Handheld instruments were traditionally meant for field applications, but these are now being used in the research and development sector as a complementary product to existing benchtop instruments. A handheld device weighs less, is rugged, relatively easy to use, and can reduce your initial expense, maintenance cost and storage space. Majority of the benchtop functions are now available in the portable form, without compromising much on accuracy and precision, which is the icing on the cake.
Before going into how to select the best handheld for a particular application, one has to understand if a handheld device is required at all.
Do I need a handheld
We differentiate handhelds from benchtops primarily based on size, portability, accuracy, features, ease-of-use, cost and ruggedness. If a light-weight, low-cost, small form factor, rugged instrument with a simple user interface (UI) is what you are looking for, and if the measurement to be taken need not be the most accurate, then you can go for a handheld device. These provide better cost performance.
With traditional instruments the only way to reduce cost was to compromise on quality, that is, use cheaper components. However, with software-defined instruments, it is possible to reduce the cost and size without compromising on quality of measurements. This is one of the reasons why handheld instruments these days are not limited to field usage; these are being used in research and development labs too.
In the field. Portable instruments are mainly used by engineers or technicians in field scenarios for installation, maintenance and monitoring application of systems. This does not generally require the most advanced functionalities or the most precise readings. What is needed is a handy, light-weight, battery-operated device that has the basic capabilities (sometimes a few advanced capabilities too), a good battery back-up and is easy to use.
In the labs. People in the labs use not only benchtops but also handheld instruments due to a variety of reasons. One is the commercial aspect. The price of the handheld is usually much lower than its benchtop counterpart. Next is the space constraint. If you stack benchtops, these will take up huge rack space, whereas the same functionalities integrated into a single portable instrument occupies much lesser space. Some of the lab-testing scenarios may require the portability feature, and handhelds would be useful there. But you also have to look at the performance of the device when it comes to lab tests, whether parameters of the device matches your test requirements. There are cases in lab where you do not require performing in-depth testing—this is where portable instruments come in.
What to consider
Here are a few attributes to look for when purchasing a new handheld device for your application.
Form factor and portability. This is the most important factor to be considered while selecting a handheld device. If the instrument is to be carried around all the time, customers prefer maximum number of functions integrated into a single system with smallest form factor. Some examples are Tektronix RSA306 spectrum analyser that weighs about 0.59kg and has a dimension of just 30.5×190.5x127mm, and R&S FSH series spectrum analysers that have a size of only about 194×300×144mm and weigh 2.5kg.
Simple UI. People who use handhelds in fields are usually not research and development engineers. Mostly field engineers and technicians use such devices and their expertise is different. They prefer instruments that perform test and measurement in very few set-ups. According to a survey by Frost & Sullivan, “Engineers are increasingly associating the concept of a UI and user experience with the one they use on their consumer electronics devices.” This means that users expect touch based UIs that respond to gestures like pinch-zoom, tap, etc. So, it is best to buy a device that has a very simple and intuitive UI.
Application-specific integration. One of the major advantages of handheld instruments is that these combine more than one test-and-measurement instruments into a single portable device. But the challenge is to make a simple UI that has the controls and displays for all instruments in one place.
Many of the handheld devices introduced in the market these days are application-specific. Almost all instruments required for one type of application, say, cable testing, are integrated into a single box. Network Master Flex/Pro network field tester and BTS Master for base-station testing by Anritsu, and FieldFox RF and microwave analyser series from Keysight are examples. You can also find some of the accessories, such as a calibration kit, built into FieldFox, thus reducing the number of instruments to be carried around.
“Even if the device is not application-specific, it is possible for the modern graphic capabilities of frameworks like Windows Presentation Foundation (WPF) to build visually-stunning and extremely-intuitive GUI that combines all instruments into a single window,” says Chinmay Misra of NI.
Modes of operation. In case you have to work on multiple projects, go for a platform that supports other applications as well. Suppose the application the user is currently working on requires a cable tester and spectrum analyser. But after a few months, they get a new application that may require a power meter and data-network analyser. So, instead of buying a separate handheld for the new application, the user can get a software upgrade to the existing instrument, which lets him or her use the power meter and data-network analyser features. There is no calibration or hardware change required as a fully-capable hardware is directly given to the user initially.
Battery life. All portable devices need not be battery-operated. Deeper integration of multiple capabilities and high-speed digital technologies in a single device calls for outstanding battery back-up, and the development of such long-lasting battery technologies is being driven by the cellular industry.
Display. For field scenarios, wide, anti-reflective displays with day and night modes of operation are available these days. Another improved feature to enhance user experience is the additional touch-enabled screen control. Software-defined instruments also let you move the UI and display to post-PC devices, like smartphones and tabs. This provides superior display capabilities, gesture recognition and much more.
For harsh environments. Some models have increased safety, protection, durability and ruggedness, thereby making these ideal for use in harsh environmental conditions without compromising on performance, especially for aerospace and defence applications. Depending on the possible operating environment of the device, you might want to check if it has passed dust protection, liquid-ingression protection, explosion protection and mechanical impact-resistance tests.
Interfacing with other devices/programs. Another safety aspect is to separate the UI and display from the instrument by remote-controlling the device using a desktop, laptop, tablet or smartphone. This enhances portability and lets you take measurements in conditions unfavourable for humans without actually being present there. Devices like Anritsu’s Network Master series and Keysight’s FieldFox series have these features. Tektronix’s RSA306 also has an open API, which allows customers to use their own custom Windows based interface, such as MATLAB or Python, to manipulate raw data coming from the instrument. Rohde & Schwarz FSH spectrum analyser comes with interference-analysis application software (FSH-K15) that makes interference hunting easier.
The author is a dancer, karaoke aficionado, and a technical correspondent at EFY. Find her on Twitter @AnuBomb.