WITE Revision 1.6

Release Notes

 

Introduction

This document contains the release notes for WITE revision 1.6 from Guzik Technical Enterprises. The highlights of revision 1.6 include:

  • SAA stability test: high-performance replacement for TAA stability test
  • Triple-track tests in 747 module
  • Improved UP7 support
  • MR impedance screen with HGA testing
  • Support for systems without VFO
  • Support for new head amplifiers, head stacks and PRML chips
All discussion of features and bugs in this document uses WITE version 1.5 as a baseline for comparison. For information about features and modifications prior to 1.5, please refer to the WITE user’s manual and to the release notes for previous revisions of WITE.

New Features in WITE 1.6

SAA Stability Test

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WITE 1.6 contains a new sector average amplitude (SAA) stability test. This test is a high-performance replacement for the TAA stability test, which is fast enough to use for several hundred iterations in production mode if desired. The test is contained in the Tests | Parametric tests menu. It reports statistical information about the amplitudes measured in individual sectors on the track. The write element can optionally be excited prior to each read operation, so each sector contains a separate write and read gate as follows:

The SAA stability test is contained in the Parametric tests module. Its setup screen allows manipulation of all test parameters:

 

SETUP PARAMETERS
Iterations Number of iterations
Sectors Sectors per revolution. Updated automatically when the number of iterations, write gate, gap or read gate is changed.
Rev. Number of revolutions. Updated automatically when the number of iterations, write gate, gap or read gate is changed.
Write Gate The length of the write gate (in microseconds)
Gap The length of the gap between write and read operations (in microseconds)
Read Gate The length of the read gate (in microseconds)
Write option Current version supports only Pattern
Pattern Pattern to write
Write Flux Not used in current version
Write excitations If checked, the write element will be excited within each sector's write gate. Default = On
Allow Offtrack measurements Currently unavailable. Will be supported in a future version
BIAS in write operation Switch read BIAS On/Off during write operation. Default = Off
Separate positive/negative pulses Check this box to calculate asymmetry results. If not checked, the value in the WITE Control|system|Peak type = {Both|Positive|Negative} menu will be used.

The SAA stability test returns several results reflecting the amplitude range, stability and optionally asymmetry.

DEFINITIONS
pSAA[i] Positive sector average amplitude for the ith iteration
nSAA[i] Negative sector average amplitude for the ith iteration
SAA[i] pSAA[i] + nSAA[i]
SAAasym[i] |pSAA[i] - nSAA[i]| / ( pSAA[i]+nSAA[i])*100


RESULTS
SAAStb StdDev(SAA[i])/Average(SAA[i])
SAARange 1 - Min(SAA[i])/Average(SAA[i])
SAAAsymStb StdDev(SAAasym[i])/Average(SAAasym[i]) [optional]
SAAAsymStdDev StdDev(SAAasym[i]) [optional]
SAAAsymRange Max(SAAasym[i]) - Min(SAAasym[i]) [optional]

Note that SAAasym[i], SAAAsymStb, SAAAsymStdDev, and SAAAsymRange will be calculated only if the "Separate Positive/Negative pulse" checkbox is checked or the Control|system|Peak type menu is set to both.

Triple-Track test in 747 module

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A new test, Triple-track, has been added to the 747 module and is available, providing you have installed the 747 module, at Tests | 747 Tests | Triple-Track. This test performs track profile-type operations to measure the degree to which adjacently written and erased signals interfere with one another.

Triple-track test algorithm

The Triple-track test measures write width, read width, write-to-read (WR) offset, squash, squeeze and OTRC parameters of the written signal.

