Two Instruments, One Test, One Question That Changes Everything
At the Keysight booth at the EMC exhibition in Cologne this January, the message on the wall was unusually direct:
Accelerate EMC Certification & Wireless Coexistence Testing.
Run more repeatable tests in less time, with deeper insight for faster debugging.
Validate real-world wireless performance with automated coexistence testing.
Not a specification. Not a frequency range. A workflow promise.
The hardware on the desk made that promise concrete: two Keysight PXE signal analyzers running simultaneously, a control laptop running a three-step automated test sequence, and a biconical antenna on a tripod positioned off to the side — a complete synchronized multi-instrument EMI and RF coexistence measurement system, live and running.
Keysight N9048B PXE EMI Receiver + two PXE Signal Analyzers · 869 MHz density display + 2.4 GHz waterfall · synchronized dual-band monitoring
The Hardware: N9048B PXE EMI Receiver + PXE Signal Analyzers
The instrument stack at this demo is three units: a top-mounted chassis identified as a Keysight N9048B PXE EMI Receiver (labeled "PIETRO SAFETY" in the lab asset tagging visible on the front panel), and two Keysight PXE Performance Signal Analyzers below it, each with its own display running a different measurement view simultaneously.
The N9048B is Keysight's full-compliance EMI receiver — a CISPR 16-1-1 certified instrument covering 2 Hz to 26.5 GHz, capable of the quasi-peak, average, and peak detector measurements that formal compliance testing requires. It is not a spectrum analyzer used for EMI work. It is purpose-built as an EMI receiver, with the detector implementations and calibration traceability that certified test labs depend on.
The two PXE signal analyzers below it are running in real-time spectrum analyzer (RTSA) mode — the configuration that enables continuous IQ capture, density displays, and waterfall spectrograms rather than swept measurement. Together, the three instruments form a system that can simultaneously run formal compliance measurements on one channel and real-time signal behavior analysis on another, correlated in time.
Two Frequencies, Two Views, One System
The split across the two PXE displays reveals exactly what this demo is testing: simultaneous monitoring of two frequency bands that are critical for wireless coexistence analysis.
Left PXE: 869 MHz — Real-Time SA, Spectrum & PVT mode
The 869 MHz band is used in Europe for sub-GHz IoT protocols (LoRa, SigFox, Z-Wave, wireless alarm systems). In an automotive or industrial electronics context, it's also a frequency range where switching power supplies can generate harmonic emissions that fall into licensed IoT bands. The density display shows the statistical emission profile at this frequency — red/yellow indicates consistent presence, green indicates sporadic. The PVT (Power vs. Time) mode adds the time-domain behavioral dimension: not just what's there, but when it appears.
Right PXE: 2.4000 GHz — Real-Time SA, waterfall spectrogram
The 2.4 GHz band is the most congested spectrum in consumer electronics: WiFi (802.11b/g/n), Bluetooth, Zigbee, and a large number of proprietary wireless protocols all share this 100 MHz span. The waterfall display on this unit shows the 2.4 GHz band's content evolving over time — horizontal lines correspond to frequency, vertical progression represents time, and color encodes amplitude. In a coexistence testing scenario, this view reveals how different protocols share the channel: when WiFi bursts occur, when Bluetooth frequency-hops, and whether a device under test is generating emissions that collide with legitimate wireless traffic.
The two views together — 869 MHz behavioral analysis and 2.4 GHz coexistence monitoring — are time-synchronized across both instruments. An event that appears at 869 MHz at the same moment as a WiFi burst at 2.4 GHz is not a coincidence to ignore; it's a potential cross-band interference correlation that only a synchronized multi-instrument capture can reveal.
What the Large Screen Display Shows
The large Samsung display above the instrument stack mirrors the MXA Signal Analyzer's real-time view, showing the measurement parameters clearly:
→ Center Frequency: 2.44000 GHz
→ Resolution BW: 479 kHz
→ Span: 100 MHz
→ Trigger: Free Run
→ Detector: Peak
→ 100% POI (Probability of Intercept)
That last parameter — 100% POI — is the specification that defines real-time capture as distinct from fast-sweep analysis. Probability of Intercept describes the likelihood that a signal event of a given duration will be captured in the measurement. At 100% POI, no event within the instrument's minimum detectable pulse width is missed. This is not a marketing claim; it is a specific architectural requirement that determines the minimum real-time bandwidth and acquisition rate the instrument must sustain.
