Hi I am detecting a weak signal, so I calculate spectra with GRC's FFT block, and then I calculate an average over hundreds of spectra by using a self-written embedded Python block.
Within each run of the work-function of my Python block, 'input_items' consists of several spectra, from 2 up to about 15. I am calculating the average until the spectrum has good enough signal-to-noise ratio. When calculating the average, I am continuously plotting the average spectrum by using 'QT GUI vector sink'. There is no need to update the plot very quickly, so it is enough if the 'output_items' of the work-function consists of only one spectrum, the current average spectrum. Thus, I want to use the basic block as the type of my Python block. Below you can find the basic elements of my Python block. The 'output_items[0]' consists of only one vector, as it should be, because len(output_items[0]) = 1 and len(output_items[0][0]) = 1024 Then flowgraph runs without errors, but the plot of the spectra (QT GUI vector sink) shows only a flat line, so something is wrong. I am using Gnuradio 3.9.5.0 (Python 3.8.10) in Ubuntu 20.04.4 LTS Cheers, Kimmo -------------------------------------------------------- class Main_control(gr.basic_block): def __init__(self, vec_length=1024,..., parameter_n=N): gr.basic_block.__init__(self, name="Averaging spectra", in_sig = [(np.float32, vec_length)], out_sig = [(np.float32, vec_length)]) self.vec_length = vec_length ... self.parameter_n = parameter_n def general_work(self, input_items, output_items): # the average spectrum is calculated here, it is given in the # vector 'average_spectrum', with a length of 1024. output_items[0] = [average_spectrum] self.consume(0, len(input_items[0])) return 1
