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Comarra offers the industry's most compact DS3 Voice Quality
Enhancement (VQE) echo canceller solution in a 19-inch, 3U
(133 mm height) chassis, with echo
tail-displacement (echo tail
off-set) feature which is user programmable from 0 ms. to 512
ms. Echo cancellation on each channel is 128 ms.
Bi-directional (near-end and far-end). |
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The DS3 VQE and echo canceller solution offers a unique, user
definable echo-tail displacement
feature which may be programmed by the user, between 0 ms. to
512 ms. on the return path to cancel echo-tails, both at the
near-end and the far-end, even in the most demanding network
conditions. |
Comarra offers echo cancellation
and voice quality enhancement solutions for the following network
situations:
- Wireline
- International Gateway
- IP Gateway
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This solutions is also an ideal
echo cancellation solution for long distance telephony, GSM,
CDMA, TDMA, VoIP, satellite and radio communication
applications. |
The VQE and echo canceller equipment is compliant to ITU-T
G.164, G.165, G.168 (2000/2002) and G.169 requirements for echo
cancellation. The echo canceller solutions offers carrier-grade
voice quality per AT&T Voice Quality Assessment Lab. Echo
cancellation on each channel is 128 ms. Bi-directional.
Key Highlights
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Comarra offers the industry
most compact DS3 Echo Cancellers and voice quality enhancement
(VQE) Solution
128 ms. Bi-directional
(near-end and far-end) echo cancellation with echo-tail
displacement from (tail off-set) 0 ms. to 512 ms.
Programmable echo-tail displacement (echo tail off-set) from 0
ms. to 512 ms.
Echo-Tail Displacement allows
user to program a delay off-set on return path and user can
cancel near-end and far-end echo from single installation
Ideally suited for GSM
Networks to eliminate "back ground noise" to enable GSM
Networks to function at half-rate (HR) with full rate voice
quality thereby doubling spectrum usage in GSM networks
Echo Cancellation on each channel is 128 ms. Bi-directional
(near-end and far-end).
Compliant to ITU-T G.164, G.165, G.168 (2000 / 2002) and G.169
requirement for echo cancellation
Electrical Echo-Cancellation
resulting from networks delays and delays arising due to
complex voice compression algorithms in hybrid PSTN and long
distance networks
Acoustic Echo-Cancellation
required for mobile networks for canceling echo-tails that
originate form cellular hand-sets designed with poorly
designed acoustic feedback
Programmable echo-tail displacement (near-end and far-end)
from 0ms. to 512 ms.
Auto Voice Level Control and
VQE (Voice Quality Enhancement features) required for reducing
background noise from calls originating from crowded public
places or other noisy environments and maintaining a uniform
Voice level in a Network. Improves voice quality
User programmable dedicated data channels
Remote access through Telnet
DS3 VQE echo cancellers in a 3U (44mm) high chassis industry’s
smallest foot print.
User Programmable signaling options.
PRI ISDN (23B+D), C7 / SS7, CCS (C6,C7), RBS (E&M, PLR, FXS-GS,
FXO-GS, FXS-LS, FXO-LS)
DS3 voice quality enhancement VQE and Echo Cancellers 19 inch,
3U (44mm) chassis, 128ms bi-directional echo canceller tail. DS3
Inputs and Outputs are balanced 75 Ohms BNC connectors.
Applications
- Wirless : GSM, CDMA, TDMA and Cellular Base Stations.
Digital Circuit Multiplication Equipment
(DCME) : Satellite Communications and Multiplexers.
PCS, mobile, and digital cordless wireless systems.
PBX and central office systems.
Datacomm: Voice Over Frame Relay, Voice Over ATM, and Voice
Over Internet.
Voice over ATM, Frame Relay or packet switching systems and
fax transmissions.
Central Office and PBX: Network Trunks, Echo Canceller Pool,
Common Equipment and Audio Conferencing Bridges
Voice over datacomm including voice over Internet (VoIP),
voice over ATM (VoAT), and voice over Frame Relay (VoFR).
Datacomm Applications
- Voice Over Frame Relay delays.
- Voice Over ATM
- Voice Over Internet / LAN
Datacomm Applications
- Voice Over Frame Relay delays.
- Voice Over ATM
- Voice Over Internet / LAN
Satellite Communications Applications
- Digital Circuit Multiplication
Equipment
Wireless Applications
- GSM, CDMA
- Digital Cordless and Cellular Base Stations
Central Office and PBX Applications
- Network Trunks
- Echo Canceller Pool
Common.
Audio Conferencing.
Voice Over ATM Applications
- A multi-channel echo canceller resource or pool is shared
among many channels to reduce cost.
- Echo cancellation is done at a DS0 level.
Voice Over Frame Relay, ATM Applications
- Frame Relay and ATM routers and switches introduce large,
variable, and unpredictable delays.
- Echoes from the Public Switched Telephone Network (PSTN) in
combination with the delays from Frame Relay and ATM equipment
yield objectionable speech quality.
