Wavetronix SmartSensor Matrix Guia do Utilizador descarregar pdf (Página 112)

APPENDIX 111

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140

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Figure E.2 – Dual Approach Monitoring

Signal-to-Noise Ratio and the Stop bar Eect

e SmartSensor Matrix collects data beyond its advertised range. However, the signal-to-

noise ratio, or the signal-to-clutter ratio, is not large enough at the far ranges to consistently

detect a vehicle. is means that even though the sensor does detect some energy, the UI

doesn’t show constrained trackers.

is will normally not aect sensor performance for stop bar applications when the sensor

detects a stopped vehicle. However, the sensor does not allow new stopped trackers to be

created within a certain distance of the stop bar unless it has been detected for approxi-

mately 15 seconds. is feature allows the sensor to prevent slow moving objects, such as

pedestrians, bicycles and cars cutting the corner, from creating false detections. is is what

is referred to as the "stop bar eect."

Occlusion

Occlusion becomes a bigger problem the farther the range. In the intersection, it is compli-

cated by the fact that the vehicles can be stopped in a long queue, for example in a le hand

turn lane, and the sensor may never see a vehicle passing in a farther lane.

If the range to the sensor of an object is doubled, then the amount of ground range that can

be occluded by on object is also doubled.

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Wavetronix SmartSensor Matrix Guia do Utilizador Página 112