RF-based Motion/Proximity Detection

The patent-pending Newtrax RF-based Motion/Proximity Detection technology monitors the signal distortions caused by the environment through which RF electromagnetic waves propagate to detect aperiodic motion and proximity of objects.

Comparing Newtrax RF sensor with sensors based on other physical phenomena

 
RF sensor
Radar Thermal Magnetic Acoustic Seismic
Orientation invariant (3D) yes     yes    
No line-of-sight shadowing yes yes   yes yes yes
Wide area influence field yes yes     yes yes
Multiple sensors can coexist in same area yes   yes yes yes yes
Reasonable signal processing yes yes yes yes yes  
Ultra low power
(<1mW)
yes   yes yes yes  
Extended operating temperature range
(-40°C to +85°C)
yes yes   yes yes yes
No special packaging required yes yes   yes    
Low cost yes   yes yes yes  

Patterns extracted by the Newtrax RF-based Motion/Proximity Detection expert system

RF senor patterns

Technology benefits

Excellent probability of detection
  • 3D vigilance, reliable performance across industrial temperature range of -40C to +85C, unconstrained by shadowing of objects, wide area of influence and takes advantage of mesh network for redundant coverage.
Energy efficient
  • Reuses the periodic/aperiodic packet transmissions required for network control or data transfers for detection. The only additional energy consumption is the expert system processing on the microcontroller.
Cost effective
  • Reuses the same microcontroller, transceiver and antenna used for communications. No modifications to hardware is required.

Application

Borders, perimeters and battlefields

Automatic activation/deactivation of infrared, magnetic, acoustic and geophone sensors based on the presence/absence of motion in the surrounding environment;

Underground mines

Automatic activation/deactivation of the ad hoc network discovery protocols required for tracking of personnel and vehicles based on the presence/absence of nomadic nodes in the tunnel;

Intermodal supply chains

Automatic activation/deactivation of new node ad hoc network discovery protocols and of six-sides integrity sensors based on the presence/absence of motion in the surrounding environment;

Technical overview

Variations in RF Received Signal Strength (RSS) are caused by noise, third party communications and multipath fading/construction.

The Newtrax RF volumetric intrusion detection expert system firmware embedded in Newtrax Wireless Nodes analyses the RSS measurements within the Newtrax low energy ad hoc wireless Mesh/FHSS network (Figure 2) to extract aperiodic multipath fading/construction variations potentially caused by a large object entering the environment through which the RF waves propagate.

The Newtrax expert system then applies pattern recognition algorithms to the extracted signal component to detect intrusions (Figure 1). For example, thresholds on the amplitude of variations enables discrimination of temperature fluctuations, effect of wind on foliage, etc. from intrusions by large objects like humans, vehicles, containers, etc..

Newtrax FHSS provides up to 75 RSS measurements per second over 64 frequency channels in the 902-928 MHz band

RF senor patterns