Electromagnetic Interference (EMI) Measurement Application Software

To avoid losing valuable time due to failing compliance testing, electromagnetic interference (EMI) measurement applications running on spectrum analyzers/signal analyzers allow you to perform pre-compliance measurements and diagnostic evaluation of your designs.

You can proactively identify and fix problems before your design goes into the test chamber with the N6141A measurement application running on a spectrum analyzer/signal analyzer, or the W6141A measurement application.

Both software are low-cost pre-compliance testing solutions. These applications have a very wide range of features, allowing you to:

– Use sweep tables to set frequency range, gain, bandwidth, and dwell time

‾ Sweep a frequency range and display the results in logarithmic or linear format

‾ Identify suspicious signals found in frequency scans

‾ Measure the peak, quasi-peak, EMI average or RMS average of these suspect signals and add the results to the signal list

‾ Easily identify signals that exceed limits set by regulatory agencies

The electromagnetic interference (EMI) measurement application is part of the Keysight Spectrum Analyzer Family Common Library. The Spectrum Analyzer Family Common Library includes more than 25 measurement applications and is an evolutionary approach to signal analysis that combines instruments, measurements, and software. The spectrum analyzer analyzers have upgradeable CPUs, memory, hard disks, and I/O ports, allowing you to keep your test instruments up to date and extend the life of your instruments. Proven algorithms, 100% code compatibility, and the X-Series' common user interface create a consistent measurement framework for signal analysis, ensuring repeatable measurement results and measurement integrity, allowing you to take full advantage of test system software to accelerate and enhance testing at all stages of product development. In addition, you can transfer application software across multiple spectrum analyzer signal analyzers to further expand your test assets.

Main features

‾ Built-in bandwidth, detector and frequency band presets that meet commercial and military standards for accurate measurement of emissions

‾ Compare measured emissions to limits set by regulatory agencies

– Use a bar meter to continuously monitor the signal to detect the maximum amplitude

‾ Collect a list of suspicious launches

‾ Differentiate between ambient signals and device emissions

‾ View signals over time to identify intermittent responses

‾ Generates measurement reports in HTML format, including signal lists, graphs and traces, as well as correction data

Electromagnetic Interference (EMI) Measurement Application Software and Options

Electromagnetic Interference (EMI) Keysight offers two EMI options for signal analyzers: Option EMC and N/W6141A measurement application software. Option EMC enables basic EMC measurements. It includes bandwidths, detectors (peak, quasi-peak, EMI average, RMS average) that comply with CISPR 16-1-1, as well as CISPR band presets (Band A to Band E) and military bandwidths that comply with MIL-STD 461D/E/F requirements. The EMI measurement application software includes Option EMC and provides a wider range of features to enable you to perform pre-compliance conducted and radiated emissions testing according to commercial and military requirements. The following table summarizes the comparison of various features.

Table 1. Comparison of electromagnetic interference (EMI) measurement application software and Option EMC features (1. Requires Option DP2 or B40. Not available for CXA spectrum analyzers.)

EMI Pre-Compliance Measurement

Pre-compliance measurements have become widely used over the past two decades. Performing pre-compliance radiated and conducted emissions measurements early in the design process reduces development costs and speeds time to market by ensuring that new designs pass final compliance testing at an accredited test house the first time without costly redesign and retesting.

Conducted Emissions Measurements The EMI measurement application allows you to measure emissions conducted along power lines. The sensor used to match the power line emissions to the signal analyzer is a line impedance stabilization network (LISN). The frequency range for conducted emissions, as specified by regulatory agencies, is 9 kHz to 30 MHz.

Radiated emission measurements

Pre-compliance radiated emission measurements are not as simple as conducted emission measurements. When measuring according to commercial standards, the antenna is usually placed 3 to 10 meters away from the device under test (DUT). To find the maximum radiation, the DUT should be rotated continuously. By adding EMI measurement application software, the spectrum analyzer/signal analyzer can be transformed into a powerful EMI pre-compliance measurement analyzer to measure designs according to the latest CISPR 16-1-1 or military standards. The reliable signal list function allows you to quickly distinguish between the device under test and the surrounding signal environment.