The following is the algorithm of the Triple-Track test:

  1. Perform Band Erase if preconditioning is enabled.
  2. Write the data track using data track settings (see below).
  3. Measure track profile according to the range and step parameters.
  4. Save maximum TAA value (MaxTAA).
  5. Build two interpolation lines according to the Interpolation range settings.
  6. Measure the distance between the interpolation lines at the 50% threshold and report it as Write Width.
  7. Measure the distance between the interpolation lines at 0% threshold (floor level), subtract the Write Width and report the result as Read Width.
  8. Measure the distance between the center of the track (Zero offset) and the center of the Write Width, and report it as WR offset.
  9. Write two adjacent tracks at the squeeze position (see below) of each side of the data track. Please note that if pattern or flux is used as the adjacent track signal, the bandpass (overwrite) filter should be used for the test.
  10. Return to the point at which TAA was previously measured as maximum and remeasure TAA (TAAsquash).
  11. Calculate the SQUASH result as the ratio of TAAsquash to MaxTAA:
    SQUASH= TAAsquash / MaxTAA
  12. Measure SQUEEZE as the difference between the Squeeze position and one half of the track width at 0% threshold (floor level).
  13. Write two data tracks on each side of the previously written signal, at a distance from the original track of Write Width * Side Track position / 100
  14. Return to the central track and write an Adjacent signal.
  15. Build a track profile according to the range and step parameters.
  16. Build two interpolation lines on internal slopes of the resulting profile.
  17. Measure the distance between these two interpolation lines at 0% threshold and report half this difference as OTRC.

Triple-track test configuration

To configure the Triple-track test, select Tests | 747 Tests | Triple-Track from the dashboard. This is the configuration dialog box:

 

The Test Options Frame configures how the test will be performed.
Iterations Specifies the number of TAA measurements at each offset point
Preconditioning Selects preconditioning to be used before the test
None: No preconditioning.
Band Erase Positive: Erase with positive DC.
Band Erase Negative: Erase with negative DC.

NOTE: If either band erase option is selected, six tracks will be erased on each side of the data track. The distance between erasing tracks is 1/3 of the track pitch specified for the product.
Filter Specifies the filter to read the signal through.
Freeze Attenuator Gain Enables/disables attenuator gain adjustment during TAA measurements. If Freeze Attenuator Gain is enabled, then gain will be adjusted only once on the maximum signal at the beginning of the test.
Use fast offset When enabled, the test will operate more quickly. This should be kept enabled unless you encounter problems.
Plot Data Enable/disable graphical output on the screen.
Program WR Offset If enabled, the measured WR offset value will be saved in the system and used by all subsequent tests when switching between reading and writing. If disabled, the WR Offset value will be reported in result table, but not used by other tests.
The Data Track frame specifies data signal options.
Pattern Pattern used for writing during the test.
Flux Flux frequency to write during the test.
Overwrite frequency Similar to the Flux option, but rather then writing a user specified frequency, the test will automatically select the frequency corresponding to the central frequency of the overwrite filter selected for the current zone/setup.
The Adjacent Track frame specifies adjacent signal options.
Pattern Pattern used for writing the adjacent track.
Flux Flux frequency to write the adjacent track.
DC Erase positive Erases the track with a positive DC signal.
DC Erase negative Erases the track with a negative DC signal.
The Track Profile range frame specifies the profiling parameters.
From Starting offset of track profile. The absolute value cannot exceed the maximum offset.
To Ending offset of track profile. The absolute value cannot exceed the maximum offset.
Step The step by which the head is moved between TAA measurements to build the track profile. This value cannot be smaller then the device step.
Device Step The size of the smallest movement (microstep) of which the device is capable. This value is provided for reference only.
Max. Offset The maximum offset of which the spinstand is capable. This value is provided for reference only.
The Normalization frame specifies the TAA normalization options.
Normalize Enable/disable the normalization of the TAA profile on the plot. If disabled, the plot will show the measured TAA values. If enabled the TAA axis on the plot will be normalized to the range from Minimum to Maximum.
Minimum The value that will be assigned to the minimum measured TAA (if normalization is enabled).
Maximum The value that will be assigned to the maximum measured TAA (if normalization is enabled).
The Track Interference frame specifies the squeeze distance and the distance between the data track and side track.
Squeeze position The distance between the data track and squeezing tracks (in microInch)
Side Track position The distance between the data track and side track. This distance is specified as a percentage of the Write Width as measured on an unsqueezed track.
The Interpolation range frame specifies interpolation parameters.
Minimum Lower threshold for interpolation.
Maximum Upper threshold for interpolation.
Best Fit Window If disabled, the full range from Minimum to Maximum will be used to build the interpolation line. If enabled, a sliding window of the specified size will be moved between the Minimum and Maximum thresholds and the window with the best correlation coefficient will be used to build the interpolation line.

