Lectrosonics announces LecNet2 firmware update
July 7, 2007
Lectrosonics has announced version 2.0 of the LecNet2 firmware for the DMTH4 telephone hybrid interface. Incorporating a series of improved algorithms used in the DMTH4’s acoustic and line echo cancellers, the new update promises greater functionality in a number of key areas, including dynamic convergence factor control, convergence regardless of system Echo Return Loss (ERL), improved metering accuracy, a more robust line echo canceller and a “boa constrictor” algorithm that prevents divergence.
The new algorithm measures residual echo content in the far side transmission signal, automatically adjusting the convergence factor as appropriate. A manual adjustment is also provided.
The improved echo canceller in the v2.0 firmware will converge even with a negative ERL in systems where the far side returns more echo level than the original signal. Because of the variable convergence factor, the echo canceller functions as a “boa constrictor” and takes advantage of even very brief pauses in speech to converge at a fast rate, and, as a result, continually makes small improvements to maximize echo cancellation depth. The line echo canceller also benefits from the improvements because it uses the same algorithms as the acoustic echo canceller. The line echo canceller is very tolerant of even gross mismatches in the termination impedance of the telephone line.
Implementing the new firmware requires no hardware modifications. The firmware can be downloaded and installed into existing DMTH4 processors and is already shipping with all DMTH4 processors; existing users can download it directly from the Lectrosonics Web site.
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