While today’s technology offers solutions for monitoring or remote reporting via mobile devices, test organisations need new expertise to unite the networking, Web services and mobile app portions of the solution
MARCH 2012: Testing plays a critical role from the very beginning of the product life-cycle, i.e., the design stage. Be it any technology or any product, unless and until it is validated and tested, it cannot be manufactured and produced for the market.
Test engineers need to measure the parameters of the signals with a high degree of accuracy and performance. Today, circuits are packed in compact assemblies and affected by a lot of interference, noise and unwanted signals. This, in turn, affects the measurements. Instruments are being designed to measure such signal levels. The measurement data also needs to be analysed. To enable this, PC connectivity has become a common feature on general-purpose test instruments.
T&M needs across different segments are broadly common. But deep-down, there are different levels of testing and different-grade T&M products being used.
Requirements across segments
Within education, where test and measurement is mainly meant for teaching or research purpose, there is quite a significant difference between two sub-segments. In undergraduate labs, basic or mid-range instruments such as digital multimeters, power supplies, oscilloscopes and function generators are mainly used to do some basic measurements and learn different aspects of testing. But in research work, high-end scopes, spectrum analysers, network analysers and vector signal generators are used in such areas as high-energy physics, nanotechnology, millimeter-wave and UWB.
In aerospace and defence, high-bandwidth, high-frequency T&M instruments are being used for state-of-the-art electronic systems such as RADAR, satellite and surveillance. Shortening the product development cycle has long been a key objective of military and aerospace organisations. One method to reduce the development time is concurrent design and test, which is often represented with the V-diagram product development model. In these industries, for which the end product is a highly complex ‘system of systems,’ the left side of the V-diagram is considered ‘design’ and the right side represents ‘test.’
Defence communication systems have traditionally been analogue in nature. However, digital technologies are replacing the traditional analogue communication systems. To successfully implement the digital systems, one needs to analyse the technology manifestations in different environments. Software-defined and modular test systems can be used to meet these requirements.
Catering to each technology, there may be various testing needs. For instance, in communication one may have to check the signal frequency, power, harmonics, etc, while in automotive one may have to do different levels of stress testing, torque testing, pressure testing, etc.
As wireless communication continues to grow, the pressure to find innovative ways to more effectively use channel bandwidth is increasing. One of the most recent innovations is the development of multiple-input multiple-output (MIMO) antennae systems to improve the signal-to-noise ratio and increase the throughput. Accurate testing of MIMO transceivers presents significant challenges to existing test instrumentation architectures. New architectures like hybrid PXI or benchtop instrumentation enable not only advanced signal processing algorithms to multiplex and de-multiplex various spatial streams but also tight synchronisation between transmit and receive antennae.
In general, T&M users are increasingly demanding the best possible measurement and source accuracy, noise, signal response, and system throughput for today’s demanding measurements. With the constant evolution of technology, they expect upgradeable instruments with backward technology support. Also, as data rates increase, there is demand for higher-bandwidth instruments. In the manufacturing domain, fully automated environment test setups are in demand. Similarly, as the communication technologies move from 2G to 3G to 4G, one needs handheld, portable but rugged instruments to deploy base stations and towers.
Users want the T&M instruments to be capable of offering universal connectivity via GPIB, USB, LXI/Ethernet and other interfaces. They increasingly expect T&M products to keep pace with rapid evolutions in desktop, mobile and Internet computing standards, the most recent of which is support for mobile devices like smartphones and tablets. The software that enables all of these advanced capabilities must be simple and easy to understand, use and integrate into human interactive and programmatic applications in the lab and the factory.
Different instruments at a glance
Oscilloscopes by and large have seen most changes over the last couple of years.
“With the availability of high-end technology like digital signal processors and field-programmable gate arrays at low cost, signal acquisition has become pretty fast. This has made it possible to get real-time display on the LCD of a digital oscilloscope, unlike in cathode-ray tube oscilloscopes. With digital oscilloscopes, it is also possible to add advanced features like fast Fourier transform, waveform recorder, data logger, advance triggering and logic channels at a very low cost,” says P. Prabhu, general manager (technical), Scientific Mes-Technik.
Other test instruments like digital multimeters, function generators and frequency counters have also shrinked in size with advanced features. Microcontroller-based designs in these instruments have helped in reducing the number of mechanical switches, thereby improving the product’s performance and life.