Application Diagram
VCL-EC-DS3, VQE and DS3 Echo Canceller
To Cancel the echoes at both ends (near-end and
far-end)
of the Network with one 128 ms Bi-directional Echo Canceller
To Cancel the echoes at both ends of the Network with one 128
ms Bi-directional Echo Canceller with user programmable Echo Tail
Displacement (Echo Tail Off-set) Features
Note: The
VCL-EC-DS3 Echo Canceller offers User Programmable Echo Tail
Displacement feature,
User Definable
Echo-Tail Displacement is selectable between 0 ms. to 512 ms. on
the return-path. This feature allows the user to cancel echo-tails
in BOTH directions (both near-end and far-end echo tails), even in
most demanding conditions that are common on VoIP networks and
satellite links.
DS3 VQE & Echo Canceller per chassis - Features & Highlights
- USER PROGRAMMABLE ECHO TAIL
DISPLACEMENT (Echo Tail Off-set): User definable echo-tail
displacement is selectable between 0 ms. to 512 ms. on the
return-path. This feature allows the user to cancel echo-tails
in BOTH directions (both near-end and far-end echo tails), even
in most demanding conditions that are common on VoIP networks
and satellite links.
USER PROGRAMMABLE SIGNALING
OPTION: The DS3 echo cancellers supports the following
signaling protocols: Signaling protocols supported: 672 (Voice
Channels) with out-of-band signaling (C7 / SS7 Signaling on any
user selected time-slot), 23B+D, PRI ISDN (23 Voice Channels+D
Signaling Channel), D4 Robbed Bit Signaling. CCS (C6,C7), RBS
(E&M, PLR, FXS-GS, FXO-GS, FXS-LS, FXO-LS ). All signaling
options are User Selectable / User Programmable. Allows digital
data transmission on any individual user-selected time-slots.
The DS3 echo canceller supports
2100 Hz fax / analog data modem tone detection and echo
canceller disabling on all channels.
USER PROGRAMMABLE DEDICATED
DATA CHANNELS: The User my specify / define the dedicated
data channels so that they are ALWAYS and COMPLETELY BYPASSED
from the echo-cancellation circuitry - leaving those
specifically assigned dedicated time-slots for digital data
transmission (including video transmission).
Option for user to select voice
echo cancellation or digital-data transmission selectively on
each time-slot for selective echo cancellation. This feature
allows the user to use selected time-slots for data transmission
to enable digital data / CCS signaling transmission.
Transmission (data mode), while
keeping the echo cancellation "ON" on the remaining time-slots
(voice mode), on which echo is required to be cancelled.
Provides voice echo cancellation
of up to 128 ms Bi-directional (near-end and far-end echo
canceller) for DS3.
Meets ITU-T G.168 (2000 / 2002)
requirements for echo cancellation.
Meets ITU-T G.169 specifications
for VQE.
Easy to use text based CLI
commands for management and configuration.
Comarra offers the industry most
compact DS3 Echo Cancellers and Voice Quality Enhancement (VQE)
solution.
Voice Quality Enhancement :
- ANR: Automatic Noise
Reduction. Removes background noise
ALC: Automatic level control
(maintains uniform VF levels)
ALE: Automatic level
enhancement (maintains uniform VF levels)
Hybrid Echo Cancellation
Acoustic Echo Cancellation
Removes undesirable background
noise and allows the natural background audio from the PSTN to
pass through unaltered to the mobile subscriber, making the call
sound clearer.
Automatic Level Control
dynamically adjusts speech levels up or down to the level
optimal for the network, improving speech clarity and
intelligibility.
Acoustic Echo Control eliminates
acoustic echo generating from digital mobile handsets and
hands-free kits, enabling full-duplex speech.
Noise Reduction reduces the
background noise on mobile calls, enhancing overall voice
quality.
2, DS-3 Interfaces. This saves
material costs, configuration and set-up time and ongoing
maintenance. Eliminates the need to have multiple T1 interfaces,
or T1 to DS3 multiplexers, Easy to install. Easy to manage.
Bi-directional echo-cancellers
have the capability of canceling 128ms echo-tails in BOTH
directions (on the Transmit as well as the Receive paths), by
installing them at a single location. Our equipment's unique
user programmable echo-tail off-set feature allows
bi-directional echo-cancellation from a single installation, in
networks which may have end-to-end delays of even up to 512ms
which are be usually found on satellite links and high latency
VoIP networks rendering the other echo-cancellers, without this
feature, in-effective.
Tone disabling per ITU-T, G.164
and G.165.
Echo-tail displacement allows
user to program a delay off-set on return path and user can
cancel near-end and far-end echo from single installation.
Signaling protocols supported:
- 672 Voice Channels with
out-of-band signaling (C7 / SS7 Signaling on any user selected
time-slot)
23B+D, PRI ISDN (23 Voice
Channels + D Signaling Channel)
Robbed Bit Signaling
CCS (C6, C7)
RBS (E&M, PLR, FXS-GS, FXO-GS,
FXS-LS, FXO-LS)
All signaling options are User
Selectable / User Programmable.
