A man placing a call on a Guardian Wave by using the active infrared sensor



By delving into the intricacies of active infrared and radar sensors, and carefully evaluating their strengths and weaknesses in in pedestrian push button (PPB) and accessible pedestrian signal (APS) applications, users can make well-informed decisions when selecting the optimal product for their requirements. With a plethora of touchless actuation products featuring various sensors available in the market, the choice between an active infrared sensor and a radar sensor can profoundly influence the reliability and effectiveness of a product. While both technologies diligently detect motion, the crux lies in selecting the most suitable technology for the task at hand. Through a comprehensive understanding of the nuances inherent to each sensor type, users can aptly discern which technology aligns best with their specific needs.


Theoretical Application of the Technology

Both active infrared sensors and radar can be used in a multitude of applications. Radar Technology is currently taking over with “the global radar sensors market size was exhibited at USD 13.11 billion in 2023 and is projected to hit around USD 39.37 billion by 2032, growing at a CAGR of 13%”. Whereas active infrared technology is much more niche with “the global infrared sensors market size reached US$ 582.8 million in 2022 and is poised to soar by 6.1% CAGR, anticipated to transcend to US$ 1.1 billion by 2033”.

Broadly speaking, several pivotal factors delineate the disparities between these two types of technology. Among the primary distinctions are:

  • Detection of Motion and Presence
    • Active infrared sensors transmit known infrared signals and look for reflections from nearby objects. Since these changes are typically caused by movement or presence, the sensors can provide reliable detection of new objects within their area. Conversely, radar sensors detect motion using the Doppler principle to determine the object’s motion. The radar transmits a 24 GHz waveform and reflects off an object that is in motion within the sensor’s field of view.
  • Detection Range:
    • Active infrared sensors are optimized for a much smaller detection range as they operate in a specific wavelength range, which minimizes interference from other sources of radiation, such as visible light or radio waves. Whereas radar sensors emit radar radiation to detect motion. However, because their detection range is much larger, they can be susceptible to outside prevalence frequencies.
  • Susceptibility to Environmental Factors:
    • Active infrared sensors are very successful in outdoor environments as they are extremely hard to be affected by environmental factors like temperature fluctuations, humidity, or precipitation. On the other hand, radar sensors are very susceptible to environmental factors specifically extreme temperature fluctuations or precipitation.
  • Installation Simplicity:
    • Active infrared sensors are generally easy to install and immediately foster accurate results. On the contrary, proper installation is crucial for the reliable operation of radar sensors. Incorrect placement or alignment can result in poor performance and obstacles near the sensor can block or reflect the radar signals, affecting its accuracy.
  • Cost-Effectiveness:
    • Active infrared sensors are very cost-effective compared to radar sensors, making them a superior choice for various applications where reliability is essential but budget constraints exist.


Which is better for APS and PPB Applications?

The reliability of a sensor hinges on a myriad of factors, including its intended application, prevailing environmental conditions, and the intricacies of installation. In the realm of pedestrian push buttons (PPB) and accessible pedestrian signals (APS), the choice between radar sensors and active infrared sensors is pivotal. While both technologies can be employed, their disparities play a crucial role in determining which is better suited for detecting motion from individuals intending to place a call for crossing.

Radar sensors boast a larger detection range in comparison compared to active infrared sensors, but this expanded scope can inadvertently lead to an increased incidence of false calls, as any motion within range triggers detection. Moreover, radar sensors are far more susceptible to environmental factors therefore complicating their reliability.

Alternatively, active infrared sensors offer a precise detection capability within a defined beam area, ideal for scenarios where pinpoint accuracy in detecting pedestrian presence is paramount, such as at intersections with heavy traffic. They are less prone to triggering false calls due to environmental factors (rain, snow, or hail) or nearby movements compared to radar sensors, ensuring heightened reliability.

In addition, active infrared sensors exhibit ease of installation and economical technology which further seats them above that which radar sensors have to offer. With outstanding energy efficiency, they are the ideal choice for applications where energy conservation is a priority, particularly in solar-powered systems.


A Deeper Look at APS Devices with Each Type of Sensor

  • Temperature Variability Performance
    • Active infrared sensor APS: The sensor will work across all temperature ranges ensuring NEMA TS2 temperature range compliance.
    • Radar Sensor APS: Touchless actuation will work as specified only within the temperature range of -4°F to +140°F. Meaning the sensor is not NEMA TS2 compliant.
  • Installation Process
    • Active Infrared Sensor APS: All products are shipped to the user after being factory-configured and virtually never need field adjustment.
    • Radar Sensor APS: A configuration process is required after the installation of the APS is complete because the radar antenna is affected by nearby metal. Proper completion of this is crucial as it will further determine what calls will be detected.
  • Weatherability
    • Active Infrared Sensor APS: The sensor will not actuate from motion from the weather, and cannot be set off by rain, snow, hail, or ice, implementing continual use during all weather conditions.
    • Radar Sensor APS: A rain lockout feature is triggered temporarily disabling the sensor during instances of precipitation because water will always be detected. Meaning, that when it rains, the sensor becomes unusable as it will place calls from the detection of something as simple as a raindrop.
  • Extended Press Functionality
    • Active Infrared Sensor APS: The sensor detects presence, whether or not the object is moving. The extended press function is intuitive meaning it will be activated by simply holding your hand in place without having to constantly move it with the hope it registers the motion in full.
    • Radar Sensor APS: Radar sensors only detect motion. Meaning, that when the extended press feature is needed, a person would have to wave their hand at the sensor continuously until registered.



Ultimately, the choice between radar sensors and active infrared sensors for APS and PPB shouldn’t come down to the product, but the reliability and functionality of the products technology. Radar sensors, while widely used, can face challenges in APS and PPB applications as they are much more compromised by external factors. While radar sensors do provide a much larger detection range this feature is ultimately a drawback in the particular application as false calls can be placed without intention. Inversely, active infrared sensors offer precision accuracy, stability, and reliability, as well as being the more feasible choice between the two.