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Newsletter: Echo Simulation And Measurement Tools

GL Communications continues to enhance and add to its extensive selection of echo canceller testing tools. This news letter describes some of these enhancements.

DSP Capability within Windows Client Server - A wide array of Digital Signal Processing (DSP) functions have been added to this popular T1/E1 automation tool. Complex echo paths and complex block diagram operations can be easily simulated using the following functions: sum, invert, filter, delay, amplify, attenuate, bxor, bor, brev, bnot, band, infile, outfile, white noise, tone, dual tone, phase shift, dtmf digits, mf digits, mfcr2 digits, power monitor, signaling bits monitor, const, bytes, and many other operators.
The DSP functionality document provides greater detail. The Windows Client Server (WCS) software can be accessed at this link (

2/4 Wire Hybrid Characterization - A new measurement tool has been introduced that permits characterization of any hybrid or echo path. The implulse response of any hybrid or filter can be determined using 'input to' and 'output from' PCM signal files. Either of two recommended methods in G.168 specification - called 'least-squares' (LS) algorithm and 'normalized least-mean square' (NLMS) algorithm are used to compute the impulse response. A graphical, tabular, and spectral representation of the impulse response is provided. The FIR form of the impulse response can be used to simulate the original hybrid to test echo canceller performance in a laboratory environment. The FIR filter produced is compatible with GL's Echo Path Delay/Loss Simulation Software. Additional features provided include visualization of the input and output PCM files using Adobe Audition. The Echo path characterisation document provides more information.

AutoECTest - This popular test tool for automatic testing per G.168 has been upgraded to include tests for tone disabler, low speed modems, and fax. A more complete description of the capabilities can be found at AutoECTest web page.

Please review the new features described above and give us a call if you are interested in GL's products/software for these or other applications. We would be happy to consult with you on solutions to your testing needs and we look forward to hearing from you.

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