Allows digital data
transmission on user-selected time-slots.
Meets ITU-T G.164, G.165, G.168
(2000 / 2002) requirements for Echo Cancellation.
Meets ITU-T G.169 specifications
for Voice Quality Enhancement
Ensures excellent voice quality
from the start of the call, during call transfer and cell
hand-offs, and even after abrupt changes in network routing.
Delivers clear voice quality in
the most challenging network environments.
Offers selection of voice
quality enhancements features that include automatic level
control and background noise reduction with acoustic echo
control.
Ideally suited for mobile (GSM
and CDMA) Networks to eliminate "back ground noise" to enable
GSM Networks to function at Half-Rate (HR) thereby doubling
spectrum usage in GSM networks.
Remote Monitoring and Control:
CLI Command Interface
Local access through COM port
(RS232 serial port).
Remote Access through a 10BaseT
Port over a TCP/IP network. Telnet.
The system is supplied with an
easy to use Windows (95, 98, Me, XP) Graphical User Interface
that provides the USER a complete control.
Ensures echo canceller maintains
excellent performance at all times in presence of tones or
signals including DTMF tones.
Improves voice quality
performance on circuits with poor echo return loss (ERL) and
unbalanced send and receive levels, resulting in improvement in
service quality.
Allows the use of a single Echo
Canceller installation to cancel echo-tails in both directions.
Stable performance across all
hybrid and acoustic conditions.
Low per-channel power
consumption reduces cooling and power costs.
Compact size reduces footprint
requirements.
Question. What is echo
tail-displacement (echo tail
off-set)
Answer:-
Echo Tail-displacement (echo tail off-set) is an important feature
used in Bi-directional echo-cancellation, to make it effective and
useful for bi-directional echo-cancellation.
Explanation:
Bi-directional (defined
as near-end and far-end automatic echo cancellation operation)
echo-cancellers have the capability of canceling echoes in BOTH
directions (on the Transmit as well as the Receive paths), by
installing them at a single location. Bi-directional
echo-cancellers can be installed at a single location, either the
Near-End or the Far-End, and used to cancel BOTH Near-End and
Far-End echo-tails, from a single installation.
Usually, satellite links and intercontinental VoIP circuits
have fixed network delays which exceed the capabilities of
commonly available (192 ms) echo-cancellers for Bi-directional
echo-cancellation, thus making them unsuitable for bi-directional
echo-cancellation.
Example: An
intercontinental satellite or a VoIP link may have a fixed
end-to-end round-trip delay of 300 ms, thereby rendering all
commonly available echo-cancellers, with even 192 ms
echo-cancellation capabilities, in-effective for Bi-directional
echo-cancellation.
Using the Echo Tail-Displacement (echo tail off-set) feature,
the user may offset and account for the fixed round-trip network
delay on the return path so that the echo-cancellation window on
the return-path is shifted by 300 ms., so as to allow the
Bi-directional echo-canceller to function effectively in BOTH
directions and to cancel BOTH near-end, as well as the far-end
echo-tails on the return path, even if the echo-canceller is
installed at the Near-end in a given network.
Echo Tail-displacement (echo tail off-set) allows the user to
program a delay off-set on the return path, so that the user may
cancel both near-end and far-end echo-tail with a single Echo
Canceller installation. The echo tail-displacement allows the user
to compensate for the fixed network delays on the return path of
the echo-tail, so that the user can effectively cancel, both
near-end and far-end echoes using a single Echo Canceller without
being limited by the fixed end-to-end delay of that network link.
Comarra’s Echo-Canceller has a user programmable "echo tail-end
displacement" (echo tail off-set) from 0 ms. to 512 ms.
This feature allows the use of a single Echo Canceller
installation to cancel echo-tails in both directions over
intercontinental satellite or VoIP links where the fixed network
delays are excessive (beyond and in excess of (example) 192 ms.
echo-cancellation capability of the commonly sold Bi-directional
Echo Canceller solutions).
Question. My Network has a total of
300ms. end-to-end delay. How can I use a 128ms. Bi-directional
echo canceller to cancel, both, near-end and far-end echoes?
Answer.
The use of the "programmable echo tail-displacement" (echo tail
off-set) feature in our Echo Cancellers allow the user to cancel
echoes on the return path even if the network delays exceed 128
ms.
The fixed network delay shall be calculated ascertained and
programmed as the "echo tail-displacement" on the return path.
This shall allow the user to use a single Echo Canceller to cancel
echoes, Bi-directionally, even if the total network end-to end
delay is in excess of 300 ms.
The Comarra 128 ms., Bi-directional Echo Canceller solution,
equipped with a user programmable " echo tail-displacement"
feature is superior than a simple single 192 ms. Bi-directional
Echo Canceller solution for canceling both near-end and far-end
echoes, even if the fixed round-trip network delays exceed 300 ms.
(please see the example above). |
