When an 80GHz FMCW radar level transmitter shows unstable, weak, or false readings, the root cause is almost always in the echo path — not a hardware failure. This guide walks through a repeatable diagnosis workflow for echo and signal problems, and links to the matching field-tested fix for each symptom.
It covers our 80GHz FMCW radar level transmitters (wired and 4G models, accuracy down to ±1 mm on wired units, IP68 housing). The same echo-principle advice applies across the product range; model-specific notes are called out where relevant.
The sensor emits a frequency-modulated continuous wave (FMCW) chirp and measures the round-trip time of the reflection. Firmware then ranks every returned echo by energy and position, and locks onto the strongest valid peak that is the real liquid/ solid surface. Every troubleshooting step below is really about making sure that locked peak is the true surface — and not a wall, a weld seam, foam, or a multipath ghost.
Most “bad reading” tickets are solved in the spectrum viewer, not by swapping hardware. Open the Spectrum Viewer (or pull raw ADC data on the upper computer) and look at what the radar actually receives:
See what the echo spectrum reveals and the matching fixes, and how to stream raw ADC data to the upper computer.
This alert means the returned surface echo is too weak to lock reliably. The usual causes, in order of likelihood:
Full cause list and fixes: why the display shows Insufficient Echo Energy.
Interpret the fluctuation magnitude before touching settings. Our field rule:
Worked examples: empty-distance data fluctuation analysis.
Foam thicker than about 3–4 cm triggers an “insufficient echo energy” alert because the radar signal cannot penetrate it. As foam builds, the sensor loses the valid surface echo and falls back to a weak-echo fault. Floating debris causes the same attenuation intermittently.
Mitigation and limits: measurement with heavy foam and floating debris.
The factory default blind zone is 0.3 m. If the surface enters the blind zone you should get an alert — but two things prevent it:
RF transmit power is left at the factory default for a reason: raising it is a fix for a specific symptom (weak or unstable true echo), not a general performance boost, and too much power can worsen near-field ghosts. Raise it only when the true-target echo is genuinely weak.
Environment matters more than power: open water tanks and rivers suffer weak true echoes and antenna interference, while enclosed vessels create multipath. Tuning recipes: how to adjust transmit power and environment-specific tuning.
The radar outputs valid data about 1 second after power-on. Amplitude-limiting filtering is enabled by factory default to smooth readings, which can make the output look laggy. Disable filtering for faster response when the application needs it. Details: why measurement lags and responds slowly.
Live readings can be normal while the stored history shows zeros or random spikes — typically a logging/ range-mapping issue rather than the sensor itself. Model-specific case: zeros or spike values in 1.5-inch 80G radar historical data.
Is the true surface peak present and dominant? If yes, the echo path is clean.
Check obstacles, antenna tilt, foam and distance — Steps 2–4.
Enable spurious echo learning; interpret the fluctuation magnitude (Step 3).
Disable amplitude-limiting filtering (Step 7).
Check blind-zone mode and range mapping (Steps 5, 8).
Only after the echo path is clean, tune RF transmit power (Step 6).
No. In the large majority of cases it is an installation or environment condition — obstacle, tilt, foam, or a too-close target. Start with the spectrum, not a return.
No. Default power is correct for most installs; raising it without a weak-echo symptom can create near-field ghosts.
Because suspended-installation mode is enabled. Switch to standard mode to restore the alert.
Field-tested fixes for each symptom above:
How to read every peak in the spectrum viewer, and the matching fix for each fault pattern — most “bad reading” tickets end here.
Pull raw ADC data on the upper computer to see exactly what the radar receives, before touching any setting.
The four usual causes in order of likelihood: obstacle, antenna tilt, non-flat target, out-of-range distance.
Read the fluctuation magnitude first: ≤ 0.4 m points to antenna-echo interference, > 0.4 m to a physical obstacle.
Why foam thicker than about 3–4 cm kills the surface echo, and what still works through it.
The surface is inside the blind zone but no alert fires — suspended-installation mode is the usual culprit.
When a within-blind-zone reading is real, and when it is a mode setting or a weak-return mistake.
A weak return mistaken for a too-close target on the 80G display model — cause and fix.
Why amplitude-limiting filtering (factory default) makes output look laggy, and when to disable it.
Live readings are fine but stored history shows zeros or spikes — a logging/ range-mapping case study.
Raising power is a fix for a genuinely weak true echo, not a general boost — when to use it and when it backfires.
Open tanks and rivers suffer weak echoes and antenna interference; enclosed vessels create multipath. Recipes for each.
Send AT command AT+OUTRAWDATA=2 via upper computer; confirm reply “OK”, then close the serial port.
Open the Spectrum Viewer software, select the correct serial port, open the port, and click FFT Spectrum to view raw ADC waveforms.
Answer: Our 80G radar operates at 76‑81 GHz and outputs valid data 1 second after power-on. Amplitude limiting filtering is enabled by factory default to smooth readings. Disable filtering for faster response — measurement accuracy remains unchanged, though transient interference echoes may be captured.
Factory filtering purpose: Water levels rise/fall gradually; filtering smooths sudden data jumps.
Limiting filter: Eliminates short-term abnormal data spikes.
Sliding-window averaging filter: Further smooths data changes on top of amplitude limiting filtering.
