50/60Hz Notch Filter: The Interference Inhibitor

Electrical Room

Power Line Interference

Power line noise can interfere with electrical, radio and TV signals. This noise is typically exhibited near power lines or power sources and is extremely frustrating when trying to make sensitive measurements at low voltages. Depending on your geographic location, this AC induced noise is typically at either 50Hz or 60Hz.

Many systems are generally noisy and power line interference just ‘blends’ in. But what about systems making highly accurate pressure measurements, thus requiring a very low noise floor? In these systems the power line noise can become dominant to the signal you are measuring. This can result in a humming sound in a radio broadcast, blur in a video stream or the inability to accurately measure pressures in a sensor system.

When it comes to making accurate measurements with high resolution pressure sensors the impact of this power line noise can be significant. To make precise measurements, you need to isolate the noise at these frequencies and eliminate it. The most common way to eliminate this AC noise is by adding a 50Hz or 60Hz notch filter to your product. A notch filter rejects the signals within a specified narrow band of frequencies and only allows signals outside of that band to be passed along.

Most electrical systems and household appliances emit this power grid noise at the 50Hz or 60Hz frequency. This is why, for example, your cell phone or WiFi signal weakens when you are near certain appliances in your home. Engineers need to design/implement a notch filter circuit in order to block out those suspect frequencies. This is typically done via an external circuit to the pressure sensor.

The NimbleSenseTM Integrated 50Hz/60Hz Notch Filter

Incorporated into all our industrial pressure sensors, Superior Sensor Technology’s NimbleSense architecture is a fully integrated sub-system that combines processing intelligence with signal path integration and proprietary algorithms to create modular building blocks that are easily selectable to support a wide array of applications. One of the building block components in NimbleSense is an integrated 50Hz/60Hz notch filter.

As all of Superior’s pressure sensors have an extremely low noise floor, theoretically power line interference can be ‘heard’ when taking measurements. The integrated 50Hz/60Hz notch filter eliminates this noise so you maintain the advantage of having such a low noise floor pressure sensor without any external interference. With the notch filter seamlessly integrated in the differential pressure sensor module, the sensor blocks out the interference caused by these frequencies before it reaches the user application. Further, as the notch filter is internal to the sensor module, it eliminates the need for an engineer to design and implement an external notch filter. This feature removes an external notch filter, so the overall system is more efficient, more reliable and less costly.

Summary of Benefits

The NimbleSense integrated 50Hz/60Hz notch filter can be beneficial for products that operate near power lines, a power source or are coupled through a power supply, such as industrial devices and HVAC systems.

To summarize the benefits of the NimbleSense integrated 50Hz/60Hz notch filter:

  1. Eliminate the noise from the power grid and AC devices before it reaches the sensing element.
  2. Simplify your product design with an integrated approach.
  3. Speed your time to market by not having to design and/or implement an external notch filter.
  4. Lower overall system cost as an external notch filter is no longer required.


Superior Sensor’s 50/60Hz notch filter is available on the following product lines:

If you have an application that has a challenging noise environment and can benefit from a lower noise floor, please contact us so we can discuss how to best implement the NimbleSense integrated 50Hz/60Hz notch filter with our advanced digital filtering capability into your product to achieve maximum overall system performance.

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