The DSPGenie G.168 Tester is a highly portable turn-key solution for all echo canceller related testing. Highly integrated DSP technology allows all tests to be carried out in real time.

Overview

One of the key technologies for improving the quality and performance of GSTN networks are echo cancellers. However, with many competing manufacturers and products on the market there is inevitably a varying degree of performance.

There is clearly the need for a reliable and efficient mechanism with which to test various echo cancellers. It is primarily to satisfy this requirement that DSPG Ltd. has developed the DSPGenie G.168 Echo Canceller Tester. The unit is part of a range of telecommunication test equipment from DSPG.

The DSPGenie ECT follows in the footsteps of DSPG’s highly successful ECT-1 unit. Advances in technology have allowed for the combination of all circuitry (multiple DSPs, dual PCM interface, switching/routing, etc.) on a single card, and thus the new unit has a much smaller form factor than any other similar test equipment available, making it far more portable and practical.

In a revolutionary advancement, the DSPGenie G.168 tester is based on a client / server relationship which allows all tests and configuration to be run from any remote location (connected using TCP/IP) via a simple web browser interface. The unit itself runs under Windows 2000 for stability and customisation reasons, but the client which controls the testing can be run on any Windows based platform.

The G.168 testing suite is only one of numerous software modules that can be installed on the DSPGenie platform. Some of the additional modules include G.164/G.165 Tone Disabler Tester and PESQ-based voice quality assessment suite. There is also a real-time subjective listening module available, offering unprecedented user control over the emulated environment in which the Echo Canceller operates. These extra software modules can be purchased and upgraded as the need arises, leading to an extremely cost-effective testing solution.

Main Features

• Based on new DSPGenie hardware platform

• Complete G.168 (2002) tester suite

• G.168 (2004) available as a download once it is standardized by the ITU-T.

• Single card based solution leads to small form factor and highly portable unit

• Flexible configurable input/output options (E1, T1, VoIP, ISDN, TDM digital, analogue)

• Entire G.168 suite can be tested at the click of a button!

• The Unit can be controlled completely remotely (via TCP/IP) and its status continually monitored

• User can run single test with various combinations of parameters, or pre-configure and run multiple tests

• All test runs are recorded, and can be viewed immediately, or offline using the stand-alone result viewer

• Ability to notify user via email when all testing is complete

• Easy to understand status screen details test progress

Results from different tests can be overlaid on the same display to allow for quick comparison

Lower cost of ownership

Highly reduced form factor

Controlled remotely via TCP/IP

Flexible input / output configuration

Future-proof (software upgradeable)

Single click testing of entire G.168 suite

The DSPGenie G.168 tester exercises the Echo Canceller under test by applying precisely controlled recommended stimuli on the R_in and S_in ports and emulating in real-time the Echo Path Model. The response S_out signal is recorded, then analysed and compared against relevant pass/fail criteria; the test results are displayed and stored for future reference.

Due to the flexible nature of its digital switching/routing architecture, the DSPGenie ECT can be configured in software to accept a wide variety of input/output options. The standard DSPGenie package includes E1, T1 and 4-wire analogue I/O, with the other options (VoIP, TDM digital and ISDN) available at an additional cost. The intuitive interface for selecting I/O configuration is shown below.

The various tests for G.168 are presented in the easy-to-use main interface. One of the features of the ECT is the ability to configure and queue multiple tests. Each test can be configured to run using the default parameters recommended by G.168 or user defined parameter ranges can be entered (and saved for re-use later). The queued tests can be selected to repeat any number of times. All G.168 (2002) tests are available, with the G.168 (2004) tests available as a software download once they have been accepted by the ITU-T. For users who do not require all the tests, a customised version of the software is available at a discount.

In order for G.168 testing to be carried out, the ECT needs a specific and timely control over the echo canceller under test. The echo canceller may be controlled either through a dedicated TTL port, V.24/RS-232 serial port or via the PCM stream. These configuration options and EC-specific control commands can be set as required (and saved), or loaded from the provided extensive canceller libraries.

The DSPGenie now has the ability to measure the delays through certain paths of the Echo Canceller, without the need for changing the physical wired connections. These delays are determined by the DSPGenie, however the user is able to modify or override the measured values. Additionally, these delay values can be saved or loaded at the user's convenience.

Each test has associated with it a relevant set of parameters (typically T_d, ERL and L_Rin). The default G.168 range can be used, or user defined parameter sets can be saved and loaded at will. The emulated echo-path model (simple three-branch or one of the complex-hybrid models) is also user selectable.

The various combinations of input parameters (T_d, ERL and L_Rin) are listed in the table, then each line of test is executed in sequence. The steady-state mask is calculated per test (usually a function of L_Rin). The current test status (in progress, passed, failed or cancelled) is reported, and the RMS value of the output signal calculated and displayed in the L_ret column. This is one of several measurements performed during each test, and conforms to the G.168 specification. The output data for every test is stored on the unit's hard-drive, and can be viewed in a graphical form during testing with a single mouse click. The figure below shows a test run in progress.

Off-line viewing is also possible using the supplied stand alone graphical display software. The pertinent parameters such as T_d, ERL and L_Rin are displayed. Any results of previous tests saved on disk may be viewed, and small details can be observed by using the zoom function.

Any of the test result displays can also be exported to various picture format (BMP, JPEG or PNG) for later use.