Dickey-john Radar III Ground Speed Radar Sensor

Overview

The Dickey-john Radar III Ground Speed Radar Sensor is an industrial-grade, non-contact Doppler radar device engineered for high-reliability vehicle speed measurement in demanding mobile applications—particularly asphalt pavers, spray sealers, and intelligent road maintenance equipment. It operates on the principle of continuous-wave Doppler radar at 24.125 GHz (±50 MHz), emitting a stable microwave signal toward the ground surface and detecting the frequency shift (Doppler shift) in the reflected echo caused by relative motion between the sensor and terrain. This shift is directly proportional to the radial component of ground velocity, enabling precise real-time speed calculation without wheel slippage, mechanical wear, or calibration drift associated with encoder- or GPS-based systems. Designed as the direct successor to the widely deployed Radar II, the Radar III integrates refined RF architecture, enhanced signal conditioning, and compact mechanical packaging—reducing footprint by 18% while improving thermal stability and electromagnetic immunity across extended temperature ranges.

Key Features

• True ground-speed measurement independent of tire diameter, inflation pressure, or surface adhesion—critical for volumetric material application control.
• Configurable output frequency scaling (e.g., 27.45 Hz/km·h⁻¹, 36.60 Hz/km·h⁻¹, 17.20 Hz/km·h⁻¹, or 10.25 Hz/km·h⁻¹) to match PLC or controller input requirements.
• Dual-voltage compatibility: supports unregulated 9–16 VDC (typical vehicular battery) and 18–32 VDC (industrial chassis bus) with current draw ≤0.6 A.
• Three selectable digital filtering modes—Slow (0.250 s time constant), Fast (0.060 s), and Ultra-Fast (0.014 s)—to optimize response dynamics for varying vehicle acceleration profiles and surface roughness conditions.
• Robust environmental sealing compliant with EN ISO 14982 and ASAE EP454, validated for continuous operation in salt-laden, dusty, wet, and chemically aggressive environments typical of highway construction zones.
• Integrated transient suppression and short-circuit protection on the output stage, meeting SAE J1113-11 and ISO 7637-2 for load-dump and inductive switching immunity.
• Fixed mounting geometry: nominal 35° downward tilt and 610 mm height above ground ensure optimal beam focus within the elliptical detection zone (major axis 546 mm, minor axis 368 mm).

Sample Compatibility & Compliance

The Radar III is designed exclusively for ground-relative speed measurement on paved, gravel, or compacted soil surfaces. It does not require retroreflective targets or surface preparation. Its 24.125 GHz band ensures minimal atmospheric attenuation and strong reflection from dielectric terrain materials. Regulatory compliance includes FCC Part 15 Subpart C (U.S.), Industry Canada RSS-210 (Canada), and CE marking under RED Directive 2014/53/EU. Electromagnetic compatibility is verified per EN 61326-1 (industrial environment) and EN 55011 (Class B emissions). Mechanical durability meets ISO 16750-3 for vibration (0.75 g RMS, 200–350 Hz; 3 g RMS, 351–2000 Hz) and ISO 16750-4 for shock (50 g, 11 ms half-sine). No user-serviceable parts; sealed housing prevents ingress of particulates or moisture under IP67-equivalent operational conditions.

Software & Data Management

The Radar III is a hardware-only analog/digital transducer with no embedded firmware, onboard memory, or communication interface (e.g., CAN, RS-485, or Ethernet). It delivers a clean, TTL-compatible 12 V square wave output (Pin 2) synchronized to instantaneous ground velocity. Integration requires external signal conditioning—typically via frequency-to-voltage conversion or direct pulse counting in a programmable logic controller (PLC) or motion controller. For traceability in regulated environments (e.g., DOT-mandated paving documentation), the sensor’s analog output may be logged alongside application rate data in SCADA or MES platforms compliant with FDA 21 CFR Part 11 when paired with audit-trail-capable controllers. Calibration verification is performed using certified speed references (e.g., fifth-wheel dynamometers per ASTM E1155) during system commissioning—not via field recalibration.

Applications

• Asphalt distributor trucks: closed-loop speed feedback for metered bitumen or emulsion application, ensuring consistent residual binder coverage per unit area.
• Chip seal and microsurfacing spreaders: synchronization of aggregate feed rate with vehicle velocity to maintain design gradation and embedment depth.
• Soil stabilizer and cold planer monitoring: real-time ground-speed validation for depth-controlled milling operations.
• Road marking vehicles: coordination of line thickness and spacing with forward velocity under variable traffic flow conditions.
• Autonomous pavement inspection platforms: primary speed reference where GPS-denied or multipath-prone urban corridors limit satellite navigation accuracy.

FAQ

Can the Radar III be used on snow-covered or icy surfaces?
Yes—its 24 GHz signal penetrates thin snow layers and reflects reliably off ice, though accuracy may degrade if surface reflectivity falls below −10 dB due to deep powder accumulation or water film interference.
Is the output signal compatible with Allen-Bradley ControlLogix PLCs?
Yes—the 12 V square wave output meets standard high-speed counter input specifications (e.g., 1756-HSC module) when wired with shielded twisted-pair cabling and proper grounding per NEMA ICS 61000-6-2.
Does the sensor require periodic recalibration?
No—Doppler radar physics is inherently stable; however, annual functional verification against a traceable speed standard is recommended for quality assurance programs aligned with ISO 9001 or AASHTO R 18.
What is the minimum detectable speed?
The lower threshold is 0.53 km/h (0.33 mph), limited by signal-to-noise ratio and internal low-frequency cutoff of the selected filter mode.
Can multiple Radar III units operate simultaneously on one vehicle?
Yes—units are electrically isolated and frequency-stable; no inter-unit interference occurs when installed with ≥300 mm lateral separation and standard mounting orientation.