Gentner Initial Configuration
The Gentner Audio Conferencing device controls and cross connects the audio streams generated by the microphones and Audio Server. This device performs echo cancellation, gain control, cross connects the input and output feeds, and powers the microphones. The device also can utilize a dial up line to support an alternate method of communication in case of network trouble. The following presets are a recommended starting point to begin tuning the Gentner for proper sound quality. In addition to the adjustments available, placement of the microphones and speakers is critical.
The following information is intended to get the user started and initially configure the Gentner system. Please refer to the Gentner manual for additional information and detailed instructions for fine-tuning your system.
Matrix Configuration
The Gentner system uses a basic X/Y grid to cross connect the input and output signals, which is accessed by clicking on the Matrix point on the main page. The configuration below depicts an example of the connections used for normal operation with an AP400 system. These points correspond with the connection points depicted in the earlier drawings. If the deployed system has greater or fewer devices connected, ensure the proper cross connections are made for your system. You may wish to use the document "How to Configure the Gentner AP400 for Use on the Access Grid" installed in the User Documentation of the 1.0 Access Grid Toolkit, and available online.
The cross connect is laid out with the inputs on the vertical and the outputs laid out across the horizontal axis. Checking the corresponding box for the connection points desired instructs the Gentner device to make a logical connection between the input and output. The Gentner will then send all of the signals from the input to the corresponding outputs. (A simple way to test your configuration through the Gentner device would be to cross connect your microphone inputs directly to your speaker outputs by checking the box between the "mic 1" and the "input 1".)
AP400 Matrix
Device Levels
The gain control for the inputs and outputs need to be tailored to your environment and specific equipment. While monitoring normalized level audio meter view in the Gentner control panel, adjust the gain so that the mean level being received by the Gentner is at 0 db for normal conversation. A good starting point for the gain setting is around -7 db. At this level the system will have the proper power needed to obtain a good signal while not distorting the voice or allowing high levels of feedback. Check and adjust the audio levels at all points of the audio path starting at the mic level, bus level, tx to codec, tx to telco, rx from codec, rx from telco and on the PC at the RAT.
Microphone levels
Additional consideration must be taken for the adjustment of the microphones since their placement relative to the speakers and source will affect sound quality. If the microphones are to close to the speakers, the gain control will need to be reduced so that excess feedback does not cause acoustic feedback or "squealing" of the system. To compensate for the lower levels, adjustments to the outgoing signal from the Gentner or the incoming signal at the distant end may be required.