8-19
IM 704420-01E
Communication Function
8
: C A L C u l a t i o n : S N U M b e r ?
: C A L C u l a t i o n : S N U M b e r ?
: C A L C u l a t i o n : S N U M b e r ?
: C A L C u l a t i o n : S N U M b e r ?
: C A L C u l a t i o n : S N U M b e r ?
Function
Queries the number of samples (number of
samples used to compute the statistics) of the
data signal.
Syntax
:CALCulation:SNUMber?
Example
:CALCULATION:SNUMBER?
→
1.000E+3
Description If the statistical value is not valid, “
NAN
” is
returned.
: C A L C u l a t i o n : T V A L u e ?
: C A L C u l a t i o n : T V A L u e ?
: C A L C u l a t i o n : T V A L u e ?
: C A L C u l a t i o n : T V A L u e ?
: C A L C u l a t i o n : T V A L u e ?
Function
Queries the period of the clock signal.
Syntax
:CALCulation:TVALue?
Example
:CALCULATION:TVALUE?
→
37.000E–9
Description The result of the query is as follows:
• If the measurement function is “
DTOC
” and
period T of the clock signal could be
measured, the measured value is returned. If
the statistical value is not valid, “
NAN
” is
returned. If period T of the clock signal could
not be measured, “
37.000ns
” is returned.
• If the measurement function is “
D3T
” and the
statistical value is valid, the result derived
from calculating “231.385 ns/
×
N speed” is
returned. If the statistical value is not valid,
“
NAN
” is returned. The “
:MEASure:SPEed
”
command is used to set the
×
N speed.
Equations Used to Derive Statistics
In the equation below, n is the number of bins in the
histogram. A bin of a histogram refers to a bar that
indicates the frequency of occurrence on the
histogram. Xi is the class value of each bin of the
histogram. Of the following items, only the jitter and
jitter ratio can be indicated on the analog meter and
display:
• Maximum value (MAX)
Indicates the maximum class value.
MAX = [ X
i
]
man
• Minimum value (MIN)
Indicates the minimum class value.
MIN = [ X
i
]
min
• Average value (AVE)
Computes the average value. Pi is the relative
frequency
*
.
AVE =
Σ
X
i
×
P
i
n
i = 1
* If the total number of samples on which the statistics are being
calculated is N, and the frequency of occurrence (number of
samples) of a certain bin is Ni, then the relative frequency
becomes Pi = Ni/N.
• Standard deviation (jitter
σ
)
Computes the standard deviation. Pi is the relative
frequency.
σ
=
Σ
(X
i
– AVE)
2
×
P
i
n
i = 1
• Peak-to-Peak (P-P)
Calculates the difference between the maximum
and minimum values.
P-P = MAX – MIN
• Flutter (
σ
/AVE)
Computes the flutter. Indicates the standard
deviation as a ratio with respect to the average
value.
σ
AVE
×
100(%)
σ
/ AVE =
• Jitter ratio (
σ
/T)
Computes the jitter ratio by using period T of the
clock signal. T is the period of the clock signal of
the CD or DVD. When the measurement function is
3T jitter, T = 231.385/N (where N is the multi-speed
value). When the measurement function is D-to-C
jitter, T is the period of the clock signal that is
applied to the clock input connector or regenerated
by the PLL circuit.
σ
T
×
100(%)
σ
/ T =
• ELError (Effect Length Error)
XCENTER is the center value of the histogram.
Originally, XCENTER represented the value around
which the measured data would be distributed.
ELError indicates the offset of the actually
measured average value AVE with respect to the
XCENTER value.
For D-to-C jitter
X
CENTER
=
T
2
For 3T jitter
3T
X
CENTER
=
T is the same as the T of the aforementioned “Jitter
ratio (
σ
/T).”
ELError = AVE
– X
CENTER
• MELE (Maximum Effect Length Error)
Computes the MELE using period T of the clock
signal. MELE is indicated as a ratio with respect to
T of ELError. For information on T, see “Jitter ratio
(
σ
/T).”
AVE – X
CENTER
T
×
100(%)
MELE =
8.7 Commands
