Comarra provides robust and cost effective E1 and T1 echo canceller and voice quality enhancement solutions for the long distance, wireline, wireless, (GSM, CDMA, TDMA), VoIP, satellite and radio communications.

The VCL-EC, E1 echo cancellers are offered to provide cancellation of 64ms / 128ms (user selectable) echo tails. The echo canceller equipment is compliant to ITU-T G.164, G.165, G.168 (2000 / 2002) requirements for echo cancellation.

The echo canceller solutions offers carrier-grade voice quality per AT&T Voice Quality Assessment Lab. The echo canceller supports fax / modem G.164 and G.165 (2100 Hz) tone disable function.

Signaling Support

The E1 echo cancellers supports the following signaling protocols:

• 30B+D PRI ISDN (Euro ISDN) signaling
• 31B (31 voice channels) with out-of-band signaling
• R2 CAS Signaling
• SS7 signaling (on any user selected time-slot)
• All signaling options are USER SELECTABLE / USER CONFIGURABLE.

Fault Recovery

The echo canceller equipment offers fault recovery feature. It offers automatic by-pass upon power-supply failure / removal power supply. (i.e. it offers E1 circuit by-pass in the event of power supply failure).

E1 Echo Canceller - Highlights

• Provides voice echo cancellation of up to 64ms Bi-directional / 128ms Uni-directional - User Selectable/User Programmable.
• Meets ITU-T G.164, G.165, G.168 (2000/2002) requirements for echo cancellation.
• Signaling protocols supported:
  • 30B+D PRI ISDN (Euro ISDN) signaling
  • 31B (31 voice channels) with out-of-band signaling
  • R2 CAS Signaling,
  • SS7 signaling (on any user selected time-slot)
  • All signaling options are USER SELECTABLE/USER PROGRAMMABLE
• The echo canceller supports fax/modem G.164 and G.165 (2100 Hz) tone disable.
• Carrier-grade voice quality per AT&T Voice Quality Assessment Lab.
• Offers RS232 serial interface for external PC CPM port and Ethernet (10Base-T) interface for remote LAN
• Adjustable Gain/loss settings on all channels. Provides the user the flexibility to adjust and optimize the voice and transmit receive levels
• Non-Linear Processor with Comfort Noise Insertion
• Redundant Power Supply (Optional)
• E1 Circuit by-pass on power failure
• Automatic by-pass upon power supply failure/removal of power supply
• 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
• Transmission (data mode), while keeping the echo cancellation "ON" on the remaining time-slots (voice mode), on which echo is required to be cancelled
• Ensure echo canceller maintains excellent performance at all times in presence of tones or signals including DTMF tones
• Fully integrated independent 30-channel voice echo canceller

Types of E1 Echo Cancellers offered:

64ms Bi-directional and 128ms. Uni-directional E1 echo cancellers - User Selectable. Our E1 echo canceller is a fully integrated 30 channel echo canceller that cancels echo up to 64ms. bi-directional/128ms. uni-directional - User Selectable. E1 Inputs and Outputs are balanced 120 Ohms, RJ-45.

Redundancy

The echo canceller is equipped to offer redundant power supply (optional).

Remote Monitoring and Control

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.

Unique E1 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 E1 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 E1 connections on the echo-canceller card.

USER PROGRAMMABLE Signaling Option:  Our echo-cancellers provide USER PROGRAMMABLE E1 signaling options whereby the user may use our E1 echo-cancellers just as efficiently over a wide spectrum of E1 signaling options. The E1 signaling protocols that we support are 30B+D PRI ISDN (Euro ISDN) signaling, 31B (31 voice channels) with out-of-band signaling, R2 CAS Signaling, SS7 signaling (on any user selected time-slot). All signaling options are USER SELECTABLE.

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).

