In their early days, oscilloscopes were simple devices, allowing engineers to view waveforms on a small phosphor screen – usually circular. Today, even entry level oscilloscopes are complex devices, offering a range of functionality. And the industry is beginning to see the emergence of devices that bring together information from the frequency and time domains.
Dean Miles, senior EMEA technical marketing manager with Tektronix, is responsible for the company’s high performance products. He said the mainstream oscilloscope market – devices with bandwidths ranging from 500MHz to 3.5GHz – continues to be an exciting part of the market. “Budgets are often constrained in this segment,” he said, “and, as a consequence, demand for high value integrated oscilloscopes continues to be strong.”
Engineers today are required to develop complex devices, with analogue and digital components, serial buses and, increasingly, some element of communication with the outside world. “This means they are having to wear ‘new hats’ while troubleshooting and debugging,” said Miles.
Hot design segments
According to Miles, some of the ‘hottest’ segments include cloud computing, wearables and energy efficient products including LED lighting. “In addition, momentum around the IoT continues to grow steadily. One interesting data point, according to Tektronix research, is that 30% of those responding are using their oscilloscopes to develop IoT products.
“Here, the trend is to pack components together to reduce footprint. With the MDO4000C and MDO3000 series of integrated oscilloscopes, engineers can use a single instrument to see how their designs perform in both the time and frequency domains.”
While IoT products almost mandate the use of RF communications, Miles pointed towards another connectivity challenge facing engineers. “A change that will increase complexity is just over the horizon as the industry shifts from the traditional USB connector to the new Type-C 24-pin reversible-plug connector.”
Another, and continuing, problem for design engineers is EMI/EMC and, as Miles notes, even after careful design and the selection of quality components, there can still be EMI issues. “In order to identify the source of an EMI problem, engineers have to first determine the source of energy and then find out how this energy is being radiated. Examining the coincidence of these EMI problems with electrical events is arguably the most time consuming process in EMI diagnostics.”
One of the biggest changes has been in the wireless area. “Most new wireless technologies are not static in the spectral domain,” Miles pointed out, “with many of the latest communications standards featuring frequency hopping. So engineers need to examine spectral content in real time.”
Tektronix said its survey of oscilloscope users found that engineers used a range of instruments several times per month in addition to an oscilloscope. Digital voltmeters were most popular, at 87%, followed by function generator (68%), spectrum analyser (45%), logic analyser (33%) and protocol analyser (15%).
Looking to meet these needs, Tektronix’ latest scope – the MDO4000C – features a built in spectrum analyser, along with an arbitrary function generator, logic analyser, protocol analyser and a digital voltmeter.
“Based on customer input and market trends,” Miles said, “a key focus has emerged around integrating more capability into the oscilloscope and doing it in a way that simplifies the engineer’s life.”
In Miles’ opinion, many embedded engineers believe the oscilloscope they already use, or a standard mixed signal oscilloscope, is sufficient for RF test application as most oscilloscopes can calculate and display a Fast Fourier Transform of an acquired time domain signal. “While an FFT can be useful for a number of applications,” he noted, “it is no replacement for a full blown spectrum analyser. What’s more, the spectrum is limited to the bandwidth of the oscilloscope.
“I believe there is strong evidence that the mixed domain oscilloscope will remain the mainstream instrument of choice for embedded design applications for the foreseeable future.”
One of the features of the MDO4000C highlighted by Tektronix is that any of the integrated instruments can be upgraded at any time after purchase.
“As speeds increase, so do the test challenges,” Miles noted. “This means engineers will need to invest in equipment that can grow with them as their requirements change.”
What are the challenges which face Tektronix when developing devices such as the MDO4000C? “The constraints for mainstream test equipment developers are essentially the same as those faced by embedded engineers everywhere. Our goal is to deliver as much performance and functionality in a package that is as compact and integrated as possible, while ensuring the product fits customers’ budgets,” Miles said.
“It’s unlikely the fundamental design and functionality will change significantly in the next few years,” he concluded. “Instead, the focus will be on solving particular measurement challenges and further improving usability.”
Acquiring data for event reconstruction and analysis
Channel synchronisation can become an even greater challenge as the number of monitored signals grows, requiring a complex multichannel test system configuration. Various transducers, detectors or instruments such as photomultiplier tubes, beam current transformers, spectrometers or fast diodes may be used to capture energies that contribute to the reconstruction of the event. Measurements and reliable conversions are needed to accurately calculate the true energy source measured by transducers. Other considerations include software, space and power. Software provides system control, measurement conversions, data storage management and signal analysis. Accommodating a small test area and limited power can be managed by selecting a digitiser in a format that offers flexibility for high channel count, power management and a smaller footprint such as PXI or AXIe. An AXIe hardware and software solution offered by Keysight Technologies includes the AXIe M9703A and M9709A (pictured) digitisers and the U1092A S0x Acqiris MAQS multichannel acquisition software. The M9703A and M9709A digitisers provide eight channels with 12bit resolution or 32 channels with 8bit resolution respectively and enable synchronised channels across AXIe chassis for systems with up to 96 channels. Four on board Virtex-6 FPGAs provide real-time processing for data reduction. The flexible AXIe configuration includes a chassis and controller with triggering and clock options for channel synchronisation. Meanwhile, measurement fidelity at GHz speed ensures crucial data is captured. Low noise and high dynamic range of the A/D conversion bring confidence in the acquired results for detailed event analysis. An ideal test system for this application would provide accurate data capture, many fast reliable measurements, synchronised channels, precision triggering, system control, fit into a specific test area and be within power limits, while achieving extreme speed and precision measurements. Author profile: |
When they need to collect large amounts of data in order to reconstruct real-time and fast transient or single-shot events, engineers face several test challenges. Selecting the best instruments to construct a reliable test system for data collection is most important. Capturing multiple real time signals generated during the event requires a high-speed digitiser that can make many very fast, accurate measurements. The digitiser’s performance determines the quality of the signal measurements, with accurate triggering and timing across all the channels to ensure reliable reconstruction of the acquired data.
