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KPVA - RATP Patent
| Summary |
The RATP has equipped all of its subway lines with a point control (K) independent speed system further to the derailing in 2000 of a subway train at the Notre Dame de Lorette station. There are currently 230 KPVA Beacon in service on the Paris subway system in certain zones considered critical. The KPVA is an system that is integrated into a Beacon installed on the track and that measures the train’s speed with a DOPPLER radar and stops it if it exceeds the speed allowed with an onboard RPS system. KPVA advantages include its speedy operations, low cost and significant reliability.
The KPVA Beacon is protected by an RATP patent and is manufactured by TLTI.
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The KPVA on its base |
The KPVA |
KPVA has two integrated radars
Speed measurement radar
When a radar points at a moving target, the frequency of the reflected wave is out of phase with the emission. This difference (Doppler shift) depends on the speed of the target. This Doppler shift also depends on the direction in which the target is moving in relation to the radar beam.
A radar is composed of the following items:
- A microwave part, a transmitter and a receiver,
- Signal treatment to measure the Doppler shift and thereby estimate the speed of the target’s movement.
The speed measurement radar integrated into the KPVA installed on the track targets the front of the train, and detects and measures the speed of the train arriving on the relevant track.
The measurement is taken rapidly and requires less than 10 m of movement over the rack.
The radar’s scope can be adjusted from 0 m to approximately 25 m.
The radar must not detect trains on neighboring tracks, whether they are coming or going.
The radar complies with all the requirements of equipment installed on tracks, in particular the RATP radio frequency plan.
Speed Radar
Presence Sensing Radar
The presence sensing radar targets upwards and detects the passing of the train above a sensor by detecting the movement of the ground crossed under the train: pipes and axles are easy to detect. It is based on a 24 GHz Doppler sensor.
The variation in the power of the signal is therefore used to detect the object.
Presence sensing radar
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