To disable filtering:
Upper computer: Set Variation Range and Duration to 0, save all settings; send AT command AT+SLIDWINFILTERNUM=0.
Bluetooth app: Set Amplitude Limit Filter Threshold (CM), Amplitude Limit Filter Count, Sliding Average Filter Window all to 0, then save.
Answer: Suspended installation mode is enabled. Switch to standard installation mode to activate blind zone alerts (default blind zone 0.3 m, adjustable downwards).
Suspended installation function: In complex echo scenarios, echoes within the blind zone are suppressed; the radar prioritizes targets outside the blind zone for distance calculation. Modify via upper computer or Bluetooth.
Configuration commands:
Adjust blind zone: AT+BLINDZONE=0.05 (minimum 0.05 m, adjust per site conditions)
Switch installation mode: AT+INSTALLTYPE=0 (0 = standard installation, 1 = suspended installation)
Bluetooth menu: App Parameter Configuration – Installation Mode – Blind Zone Distance
Answer: The measured distance is shorter than the blind zone distance; the factory default blind zone is 0.3 m.
Solutions:
Adjust the sensor-to-target distance to ensure it exceeds the blind zone.
Reduce the blind zone distance (minimum 0.05 m); set a proper value based on actual conditions.
Configuration:
Modify blind zone via upper computer AT command: AT+BLINDZONE=0.05.
Modify blind zone via Bluetooth: App Parameter Configuration – Blind Zone Distance.
Minimum blind zone specifications by measuring range:
10 m range: Minimum blind zone 0.05 m
20 m range: Minimum blind zone 0.10 m
30 m range: Minimum blind zone 0.18 m
40 m range: Minimum blind zone 0.20 m
Answer: Possible causes:
Obstacles between the sensor and the target weaken reflected echo energy.
The sensor is not parallel to the target surface, leading to weak reflected echoes.
The measured target is not a flat solid surface or liquid surface.
The water level rises too high and submerges the probe.
Solutions:
Verify vertical/horizontal installation of the device; ensure no obvious obstructions on the radar probe.
Weak echoes in open environments may stem from antenna echo interference; increase RF transmit power.
Answer: Foam thicker than 3‑4 cm triggers an “insufficient echo energy” alert. As foam thickness increases, radar signal penetration degrades, the sensor fails to capture valid target echoes, and outputs weak echo fault signals.
Typical issues: Weak true target echoes, frequent antenna echo interference, unstable distance readings.
Increase RF transmit power (secondary echoes rarely occur in open spaces).
Run spurious echo learning to eliminate antenna interference.
Enable suspended installation and widen blind zone if short-range measurement is unnecessary.
Disable nearest peak selection.
Typical issues: Variable true echo strength, occasional antenna echo interference, frequent secondary echoes.
Run spurious echo learning to eliminate antenna interference.
Enable suspended installation and widen blind zone if short-range measurement is unnecessary.
Increase RF transmit power if true echoes are weak; enable nearest peak detection.
Nearest peak command: AT+NEARESTPEAK=1 (0 = disabled, 1 = enabled)
Fluctuation ≤ 0.4 m: Likely antenna echo interference.
Fluctuation > 0.4 m: Obstacles exist between radar and target.
Readings are approximately twice the actual value: Secondary echo interference is the primary cause.
Spurious echoes detected → Enable spurious echo learning.
Secondary echoes detected → Enable nearest peak detection and inspect RF settings.
Weak/unstable true target echo energy → Optimize RF power and filter parameters.
Answer: RF transmit power is normally left at the factory default — raising it is a fix for a specific symptom, not a general performance boost.
In closed metal tanks or narrow pipes, higher power makes multipath and wall echoes stronger and usually makes the reading worse — correct the installation position first.
Change the RF transmit power setting in the upper-computer software or in the Bluetooth app parameter configuration, then re-check the echo spectrum: the true surface peak should rise clearly above the noise floor without new ghost peaks appearing. Run spurious echo learning first so you tune against a clean spectrum.
If you are unsure, capture the echo spectrum and send it to our support team together with an installation photo.
Model: JJY-YLD128SP — 80 GHz radar level transmitter with display
The ranging result shows the radar reporting “within blind zone”.
The working condition produced a weak reflection signal, so the returned data fell into the antenna blind zone.
Change the installation to suspended mounting (keep the antenna away from the surface and obstructions) and set the blind zone to 0.3 m. The issue was resolved.
Model: JJY-YLD128HS-1.5 — 1.5-inch 80 GHz radar level transmitter
During commissioning the live readings were normal, but the historical data contained zeros. Also, when the actual level was 0.5 m, occasional readings of several metres appeared. Filtering and echo learning did not stop the fluctuation; changing the blind zone and switching to a nearby frequency band also failed.
Replace the YCD8S unit with the YLD8S and upgrade to the latest firmware (2025-12-17 build). After the swap the jumps stopped and no further fluctuation was reported.
To prevent sudden jumps, set the sliding-window averaging to 10 / 30 / 60 — a larger window smooths out spikes.
Tell us your tank geometry, medium and output requirement (4–20 mA / RS485 / 4G) — our engineers will recommend the matching model. Module JJY-YLD138M-32: MOQ 1 with free prototype.
Copyright @ 2026 JiaJia Eye
Scan to add WeChat