DTR 3000 Discrete Track Recording Test System

DTR 3000 System Overview

The Guzik DTR Test System belongs to a new generation of Guzik test systems designed for R&D and Production of Discrete Track Recording components. Every component of the DTR Test System has been re-designed from the ground up to provide the critical measurement capability needed to address the emerging need for Discrete Track Recording measurements. The system features up to 4 Gbit/s write channel, up to 6 GHz read channel connected to 20 GS/s waveform digitizer, a highly stable spinstand platform designed for recording densities beyond 700kTPI, and a state of the art programmable drive servo decoder for DTR and conventional media.

Measurement requirements are complex for this new emerging technology, and Guzik has fully integrated all required system components to provide a complete test system for head and media testing applications.

Product Highlights

• Digital Decoder for Drive Servo with Programmable Parameters
• Amplitude and Phase Servo Decoding
• Servo Signal Analog bandwidth up to 250 MHz 1
• Automatic Media Centering Mechanism (2) to Mechanically Align Media to Reduce Track Eccentricity below 800 nm within 20–30 seconds (typical)
• Track Following with residual RRO better than 5-7 nm 3
• High-bandwidth Servo Loop with typical 0.2–0.6 nm NRRO 3, 1σ
• Full Range of WITE32 Tests, including Parametric, 747, ATI, BER, etc
• Digital Media Scan Test (Digital MSCAN) 4
• Full compatibility with existing custom WDK modules
• System Supports both DTR Media and Conventional Continuous Media
• System Supports both Drive Servo and Guzik Servo

1. All specifications are subject to change without notice
2. US Patent Pending
3. Performance may depend on the actual product (head and media combination)
4. Optional test module

The Guzik DTR Test System bundles all critical components required for DTR testing. In addition to our WITE32 Test Environment software, the DTR 3000 consists of:

1. RWA DTR 3000 Series Read-Write Analyzer.
2. Spinstand DTR 3000 with Media Centering System and Piezo Actuator Cartridge.
3. WDM5000 Series Waveform Digitizer.

 

Block Diagram of DTR 3000 System

 

DTR 3000 Spinstand

The Guzik DTR 3000 spinstand includes a media centering system. When a disc with pre-printed servo information is mounted on a spinstand, the servo and data tracks can have eccentricity up to 50–100 micro-meters in respect to the spin axis. The media centering system mechanically aligns the disk to reduce track eccentricity below 800nm. The process is completely automated and typically takes less than 30 seconds.

 

Centering of the Media to Reduce Track Eccentricity

Track Eccentricity before Media Alignment (RRO 80,000 nm)

Track Eccentricity after Media Alignment (RRO 350 nm)

Next, the piezo actuator cartridge further reduces the repeatable run-out below 5-7 nm using a high bandwidth servo loop combined with a servo feed-forward approach.

Track Eccentricity in Track Follow Mode with Servo (RRO 5 nm)

This combination of precision track centering, a high stability air bearing spindle, and a high bandwidth servo loop are the crucial components that allow for high-TPI DTR testing.

Position Error Signal (PES)

Micro-positioning in Servo and Non-Servo Modes

Guzik DTR 3000 spinstand can use one of the two following modes for the head positioning:

• Non-servo mode, when the actuation is done by the piezo element with feedback from the glass linear scale.
• Embedded servo mode, when the actuation is performed by the piezo element, with feedback from the servo bursts written on the same track with the data signal.  These bursts are located at the beginning of every sector.  Guzik DTR 3000 spinstand supports sector sampling rates up to 50 kHz (20 µs).

Using the servo mode assures high positioning repeatability.  The head suspension and some spinstand parts expand when temperature changes during measurements.  The embedded servo eliminates the positioning errors caused by this thermal expansion.  The spinstand in the servo mode also suppresses low-frequency vibrations transmitted from the floor.

The track profile repeatability observed on the Guzik DTR 3000 spinstand in servo mode is 0.6 – 1.0 nm (0.024 – 0.039 µInch).  The typical non-repeatable runout (NRRO), measured as 1 s of the Position Error Signal (PES) from the embedded servo, is 0.2 – 0.6 nm (0.008 – 0.024 µInch).  Repeatability and NRRO significantly depend upon the particular head and media used but are consistent for the same head type.  The data above was obtained using a 7200 RPM product.

Advanced Linear Scale Interpolator

Guzik DTR 3000 spinstand features an advanced linear scale interpolator developed by Guzik Technical Enterprises.  The spinstand with 2 µm period glass scales and the interpolator has measurement accuracy of ±0.3 nm (±0.012 µInch).

