Checking Audio Polarity

When and where to use:

Use this procedure upon initial optimization and any time system changes are performed. Once completed and if the system has not changed, there is no need to perform these steps every time the system is re-optimized.

Procedure:

  1. Perform the following actions depending on system configuration:
    If… Then…
    If the system is circuit-based, perform the following actions:
    1. Inject into the CSCI an asymmetrical waveform (a 10 Hz sawtooth is ideal and is available from the ACTS DSA) and set the level to produce 60% system deviation. The deviation is not critical, ensure that modulation limiting does not occur.
    2. From the prime site, key up one channel at a time and observe the modulation waveform on either the CSA or the DSA. On the first channel, note the shape of the waveform.
    If the system is IP-based, perform the following actions:
    1. Follow the steps in Performing Coarse Level PL/DPL Adjustment (Conventional Systems) to set the PL/DPL list to DPL to specify DPL should be inserted into the voice stream.
    2. Start the test tone.
    3. From the prime site, key up one channel at a time and observe the modulation waveform on either the CSA or the DSA. On the first channel, note the shape of the waveform.
  2. Individually key up the channel at each site and observe the waveform. It should be identical to the waveform observed in step 1. If the waveform is reversed, an audio polarity reversal exists and must be corrected.
  3. Check the remaining channels, one site at a time and verify that the waveform is correct.