A Display That Changes How You Think About Signals
At a professional electronics exhibition in Turin this February, the Teledyne LeCroy demo stopped me mid-step.
Not because the instrument was large. Not because the waveform was impressive on its own.
Because the same signal was displayed four ways simultaneously — and each view told a completely different story.
Top left: a clean square wave in the time domain.
Bottom left: an FFT revealing ten harmonics, each precisely labeled and tabulated.
Bottom right: a peak frequency list with amplitude values down to −71 dBm.
Top right: a 3D spectrum — a glowing orange landscape of time, frequency, and amplitude stacked into a structure that looked more like terrain than a waveform.
This was the Teledyne LeCroy WavePro 804HD-MS — 8 GHz bandwidth, 20 GS/s sample rate, 12-bit HD4096 resolution. And the demo was making an argument that went well beyond specs.
HD4096: What 12-Bit Resolution Unlocks in the Frequency Domain
The HD4096 designation refers to Teledyne LeCroy's 12-bit acquisition architecture — 4,096 vertical quantization levels versus the 256 of a standard 8-bit ADC. That's 16× more vertical resolution, and in spectral analysis the impact is direct:
→ Lower FFT noise floor — quantization noise is distributed across the spectrum; with 12-bit, that noise sits roughly 24 dB lower than on an 8-bit ADC, revealing harmonic content that was previously buried
→ Weak harmonic visibility — in the FFT display on the demo, peaks from the 10th harmonic at 100 MHz were clearly resolved at −22 dBm; on an 8-bit scope, those components would be near or below the noise floor
→ Dynamic range for co-existing large and small signals — a fundamental at −2.7 dBm and its 9th harmonic at −35 dBm are captured in the same acquisition without one masking the other
For engineers working on power electronics, motor drives, or any system where spectral purity matters — converter efficiency, EMI pre-compliance, gate drive harmonic content — this is the resolution range where measurements start becoming actionable rather than indicative.
The FFT Display: Reading Harmonic Structure
The FFT view in this demo was not just a spectrum trace. It was a full harmonic analysis workflow.
What the peak list table showed:
→ Fundamental: 10.000 MHz at −2.7 dBm
→ 2nd harmonic: 19.999 MHz at −14.3 dBm
→ 3rd harmonic: 30.000 MHz at −15.0 dBm
→ 4th harmonic: 39.998 MHz at −19.0 dBm
→ Through to the 10th harmonic at 64.927 MHz at −71.4 dBm
The instrument is automatically detecting, labeling, and sorting spectral peaks — not just drawing a trace. That automated peak identification is what separates this from a manual cursor measurement: you get a structured dataset, not a visual estimate.
For EMI pre-compliance purposes, this is directly useful. The frequency and amplitude of each harmonic maps onto standard emissions limits. Knowing that your 5th harmonic sits 6 dB above your target margin tells you something specific about what needs to change in the layout or filtering. A blurry FFT on an 8-bit scope tells you much less.
The 3D Spectrum: When Time Becomes the Third Axis
The orange landscape in the top-right quadrant is the feature that takes the most explanation — and delivers the most insight once understood.
A standard FFT shows you the spectrum at a single moment in time, or averaged over many acquisitions. The 3D spectrum does something different: it stacks sequential FFT frames along a time axis, creating a surface that shows how the frequency content of a signal evolves over time.
In the WavePro 804HD-MS display, each orange "ridge" represents one FFT frame. The peaks — the harmonics of the square wave — appear as bright edges running through time. The fact that they're consistent ridges rather than shifting peaks tells you the signal is spectrally stable. In a different scenario, you might see:
→ Spread-spectrum switching — harmonic peaks that shift left and right over time as the switching frequency is deliberately modulated to spread EMI energy
→ Thermal frequency drift — a crystal oscillator or switching converter whose frequency slowly moves as the board warms up
→ Load-dependent modulation — harmonic structure that changes with current draw, revealing supply impedance effects
→ Intermittent interference — a spectral component that appears and disappears, invisible on a static FFT average
None of these behaviors are visible in a single-frame FFT. The 3D spectrum makes them structural — you see the behavior over time, not just the state at one moment.
This is the shift from observation to characterization.
The Demo Board: ADI Hardware as the Signal Source
The signal source for this demo was an Analog Devices evaluation board — a detail worth noting. This is not a purpose-built clean demo signal; it's a real engineering development board producing real switching waveforms with real harmonic content and real measurement challenges.
The choice is deliberate. Using an ADI evaluation board as the source means the harmonic structure the scope is analyzing comes from an actual converter or signal chain, not a function generator configured to produce ideal waveforms. The noise, the non-idealities, the subtle frequency content — all of it is present in the measurement because it's present in the hardware.
This is the version of a demo that earns technical credibility. Engineers in the audience recognize the board, understand what it's doing, and can map the measurement results to their own development challenges.
What This Demo Is Actually Selling
The WavePro 804HD-MS is an 8 GHz instrument in a market segment occupied by experienced users — engineers who already know what bandwidth they need and what an FFT is. The demo is not explaining basics.
What it's demonstrating is a workflow:
→ Capture a signal at 12-bit resolution
→ Analyze its time-domain behavior simultaneously
→ Resolve its spectral content with enough dynamic range to see weak harmonics
→ Track how that spectrum behaves over time
→ Get an automated table of significant peaks without manual cursor work
All of this in a single acquisition setup, without switching instruments or modes.
The argument is efficiency: the time it takes to move from "signal capture" to "I understand what this circuit is doing and why" is dramatically shorter when all four analytical perspectives are available simultaneously. In a development cycle where debugging a converter's EMI signature might take days, tools that compress that workflow have direct economic value.
Teledyne LeCroy is not competing on bandwidth or sample rate at this level. Those specs are table stakes. The competition is on depth of analysis per engineering hour — and the 3D spectrum, the automated peak list, and the multi-domain display layout are the evidence for that argument.
The Underlying Principle
There's a broader insight in what this demo illustrates, beyond the specific instrument.
A waveform on an oscilloscope is always a snapshot — one temporal slice of a signal's behavior. In simple systems with simple signals, that snapshot is enough. In modern power electronics, RF systems, and mixed-signal designs, it almost never is.
The signal you're measuring is the output of a dynamic system. It responds to load, temperature, interference, and control loop behavior. Characterizing it properly means understanding that dynamic — not just confirming that the waveform "looks right" in a single capture.
The 3D spectrum, the automated harmonic analysis, the 12-bit noise floor — each of these is an answer to a specific limitation of traditional oscilloscope measurement. Not features added to a spec sheet. Solutions to real analytical gaps.
That's the version of test equipment that earns its place in a development workflow.
Instrument observed: Teledyne LeCroy WavePro 804HD-MS · 8 GHz · 20 GS/s · 12-bit HD4096 · High Definition Mixed Signal Oscilloscope · with Analog Devices evaluation board signal source
All photos: Thomas · @SignalByThomas
