1/T1 G.703
Module 2
E1/T1 G.703
Module 3
E1/T1 G.703
DC power
The FPGA's parallel operation is exploited to provide very high performance for
specific bit manipulations such as encryption/decryption, IP packet
analysis/generation and low level protocol processing.
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The GTH is designed for very high reliability. The design is based on long
experience from both military and public communication systems.
System reliability
Reliability in a system consisting of several GTH modules is created by
combining simplicity, symmetry and robustness.
• Simplicity: A system is built from one or several identical modules. It can be
scaled from small to large without limitations.
• Symmetry: A system built with several GTH modules has no single, central point
of failure.
• Robustness: A system is built from physically, electrically and functionally
isolated parts. The parts are interconnected via well defined serial interfaces. It is
easy to verify correct operation at these interfaces. A hardware or software fault
is contained within one GTH module and affects only a small number of
Hardware reliability
• State of the art technology allows us to to put a complete telecom system with
all resources on a single board. The component count is relatively low and
classical failure points such as board-to-board inteconnects is avoided.
• The power dissipation is low and well distributed. Low temperature greatly
improves MTBF.
• No moving parts are used. Fans are not needed and the hard drive uses solid
state technology.
• Each module can take power from two power sources simultaneously. If one
power source fails, the module automatically switches to single supply mode
without interruption.
Software reliability
All real-time critical issues are handled in hardware. This avoids the need for hard
real-time software and allows Linux to be used as the operating system.
An important advantage of GTH-based systems over PCI and compact PCIbased systems is that the GTH modules are physically, electrically and
functionally isolated from each other and from the rest of the system.
Physical isolation
Up to three GTH modules are mounted in a 19" chassis. The modules are
independent of each other, sharing only the two external power connectors. The
modules are also completely independent of the server; the server could be in
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another room or even another building. In a PC or other backplane system the
boards affect each other with heat and electromagnetic interference in ways
which are not always predictable.
A system can be scaled linearly. When the number of interfaces are increased,
all other resources are also linearly scaled. In a more classical design there are
normally limitations such as backplane positions, power supply and processor
The 19" chassis with the modules is separately approved for safety, EMC and
specific telecom requirements. The safety and EMC responsibilities for boards in
a PC are not completely clear.
Electrical isolation
All of the GTH's external interfaces (E1/T1, ethernet and power) are transformer
isolated, i.e. galvanically isolated. Transformer isolation is possible because no
backplane is used and all external interfaces use serial communication.
The interface between the GTH module and the server is ethernet. It is difficult for
a malfunctioning module to electrically interfere with the server or other parts of
the system. A malfunctioning board in a backplane system can seriously affect
other boards.
The DC/DC converter in each GTH module accepts two separate,
polarity-independent input voltages of 38 - 60V. This makes the module relatively
insensitive to supply variations. A board in a backplane system shares a low
voltage supply with other boards. Power consumption fluctuations from different
boards can cause voltage dips which are difficult to diagnose and localise to a
particular board.
Replacing a module in a running system (hotswap) is often considered important
in telecom systems. In a backplane system, hotswap is normally quite complex
and requires both hardware and software support. With a GTH module, hotswap
is trivial: just pull out the cables.
Functional isolation
The API is an XML structured text protocol over TCP/IP. No constraints or
requirements are put on the application programming language or the server's
operating system.
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It is very unlikely that a misbehaving GTH module can cause a crash or reboot of
the server. In a PC or in a backplane system, a bug in a low level board driver
can more easily affect the host.
An attractive side-effect of a physically, electrically and functionally separated
equipment is that future hardware upgrades can be made with little impact on the
system as a whole.
Technical data
The GTH is delivered in a 1U high 19" chassis. Each chassis can be equipped
with one, two or three modules. Two chassis variants are available for front or
rear cabling.
• Total size (H x W x D): 44 x 482 x 345 mm
• Size in 19” rack (H x W x D): 44 x 435 x 343 mm
Each GTH module has the following interfaces:
• 8x duplex or 16x Rx only G.703: Software selectable E1 or T1 standard, 75 or
100/120 ohm. Balanced or un-balanced operation is selected by the cable.
• 2x 10/100-BaseT Ethernet: Both interfaces can be used as media and/or control
• 2x Power: Polarity independent, 38-60V DC. If supplied from two sources
simultaneously, the module selects the source with the higher voltage. The power
consumption is between 8W and 10W, depending on application.
Each module is equipped with a stable, temperature compensated voltage
controlled oscillator (TC-VCXO). The temperature stability is 1 ppm. The
oscillator can be locked to any interface or it can operate stand-alone.
More information
The API manual, list of frequently asked questions, application notes and contact
details are available online at
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