Automatic gate sensors are a critical part of any automated gate system. They can open your automatic gates when they sense your proximity, and just as importantly they can prevent the gates from closing when you’re only part way through.
But what types of automatic gate sensors exist and how do they work?
Short and Sweet: How Automatic Gate Sensors Work
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Automatic gate sensors function by detecting the presence of vehicles, people or other objects. This information is fed back to the controller, so that appropriate action can be taken.
A good example would be if your car stalls while you’re driving through your automatic gates. Clearly it would be quite dangerous in this situation if the gates began to close again with your vehicle still in the way. In this case, therefore, the sensors would detect that the gateway wasn’t yet clear, and so would prevent the gates from closing on you.
Equally, automatic gate sensors can be used to open your gates when installed correctly. This is particularly useful when it comes to exiting your property. Your automatic gates can be set to open when they sense your approach from the inside – allowing you to easily leave.
Most Common Types of Automatic Gate Sensor
While there are numerous automatic gate sensors on the market they largely fall into two different categories: contact sensors and non-contact sensors. As their names suggest, they work in different ways.
A contact sensor will sense contact. An example of this might be a pressure sensor on your driveway. As you drive up to your gate from the inside, the pressure from your vehicle triggers the gates to open.
In contrast a non-contact sensor will detect changes to light, heat or other factors in the vicinity. When the change meets the preset threshold then a message is sent that action is required.
Both these sensors can be useful depending on the situation though broadly non-contact sensors are more popular. This is because they lend themselves to a greater range of situations and they are typically less intrusive and expensive to install.
Common examples of non-contact automatic gate sensors are:
- Infrared gate sensors
- Microwave gate sensors
How Different Types of Automatic Gate Sensors Work
Now we know the basics of what automatic gate sensors do, and the different types on the market, let’s now turn our attention to a more detailed investigation. How do each of the popular automatic gate sensor types actually work in practice?
How Infrared Automatic Gate Sensors Work
Infrared gate sensors function using the same principles as many home security systems and motion-detection outdoor lights. Infrared waves are better known to people like you and me as “heat”. In essence an infrared gate sensor monitors nearby temperature changes that indicate a person or vehicle may be nearby.
However there is an important distinction to make here. There are two types of infrared gate sensors, and they both work in slightly different ways. This means one may be more suited than the other for your unique situation.
How Active Infrared Automatic Gate Sensors Work
The first “subcategory” of infrared gate sensors is known as an active infrared sensor. Active infrared gate sensors send out a beam of infrared light which is undetectable to the eye. A sensor monitors the infrared waves being reflected back from surrounding objects.
As one might expect, a person or vehicle approaching the invisible beam will result in changes to the waves being detected by the sensor. This can then trigger an event such as opening the automatic gate.
Due to their nature, active infrared automatic gate sensors can be programmed very precisely. For example the beam may be directed specifically to detect vehicles approaching from a certain direction.
How Passive Infrared Automatic Gate Sensors Work
Passive infrared gate sensors, often known by the acronym PIR, do away with the infrared production utilized by active systems. Instead, a passive infrared sensor simply monitors ambient infrared light in the vicinity.
A person approaching the gate will naturally be warmer than the surrounding area, so should trigger the sensor when they get within range.
How Microwave Automatic Gate Sensors Work
Microwave gate sensors work by pulsing out a beam of invisible microwaves. These microwaves bounce off nearby objects and are then reflected back into the sensor.
This “image” creates a baseline for the gate sensor. When changes are detected the sensor will be triggered, though you have some control over the sensitivity of the device.
In this way a completely clear driveway, versus one in which you’ve driven up the gate, will look very different indeed to the system.
While in many ways infrared and microwave gate sensors sound very similar in their activity there are some critical differences that may make one option more suitable than others.
Generally microwave sensors are able to detect motion from a greater distance. The microwave beams are able to pass through solid objects like walls, making them incredibly sensitive to nearby movement. In fact, for some instances, microwave sensors may be too sensitive. For example if your driveway opens onto a busy road there is a risk that the non-stop passing cars and pedestrians may continually trigger your sensors.
In contrast infrared sensors tend to be less sensitive. Depending on the situation this may be a positive or negative trait. It is worth noting that the way infrared sensors monitor temperature means they can be rather less reliable in different seasons. They can particularly struggle as ambient temperatures increase, reducing the temperature difference between people and the environment.
How Contact Automatic Gate Sensors Work
As the name suggests, contact gate sensors work by sensing contact – typically changes in pressure. Contact gate sensors typically do this by circulating a low voltage current. When contact is made to the sensor, it disrupts this electrical current and so triggers the sensor.
One common example might be the placement of a contact sensor on your driveway, so the gates can sense when your vehicle is approaching. Another good example could be sensors on the gates themselves, that stop the gates from closing any further if they come into contact with an obstacle.
Conclusion
Automatic gate sensors work by detecting motion (microwaves), heat (infrared) or contact (pressure). Each type of sensor has their unique strengths and weaknesses, depending on your situation and how you plan to use your automatic gates. It would be wrong to say that either is “better” than another.
Just as importantly, automatic gate sensors don’t necessarily need to be an either-or situation. It is quite common to use a range of different sensors to ensure your gates function exactly as you’d like irrespective of season, weather conditions and so on.