Re: Interpolating FIR Filter - sample delay

[Cinaed Simson]

Hi - first, it appears you're using version 3.7.x of gnuradio which is no longer supported. The constellation encoder for your version appears as a missing block on 3.8.

Second, there was no constellation posted for some reason.

Third, it appears you're using 2 stream sources and a streaming mux and then tagging on the packet_length - but it's difficult to figure out what's going on with the missing block.

Try using the tag probe and floats - and keep it simple.
 
See

   https://wiki.gnuradio.org/index.php?title=File:Tags_interp.grc.png

And see

    https://wiki.gnuradio.org/index.php/Simulation_example:_BPSK_Demodulation

for first step in BPSK demodulation.

-- Cinaed

On 4/22/22 02:32, Marcin Puchlik via GNU Radio, the Free & Open-Source Toolkit for Software Radio wrote:

Hello 

I was playing with the Interpolating FIR Filter Block and noticed that the mentioned filter delays tags not properly. What I mean is that when the interpolation factor is different than 1, then the filter delays the tags by the Sample Delay * Interpolation factor value. In my opinion this is not correct behavior. Group delay of the filter is constant and the interpolation factor shouldn't affect the process of delaying the tags. Below, I am attaching the plot and GRC flowgraph which demonstrate the problem and where you can see the observed behavior. 

Number of the taps in RRC filter used in the simulation: 41

Group delay: 20

Actual group delay: 40

What do you think?