Nortel Networks operation manual RTU-292 Operations Manual, Vox Sensitivity Measurement

RTU-292 Operations Manual

6.5.3 VOX SENSITIVITY MEASUREMENT

The following test procedure measure the sensitivity of the VOX in the RTU-292. This is the amplitude of the incoming signal from the telephone line required to trigger the VOX.

Figure 6-2 VOX Sensitivity Test Set-Up

6.5.3.1 VOX Test Procedure

1.Disconnect the RTU-292 from all other equipment and connect the test equipment as shown on Figure 6.2.

2.The PSTN level setting must be known. To determine this, remove the top cover and note the positions of SW2-1, -2, and -3.

3.Start with the following pushbuttons OFF: TEL LINE/PHONE and TEL LINE/RADIO. Push the TEL VOX button ON. The positions of the other buttons are unimportant.

4.Set the audio signal generator frequency to 1 kHz with an output amplitude of less than - 40dBm (7.7mV rms).

5.Push the TEL LINE/RADIO button to start the adaptation cycle.

6.When the initial adaptation cycle is complete, slowly increase the audio generator amplitude until the Keyed LED on the RTU-292 comes on. The audio generator amplitude at this point (read directly by the audio voltmeter) is the VOX sensitivity. The VOX trip point is dependent on the setting of the PSTN levels and the VOX sensitivity setting. It should be 16 + 2 dB below the PSTN setting as listed in the table below:

VOX Sensitivity	VOX Trip Point
MAX	19 + 2 dB below the PSTN setting
MED	16 + 2 dB below the PSTN setting
LOW	13 + 2 dB below the PSTN setting
MIN	10 + 2 dB below the PSTN setting
	6-23	JPS Communications, Inc.