GS6151 Datasheet, PDF (42/77 Pages) Semtech Corporation – Multi-Rate 6G UHD-SDI

HEM Eye Width Measurement vs. Input Jitter
120
110
100
90
80
70
60
50
40
30
20
10
0
0.00
0.20
0.40
Jitter Amplitude (UI)
Figure 4-23: HEM Eye Width vs. Input Jitter
3G, HD Data
0.60
0.80
The eye scan state machine counts errors at each of the 128 phases to determine the
above eye parameters, returning a 1 in the appropriate bit of the bitmap for an error-free
measurement, and a 0 when an error has been detected. The length of each
measurement, SAMPLE_TIME, is determined by Equation 4-4 .
SAMPLE_TIME = MEASUREMENT_PREDIVIDER × (MEASUREMENT_TIME + 1) × 1 ⁄ (108MHz)
In Equation 4-4 , MEASUREMENT_PREDIVIDER and MEASUREMENT_TIME are bits of the
EYE_MON_CONTROL_REG_1 and EYE_MON_CONTROL_REG_2 registers, respectively.
By default MEASUREMENT_PREDIVIDER is set to 4x (bit value 0) and
MEASUREMENT_TIME is set to A8B_h yielding a default measurement time per phase of
100μs. The length of time to complete a full eye scan is then approximately 128 bits x
SAMPLE_TIME x 2 passes. Two passes are executed by the state machine when checking
arbitrary data to map the left and right portions of the eye separately.
The equivalent bit-error-rate is then defined as at least ERROR_THRESHOLD / (data rate
* SAMPLE_TIME) for phases with errors.
Equation 4-4
4.12.1.2 Single Timed Measurement
A manual timed measurement can be used to count the number of errors at a single
phase for a pre-defined length of time. The length of the measurement is defined by the
number of bit errors recorded is stored in the ERROR_COUNT bits of the
GS6151
Final Data Sheet
PDS-060389
Rev.4
August 2015
www.semtech.com
42 of 77
Semtech
Proprietary & Confidential