Broadcast

Using a modulation monitor as a reference, good calibration can be achieved.
However, please note that calibration will only be as good as the modulation monitor.
Make sure you modulation monitor displays peak - not average / RMS.

If you are using Breakaway Broadcast's stereo encoder (MPX output):

  • Connect BBP's MPX output to your exciter.
  • Open the Signal Settings window (click Settings in the main window).
  • Set the tone generator to output 400hz.
  • Adjust modulation until you see 100% (+/- 75 kHz deviation) modulation on the modulation monitor. You can adjust the level either using the MPX Ref Level control, or with gain controls on the stereo generator / exciter. If using the MPX Ref Level control, make sure not to exceed -3dB -- the headroom may be necessary for tilt correction.
  • Set the tone generator to output 60hz square.
  • Adjust Tilt (MPX out) for the lowest possible modulation readout. Ideal is 70.7% modulation (+/- 53 kHz deviation).
  • Set the tone generator to output 31187.6 Hz.
  • Do not adjust any settings! Verify that you're seeing close to 100% on the modulation monitor. If you're seeing no modulation at all, verify that your sound card is really running at 192 kHz!
  • Set the tone generator in BaFM to output 57000 Hz.
  • Do not adjust any settings! Verify that you're seeing at least 50% (+/- 37.5 kHz) on the modulation monitor.
    Do not be alarmed if the signal level has dropped below 100% (+/- 75 kHz) -- 57000 Hz at full deviation is not a normal test case, causes very wide sidebands, and may be distorted by the IF filter in the modulation monitor.
    However, if you're seeing no modulation at all, verify that your sound card is running at 192 kHz. If the sound card does not support 192 kHz, drastic loss of stereo separation will result, even though the stereo light on your receiver will be on.
  • Turn off the test tone, play normal program material.
  • Verify that peak modulation (according to the modulation monitor) stays around 100% (+/- 75 kHz) and doesn't overshoot.

Calibration complete!

 

If you are using an External Stereo Generator:

  • Connect BBP's L/R analog outputs into your hardware stereo generator.
    Turn off the 19 kHz pilot on the hardware stereo generator.
    If the stereo generator has any protection clipping, limiting or filtering, make sure they are off, or overshoots / distortion / loudness loss may occur.
  • Open the Signal Settings window (click Settings in the main window).
  • Set the tone generator to output 400hz.
  • Adjust modulation until you see 100% (+/- 75 kHz deviation) modulation on the modulation monitor. You can adjust the level either using the L/R Ref Level control, or with gain controls on the stereo generator / exciter. If using the L/R Ref Level control, make sure not to exceed -3dB -- the headroom may be necessary for tilt correction.
  • Set the tone generator to output 60hz square.
  • Adjust Tilt (L/R out) for the lowest possible modulation readout. Ideal is 70.7% modulation (+/- 53 kHz deviation).
  • Set the tone generator to output 400hz.
  • Turn on the 19 kHz pilot, and adjust pilot level until you see 108% modulation (+/- 81 kHz deviation).
  • Turn down L/R Ref Level until you again see 100% modulation (+/- 75 kHz deviation).
  • Turn off the test tone, play normal program material.
  • Verify that peak modulation (according to the modulation monitor) stays around 100% (+/- 75 kHz) and doesn't overshoot.

Calibration complete!