X-Stream Operator’s Manual
WM-OM-E Rev I 355
Reference for guidelines on using a Reference.
5. Touch the Trace On checkbox to turn the Head Signal on.
6. Touch inside the Read Gate field and select a source from the pop-up menu. The choices
include Ref and none. Read Gate If the Read Gate signal is connected to a DDA-5005A
channel and specified, it will be used to determine the regions of the signal to be analyzed.
Since the VCO Synch field is required for Channel Emulation with Reference and is
normally present in the head signal in every block just after Read Gate goes true, it is
recommended that Read Gate be used. If Read Gate is not present, the entire waveform
will be used unless the Analyze Region cursors are enabled.
7. If for Read Gate you selected other than none, Touch inside the Gate Polarity field and
select positive or negative polarity.
8. Touch inside the Compare to Reference checkbox to enable comparison of the Head
Signal to the Reference. Then touch the Store Reference button.
9. Touch the Stop on SAM checkbox if you want to stop the acquisition when the signal falls
below a user-defined SAM value. Stop on SAM When this mode is enabled, the
DDA-5005A is placed in what is essentially a test mode for PRML signal quality based on
SAM. When in Normal acquisition mode, the DDA-5005A will continuously acquire and
analyze head signals until it finds a PRML sample value with a SAM value below a
user-specified level. When this occurs, acquisition will be stopped, and you can directly
view the locations below the selected SAM threshold. This mode of operation is particularly
useful for capturing intermittent errors.
10. Touch inside the SAM Threshold data entry field and enter a value from 0 to 2 , using the
pop-up numeric keypad. See SAM in "PRML Channel Emulation" then touch Back
to complete this setup.
11. Touch the Show ML Markers checkbox to enable the markers. ML Markers The ML
Markers indicate the location of the ideal PRML sample values based on the DDA-5005A’s
channel emulation.
12. Touch the Show Level Markers checkbox to enable the markers. Level Markers The Level
Markers indicate the vertical position of the PRML levels based on the amplitude of the
acquired PRML signal. The Level Markers indicate the vertical position of the PRML levels
based on the amplitude of the acquired PRML signal. They reflect the levels at the center of
the display.
13. Touch the Specify Region checkbox to specify a start and end time, if desired. This may
be necessary if you are not using a Read Gate. If you are not using Read Gate, the
Analytical Region must start with a preamble for VCO synchronization. Touch inside the
Start and End data entry fields and enter starting and ending time values from -1.0 ks to
+1.0 ks, using the pop-up numeric keypad.
14. To jump to a position in the head signal, touch inside the "Position" Segment field and
enter a value from 1 to 999, using the pop-up numeric keypad. Then touch inside the Byte
field and enter a value from 50 to 50,000.
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