Message 221
Message
Clock Recovery Emulation (CRE) is enabled. Ensure that clock-to-data delays are properly matched.
Description
This informational message warns you about additional requirements when using Clock Recovery Emulation (CRE) with the following hardware:
- External Clock Recovery is used (for example, N1076A) and
- N1000A Internal Precision Time Base (option PTB) is used.
In this situation, you must ensure that the clock-to-data path delays are matched. The recommended N1027A-76A electrical clock recovery phase matching kit provides a delay-line assembly that adds the required amount of delay. As shown in the following picture, the delay-line assembly attaches to the N1000A's rear panel to replace a rear-panel jumper cable. For instructions on installing the delay line with drawings of example test setups, download the N107x-series user's guide from keysight.com. You do not need to worry about adding delay, if you are using an 86107A precision timebase module or an 86108A/B precision waveform analyzer module.
![](../../Resources/Images/Common/delay_line_attache.png)