At 100% POI in a 100 MHz span at 2.44 GHz, the instrument is guaranteeing that every Bluetooth frequency-hop, every WiFi burst preamble, and every brief interference event in the band is captured — none are statistically probable to fall between acquisition windows. This is the measurement foundation that makes coexistence analysis credible rather than probabilistic.
The Automation Layer: Keysight Equipment Function
On the right side of the instrument stack, the laptop is running the Keysight Equipment Function automation software — displaying a three-step sequential test workflow interface.
This software layer is what converts the hardware capability into a repeatable measurement process. The three steps visible on the screen represent the structured sequence a coexistence or EMC test follows: configuration, execution, and results analysis. The right-side panel in the software interface shows a log of executed test steps — the system running through its sequence automatically, logging each result without operator intervention for each step.
This automation approach is the practical answer to one of the most consistent complaints in EMC and coexistence testing: repeatability. Human-operated test sequences introduce variability at every step — different antenna positions, different timing relative to DUT state, different trigger conditions. Automated sequences eliminate that variability by executing the same configuration identically each time, making results from test session to test session directly comparable.
For a product development team doing iterative EMC pre-compliance work — measuring, changing the design, re-measuring — repeatability is the prerequisite for being able to attribute a change in the result to a change in the design rather than to measurement variation. The automation layer is not a convenience. It is the engineering validity of the comparison.
Wireless Coexistence Testing: What It Actually Requires
The Keysight pitch — Validate real-world wireless performance with automated coexistence testing — points to a testing category that has grown sharply in relevance as products have accumulated more wireless interfaces.
A modern embedded system might contain WiFi, Bluetooth, Zigbee, LTE, UWB, and NFC simultaneously. Each of these protocols operates with assumptions about the RF environment — channel availability, interference levels, timing. When they share the same device, their antennas are separated by centimeters rather than meters, their switching power supplies share a ground plane, and their transmit events can overlap in time.
Coexistence testing asks: does the device work correctly in the presence of its own radios? And does it work correctly in the presence of the wireless protocols it is likely to encounter in deployment?
Answering these questions requires simultaneously measuring what the device emits and what it receives, at multiple frequencies, under controlled stimulus conditions. The two-instrument setup at this demo — one instrument monitoring the 869 MHz band, one monitoring 2.4 GHz, both time-synchronized, with an automated test controller coordinating the sequence — is a direct implementation of that requirement.
The biconical antenna on the tripod visible in the booth photo completes the chain as the radiated emissions receive antenna — the same antenna type used in formal CISPR radiated testing, here also serving as the receive element for the over-the-air coexistence monitoring.
The Shift This Represents: From Instrument to Platform
What the Keysight demo in Cologne was showing is not a new spectrum analyzer. It is a measurement platform assembled from coordinated instruments, controlled by software, executing structured test sequences, and producing results that are repeatable, time-correlated, and multi-dimensional.
The individual components — the N9048B EMI receiver, the PXE signal analyzers, the MXA — are each capable instruments in isolation. Their value in this configuration comes from synchronization: shared triggers, common time references, and a software layer that treats them as a unified measurement system rather than independent boxes.
This is the pattern that defines where high-end T&M is moving. Not faster individual instruments, but coordinated systems where the measurement insight emerges from the combination of data streams across multiple synchronized capture points. The question being answered shifts from "what is the emission level at this frequency?" to "how do these signals relate to each other across frequency, time, and space?"
That second question is the one product engineers actually need answered in complex wireless systems — and it requires exactly the architecture this demo was running.
Instruments observed: Keysight N9048B PXE EMI Receiver · Keysight PXE Performance Signal Analyzers · Keysight MXA Signal Analyzer · Real-Time SA mode · 100% POI · Equipment Function automation software · synchronized multi-instrument EMI and RF coexistence measurement system
All photos: Thomas · @SignalByThomas