With automation for mass and quality product manufacturing, there is increase in the use of measuring instruments in production lines. Sometimes the measurement data needs to be collected and analysed in less than 10 seconds. Multiple data needs to be collected while the product is on the conveyor belt for a very short duration. These challenges are being met with new instruments.
Specifically, general-purpose T&M instruments have witnessed the following changes in terms of technology:
Oscilloscopes. The current generation of oscilloscope is digital storage oscilloscope, digital phosphor oscilloscope, mixed-signal oscilloscope and mixed-domain oscilloscope. Analogue oscilloscopes too have become digital read-out type and offer various connectivity options.
Each type has its own distinct features. Digital storage oscilloscopes provide a high real-time sampling rate and memory depth. Besides, these perform a number of automatic measurements and display results on an LCD screen. With digital technique, they can be remotely operated and become a part of the automatic test setup.
Spectrum analysers. Spectrum analysers are available in frequencies ranging from 1 GHz to several GHz and are capable of a number of power calculations in different units with comparisons. EMI pre-compliance capability, limit lines, improvement in dynamic range and connectivity are some of the technical improvements.
Multimeters. Multimeters today are digital with LCD read-out. Human safety is of prime importance in both handheld and benchtop types. Resolutions up to 6.5, 7.5 and 8.5 digits are available.
New digital multimeter designs are increasingly expected to provide higher levels of precision and stability, as well as more standard built-in functions like capacitance, frequency and temperature measurement. End users are also looking for digital multimeters that can ensure near-universal connectivity and come with simple software drivers, utilities and application-support software.
Digital multimeters are frequently being integrated with switch mainframes to provide more complete test and measurement solutions in a single enclosure.
Keithley’s Series 3700A system switch/multimeter family is one example. “It offers scalable, instrument-grade switching and multi-channel measurement solutions that are optimised for automated testing of electronic products and components. Series 3700A mainframes are equipped with many standard features. For example, easy connectivity is supported with three remote interfaces: LXI/Ethernet, general-purpose interface bus (GPIB), and universal serial bus (USB). Fourteen digital I/O lines are also included, which are programmable,” informs Chuck Cimino, marketing director, Keithley Instruments.
Arbitrary waveform generators. VLSI technology based arbitrary waveform generators offer a number of arbitrary waveforms in the built-in library.
Signal generators. Advancements in signal generator design include more programmable signal control, faster and deeper waveform memories, improved usability and connectivity, and greater throughput and signal performance. Other improvements include the simulation of high-speed serial interface clocks and data layers, as well as LTE modulation evolution.
Power meters. With the growth of the smart grid, line power meters are increasingly required to provide serial communication capabilities, in addition to standard features like flexible connectivity, usability and application-support software. RF power meters must support higher frequencies and more selectivity due to increasingly complex communication modulation standards and tighter regulations on in-band and out-of-band transmitter power qualifications and testing.
The main technological advancements which are applicable to any T&M product are modularity or upgradeability, PC controllability and interconnectivity, application software, ruggedness, high bandwidths, accuracy, repeatability and multiple functionalities in the same instrument.
Also, the emphasis is on intelligent battery charging and power efficiency.
Above all comes the safety of operator and installation. “That’s why the complete range of IDEAL’s industrial clamps is designed with TightSight display. It allows an electrician to keep his head and face out of potentially dangerous panels while viewing the measurement. The high-voltage indicator is another feature that indicates presence of voltage even with the dial set to the wrong function. The clamps carry CAT III and IV ratings, and come in a rugged construction. UL listing adds to safety measures,” says Sushil Tare, sales manager, electrical, Ideal Industries India.
There is a trend to use common development platforms on which a range of instruments can be built. This approach has several advantages for test system manufacturers and, in turn, their customers. It makes it more economical to deliver common interfaces and improved usability benefits. It also helps reduce development cycle times and provides greater economies of scale, which enable more product functionality and features to be offered at lower prices.
“Through shared components, high-speed buses, and open, user-defined software, modular instrumentation is best suited to meet the needs of test and measurement today and in the future. NI modular instruments are the building blocks of economical and versatile automated test systems. With modular instruments, you can choose from a wide variety of measurement, signal generation, RF, power and switch modules and then configure the instruments in software to meet your specific measurement tasks. Because these instruments are modular and software-defined, they are quickly interchanged and easily repurposed to meet evolving test needs. Additionally, NI modular instruments provide high-speed test execution by harnessing the power of industry-standard PC and advanced timing and synchronisation technologies. Options are available for a variety of platforms including PXI, PXI Express, PCI, PCI Express and USB,” informs Nandini Subramanya, senior marketing communications manager, National Instruments India.
