The CHD1812 (with no external reference connected) and the CHD1802 per default are locked to the HDMI input signal.

We recognized that a few HDMI sources have a very high jitter on their HDMI video outputs, which in turn

could lead to a very high jitter on the CHD18x2 SDI video output (in case the module is locked to the HDMI input).

If you have a very high jitter on the SDI output you can do the following things:

  1. CHD1812 modules can be referenced with an external reference signal on the REF input.
  2. In case there is no reference signal available or you have a CHD1802, you can force the module to free run instead of locking to the HDMI input signal. 


Forcing the module in free run mode can lead to audio disturbances / errors with encoded audio content (e.g. Dolby D).

As the module is running in free run mode, not locked to the HDMI input, a vertical shift of the active picture can occur.

In order to force the module in freerun mode, please connect to the yelloGUI and open the Expert-TAB.

Set "Force to Free Run" to "on" (available in yelloGUI version 1.2.0 and above for CHD1802, 1.1.0 and above for CHD1812).

Additional yelloGUI information: