From Frequency Trace to Three-Dimensional Reality
At the Gauss Instruments booth at the professional EMC exhibition in Cologne this January, the headline number had doubled since their previous display.
last Article covered their 510 MHz real-time IQ system. This one said 1000 MHz.
But the bandwidth upgrade wasn't the most significant thing I saw at this booth. Behind the TDEMI® Ultimate instrument, on the large display screen, was something that fundamentally reframes what EMI measurement can be: a 3D spectrogram shaped like a blue tornado — frequency on one axis, antenna rotation angle on another, time and measurement height on the third — showing the complete radiated emissions profile of a device under test, captured simultaneously across the entire 1 GHz bandwidth.
This is not a frequency sweep result. It is a spatial map of electromagnetic behavior.
Reading the 3D Spectrogram: Three Axes, One Complete Picture
The 3D visualization on the display is labeled precisely: Spectrogram Mode QP below 1 GHz Scan!, Polarization H, with Height @ 100 cm.
Each axis carries specific physical meaning:
→ Y-axis: Frequency (MHz), 0 to 1000 — the full 1 GHz capture bandwidth, every frequency simultaneously
→ X-axis: RPM / rotation angle — the angular position of the device under test on an automated turntable, as it rotates through 360°
→ Z-axis / color intensity: amplitude — the emission level at each frequency at each rotation angle
The result — that blue conical structure — is a complete radiation pattern map of the DUT across the full frequency range, at a fixed antenna height of 100 cm, in horizontal polarization. The "mushroom" or "tornado" shape is not decorative: it reflects the actual directional emission characteristic of the device. Frequencies and angles where the device radiates strongly appear as brighter, taller structures. Frequencies where radiation is low appear flat.
What this visualization replaces is a workflow that, in a traditional semi-anechoic chamber, would require dozens of individual measurement passes: one frequency at a time, rotating the turntable for each, logging the maximum at each angle, then stepping to the next frequency. At 1 GHz real-time bandwidth, the TDEMI® system captures every frequency simultaneously as the turntable rotates — a single physical rotation produces the entire 3D dataset.
The TDEMI® Ultimate: What "Ultimate" Means in Practice
The TDEMI® Ultimate is the top-tier configuration in the Gauss Instruments product line — the same TDEMI® architecture as the S Series covered in Article 020, scaled to 1000 MHz real-time capture bandwidth.
The software task list visible in the laptop display gives a precise picture of the measurement sequence this system runs:
→ Scan (1 GHz, 10 kHz, 120 kHz, QP, 200 ms) — full 1 GHz frequency scan with quasi-peak detector, 200 ms dwell time
→ Receiver Mode QP above 1 GHz — switching to narrowband quasi-peak receiver for frequencies above the real-time capture window
→ Spectrogram Mode above 1 GHz only with Ambient — capturing the ambient background reference above 1 GHz for subtraction
→ Real-time Analyzer Mode — the continuous IQ capture mode that produces the density displays and 3D spectrograms
This task list is the complete workflow for a formal radiated emissions measurement — from pre-scan to final quasi-peak confirmation — running as an automated sequence. The engineer defines the sequence once; the system executes it, including turntable rotation, antenna positioning, and frequency stepping, without manual intervention.
The Fully Automated System: TDEMI + Ebi 64k
The black circular turntable base to the right of the main instrument unit carries the label that completes the picture: FULLY AUTOMATED · EMISSION MEASUREMENTS · FULL CHARACTERIZATION, alongside the Ebi 64k automation software suite designation.
The Ebi 64k software is the orchestration layer that coordinates the TDEMI receiver, the antenna mast height controller, the turntable rotation, and the measurement sequence. In a conventional radiated emissions test setup, this coordination is what consumes the majority of measurement time: the engineer manually sets antenna height, waits for the turntable to step, triggers the receiver, logs the result, and repeats for every combination of height, angle, and frequency.
In a fully automated configuration, the system executes the complete measurement matrix — multiple antenna heights, full 360° rotation, all frequency points — while the engineer is away from the bench. The output is a complete 3D dataset, ready for analysis and limit line comparison, produced in the time a traditional setup would need just to complete a single antenna height pass.
