Network Simulation Software from GL Communications, Inc.

Fully Automated EC Compliance Testing Software per ITU G.168 -- XX067

Fully Automated EC Compliance Testing Software per ITU G.168 -- XX067 -- View Larger Image
Fully Automated EC Compliance Testing Software per ITU G.168 -- XX067-Image

Auto EC Test Software (XX067) is an application used to perform echo cancellation compliance testing automatically. per ITU G.168 specification. ITU G.168 spec refers to characteristics of Line Echo Cancellers (LEC). Line Echo Cancellers are either high density standalone devices, i.e. many T1s or E1s in a landline network. Or they may be embedded in Gateways (between an IP and TDM networks or between Wireless and TDM networks) as shown below

AutoECTest uses GL’s T1 E1 hardware platforms and can be used in TDM, Wireless, and VoIP configurations. Some typical scenarios are discussed below-

Landline to Landline – In such calling scenarios, two LECs are involved in each call. Each LEC cancels echo at its “tail circuit”. It possible that the delay in each tail circuit could be as great as 128 ms.

Wireless to Landline – Only one tail is involved in wireless to landline calls, and therefore only one LEC is required at the landline end.

VoIP to Landline – Only one tail is involved in VoIP to landline calls. The LEC is usually in a Gateway.

Auto EC Test Viewer (AEC001) supplements AutoEC Test software using which the EC test results are analyzed and graphically viewed.

The Auto EC Test Software uses GL’s T1 E1 Analyzer products and the customers LEC hardware to perform Automated Echo Canceller testing in accordance with ITU-T Specifications G.168. In the last 10 to 12 years, ITU G.168 has under gone many revisions with greater and greater detail and specificity. AutoECTest software has been updated accordingly.

  • G.168 (04/2000)
  • G.168 (06/2002)
  • G.168 (08/2004)
  • G.168 (01/2007)
  • and most recently G.168 (03/2009)

Rin and Sin files (stimulus and echo) are prepared and generated in real-time by Auto EC Test software in accordance with user inputs.

There are two solutions for different scenarios:

  • Solution 1 uses WCS (Windows Client Server) software to transmit/receive files and to simulate the echoes in real time, The diagram below shows this diagrammatically.
  • Solution 2 is designed for special applications where the LEC is still in development form, i.e. software only. Also, no GL hardware is required, as everything is file based.


  • Simulation of echo path with various delay, attenuation, hybrid filters, noise level, etc.
  • Real-time as well as off-line analysis with tabular Pass/Fail results
  • Auto or Manual control of the EC during testing
  • Auto analysis of the response according to G.168 (2000/2002/2004/2007/2009) requirement
  • Detailed graphical and tabular results for individual and overall test
  • Option to zoom-in on any test results to investigate further
  • Simulates long haul delay
  • MS-Windows OS (WIN 2000 or XP) with User-Friendly Graphical User Interface
  • Compatible with GL's T1/E1 HD Cards and USB portable T1/E1 units

Theory of operation

Real-Time Approach - Sin is created real-time from the Rout by the Windows Client Server (WCS) Software to perform real-time functions.

All four port captures (Rin, Rout, Sin, and Sout),a nd the echo path simulation are realized by the WCS scripts. It is applicable to TDM, VoIP, and VoATM Networks. In this design, users are permitted to set:

Test # 1 to 16B of G. 168 (03/2009), G.168(01/2007), G.168 (08/2004), G.168 (06/2002), and G.168 (04/2000) (Test 14 is optional)

  • Framing format (D4 and ESF for T1, CAS and CCS for E1)
  • Timeslots
  • Levels for pseudo speech/noise
  • Levels for noise
  • Hybrid filter types including multiple echo paths
  • Echo path delays and ERL

The software applies the Rin and captures the Sout (the output of the Echo Canceller). Sin may be generated in real-time by WCS and double talk signals may be mixed with the echo for some tests. During the application of Rin and Sin, the Echo Canceller is manually or automatically controlled for

  • Zeroing the contents of the echo canceller's H-register.
  • Enabling and inhibiting echo canceller convergence.
  • Enabling and disabling the non-linear processor.
  • If the echo canceller has a comfort noise feature, enabling and disabling the comfort noise generator.

Rout and Sout files are captured and automatically assessed. Graphical and tabular data is provided for all tests for easy interpretation. Objective test results are displayed and user can easily identify passed or failed tests. Users can zoom-in on any test result to further investigate. The detailed graphical analysis of tests is also a click away to gauge overall performance of the echo canceller.

Using AutoECTest Software (Basic setup without customer's EC hardware)

The AutoECTest Software (xx067) is intended to work with GL hardware (T1 or E1 dual cards) and the customers EC hardware. But it can also be used to test development EC software, that is, the customer's EC hardware is not required. For more information, please click here

Test Cases supported

GL's Semi-Automated and Scripted Echo Canceller Testing Suite provides support for the basic set of G.168 (2000/2002/2004/2007/2009) compliance tests. Click here for more information.

For the G.168 – version 03/2009, the Test cases are as shown in the figure below.

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