Rohde & Schwarz RTP Series - Clock Data Recovery; Software CDR

Jitter analysis and clock data recovery
R&S
®
RTP
1056User Manual 1337.9952.02 ─ 12
18.3 Clock data recovery
The process of clock data recovery (CDR) generates a reference clock from a high-
speed serial data stream that is sent without a dedicated clock signal. The generated
clock signal matches the frequency and is aligned to the phase of the data stream. The
recovered clock can be used to sample the data stream, to obtain the sequence of
transmitted bits, and to measure jitter parameters.
There are two ways to recover the clock signal:
●
Using software algorithms that calculate the clock from data signal edges (option
R&S RTP-K12):
Chapter 18.3.1, "Software CDR", on page 1056
●
Using hardware CDR (option R&S RTP-K140/K141):
Chapter 6.10.2.1, "Basic settings for serial pattern trigger", on page 256
18.3.1 Software CDR
You can define two independent software CDR instances to recover clock signals.
These clock signals are used for data timing measurements: time interval error, unit
interval, and data rate (frequency of the clock signal). The lower the signal bandwidth
and the higher the relative bandwidth, the longer is the settling time.
Software CDR is based on acquired data, needs a synchronization time to set up the
clock. To get correct measurement results, the data acquired during synchronization
time has to be discarded.
You can also display the recovered clock signal as a math waveform, see Chap-
ter 18.3.2, "Displaying the recovered clock signal", on page 1059.
Access: [App Cockpit] > "Analysis" tab > "CDR" > "Software1"/"Software2"
Clock data recovery