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|   DS3 Echo Canceller with VQE   |

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Description

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).

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

  • Wireless

  • Satellite

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

  • 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).

Others Links:

  Multiplexers
  STM SDH Multiplexers
  E1 VoIP-GSM Gateways
  VoIP SS7 and C7 Solution
  Echo Cancellers and VQE Solutions
  GSM Gateways / GSM Channel Banks
  E1 and T1 over Ethernet (TDM over IP)
  Digital Access Cross Connect Switch (DACS)
  E1, T1, E3, DS3, Ethernet Converter (IP over TDM)

Technical specifications are subject to change without notice.
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