Data-acquisition box adds voice annotation, real-time DSP
By Dan Strassberg -- EDN, April 24, 2003
When deciding which features to include in its test-and-measurement products, Yokogawa Corp marches to the beat of a different drummer. Nowhere is this characteristic more obvious than in the company's DL750 ScopeCorder portable data-acquisition unit (Picture). Although it resembles an oscilloscope, in return for 5-MHz-maximum bandwidth, it offers 16 analog and 16 digital channels and many more signal-conditioning options—some with transducer excitation. It also offers resolution to 16 bits, and—with most input modules—inputs that are ohmically isolated from the chassis.
Unlike competitors, the DL750's designers seem unconcerned that adding features can impair usability. Purchasers may initially find the multitude of capabilities a bit daunting, but users who learn how to access needed features often find the results so rewarding that they become evangelists for the product. The latest version of the DL750 sells for $5600, not including input modules, which add approximately $1000 for each analog-channel pair. The new version also offers several new capabilities, of which two—Voice Memo and Real-Time DSP—are especially noteworthy.
Voice Memo, which is now a standard feature of the DL750 mainframe and which the company can retrofit at no charge to existing units, addresses a need that most instrument users understand all too well. When you take measurements, you must record a host of information about the test conditions. Traditionally, you would place this information in an old-fashioned paper notebook. In the heat of the battle, however, finding time to write everything down can become a problem, and with computer-based instruments, the notebook is too easily separated from the data files. If your data-acquisition unit includes a CPU that runs general-purpose software, taking notes with a word processor keeps the notes and the data on the same hard drive, but it doesn't make note-taking any easier, and the different applications still keep the notes and the data in separate files. Voice Memo solves many of these problems, and Yokogawa gives you several ways to use it. You can make running commentaries on slow data, which the unit displays in a "roll mode" that emulates a strip chart scrolling off the left side of the screen as new data appears on the right, or you can annotate screen captures of faster data. In both cases, the unit links the graphics file to the voice file, which can be as long as 100 sec.
Like Voice Memo, Real-Time DSP resides in the DL750 mainframe. Unlike Voice Memo, however, the real-time capability is an extra-cost ($1050) option. Although the unit's main processor can perform many of the same calculations after the instrument has acquired the data, Real-Time DSP enables the instrument to process the data as it is acquired. For example, units equipped with the option can add, subtract, integrate, differentiate, filter, or compute FFTs and display the results while acquisition continues.
Yokogawa Corp of America, 1-800-258-2552, www.us.yokogawa.com.
