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Type of Echo Canceller offered: DS3 Echo canceller
VCL-EC, DS3 echo cancellers are offered to
provide cancellation of upto 128ms echo tails. The echo canceller equipment is compliant
to ITU-T G.164, G.165, G.168 (2000 / 2002) requirements for echo cancellation.
Valiant offers echo cancellation and voice quality
enhancement solutions for the following network situations:
- Wireline
- Wireless
- Satellite
- International Gateway
- IP Gateway
DS3 Echo Canceller - Features and Highlights
- Valiant 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 offset) 0 ms. to 896 ms.
- Fully integrated independent 672-channel
voice echo canceller.
- Programmable echo-tail displacement (echo tail off-set) from
0 ms. to 896 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 896 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.
- Fax / Modem G.164, G.165 - 2100 Hz tone
disable as per ITU-T G.164/G.165 Recommendations. Allows fax and analog modem data
transmission through automatic echo-cancellation enable / disable function.
- Disable Tone detection supported on all
audio paths.
- Option for user to select data or voice
channels for selective echo cancellation. This feature allows the user to use selected
time-slots for data transmission to enable digital data / CCS signaling transmission.
- Data Transmission on select slots (data
mode), while keeping the echo cancellation "ON" on the remaining time-slots
(voice mode), on which echo is required to be cancelled.
- DS3 Circuit by-pass in the event of power
supply failure. This feature enables the by-pass of the DS3 Circuit in the event of power
failure. This ensure continued service even if the power to the echo-canceller fails.
(i.e. it offers T1 circuit by-pass in the event of power supply failure).
- Programmable Double-Talk detection
threshold.
- Adjustable gain/loss settings on all
channels. Provides the user the flexibility to adjust and optimize the voice and transmit
receive levels.
- Redundant Power Supply
- The equipment offers RS232 serial interface
for configuration through a PC COM Port, and an Ethernet (10BaseT) interface for remote
LAN configuration and monitoring which allows the user to monitor and configure the
equipment over a TCP-IP network from anywhere in the world.
- Removes residual echo and minimizes
switching effects thereby providing high perceived speech quality.
- Ensure echo canceller maintains excellent
performance at all times in presence of tones or signals including DTMF tones.
- Instability detector suppresses variable
pitched ringing or oscillation.
- Path change detect permits fast
re-convergence when a major change occurs in the echo channel.
- Usable in telecommunications systems
worldwide.
- Built-in cross-connect at DS-0 level. Allows
user to cross-connect DS-0 to any DS-0 and by-pass all signaling, digital data and video
channels.
- 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.
Voice Quality
- Acoustic Echo Control (AEC)
- Adaptive Noise Reduction (ANR)
- Automatic Level Control (ALC)
- Adaptive Listener Enhancement (ALE)
Fault Recovery
DS3 Circuit is by-passed in
the event of power supply failure. This feature enables the by-pass of the DS3 Circuit in
the event of power failure. This ensure continued service even if the power to the
echo-canceller fails.
Remote Monitoring and Control
- Remote access through telnet over LAN / TCP-IP link
(10/100BaseT)
- Local access through COM port (RS232 serial port)
Redundancy
The echo canceller is equipped to offer
redundant power supply (optional).
Unique DS3 Echo Canceller Features
USER PROGRAMMABLE TAIL-SIDE: Echo cancellers are
always required to be installed, such that, the tail-side of the echo-canceller always
faces towards the source of the echo. Our DS3 echo-cancellers have a User Configurable
tail-side so that the USER may remotely change the direction of the tail-side of the echo
canceller - without having to physically change the DS3 connections on the echo-canceller
card.
USER PROGRAMMABLE SIGNALING OPTION: Our DS3
echo-cancellers provide User Programmable DS3 signaling options whereby the user may use
our DS3 echo-cancellers just as efficiently over a wide spectrum of DS3 signaling options.
The DS3 signaling protocols that we support are 24B (24 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. All signaling options are User
Selectable / User Programmable. Allows digital data transmission on user-selected
time-slots.
USER PROGRAMMABLE DEDICATED DATA CHANNELS: The User
my specify / define the dedicated data channels so that they are 'always' and 'completely
bu-passed' from the echo-cancellation circuitry - leaving those specifically assigned
dedicated time-slots for digital data transmission (including video transmission).
The DS3 echo canceller supports 2100 Hz fax / analog data
modem tone detection and echo canceller disabling on all channels.
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,
ineffective 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.
Valiant's Echo-Canceller has a user
programmable "echo tail-end displacement" (echo tail off-set) from 0 ms. to 896
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. Bidirectional 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 Valiant 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.
Applications for
the DS3 Echo Cancellers
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