Tektronix MTG100 - Manual (Page 149)

Adding Jitter to PCRs (MTG300 only)
3Ć90
MTG100 & MTG300 MPEG Generator User Manual
3. The PCR Stress dialog box lets you set how the parameters for how jitter
will be added to the PCR. The PCR Stress dialog box is divided into the
following two fields:
H Interval Jitter. Use this field to add jitter to the period of the transport
stream packets containing a PCR.
H Value Jitter. Use this field to add jitter to the program_clock_refer-
ence_base value and the program_clock_reference_extension value in the
adaptation field.
Refer to PCR Stress Dialog Box on page 3-51 for information about the
dialog box parameters. For detailed information about the two jitter
functions, refer to Interval Jitter Function on page 3-90 and Value Jitter
Function on page 3-92.
4. After you have set the parameters, press the Interval Apply bezel button
and/or the Value Apply bezel button to enable one or both of the jitter
functions.
Interval Jitter Function
The Interval Jitter function, accessed through the PCR Stress dialog box (see
Figure 3-31), allows you to add jitter to the period of packets containing a PCR.
Refer to PCR Stress Dialog Box on page 3-51 for information about the dialog
box parameters.
The Interval Jitter function provides two function modes: Period and Deviation.
This subsection describes the differences between the two modes.
Period Mode. In this mode, amplitude variation of the waveform selected in
Pattern item is added to PCR interval currently set.
Figure 3-32 shows the variation of PCR interval in Period mode with following
settings:
PCR Interval: 30 ms, Pattern: Square, Period: 8 [Packets], Amplitude: 10 ms
In this mode, PCR interval after jitter insertion can be defined by the following
equation:
PCR(n) =PCR_Reference +
ŕSquare(t)
Where: PCR_Reference is the PCR interval set in the PCR Interval item, and
Square(t) is the square waveform defined by the Amplitude and Period items.
Period Mode and
Deviation Mode
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