Band-Pass Filter on GNU Radio

As we know Wireless technology has made communication a lot easier with its better efficiency and ease of accessibility. But this wireless technology can be made even more efficient with the help of Band-Pass Filters.

Filters are a deliberate manipulation or rejection of frequencies to make it more favorable to the receiver. There are a number of filters available and one of them is the Band-Pass filter.

With the help of Band-Pass Filter the GNU Radio application can be made a lot more efficient. Before we go in to the use of Band-Pass Filter in GNU Radio, let us see what GNU Radio is,

GNU Radio is an open source software tool that provides signal processing blocks to implement communication and signal system applications. And now we will discuss about how to implement the Band-Pass filter in GNU Radio platform.

Let’s understand how Band-pass filter works

A Band-Pass Filter is a device that passes only some band of frequencies by attenuating other bands.


Now let’s have a look on the Circuit

By seeing the circuit diagram below, it tells us that the Band-Pass Filter can be made by combining low pass and high pass filters. Unlike a Low-Pass filter that only pass signals of a low frequency range and High-Pass filter which pass signals of a higher frequency range, a Band-Pass Filters passes signals only within a certain band of frequencies without adding extra noise to input.


Bandwidth is commonly defined as the frequency range that exists between two cut-off frequencies (ƒc).

Bandwidth of Band-Pass Filter is given by BW = ƒH – ƒL.


  • ƒL is the lower -3dB cut-off frequency point
  • ƒH is the upper -3db cut-off frequency point

Some applications of Band-Pass Filters

  • Band-Pass Filters are widely used in wireless transmitters and receivers.
  • In a receiver, a Band-Pass Filter allows signals within a selected range of frequencies to be heard or decoded
  • A Band-Pass Filter also optimizes the signal-to-noise ratio and sensitivity of a receiver.

To learn more about the working of Band-Pass Filter in GNU Radio companion, please click on the link for the application note below,

Band-Pass Filter on GNU Radio by Rakesh S K

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