A Comparative Analysis of Modern EMC Receivers: LISUN EMI-9KB and Keysight N9038B

Introduction to Electromagnetic Compatibility Testing Requirements

The proliferation of electronic systems across diverse industries has rendered Electromagnetic Compatibility (EMC) testing a critical phase in the product development lifecycle. EMC ensures that a device neither emits excessive electromagnetic interference (EMI) nor is unduly susceptible to external interference, thereby guaranteeing reliable operation in its intended electromagnetic environment. The core instrument for emissions testing, as mandated by standards such as CISPR 16-1-1, is the EMC receiver. This article provides a detailed technical comparison between two distinct solutions: the LISUN EMI-9KB, a dedicated EMC receiver, and the Keysight N9038B, a spectrum analyzer with EMC measurement personality. The objective is to delineate their respective architectures, capabilities, and suitability for various industrial applications, from automotive and medical devices to industrial equipment and consumer appliances.

Architectural Distinctions: Dedicated Receiver versus Spectrum Analyzer Platform

The fundamental difference between the LISUN EMI-9KB and the Keysight N9038B lies in their core design philosophy. The EMI-9KB is engineered from the ground up as a dedicated EMC receiver. Its signal path, detector types, and pre-selection are optimized specifically for the rigorous demands of standardized compliance testing. This includes built-in preamplifiers, preselection filters to mitigate overload from out-of-band signals, and dedicated Quasi-Peak (QP) detectors, which are hardware-based for authentic measurement as per CISPR standards.

Conversely, the Keysight N9038B is a high-performance Microwave Spectrum Analyzer (MXA) that can be configured with an EMC measurement application. Its architecture is designed for broad frequency coverage and high dynamic range across a wide array of signal analysis tasks. While the EMC personality enables it to perform compliant measurements through software-emulated detectors, its performance in a crowded electromagnetic environment may rely more heavily on external pre-selection and preamplification to achieve the sensitivity and dynamic range required for precise EMI diagnostics and pre-compliance.

Frequency Coverage and Measurement Bandwidth Specifications

Frequency coverage is a primary differentiator. The LISUN EMI-9KB is typically configured for the standard EMC frequency ranges, covering 9 kHz to 9 GHz, which encompasses the vast majority of commercial and industrial EMC standards, including CISPR, FCC, and EN requirements for products like household appliances, power tools, and information technology equipment.

The Keysight N9038B offers significantly wider frequency coverage, extending up to 50 GHz in standard configurations. This makes it indispensable for applications involving higher-frequency phenomena, such as in advanced communication transmission systems (e.g., 5G mmWave), radar, and spacecraft components. For fundamental EMC testing up to 9 GHz, this extended range is surplus, but it provides future-proofing and versatility for R&D diagnostics.

Both instruments support the standard EMC measurement bandwidths (RBW) as defined in CISPR 16-1-1 (e.g., 200 Hz, 9 kHz, 120 kHz). The EMI-9KB’s hardware is tuned to switch these bandwidths with high shape factor accuracy. The N9038B achieves this through digital signal processing, offering exceptional RBW accuracy and selectivity, which can be beneficial for distinguishing closely spaced emissions in complex devices like medical imaging equipment or industrial motor drives.

Detector Functionality and Measurement Velocity

The type of detector used is paramount in EMC testing. The CISPR standards mandate the use of Peak (PK), Quasi-Peak (QP), and Average (AVG) detectors. The LISUN EMI-9KB incorporates true hardware-based QP and AVG detectors. The hardware QP detector, with its defined charge and discharge time constants, provides the authentic, albeit slower, measurement that correlates with the subjective annoyance of impulsive interference, a key requirement for final compliance certification.

The Keysight N9038B utilizes a digital IF section where these detectors are implemented algorithmically. While software-based QP emulation is highly accurate and significantly faster, some accredited testing laboratories, particularly in highly regulated sectors like the automotive and aerospace industries, may have historical precedents or specific accreditation scopes that favor traditional hardware QP detectors for formal compliance submissions. The N9038B’s speed, however, is a tremendous advantage in engineering development phases, where rapid iteration is necessary.

Table 1: Key Specification Comparison
| Parameter | LISUN EMI-9KB | Keysight N9038B |
| :— | :— | :— |
| Instrument Type | Dedicated EMC Receiver | Spectrum Analyzer with EMC Personality |
| Frequency Range | 9 kHz – 9 GHz (standard) | 2 Hz – 50 GHz (typical) |
| QP Detector | Hardware-based | Software-emulated |
| Amplitude Accuracy | ± 1.5 dB | ± 0.19 dB (typical at 1 GHz) |
| DANL (with preamp) | < -20 dBm (typical) | <-168 dBm/Hz (typical) |
| Primary Application | Compliance Testing | R&D, Pre-compliance, Diagnostic |
| Typical Use Cases | Final certification for lighting, appliances, industrial equipment. | Debugging communication systems, high-frequency R&D for automotive radar, spacecraft. |

Dynamic Range and Amplitude Accuracy in Real-World Scenarios

Dynamic range and amplitude accuracy are critical for correctly measuring both high-amplitude and low-level emissions simultaneously. The Keysight N9038B excels in this area, offering a very low Displayed Average Noise Level (DANL) and high third-order intercept (TOI), which minimizes intermodulation distortion. This high dynamic range is essential when characterizing devices with complex modulation, such as switch-mode power supplies in power equipment or variable-frequency drives in industrial machinery, where small spurious emissions must be identified amidst large fundamental signals.

