Everything for Electronics
Posted in: Developing Perspectives (August 2011)

Virtual Portable Instruments

By Bryan Bergeron

Virtual instruments aren’t perfect, however. They usually tie you to a desk or desktop, and the interface boxes and cables running to a laptop can be difficult to keep straight. In addition, in most cases you can’t run multiple instruments simultaneously. For example, you can run either a virtual oscilloscope or virtual DMM, but not both at the same time.
Enter the smart phone and tablet computers. Companies are now introducing virtual instruments that convert your phone or tablet into an oscilloscope or other virtual instrument. I’ve been working with the iMSO-104 — an oscilloscope for the iPhone/iTouch/iPad by Oscium ([url=http://www.oscium.com]http://www.oscium.com[/url]). The $298 scope consists of a small interface that plugs in directly to the connector port on the i-device and software from the AppStore. You supply the iPad.

Specs for the 5 MHz/12 MSPS (million samples per second) scope fit squarely in the hobbyist market, with one analog and four digital channels. In other words, it’s a nice scope if you’re working with audio, digital, or analog servos and the like. However, if you’re working on a high speed digital circuit or RF communications circuit, you’re out of luck. Still, I expect specifications to improve and the price to drop with time and competition.

An alternative to virtual instruments is ultra-portable dedicated instruments, such as the DSO-NANO DSONV-11 pocket oscilloscope. I picked up this $89, single channel digital storage scope from Seeed Studio ([url=http://www.seeedstudio.com]http://www.seeedstudio.com[/url]) about a year ago. I have to admit that I’ve only used the cell phone-sized unit a handful of times, in part because I seldom have the 1 MHz scope with me, and in part because it takes me a few minutes to figure out the interface every time I turn it on. The current model apparently provides an updated interface that’s easier to use. There’s also a four-channel version available for $200.

The potential advantage of a library of virtual instruments that abide by a single user interface guideline – say Android or iPad – is that any instrument is easy to pick up and use without wasting time to remember or learn the interface. Given the relatively lax standards for Android apps, this standardization may appear first on the iPad. At this point, it’s too early to tell.

While using my Oscium oscilloscope, I discovered another issue with virtual portable instruments – sometimes you need the supporting tablet or phone for something else. On a stand-alone instrument, you’re not likely to be interrupted by a phone call or a signal that you’ve got mail. Moreover, you can easily answer your smart phone while working on a circuit. Not so if everything sits in your cell phone. I’m sure someone will think of a work-around.

Given the falling price of computer-based instruments in general, dedicated instruments may go the way of the DMM – that is, nearly disposable. DMMs are so inexpensive these days that you can dedicate one to, say, your power supply project. It’s nearly the same with pocket oscilloscopes. At $89, it’s almost economical to permanently affix a DSO-NANO scope to your audio amp or other device, versus building a separate audio level monitor circuit and display.

One thing is certain. The days of a hobbyist’s workbench loaded with large, dedicated boxes of instruments are numbered. Economics, limited space, and technology are driving companies to offer instruments that leverage the processing power and displays of increasingly powerful phones and tablets. NV