With the availability of improved semiconductor devices in smaller sizes, T&M instruments have not only become cost-effective but also smaller in size and better in performance.
“Digital storage oscilloscope is a good example. The MDO 4000 mixed-domain oscilloscope from Tektronix combines digital storage oscilloscope and spectrum analyser functions in a single unit. Scientech’s i-series products, viz, Caddo 831i oscilloscope, 4064i function generator and 4074i programmable power supply, offer digital read-out and Ethernet connectivity,” explains J.K. Baldua, director-technical, Scientech Technologies.
Agilent Technologies works closely with various standards and organisations and helps users with innovative and reliable test products.
Sadaf Arif Siddiqui, technical marketing specialist, Agilent Technologies India, informs, “Be it a basic test instrument or a high-performance instrument, we go hand-in-hand with technological advancements across all segments. A typical example is the upgradeability feature, which is present in our entire range of oscilloscopes, spectrum analysers and network analysers. We have also incorporated some unique features in our products, such as OLEDs in digital multimeters, no fans and no vents in handheld spectrum analysers, and function generator in benchtop oscilloscopes.”
Overcoming the challenges
Production volumes for T&M instruments are generally much lower than for consumer devices like PCs, smartphones and tablet computers. This means that leading-edge features common to these consumer devices, such as capacitive touchscreen interfaces and super-high-resolution colour screens, aren’t as affordable for T&M applications.
T&M instruments need to be designed with industrial-grade components that remain available for many years for design stability reasons. One reason why industrial products are typically a few generations behind consumer devices as far as interfaces and related elements are concerned is the time it takes for displays and other such components to become available for industrial products. Also, the product cycles of typical T&M product designs are much longer than for consumer devices.
Despite challenges related to scale and T&M product longevity and design cycles, a growing number of industrial components suppliers are working to close these gaps. The use of shared product platforms can help raise volumes to interesting levels for individual vendors and through value-added suppliers of such assemblies.
On the signal conditioning front, ongoing advances in semiconductor devices and analogue and RF ICs are helping to push sensitivity, signal range and speeds when used in instrumentation front-ends. Refreshing product designs frequently and, in some cases, using modular design approaches can help enable fresh access to the latest analogue components, as well as displays and user interface technologies.
Processing power for embedded designs also continues to evolve exponentially with specialised DSP and FPGA devices that are constantly increasing in speed. Multi-core processors are now available in industrial and mil-grade versions to allow more sophisticated user interfaces and digital signal processing to be used in medium- and lower-cost instruments.
Doing more in software rather than hardware helps reduce costs and improve functionality and flexibility for users and can also facilitate platform reuse and leverage.
Key trends driving next-generation devices
The global race to achieve useful, intuitive, elegantly integrated products is well underway in the T&M sphere, just as it is in the mobile phone and computing worlds.
Many of the advances in the next generation of instruments will be related to usability and connectivity to support the Internet-friendly generation of users. Though signal performance in T&M will always remain a top priority, human-to-machine and machine-to-machine interfaces will get some much needed attention.
To understand the implications of these interfaces for T&M products and vendors, one needs to just look at the smartphone revolution to see how product innovation and brand leadership in such devices can shift the dynamics of a very large consumer industry in just a few years.
To meet the reduced profit margins due to increased competition, T&M manufacturers will need to innovate and use new technologies of smart mobile devices and cloud computing.
While tablets and smartphones cannot replace ubiquitous PC or PC-based measurement platforms like PXI, they offer unique benefits when used as extensions to a test system. When The Nielsen Company surveyed consumers in 2011 to understand why they were using tablets instead of traditional PCs, the top reasons cited included user experience improvements like superior portability, ease of use, faster startup time and longer battery longevity. Given this information, the expected use cases for mobile devices within automated test include test system monitoring and control and test data and report viewing.
While today’s technology offers solutions for monitoring or remote reporting via mobile devices, test organisations will need new expertise to unite the networking, Web services and mobile app portions of the solution.
“Development of next-generation single-chip T&M instruments using the latest extreme ultraviolet technology will help increase the operating margins without any compromise on the functionality. With the rapid rise in communication technologies like 3G and 4G, the implementation of remote testing will reduce the costs significantly,” says Paras Dagli, executive director, Dynalog (India).
In short, the Internet and the seemingly never-ending demand for more mobile computing devices and capability means that future generations of T&M equipment will also continually be challenged to deliver faster, better and easier to obtain results!
The author is an executive editor at EFY