Triple-track test output example

Triple-track test result processor output:

 

If the plot data option is enabled, graphical output will be displayed:

Support for systems without a VFO board

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WITE 1.6 provides support for RWA systems without a VFO board, as a cost reduction for customers using only PRML-based testing. The following tests cannot be run without a VFO board:

  • Bitshift rate
  • Comparator in "peak detection" mode
  • Comparator error rate in "peak detection" mode

Also, any user-written tests that use peak detection mode will be unable to function in systems without a VFO board.

MR impedance screening enhancement

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In WITE 1.5, an HSA MR impedance screening test was added. In 1.6, this test can be used for HGA testing as well. This test measures the impedance of each head, without starting the spinstand, before starting a production. This is not a gradable test, but is intended as a quick check to ensure that all heads are properly connected and at least minimally functional before beginning production testing. It is enabled by the HSA MR Impedance Test checkbox on the Head S/N tab of the production setup form.

Improved UP7 support

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WITE 1.6 includes many enhancements to the completeness of the UP7 support and the accuracy of measurements made with the UP7.

The gain menu in Control | Gain contains several enhancements specific to UP7:

 

Support for new head amplifiers and head stacks

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WITE 1.6 supports the following new head amplifiers:

  • RRVM620212
  • VM6182
  • 321607AR
  • 321608R
  • 32R1901R

WITE 1.6 supports the following new head stacks:

  • VM6182
  • 32R1606R
  • 32R1607AR
  • HSA_32R1608

Bugs Fixed in WITE 1.6

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When custom fields were defined for production, values could be entered but they were not included in the output. In WITE 1.6, these custom fields and their values are correctly included in the output.

The spectral elimination test incorrectly created a separate line of output in production mode. In WITE 1.6, the spectral elimination results are included in the same line with the other appropriate results.

An incorrect "ambiguous write" message could appear when the alternative spectral elimination test was run. This message does not appear in WITE 1.6.

Known bugs in WITE 1.6

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Some bugs were found too late to be fixed for the 1.6 release and will be fixed in a later release. This section contains all known bugs that you are likely to encounter. A bug’s presence here means that we are aware of the problem and actively working to solve it. If you encounter a problem not on this list, please report it to Guzik customer support.

When upgrading from WITE 1.45 to WITE 1.6 on a system with a Coldfire spinstand, the spinstand must be in IPL mode to load the new spinstand code. If the spinstand is not in IPL mode, then you will see the error message "Driver installation error 4005: SPN 2021: (PRGR) Instruction Error." When this occurs, quit WITE, press the red button to place the spinstand in IPL mode, and re-run WITE. Press the "OK" button when informed that the spinstand is in IPL mode. This error is contained in the Coldfire spinstand code included with WITE 1.45, but manifests itself when upgrading. It does not affect upgrading from versions of WITE other than 1.45.

The MR impedance pre-test screening procedure is incompatible with some head stacks. We recommend that you qualify the screening procedure with your particular head stack model before using this screening procedure in a production environment.

After changing the product alignment parameters in WDCP (track pitch, number of tracks, etc.) WITE won’t use the updated parameter values until the current product is reloaded.

The "retest with next setup" option in the "Production | Grd/Norm" menu does not register results to the database after the first setup. It should not be used.

Some DOS applications interfere with communication with Guzik hardware and can result in unstable test results. Please exit all DOS applications before running WITE.

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