28 November 2019
Using sensing analytics to provide complex intrusion detection in tunnels
Unauthorised access into tunnels is a major concern for railway or subway operators; people can be injured, infrastructure can be damaged incurring extra maintenance cost, and intrusions can lead to a security risk. What is already a difficult task becomes even more challenging when there is a moving vehicle in the tunnel.
Sensing analytics to cope with challenging environments
Railway or subway tunnels are enclosed, echoey, dark and often humid spaces. Laser sensors are not affected by lighting conditions which makes them ideal for these applications. Additionally, OPTEX Lasers feature environmental analytics enabling the area of detection to be adjusted, to auto-learn changes to the environment, and to indicate to the security control system if its ability to detect is affected by, for instance, a soiled lens. Such ‘health monitoring analytics’ provide the security operator with peace of mind.
Size and distance analytics
OPTEX LiDARs analyse the speed, size and distance of the objects detected, meaning they track the objects within the detection area and understand the ratio size/distance of the object, so it can accurately detect a specific size of object at distance and close up – in this application it can distinguish between humans and trains.
Bespoke algorithm
For a successful ‘tunnel intrusion detection’, the solution is required to ignore the trains but detect people, and this was achieved by developing a bespoke detection algorithm for our long range REDSCAN 3060 series. If a moving object the size of a train enters the tunnel no alarm is generated, but if an object the size of a human enters the tunnel, even if a train was entering at the same time, then an alarm is generated.
Detection speed
The speed of detection is another important factor for the application to be successful, as it is difficult for any system to detect fast moving objects. Part of the requirement was to test if the LiDAR could detect a person running inside the tunnel when a train was entering at the same time. And thanks to the scanning speed of the Laser sensor, this criteria was also achieved.
For more information about this application and any other specific detection requirements, please contact us.
SMDA logic (Super Multidimension Analysis)
Years of experience in outdoor detection and feedback from customers made us aware of the challenges of outdoor detection: temperature changes, vegetation, noise and small animals are factors that can confuse many sensors and generate false alarms.
SMDA Logic (Super Multidimension Analysis) brought the ultimate sensitivity optimisation to PIRs and created what we call ‘intelligent detection’. Sensors equipped with SMDA logic feature a digital microprocessor with the ability to analyse the signal received and differentiates the ones generated by moving people and/ or vehicles from the ones generated by other environment conditions, or animals. This intelligence makes the sensor very stable and the risk of false alarm very low.
SMDA logic was first introduced in the FTN series - short range curtain detection - in 2009 and has since become a standard feature in all our PIR outdoor sensors, including our best-selling VX Infinity series and the recently launched WX Infinity and WX Shield series.
Top benefits of SMDA logic
- Frequency analysis: SMDA Logic adjusts the sensitivity level to avoid catching vegetation sway, but not to miss human movement.
- Temperature compensation: When background temperature is nearly equal to human temperature, SMDA logic adjusts the sensitivity to satisfy detection.
- Noise cancellation: by analysing detection patterns and environmental information, SMDA improves immunity against various noise factors such as sunlight or animals and can distinguish between the cause of nuisance false alarms and genuine intrusions.
Tech tip: Winter maintenance for IR beams
Winter has arrived in the Northern hemisphere and cold weather, especially frost, can impact the functioning of infrared beams; and so can the deposit of salt or grit on the beams cover. It is a good time to check that all is working as it should.
Wireless beams
- Clean the beam cover:
Salt, mud, grit can sit on the beam cover and affect the detection performance, it is recommended to clean them with a damp cloth. - Check the batteries:
By using a multimeter you should check the batteries are between 3.5 and 3.6 Volt - Check the DQ, environmental trouble is working. The best way to test is to cover the beam with a plastic bag and see if the “trouble” output has been triggered.
Please note that heaters cannot be fitted in battery-powered beams, as the power provided by the batteries isn’t enough.
Hardwired beams
- Clean the beam cover as indicated above
- Check the DQ is working in the same qway as indicated above
- If the beams are installed in an area prone to frost, it is recommended to add heaters.
The heaters HU-3 comes in pack of two units. For the short range AX beams, one pack suffices for the pair of beams. For the long range SL infrared beams, it is recommended to have two heaters in each beam (one at the top and one at the bottom) so two HU-3 should be ordered.
Please note that heaters required 24V DC/ 1A power supply per beam, so it is important to check which power supply is in use before adding the heaters.
Hardwired beam towers
OPTEX’s pre-built, hardwired beam towers come automatically with heaters and thermostat to prevent any risk of frost.
- Clean the beam tower’s cover with a damp cloth
- Check the DQ is working as described in previous section
- Check the tamper is working:
The best way to check is to open the cover, push the tamper switch while measuring the continuity loop with your multimeter. You should hear a continuous beep to indicate it is working. Please refer to the diagram above. - Check the anti-climb tamper is working
Press the anti-climb tamper switch and similar to the previous point, measure with your multimeter the 'Anti-climb' Continuity loop. To check the tamper and anti-climb tamper, make sure the multimeter is on the continuity settings - Test the heaters
The easiest way to test the heater is to press the “Heater Test” button on the thermostat (refer to the diagram above)
If you would like further advice on OPTEX’s IR beams, please contact us here and our tech team will be happy to help.