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Drive Processing Functions
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| Head Filter/Equalizer Emulation
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Type:
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Utilizes a
seven-pole, two-zero equiripple filter. Values for –3 dB frequency,
boost and group delay can be independently adjusted
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Boost:
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0 to 13 dB
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FC:
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10 MHz – 200 MHz Group Delay: –30% to 30%
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In addition, DDA can autotrain on a PRML signal using a 2D search of fc and Boost to automatically set fc and Boost. A 21–tap FIR (Finite Impulse Response) filter — settable through GPIB control — is also available for channel emulation. Filter tap weights can be asymmetric to minimize delay through the filter.
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Channel Emulation
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Channel emulation capability is provided to analyze PR4, EPR4, E2PR4, and user-defined trellis PRML head signal quality. The channel emulator includes a resampling ADC, PLL, Automatic Gain Control (AGC) and Viterbi detector. Maximum likelihood levels are independently controlled and can adjust for MR head asymmetries.
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SAM Histograms
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Histograms of SAM values can be automatically displayed for the head signal SAM values determined in channel emulation. SAM histograms give an overall view of the distribution of SAM and, thereby, overall head signal quality, noise contribution, and quality outliers from a PRML channel perspective.
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Plot of SAM Values
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A sequential graph of SAM values can be displayed along with the PRML head signal. The plot of SAM values provides a rapid visual indication of the location of PRML signal problems.
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PES Runout Analysis
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Provides a table of runout values for PES (Position Error Signal) for each servo wedge captured; includes Repetitive Runout, Maximum IRO, Minimum IRO, Instantaneous Runout, and Sigma.
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Analog Compare
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Provides automatic comparison of a stored reference head signal and acquired head signals, with automatic adjustment for spindle speed variations. Differences between head signals are calculated using a 3–byte sliding window, and a calculation of the Mean- Square-Distance (MSD) is computed.
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Cursor Measurements
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Relative Time
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A pair of arrow cursors measures time differences and voltage differences relative to each other
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Relative Voltage
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A pair of line cursors measure voltage differences relative to each other
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Absolute Time
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A cross-hair marker measures time relative to the trigger and voltage with respect to ground
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Absolute Voltage
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A reference bar measures voltage with respect to ground
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Automated Measurements
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The following parametric measurements are provided together with their average, highest, lowest values and standard deviation:
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amplitude
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cycles
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duty
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lper
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period
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std dev
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delay
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fall
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maximum
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peak-to-peak
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t@level
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base
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?c2d- (hold)
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f 80-20%
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mean
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phase
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top
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cmean
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?c2d+ (setup)
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f@level
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median
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rise
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width
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cmedian
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?delay
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first
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minimum
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r 20-80%
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crms
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?t@level
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frequency
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overshoot+
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r@level
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csdev
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duration
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last
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overshoot-
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rms
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The following Disk Drive Measurements are provided:
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TAA
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TAA+
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TAA-
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PW50
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PW50+
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PW50-
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Resolution
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Overwrite
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lbase
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lbsep
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lmax
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lmin
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lnum
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lpp
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ltbe
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ltbp
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ltbt
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ltmn
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ltmx
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ltot
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ltpt
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lttp
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ltut
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NLTS
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ACSN
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msnr
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rsnr
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m_to_r
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nbph
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nbpw
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The following histogram parameters are provided:
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Low
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High
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Range
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FWHM
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maxp
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Average
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Sigma
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totp
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XAPK
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PKS
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Median
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Mode
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Percentile
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PASS/FAIL: Pass/Fail testing allows any items (parameters and/or masks) to be tested against selectable thresholds. Waveform Limit Testing is performed using Masks that may be defined either inside the instrument or by downloading templates created with MaskMaker — a utility that is part of the
Polymask option. Any failure will cause preprogrammed actions such as Stop, Hardcopy, Save to Internal Memory, Save to mass storage device (card or disk), GPIB
SRQ, or Pulse Out.
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