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Type of T1 Echo Canceller offered -
8, T1 echo cancellers per 19 inch, 1U (44mm) chassis
T1 echo canceller: 128ms. bi-directional. T1 Inputs and
Outputs are balanced 100 Ohms, RJ-45
Key
Highlights of the Valiant T1 Echo Canceller solution
- Valiant offers the industry most compact 8, T1 (and E1) Echo
Cancellers and Voice Quality Enhancement (VQE) solution. T1 (or E1) echo cancellers in a
1U (44mm) high chassis – industry’s smallest footprint.
- Ideally suited for GSM Networks to eliminate "back
ground noise" to enable GSM Networks to function at Half-Rate (HR) thereby doubling
spectrum usage in GSM networks.
- 128 ms. bi-direction echo cancellation with echo-tail
displacement from 0ms. to 896ms.
- Programmable echo-tail displacement from 0ms. 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.
- Cancels near-end and far-end echo from single installation
- Echo Cancellation on each channel is 128ms. bi-directional.
- User programmable signaling
protocol options:
- 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),
- 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 user-selected time-slots.
- Compliant to ITU-T G.164, G.165, G.168 (2000/2002)
requirement for echo cancellation.
- Electrical echo-cancellation resulting from network 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
cancelling echo-tails that originate from cellular hand-sets poorly designed acoustic
feedback.
- Background Noise Reduction and Auto Voice Level Control
(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 data channel(s)
- Remote access through telnet
- 8 T1 (or E1) echo cancellers in a 1U (44mm.) high chassis -
industry's smallest footprint
- Applications include wireline, wireless, satellite,
international / long distance gateways, DCME and radio communication networks
- Usable in telecommunications systems worldwide.
Question. What is tail-displacement?
Answer: Tail-displacement is an important feature used in bi-directional
echo-cancellation, to make it effective and useful for bi-directional echo-cancellation.
Explanation: Bi-directional echo-cancellers have the
capability of cancelling 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 (192ms)
echo-cancellers for bi-directional echo-cancellation, thus making them unsuitable for
bi-directional echo-cancellation.
Example: An inter-continental satellite or a VoIP
link may have a fixed end-to-end round-trip delay of 300ms, thereby rendering all commonly
available echo-cancellers, with even 192ms echo-cancellation capabilities, in-effective
for bi-directional echo-cancellation.
Using the Tail-Displacement 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 300ms., 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..
Tail-displacement 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 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
"tail-end displacement" from 0ms. to 896ms.
This feature allows the use of a single Echo Canceller
installation to cancel echo-tails in both directions over inter-continental satellite or
VoIP links where the fixed network delays are excessive (beyond and in excess of (example)
192ms. echo-cancellation capability of the most 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 tail-displacement" feature in our
Echo Cancellers allow the user to cancel echoes on the return path even if the network
delays exceed 128ms.
The fixed network delay shall be calculated ascertained and
programmed as the "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 300ms.
The Valiant 128ms., bi-directional Echo Canceller solution,
equipped with a user programmable "tail-displacement" feature is superior than a
simple single 192ms. bi-directional Echo Canceller solution for cancelling both near-end
and far-end echoes, even if the fixed round-trip network delays exceed 300ms (please
see the example above).
T1 Echo Canceller - Highlights
- Provides voice echo cancellation of up to 128ms
Bi-Directional for 8 T1 echo cancellers
- Meets ITU-T G.164, G.165, G.168 (2000 / 2002) requirements
for echo cancellation
- Custom user definable echo-tail displacement between 0ms. to
896ms. This allows the user to cancel echo in both directions (near-end and far end), even
in most difficult conditions i.e. excessive transmission delays that are common on VoIP
networks and satellite links
- Voice Quality Enhancement:
- Removes background noise
- Automatic level control (maintains
VF levels)
- Signaling protocols supported:
- 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),
- 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 user-selected time-slots.
- Allows digital data transmission on user-selected
time-slots.
- T1 link by-pass on power failure. This feature helps to
maintain the link integrity even in the event of power failure
- The echo canceller supports fax / modem G.164 and G.165
(2100 Hz) tone disable
- User selected clock / synchronization option - Internal,
External and Loop-Timed clock
- Stratum 3e clock for stable Internal clock / holdover clock
in the event of failure of any of the selected clock sources
- Remote access through telnet over LAN / TCP-IP link
(10/100BaseT)
- Local access through COM port (RS232 serial port)
- Easy to use text based CLI commands for management and
configuration
- Adjustable gain/loss settings on all channels. Provides the
user the flexibility to adjust and optimize the voice, transmit and receive levels.
- Non-Linear Processor with Comfort Noise Insertion
- 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.
- Ensure echo canceller maintains excellent performance at all
times in presence of tones or signals including DTMF tones.
- Fully independent 8 T1 (or E1) echo canceller
Unique T1 Echo
Canceller Feature
USER PROGRAMMABLE TAIL DISPLACEMENT: User
definable echo-tail displacement is selectable between 0ms. to 896ms. 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 T1 echo
cancellers supports the following signaling protocols: Signaling protocols supported: 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), 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 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
BYPASSED from the echo-cancellation circuitry - leaving those specifically assigned
dedicated time-slots for digital data transmission (including video transmission).
The T1 echo canceller supports 2100 Hz fax / analog data
modem tone detection and echo canceller disabling on all channels.
Signaling Support
The T1 echo cancellers supports the following
signaling protocols:
- 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),
- D4 Robbed Bit Signaling,
- CCS (C6, C7),
- RBS (E&M, PLR, FXS-GS, FXO-GS, FXS-LS, FXO-LS)
- Allows digital data transmission
on user-selected time-slots.
Voice Quality
- Acoustic Echo Control (AEC)
- Adaptive Noise Reduction (ANR)
- Automatic Level Control (ALC)
- Adaptive Listner Enhancement (ALE)
Fault Recovery
The echo canceller equipment offers fault
recovery feature. It offers automatic by-pass upon power-supply failure (i.e. it offers T1
circuit by-pass in the event of power supply failure).
Remote Monitoring and Control
- Remote access through telnet over LAN / TCP-IP link
(10/100BaseT)
- Local access through COM port (RS232 serial port)
Applications for
the T1 Echo Cancellers
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.
Application
Diagrams for the T1 Voice Echo Cancellers
- Application Diagram - 128ms Bi-Directional T1 Echo
cancellers
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