Preface

As the performance criteria for each successive generation of hard disk drives become more stringent, the test equipment used in disk drive design must keep pace. This applications booklet describes the use of two essential tools--the arbitrary waveform generator and the digitizing oscilloscope--in solving some of the most demanding disk test problems encountered today.

Arbitrary waveform generators (AWGs), with their ability to create almost any waveform imaginable, have become an indispensable design and test tool in the engineer's kit. The Tektronix 2000 Series AWGs are especially well-equipped to deal with the unique problems encountered in disk drive testing. In particular, the AWG 2041 provides the clock rate and record length needed for the most advanced rotating media testing requirements.

 

The 2000 Series products offer much more than just raw performance. Each of the three AWG models in the series--the AWG 2041, the AWG 2021, and the AWG 2005--has a powerful graphical user interface built in. Their screen-based control panels are coupled to soft keys that access such functions as range and mode selection, display format, and marker placement. Scrolling, cut/paste selection, cursor position, and file selection are controlled by a continuous knob on the instrument's front panel. Every pertinent function, status, and value is available on the screen, only a menu away.

Another important facet of the 2000 Series is its wide range of waveform editing tools. Most conventional AWGs require an external computer and software for complex waveform editing. Others provide only simple front panel tools, like keypad formula entry. In contrast, the 2000 Series includes seven built-in ways to edit, as well as compatibility with Tek's powerful WaveWriter software for external computers. Several of these integrated waveform tools are especially useful for disk drive testing: the graphical editor, the FFT editor, the equation editor (ideal for producing Lorentzian pulse waveforms), and the sequence editor. Each of these functions is discussed in detail in this booklet. Also of interest is the 2000 Series direct DSO transfer capability, which permits waveforms acquired from a reference source (such as a known-good UUT) to be loaded into the AWG and reproduced.

The TDS 744A digitizing oscilloscope is the perfect complement for the AWG 2041 in disk drive applications. The TDS 744A's record length of up to 500k is eminently suited for storing multiple waveform cycles. The scope's 2 GS/s sample rate and peak detect capability help isolate the tiny glitches and view fast signal edges. And of course, the TDS 744A offers direct waveform transfer compatibility with the 2000 Series AWGs.

The test problems described here are "real world" examples that reflect today's concerns among designers and manufacturers of high-speed, high-capacity hard disk drives. The solutions, though, are also useful for a host of design verification applications for products ranging from cellular telephones to biomedical monitors.