Regulatory standards

A spectrum analyzer/signal analyzer with EMI measurement application software can perform pre-compliance measurements according to any international EMC standard. You only need to select the performance level and frequency range that suits your application.

Easily identify device emissions that exceed standard limits

The signal list, frequency sweep and activated detectors are displayed on a single screen, making it easy to review measurement results. You can continuously sweep a specific frequency range, or sweep and search for signals that exceed margin or limit values ​​and place them in the signal list. Use simultaneous detectors to continuously measure selected signals while maximizing amplitude expansion; use up to three detectors to measure all signals with the search and measure function; choose between peak, quasi-peak, EMI average or RMS average detectors; compare measurement results with the limits specified by regulatory agencies in the Δ to limit column.

Setting the frequency range using a scan table

The EMI measurement application includes a scan table with up to 10 ranges to set a specific frequency range. The scan table also includes resolution bandwidth selection, step size, number of points per RBW segment, attenuation selection, and preamplifier selection. The frequency range can be easily set in the scan table using the CISPR band presets.

Figure 1. Frequency sweep

Figure 2. Conducted emissions using Δ to limit values.

Figure 3. Scan table

Tune and listen for signals in the frequency scan table

Testing in an open test field means you must distinguish between ambient signals. To distinguish between the DUT signal and the ambient signals, you can use the tune and listen function to demodulate AM, FM, or phase modulation.

Figure 4. Radiation scan using the meter.

View signals over time using bar graphs

Bar graphs allow you to view signals over longer time periods to identify long interval discontinuities. You can display limit lines on the screen for comparison with regulatory agency limits.

Figure 5. Bar chart

Generate a report of test results

Generates HTML reports that include screen shots, signal listings, correction factors, trace data, limit lines, and test and product descriptions.

Figure 6. Report generation

Time Domain Scan Acceleration Test

The EMI measurement application offers three frequency sweeps: swept, stepped, and time domain.1 When longer measurement dwell times are required, the time domain sweep can significantly reduce total test time by shortening the overall pre-scan collection time.

Time domain scans use highly overlapped Fast Fourier Transforms (FFTs) to simultaneously collect emission data across the acquisition bandwidth (which is as wide as a multiple of the resolution bandwidth), thereby speeding up measurements. In contrast, frequency measurements collect data in a single resolution bandwidth.

With time domain testing, you can quickly collect a list of suspect signals, significantly reducing overall test time and increasing throughput.

Figure 7. Comparison of resolution bandwidth and FFT acquisition bandwidth.

Automatic single-click measurement

Easily perform non-continuous interference (or single-shot) pre-compliance measurements as specified in the CISPR 14-1 standard using the built-in interference analyzer. It simplifies and automates data collection, analysis and report generation tasks for these commonly tested emissions, enabling more efficient testing.

Figure 8. Simplify and automate data collection, analysis, and report generation for more efficient single-click measurement

Find the largest emission using the smallest monitoring spectrum

To ensure that you identify the frequencies of the largest emissions in your list of suspect signals, the EMI measurement application offers a new feature, Monitor Spectrum.1 This feature provides both a live spectrum and a meter display, allowing you to easily see emission levels and find the largest emissions while adjusting the center frequency. Ultimately, Monitor Spectrum can greatly speed up overall measurements by reducing the time needed to prepare a list of signals for the final measurement.

Figure 9. Monitoring the spectrum to find the frequency of peak emissions.

Preparing to perform an Amplitude Probability Distribution (APD) measurement

The EMI measurement application helps your lab prepare for future testing challenges by providing the Amplitude Probability Distribution (APD) capability, an essential tool for performing CISPR microwave oven emissions testing.

To characterize slowly varying emissions, the Amplitude Probability Distribution (APD) feature shows the probability that an emission will reach or exceed a specified level. To facilitate the use of this new feature, the EMI measurement application also provides specific limit line types that can be used in conjunction with the built-in evaluation functions to simplify testing of the device under test.

Figure 10. Prepare for future applications using the amplitude probability distribution (APD) function.