The E1 echo canceller supports 2100 Hz fax / analog data modem tone detection and echo canceller disabling on all channels. For dedicated digital data or video channels, if you wish to assign certain specific times-slots of the E1 circuit for dedicated video you may do so, using our E1 echo cancellers. Our E1 echo-cancellers allow the USER to PROGRAM / ASSIGN dedicated time-slots for digital data or video transmission. The USER may specify / define the dedicated data channels so that they are ALWAYS BY-PASSED from the echo-cancellation circuitry - leaving those dedicated time-slots for digital data communication / dedicated video transmission only.

Applications for the E1 Echo Cancellers

• Wireless: GSM, CDMA, TDMA, PCS and Cellular Base Stations

• Digital Circuit Multiplication Equipment (DCME) : Satellite Communications and Multiplexers

• PCS, cellular, 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 that provide a separate channel to carry V.32/V.32bis/V.34 modem 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 (VTOA) and voice over Frame Relay (VoFR)

Datacomm Applications

• Voice Over Frame Relay

• Voice Over ATM

• Voice Over Internet / LAN

Central Office and PBX Applications

• Network Trunks

• Echo Canceller Pool

• Common Equipment

• Audio Conferencing Bridges

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

Satellite Communications Applications

• Digital Circuit Multiplication Equipment (DCME)

Wireless Applications

• GSM, CDMA, TDMA

• Digital Cordless and Cellular Basestations

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

E1 Echo Canceller Features and Highlights

• User Selectable - 128ms - Uni-directional or 64ms - Bi-directional. The user selection is made through a user configurable software interface command

• Compliant to ITU-T G.164, G.165, G.168 2000, G.168 2002) requirements

• Carrier-grade voice quality per AT&T Voice Quality Assessment Lab

• 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

• Fully integrated independent 30-channel voice echo canceller

• 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

• Transmission (data mode), while keeping the echo cancellation "ON" on the remaining time-slots (voice mode), on which echo is required to be cancelled

• E1 Circuit by-pass in event of power supply failure. This feature enables the by-pass of the E1 Circuit in the event of power failure. This ensure continues signal even if the power to the echo-canceller fails

• E1 Circuit by-pass on power failure

• E1 Circuit by-pass on Echo Canceller card removed. This feature allows the USER to by-pass the E1 Circuit by simply removing the echo-canceller card. E1 circuit connects "through" as soon as echo-canceller is removed from its slot

• Non-Linear Processor with adaptive suppression threshold and comfort noise insertion.

• Programmable Double-Talk detection threshold

• Narrow-Band signal detection

• Adjustable Gain / loss settings on all channels. Provides the user the flexibility to adjust and optimize the voice and transmit receive levels

• Signaling Support:

  • 30B+D PRI ISDN (Euro ISDN) signaling

  • 31B (31 voice channels) with out-of-band signaling

  • R2 CAS Signaling

  • SS7 signaling (on any user selected time-slot)

  • All signaling options are USER SELECTABLE / USER CONFIGURABLE

• Redundant Power Supply (Optional)

• Non-Linear Processor with Comfort Noise Insertion

• TCP / IP remote access for remote configuration and control.

• Assures operability with V.32 / V.32bis / V.34 modem and fax transmissions. Conforms to standards assuring proper public network operation and facilitating system integration

• Removes residual echo and minimizes switching effects thereby providing high perceived speech quality. Unique design provides the industry's best sounding single chip echo canceller

• Ensure echo canceller maintains excellent performance at all times in the presence of non-echo voice signals. Useful for trunks that have very low echo-returns loss

• 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

• User selectable tail-end side. This feature allows the USER to select the "Tail-End" side of the Echo-Canceller. The "Tail-End" side of Echo-Canceller is that part of the network which generates / causes to generate the Echo. Uni-directional Echo-Cancellers MUST ALWAYS be installed on far-end of any network from the point at which an Echo is being heard. The "Tail-End" side MUST ALWAYS face the "Source Side" of the network which is generating the echo. Ideally suited to handle most echo situations.

• Usable in telecommunications systems worldwide. Able to interface in most systems where linear samples are available.

Application Diagrams for the E1 Voice Echo Cancellers

Application Diagrams

• Application 1

• Application 2

• Application 3

• Application 4

• Application 5