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EC Compliance Testing per G.168
Using Manual Methods

Testing Echo Cancellers:

GL's Manual Test Suite for testing compliance of ECs with G.168 provides the ultimate flexibility for almost any type of network environment and configuration including:

  • Conventional Telephone Networks
  • Networks With Satellite Connectivity
  • Wireless Networks such as Cellular and PCS
User's Guide
Product Brochure
View Presentation

The system uses two of GL's T1 or E1 Cards (Dual HD Cards, USB cards, and Universal cards). One Card emulates the Far End circuit, provides the stimulus to the Echo Canceller, and captures its response. The second Card emulates the Near End circuit, i.e. models the echo path, and injects noise and voice signals. This PC based system also controls the Echo Canceller modes (NLP on/off, freeze, disable, etc.) and provides a captured PCM stream for analysis.

Main Features:

  • Far End emulation is performed with GL's GUI-based File Playback and File Record Software (part # XX020)
  • Near End emulation of hybrids by using GL's GUI based Delay/Attenuate Software (part # XX062)
  • Echo canceller control using standard terminal emulation software, e.g. Hyperterminal
  • Millisecond-level visibility and Analysis using GL's GLCView software
  • Additional analysis capability using Syntrillium's Adobe Audition Software or Goldwave Software
  • All T1/E1 framing formats, signaling modes, and receiver interface strategies supported.
  • Complete set of G.168 echo path models for emulation of Near End echo paths.
  • G.168 CSS Single- and Double-Talk files recorded at various power levels.
  • Detailed procedures for conducting G.168 compliance tests and analyzing results.
  • VF Input and Output available at telephone handset for subjective evaluation of echo canceller performance.
  • GL's family of T1/E1 cards and its T1/E1 Analyzer GUI Software and Windows Client Server Software are general-purpose products supporting a wide range of T1/E1 testing requirements

Delay/Attenuate Software Supports Hybrid Simulation

This application allows you to apply delay, attenuation, and/or filtering to a received signal on any number of timeslots. You may also mix in additional signals from a number of sources, including

  • Speech and/or Noise signals from files
  • Speech signals inserted via VF input
  • Gaussian noise signals generated internally

Transmitted signaling bits may be Onhook/Offhook, user-specified, or passed through from received to transmitted timeslots. To view the Delay/Attenuate Timeslots screen, please click here, or details for the entire application are provided at

The Delay/Attenuate Timeslots application may receive and transmit on either one or two boards. While there are a number of different operating configurations, the most common and useful are:

  • Looping back a processed signal- Applying delay, attenuation, and filtering to a received signal and retransmitting the processed signal on the same board on which it was received. Speech and/or noise may also be mixed in. Click to view a diagram of this configuration.

Note that the layout of the Delay/Attenuate Timeslots Dialog closely matched this diagram

  • Applying pure delay to a signal- A received signal is delayed before being retransmitted
  • Inserting a Simulated Echo Loop- A two-board system is inserted into a T1 or E1 trunk and is used to simulate an echo path having known characteristics. Click here to view a diagram of this configuration.

The layout of the Delay/Attenuate Timeslots application has been designed to closely resemble the above block diagrams. Click here to view an illustration of this resemblance for one such configuration.

Total Visibility and Analysis with GLCView

GLCView is a GL Software tool developed especially for G.168 testing. Among this product's features:

  • Displays files captured during G.168 testing.
  • Linear and Power displays shown.
  • Zoom in on power window down to millisecond-level time scale.
  • User-settable power calculation window from 1 ms to 35 ms.
  • Multiple files viewable in single window.
  • Print out graphs.

Screen Shot of GLCView

Supported G.165 and G.168 Tests

Tests G.165 G.168
Test 1: Steady state residual and returned echo level test (G.168 version 04/2000 only) NLP On
Test 2: Convergence test Test 2A: NLP On
Test 2A Part b (G.168 version 01/2007): Re-convergence with NLP On
Test 2B: NLP Off
Test 2B Part b (G.168 version 01/2007): Re-convergence with NLP Off
Test 2C with NLP On: Convergence test in presence of background noise
Test 2C with NLP off: Convergence test in presence of background noise
Test 2C-c (G.168 version 01/2007) for noise level -55 dBmO: Convergence test with NLP Off and background noise
Test 3: Double talk test Test 3A: low cancelled-end level
Test 3B: high cancelled-end level
Test 3B Part b (G.168 version 01/2007): stability test with low cancelled-end levels
Test 3C: simulated conversation
Test 4: Leak rate test Yes Yes
Test 5: Infinite return loss convergence test Yes Yes
Test 6: Non-Divergence on narrow-band signal test Optional Yes
Test 7: Stability test Optional Yes
Test 8: Overload test Yes No
Test 8: Non-convergence of EC on SS5/SS6/SS7 tones in-band signaling and continuity check tones No Yes
Test 9: Comfort noise test Yes Yes
Test 10: Facsimile test Test 10A (with NLP On and NLP Off): Canceller operation on the calling station side
Test 10B (with NLP On and NLP Off): Canceller operation on the called station side
Test 12: Residual acoustic echo test No Yes
Test 13: Performance with ITU-T low-bit rate coders in echo path No Yes
Test 14: Low speed modem test No Yes
Test 15: DC Off sets Test 15A:
Test 15B:
Test 16: DTMF tests Test 16A: DTMF transparency in the presence of a dial tone
Test 16B: DTMF transparency in the presence of speech

Note: The G.165 and G.168 Tests differ in the time to perform the tests. For example, Test 1 steady state residual test requires 180 seconds in G.168, but it does not specify the exact time in G.165. With small modifications of the test procedures (mainly the times), we can use the G.168 test procedures to perform the G.165 tests. As per the customerís requirement the manual test procedures can be modified. Contact GL for further details

Buyer's Guide:

Please Note1: The XX in the Item No. refers to the hardware platform, listed at the bottom of the Buyer's Guide, which the software will be running on. Therefore, XX can either be ETA or EEA (Octal/Quad Boards), PTA or PEA (tProbe Units), UTA or UEA (USB Units), HUT or HUE (Universal Cards), and HDT or HDE (HD cards) depending upon the hardware.

Item No. Item Description
XX065 G.168 Test Suite for T1 or E1 Echo Cancellers (Manual Testing Procedures)
GLCView Software Provided
XX020 File Record/Playback Software
XX062 Echo Path Delay/Loss Simulation Software
XX063 Echo Path Delay/Loss Measurement Software
  Related Software
XX066 Digital Echo Canceller
XX067 Automated Echo Canceller Testing with or without VQT
XX068 Semi-Automated and Scripted Echo Canceller Testing Suite
XX610 File based Record/Playback (included)
XX630 DSP Functionality (included)
PKB081 Automated Acoustic Echo Cancellation (AEC) Compliance Test Software
  Related Hardware
HDT001/HDE001 Legacy HD T1 or E1 (PCI) Cards with Basic Analyzer Software
HTE001 Universal T1/E1 Card with Basic Analyzer Software
UTE001 Portable USB based Dual T1 or E1 Laptop Analyzer with Basic Analyzer Software
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SA048 Goldwave Software
SA017A RJ48C to RJ48C Straight Cable, 10ft. cable
SA017A RJ48C to RJ48C Crossover Cable, 10ft. cable
SA008a Handset Adapter with Handset
SA022 Extended 1 Yr. Software Upgrades and Hardware Warranty, and Comprehensive Support for Basic and Optional Software

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