Key Features

Guzik DTR 3000 spinstand performs software controlled alignment for each tested head.  The alignment procedure takes one second and measures the position of the disk center with accuracy 80 µInch (2 µm). The results can be improved by averaging.  The procedure increases the accuracy of track and skew angle positioning.  As a result, Guzik DTR 3000 spinstand achieves higher accuracy of WROffset, Writer Width, and Reader Width measurements.
There are no head amplifier boards on the cartridges for Head Loading Mechanism HLM-3000.  The new cartridge design has only a small board integrated with a head connector.  The head amplifier boards are removed from the cartridges and installed on the swinging platforms of HLM-3000 without sacrificing electrical performance.

Guzik DTR 3000 spinstand can be used for head (HGA, HAA) testing and, after mechanical conversion, for headstack (HSA) testing.  Guzik Technical Enterprises offers tooling for specific HGA, HAA, and HSA designs.

Crash-Proof Design

Guzik DTR 3000 is a crash-proof spinstand due to the new patented design of the Head Loading Mechanism HLM-3000.  The arms of the V-shaped HLM-3000 are rotated 45 degrees in respect to the X and Y coordinate axes of the spinstand.  Such geometrical configuration and the mechanical limit on the movement along the Y axis set the working area over the lower quadrant of a media (see Figure 1).  This prevents the cartridge from the collision into the spindle/media when the mechanical parameters of the spinstand or the head geometry are specified incorrectly in the software.

 

Working Area of HLM-3000

Performance Measurements

The Track Profile Plot on Figure 2 demonstrates typical 0.6 – 1.0 nm / 0.024 – 0.039 Inch positioning repeatability of the Guzik DTR 3000 spinstand.  Signal was written on the track and the amplitude of the read signal was measured at 5 nm / 0.2 Inch increments across the track.  The measurements were repeated 50 times in forward direction, and 50 times in backward direction.

Normalized Track Profile Plot (50 Runs Forward + 50 Runs Backward)

The figures below demonstrate Position Error Signal (PES) measured on DTR 3000 spinstand. Position error signal is derived from servo bursts written on the media in every sector. Each sector delivers one position error value, expressed in nano-meters. PES was captured for 800 consecutive revolutions and plotted in time shown below. The standard deviation (one sigma) of PES data in every sector characterizes the non-repeatable runout (NRRO) of the head. The NRRO value shown on the plots below is 0.2 – 0.6 nm (0.008 – 0.024 µInch), measured at 7200 RPM with Piezo-Actuator Cartridge.

Position Error Signal at ID

Position Error Signal at OD

 

RWA DTR 3000 Series

The new generation of Guzik Read-Write Analyzers includes the RWA DTR 3002, RWA DTR 3003, and RWA DTR 3004. These analyzers feature dual servo channel that are capable of decoding both Guzik Servo and Drive Servo.
Servo decoding is performed by the programmable digital decoder. You can choose between Amplitude Servo mode and Phase Servo mode. You can also specify parameters of the servo pattern, such as clock frequency, preamble length, number and configuration of the servo bursts, etc.

The decoder uses a programmable digital signal processor instead of being based on a PRML chip. This provides media design teams with the flexibility to experiment with various configurations of servo patterns without waiting for a new revision of a PRML chip.

 

The WDM 5044 Waveform Digitizer is a critical component of the complete DTR 3000 Test System, which provides the following key features not available with a traditional peak detector approach:

• Accurate digital measurements with 1% accuracy for heads with signal-to-noise ratio down to 12dB
• Digital media scanning (Digital MSCAN Test, optional purchase)
• Test servo area
• Jitter and Eye Diagram measurements
• Nano-scale magnetic field imaging (3D Pulse Profile Test)
• Capture read-back signal waveforms around a defect area

The software for WDM 5000 Series includes the following tests and measurements:

• Digital Parametric Measurements
• Digital Media Scanning
• Jitter and Eye Diagram Measurements
• 3D Pulse Profile Test for Magnetic Field Imaging
• Fast Spectral Measurements

Digital Media Scan Test (MSCAN)

Magnetic Field Image of Servo Area Captured with WDM5000 Series

DTR Software Modules and Tests

In addition to the full range of standard WITE32 tests, Guzik offers the following tests specifically designed for DTR application:

• Media Alignment Test
• Servo Distortion Test
• Servo Track Pitch Calibration Test
• Sector Selection Test
• Servo Burst Amplitude and Phase Analysis
• PES Test with Invalid Servo Sector detection

Guzik is currently working on the following additional DTR tests:

• Servo Area scanner for Digital MSCAN test
• Servo Defect Waveform Capturing
• Servo Linearity Test

Standard Tests Included with DTR System Purchase

 

Specifications

 

Air Bearing Spindle
	Motor	Brushless DC, programmable 100 RPM – 20,000 RPM
	Interchangeable Spindle Chucks	0.85", 1.0", 1.8", 2.5", and 3.0”/3.5" available Vacuum version and screw clamping version
	RPM Jitter	0.005% typical
	Acceleration	0 – 10,000 RPM in approximately 2.4 seconds with 3.5" disk mounted
	Balancing	Included as standard
	Shroud	Included as standard (two options: automated for media testing or for HGA testing)
Coarse Positioning Mechanism
	Actuator Type	X and Y linear motors
	Movement Type	Simultaneous dependent XY trajectory movement
	Skew Angle Control	Software controlled skew angles
Micro-Positioning Mechanism
	Actuator Type	Piezo element
	Micro-Positioning Encoder Type	Heidenhain glass scale encoder and embedded servo
	Drive Servo	supports Drive Servo for DTR testing
	Guzik Servo	supports Guzik Servo Revision 3 and Revision 4
	Local Micro-Positioning Accuracy of Glass Scale within Piezo Range	±0.3nm (±0.012 µInch)
	Position Repeatability	0.6 – 1.0 nm / 0.024 – 0.039 µInch typical, measured as maximum deviation of the track profile slope in servo mode (measured at 7200 RPM)
	Non-Repeatable Runout	0.2 – 0.6 nm / 0.008 – 0.024 µInch typical, 1 s (measured at 7200 RPM with Piezo-Actuator Cartridge)
	Hysteresis	Closed loop system, no hysteresis

Head Loading Mechanism
	HGA, HAA, and HSA tooling
	Tooling can be designed to custom specifications
Spinstand Electronics
	Separate Control Box and Spinstand Frame for electrical and mechanical noise reduction
	Control Box Type: SCB DTR 3000 control box
	Connection to PC: USB interface
Physical
	Spinstand Size:  32" x 19" x 17",
	Spinstand Weight:   256 lbs
	Control Box Size:   18" x 18" x 8"
	Control Box Weight:  36 lbs

Operational
	Environmental	15 C to 40 C, 90% maximum relative humidity, with no condensation, clean room environment
	Power Supply	110 VAC 15% 50/60 Hz, 3 A approximately 230 VAC 15% 50/60 Hz, 2 A approximately
	Air Supply	90 PSI minimum, clean dry air
	Air Consumption	1.6 scfm mass airflow, typical with vacuum chuck

* Specifications are subject to change without notice

Documentation

The following documentation is available for the DTR 3000 Discrete Track Recording Test System. Return often for new and updated documents.

 

Photos and Videos

Overview of Media Centering Mechanism

Accessories

Optional Purchase Tests

 

Digital MSCAN – Media Scanning

• Missing Pulse Detection
• Super Pulse Detection
• Transition Shift Detection
• Thermal Asperity Detection (written signal)
• Thermal Asperity Detection (erased track)

WESA – Write Excited Sectored Amplitude Test Module

• Separate Amplitude Asymmetry Stability
• Triple Amplitude Asymmetry Stability
• Write Induced Instability
• Pole Erasure

WATI – Adjacent Track Interference Test Module

• Adjacent Track Interference Test
• Adjacent Track Interference Multi-Track Test (WATI MT)

Bit Error Rate (BER) Test Module

• BER 747A Test
• BER Linear Density Test
• BER Error Distribution Test
• BER Performance Test

Micro-Actuator Test Module

• Stroke Test
• Mechanical Frequency Response Test
• Micro-Actuator Loop Setup Test
• Micro-Actuator Loop Frequency Response Test

Perpendicular Parametric Test Module

• Differentiator Optimization
• Roll-off
• Rise and Fall Time
• Saturation Asymmetry
• Amplitude Asymmetry

 

Pricing

System	Pricing
DTR 3004 4 Gbit/sec Discrete Track Recording Test System	Call
DTR 3003 3 Gbit/sec Discrete Track Recording Test System	Call
DTR 3002 2 Gbit/sec Discrete Track Recording Test System	Call