1-6
IM 704420-01E
D-to-C Jitter «See 4.1 for the operating procedure»
Time difference measurement
Measures the time difference between the rising (or falling) edge of the data signal to
the first rising (or falling) edge of the clock signal of a digital versatile disk (DVD).
Measurement
Measurement
Data
signal
Clock
signal
Data
signal
Clock
signal
• Example 1
Slope of the data signal
: Rising
Slope of the clock signal : Rising
• Example 2
Slope of the data signal
: Both rising and falling
Slope of the clock signal : Rising edge
Measurement
Measurement
Measurement
Jitter
σ
and jitter ratio
σ
/T
Determines a histogram (frequency distribution) from multiple measured values of
time difference, and calculates the standard deviation
σ
from the histogram. This
standard deviation
σ
is the D-to-C jitter. The D-to-C jitter ratio is derived by dividing
the standard deviation
σ
by the period T of the DVD clock signal. The time-averaged
value of the measured time difference signal is the average value AVE.
σ
=
Σ
(X
i
– AVE)
2
×
P
i
n
i = 1
n : Number of bins (histogram lines) of the histogram
X
i
: Class value of each bin
P
i
: Relative frequency
(Ratio of frequency Xi of a single bin with respect to
the total number of samples)
T : The period of the DVD clock signal.
(Varies depending on the measured signal, because it is
measured simultaneously with the data signal.)
• Jitter
AVE =
Σ (
X
i
×
P
i
)
n
i = 1
• Average value
• Jitter ratio
σ
T
×
100(%)
Note
You can also read statistics other than jitter, jitter ratio and average value by making inquiries
using communication commands. For details, see section 8.7.2, “CALCulation Group.”
1.3 Measurement Functions (Measurement Items)
