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Sensor · Passive radar

Silent Sentry (legacy)

Lockheed Martin · United States

The original commercially launched passive radar — Lockheed Martin Mission Systems, 1998. Uses FM radio and analogue TV signals (40–100 MHz). Detects aircraft, helicopters, cruise missiles, ballistic missiles, RPVs / drones. Update rate 200+ tracks at 8 Hz; total system fits in ~27 sq ft. Two antenna variants: 360° four-beam Adcock array, and 100°/six-beam linear array. Range up to ~100 nautical miles. Programme dormant but the architectural reference for everything that followed.

CountryUnited States
SubcategoryRF / SIGINT detection
Price$3–5M historical (per system)
SubtypePassive radar
Form factor~100 NM · 200 tracks/8 Hz
UseAir surveillance
TypePassive
SWaPVME rack; transit cases; 1.5 kW 120V; 1-2 person setup
Sensor modalityFM/TV PCL
Notable partnersDeveloped by Lockheed Martin Mission Systems (Gaithersburg, MD); research partnership with University of Illinois; US gov customers (confidential)
Coverage3D
Scan typePassive
MountingFixed/mast, Vehicle
ArchitecturePassive Coherent Location exploiting FM/TV broadcast transmitters; COTS, no moving parts
Output dataPosition, Velocity, Altitude, Track ID
Frequency (GHz)~40-100 MHz FM/TV illuminators
Active/PassivePassive
Update/revisit rateContinuous (no moving parts)
Detection range (km)278
Tx power & licensingNo transmitter; covert; no emission licensing
Detection range (km)278
Integration interfacesSilent Sentry track format or OTH Gold; Link 16/XML planned
All-weather / day-nightAll-weather, day & night
Angular accuracy/resolution150 m horizontal, 1000 m vertical (FM)
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Review-stage catalogue data — specs corroborated from manufacturer and secondary sources; not for procurement decisions. Source: www.lockheedmartin.com