The biconical antenna on the wooden tripod visible on the right is the measurement antenna for the 30 MHz – 1 GHz radiated emissions range — the standard antenna type specified in CISPR 16-1-4 for that frequency range. Its presence in the demo confirms this is not a simplified bench demonstration but a representation of the actual measurement chain used in a formal compliance test environment.
Why 1000 MHz Real-Time Bandwidth Changes the Automation Equation
The connection between the 1000 MHz real-time bandwidth and the fully automated system is not coincidental — it's the reason automation at this level becomes practical.
In a traditional swept EMI receiver system, automating a full radiated emissions measurement means sequencing through frequency steps slowly enough for the receiver's bandwidth filter to settle at each point. For a quasi-peak measurement with 120 kHz RBW across the full 30 MHz – 1 GHz range, this takes many minutes per antenna height per polarization. Multiply by multiple heights, both polarizations, and 360° turntable rotation, and a complete characterization dataset requires hours.
At 1000 MHz real-time bandwidth, the receiver captures the entire frequency range in a single acquisition — the time per "scan" is no longer dominated by sequential frequency stepping but by the turntable rotation speed and the required dwell time for detector settling. The spectrogram in the 3D display was generated during a single turntable rotation pass, at a single antenna height, capturing all frequencies simultaneously. What that represents in measurement time reduction — compared to an equivalent swept-receiver dataset — is roughly one to two orders of magnitude.
This is why automation becomes viable: the system can complete a full characterization matrix in a time window that fits within a product development sprint rather than requiring a dedicated lab booking.
The Three-Layer Software Display
The large dual-screen display at the booth shows what the engineer sees when the measurement is running.
The left screen carries the multi-trace EMI spectrum — multiple colored curves (red, cyan, green) across the full frequency range, with limit lines overlaid. These are the conventional compliance-oriented views: peak hold, average, quasi-peak, ambient reference, each in a different color. The limit line comparison is immediate and direct.
The right screen — and the laptop — show the 3D spectrogram: the same data, represented spatially. The blue conical structure is the emission fingerprint of the device. An engineer looking at the 3D view can immediately identify which frequency bands produce directional emissions (sharp ridges in the 3D surface) versus isotropic emissions (uniform height at all rotation angles) versus background noise (flat, low amplitude).
These are not two separate measurements. They are two representations of the same IQ dataset — generated simultaneously from the single real-time capture. The ability to switch between compliance-oriented 2D views and spatially-resolved 3D views without re-measuring is the direct consequence of the underlying data architecture.
What This Signals About Where EMI Measurement Is Going
Taken together — the 1000 MHz real-time bandwidth, the automated turntable and antenna mast system, the 3D spectrogram visualization, the Ebi 64k software orchestration — the TDEMI® Ultimate represents a coherent answer to a question the EMC testing industry has been working on for two decades: how do you make comprehensive radiated emissions characterization fast enough to fit into iterative product development?
The traditional answer was "you don't, you schedule it." EMC testing happened at the end of the development cycle, in a booked anechoic chamber, against a hard compliance deadline. Failures at that stage are expensive — redesign, retesting, schedule impact.
The TDEMI® approach is a different answer: make the measurement fast enough and automated enough that it can happen continuously throughout the development cycle. A 3D emissions map generated in minutes, in a near-field or semi-anechoic setup, after each significant firmware or hardware change, gives the development team a continuous feedback loop on electromagnetic behavior rather than a single pass/fail gate at the end.
The 3D visualization is not just a compelling exhibition display. It's evidence of the data density this architecture produces — and a hint at what becomes possible when EMI characterization data is treated as a continuous asset rather than a periodic compliance test result.
Instrument observed: Gauss Instruments TDEMI® Ultimate · 1000 MHz Real-Time Bandwidth · TDEMI® Technology · with biconical antenna, automated turntable, Ebi 64k automation software suite · full radiated emissions characterization system
All photos: Thomas · @SignalByThomas