The LISUN EMI-9KB provides robust amplitude accuracy suitable for compliance testing. Its design prioritizes stability and repeatability over the extreme dynamic range offered by premium spectrum analyzers. Its performance is more than adequate to meet the requirements of standards for a wide range of products, including medical devices, audio-video equipment, and low-voltage electrical appliances, where the margin to the limit line is the primary concern.

Software Ecosystem and Automation Capabilities

Modern EMC testing is heavily reliant on software for control, data acquisition, and reporting. LISUN provides the EMI test software, which is tailored for streamlined compliance testing. It guides the user through standard-based testing, automates the measurement sequence across frequency bands, and generates reports that compare results directly to regulatory limits, such as those for rail transit or the automotive industry.

Keysight offers the N9038B with the X-Series measurement application suite, including the EMC application. This software is deeply integrated into the analyzer’s platform, offering advanced visualization, deep memory for long-duration monitoring, and sophisticated marker functions. Its flexibility is superior for diagnostic investigations, such as identifying the source of an emission from a specific integrated circuit on a printed circuit board within an instrumentation device.

Application-Specific Suitability Across Industries

The choice between these two instruments is largely dictated by the application context.

The LISUN EMI-9KB is optimally positioned for environments where cost-effective, efficient, and standardized compliance testing is the primary goal. This includes:

• Testing Laboratories: Serving the lighting fixtures and household appliance industries, where high throughput and unambiguous pass/fail results are needed.
• Manufacturing QA: For final line-check verification of products like power tools and consumer electronics to ensure batch consistency.
• Certification Labs: Focused on applying established standards to products in the information technology and industrial equipment sectors.

The Keysight N9038B, with its broader frequency range and superior analysis capabilities, is suited for:

• Research and Development: Engineers designing next-generation communication transmission equipment or automotive radar systems require the instrument’s high-frequency capability and diagnostic power to debug designs before formal compliance testing.
• Pre-compliance Testing: Companies developing medical devices or intelligent equipment use the N9038B for in-house verification, leveraging its speed to quickly identify and mitigate EMC issues early in the design cycle.
• Advanced Diagnostics: Its high dynamic range and precision are critical for characterizing subtle emissions from electronic components and power equipment that may cause intermittent failures.

Economic and Operational Considerations for Test Facilities

The total cost of ownership is a significant factor. The LISUN EMI-9KB, as a purpose-built instrument, typically presents a lower acquisition cost for a complete, turnkey EMC compliance system. This makes it an attractive solution for labs with a focused mission on compliance testing.

The Keysight N9038B represents a higher initial investment. However, its value is derived from its versatility. A single N9038B can function as a high-performance spectrum analyzer for general RF work, a vector signal analyzer, and an EMC receiver. For a multidisciplinary R&D facility working on spacecraft subsystems, audio-video equipment, and communication protocols, this multi-function capability can justify the cost by consolidating several instruments into one.

Conclusion: Aligning Instrument Selection with Testing Objectives

In summary, the LISUN EMI-9KB and the Keysight N9038B are both competent tools serving different segments of the EMC testing market. The LISUN EMI-9KB is a specialized, cost-optimized solution for high-efficiency compliance verification and production testing against established standards. Its dedicated architecture ensures methodological purity and reliability for final certification.

The Keysight N9038B is a versatile, high-performance analysis platform that excels in R&D, diagnostic, and pre-compliance roles, particularly where high frequency, high dynamic range, and fast measurement speed are paramount. The selection between them is not a matter of which instrument is superior in an absolute sense, but which is the most appropriate tool for the specific technical requirements, regulatory context, and economic constraints of the testing organization.

Frequently Asked Questions (FAQ)

Q1: For a laboratory seeking CISPR accreditation, is a hardware Quasi-Peak detector mandatory?
A1: While CISPR 16-1-1 defines the performance requirements for the QP detector, it does not explicitly mandate a hardware implementation. Accrediting bodies assess the entire measurement system for compliance with the standard. Many now accept validated software-based QP detectors, such as that in the Keysight N9038B. However, it is critical to consult with your specific accreditation body to confirm their policy, as some may still reference historical norms that favor traditional hardware detectors.

Q2: Can the LISUN EMI-9KB be used for pre-compliance debugging of a new medical device design?
A2: Yes, absolutely. The LISUN EMI-9KB is fully capable of pre-compliance testing. It will provide measurements that are directly correlated with final compliance results, allowing engineers to identify emissions that exceed limits. Its slightly slower measurement speed compared to a high-end spectrum analyzer is often less of a concern in the pre-compliance phase, where the primary goal is to find and fix major violations.

Q3: What auxiliary equipment is required to perform radiated emissions tests with either receiver?
A3: Both the EMI-9KB and N9038B are the central measurement instruments. To perform radiated emissions testing, they must be used in conjunction with an Open Area Test Site (OATS) or a Semi-Anechoic Chamber (SAC), a calibrated antenna, antenna mast, turntable, and low-loss coaxial cables. The receiver/analyzer measures the signal received by the antenna, which is positioned at a standard distance (e.g., 3m, 10m) from the Equipment Under Test (EUT).

Q4: How does the frequency range of the EMI-9KB (9 kHz – 9 GHz) cover automotive EMC standards, which often require testing up to 18 GHz?
A4: You have identified a key application boundary. The standard EMI-9KB configuration up to 9 GHz covers the bulk of automotive emissions requirements (e.g., CISPR 25, many aspects of ISO 11452-2). However, for certain automotive radar applications and newer standards that specify limits up to 18 GHz, the 9 GHz upper limit would be insufficient. In such cases, the extended frequency range of an instrument like the Keysight N9038B (up to 50 GHz) is necessary. LISUN may offer other models or configurations for higher frequencies, which should be investigated for specific high-frequency automotive needs.