full-duplex speakerphone

full-duplex speakerphone
Full-Duplex Speakerphone
http://www.vocal.com
VOCAL Technologies, Ltd. modem and telephony software libraries include Full-Duplex
Speakerphone functions in ANSI-C and optimized assembly language for ADI, AMD-Alchemy, ARM,
DSP Group, LSI Logic ZSP, MIPS and TI. This software is modular and can be executed as a single
task under a variety of operating systems or it can execute standalone with its own kernel
The line interface for the full-duplex speakerphone may be an analog front end (codec and DAA) or a
digital interface such as T1/E1, Switched 56, and ISDN.
This full-duplex speakerphone software can be combined with telephony functions, DSVD voice
compression, data modulations (V.92, V.90, V.34, V.32bis/V.32 and V.22bis/V.22/V.23/V.21) and
facsimile modulations (V.17, V.29, V.27ter and V.21 channel 2). Compatible with VOCAL controller
firmware for data protocols and command set controls.
A full-duplex speakerphone device digitizes the signal coming out of its speaker. It then edits this info
out of the signal it's transmitting using a built-in digital processor. This eliminates echo effect and
more importantly, does away with the on-off mic/speaker dilemma. Full-duplex devices do all of this
virtually instantaneously.
Full-duplex conversation, where both transmit and receive channels are active simultaneously, is the
conversation. Full duplex for hands-free communications is achieved using Echo Cancellation. Echo
Cancellation reduces overall loop gain and the acoustic coupling between speaker and microphone.
This coupling reduction prevents the annoying effect of hearing one’s own delayed speech, which is
worsened when there is delay in the system, such as vocoder delay.
Features:
•
•
•
•
•
•
•
•
•
•
Full-Duplex Speakerphone operation.
Lower MIPS Half-Duplex version available.
Acoustical Echo Cancellation.
Line Echo Cancellation (G.165 (03/93) and G.168 (2000) compliant).
Automatic Gain Controls.
Frequency response (+/-3 dB referenced to 1kHz) of 300 Hz to 3.4 kHz.
2048 coefficients.
Train on voice (no training tones) for the Full-Duplex Speakerphone operation.
Convergence Time of 300 ms maximum.
Acoustic Tail Length of up to 256 ms.
Technologies, Ltd.
© 2004 VOCAL Technologies, Ltd.
http://www.vocal.com
Full-Duplex Speakerphone-01
Custom Product Design Division
200 John James Audubon Parkway
Buffalo, New York 14228
716-688-4675
Configurations:
•
•
•
•
•
•
Seamlessly integrates into VOCAL's kernel.
Can be combined with North American and International telephony platforms. These platforms
feature voice activity detection, international call progress, caller ID.
Full-Duplex Speakerphone operation can be combined with data modulations and protocols
(modulations through V.92 and V.44/V.42/V.42bis and MNP 1-5 data protocols).
Can be combined with facsimile modulations and protocols (modulations through V.34 fax and
T.4/T.30 facsimile protocols).
Full-Duplex Speakerphone can be combined with data, facsimile and voice command sets.
Can be combined with speech coders including iLBC, MELP, G.723.1, G.723.2, G.728, G.729
Annex A, Annex B etc.
Full-Duplex Speakerphone operation Resource Requirements:
•
•
•
•
12 MIPS with Acoustic Echo Cancellation peak loading
14 MIPS with Acoustic and Line Echo Cancellation peak loading
4k words of program memory at an Acoustic Tail Length of 256 ms
4k words of data memory at an Acoustic Tail Length of 256 ms
Technologies, Ltd.
© 2004 VOCAL Technologies, Ltd.
http://www.vocal.com
Full-Duplex Speakerphone-02
Custom Product Design Division
200 John James Audubon Parkway
Buffalo, New York 14228
716-688-4675
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertisement