Filter designer tool update#
Filter designer tool code#
Filter designer tool windows#

Here's another fun experiment that I did. In this static case, I just designed a band-reject filter around the higher frequency. This image shows the original signal (we've just been storing the maximum value at all FFT points since the start, so we turn on that plot curve) and the new signal through our filter.

Filter designer tool windows#

I've put a screen shot of both windows below. Whenever we design a new filter, we can immediately see the effects on the real signal that's running through GNU Radio. So when you run this program, both the filter design tool and the QT GUI window showing the signal pop up. We then have a function called 'update_filter' that is used as the callback function with the filter design tool. The filter starts of with just a single tap of 1, so it's really not doing any filtering. Two sinusoids are created at different frequencies, some channel noise is added to them, then they are passed through a filter and finally displayed on a QT GUI. So we built up an example (found in gr-filter/examples/gr_filtdes_live_upd.py) that constructs a simple flowgraph.

Filter designer tool update#

So what did I want to do? I wanted to do a live update of the filter on a live signal. Sreeraj also adds a callback function, so that every time the filter design is updated, this callback function is called and it is passed the filter object.

Filter designer tool code#

We launch the filter design tool from the program and can have it return the resulting filter to us in the code to use directly with our filters.

The gr_filter_design tool nicely ties into Python and GNU Radio projects. Each plot features zoom functionality to visually focus on relevant areas and allow for precision editing.Some quick work between myself and (mostly) Sreeraj helped me realize something that I instantly wanted to do with his new API for using gr_filter_design. The different plots can be exported into PDFs. The user can save individual filter designs. Alternatively, the code of a double precision MatlabВ®-Function, or C-function is provided and can be exported into a file. The resulting filter coefficients of the corresponding recursive time domain algorithm are available for further use and accessible by Copy&Paste. The filter function can be generated for signal postprocessing or for real time applications, where new data is entering the system at a given rate. The numerical stability of the resulting algorithm is calculated for a DOUBLE-precision implementation. The resulting filter algorithm can be realized in a normal form or a second order structure in the direct form 1 or direct form 2. The raw and the filtered signal are displayed either in the time or in the frequency domain (i.e spectral analysis). The test signal resembles either a shifted noisy sine wave, or a step, respectively, delta impulse signal. The resulting digital filter is instantaneously applied to a test-signal or an imported data set (csv, ascii, txt - format).

The design and simulation occurs in real-time and is done either by mouse or text input. The phase shift, the group delay and phase delay and the location of the poles and zeros of the transfer function are displayed along with the filter gain. It is structured into four views for designing the gain, analyzing the phase, simulating test signals, and generating code and filter coefficients.ДЇor a given filter brickwall specification of a digital lowpass, highpass, bandpass, or bandstop, it instantaneously finds the optimal Butterworth, Cheby-I, Cheby-II, or Elliptical filter of lowest order. > Check out the complete new FilterDesignLab-PRO in the AppStoreДЇilterDesignLab-IIR is a design and simulation environment for digital Infinite Impulse Response (IIR) filters.