Troubleshooting Misaligned Reference Modulation Compensation (Final System-Level Check — IP Based Simulcast)

Coarse level calibration and fine amplitude adjustment procedures are important steps to ensure the reference modulation compensation in an IP-based simulcast system.

When and where to use:

During a final system level check on IP-based simulcast systems, if the levels between sites (that is, the output of the channel across the subsites) for a given frequency vary by more than 0.3 dB of the reference site, this variance indicates a misaligned reference modulation compensation on one or more base radios. The coarse level calibration and fine amplitude adjustment procedures were likely not performed correctly and must be repeated.

Procedure:

  1. In the MLC 8000 Configuration Tool with Analog Display and Control, select an MLC 8000 Subsite Link Converter (AGU) in the channel cluster tree, click the Audio Monitoring button.
    The Audio Monitoring and Calibration — IP Simulcast: BR Calibration tab appears. Use this tab to troubleshoot the modulation compensation issue. Unlike the window that appears when you select an MLC 8000 Analog Comparator (VGU), this window contains arrows used to adjust the digital gain.
  2. Press the Start button.
    NoteYou must press the START button before you can adjust the Gain values.
  3. Use the up/down arrows to adjust the Gain for one or more MLC 8000 Subsite Link Converters until the non-reference site is <= 0.3 dB of the reference site.
  4. Click Save to File to save the gain information to a file for later reference.
  5. Return to Configuring the MLC 8000 for IP-Based Simulcast.
  6. For the GTR 8000 Base Radios, repeat the coarse level calibration and fine amplitude adjustment procedures.