Hi Marcin,
Thank you very much! I found my error, I forgot the "gain" which is the
first parameter to the filter. The first parameter I wrote in the filter
method was the "sample_rate" (which was a large number), hence the filter
function could not converge. It is all good now, thank you.
I have two questions related to the remez filter (you may or maynot be able
to give me an answer(s)):
Q1. If I write a line of code to extract the remez taps, say:
lpfilter =
gr::filter::pm_remez ( int order,
const std::vector< double > & bands,
const std::vector< double > & ampl,
const std::vector< double > & error_weight,
const std::string filter_type = "bandpass",
int grid_density = 16
)
The pm_remez has a squidly line under it and if I hover it with the mouse,
it says gr::filter has no member function pm_remez. (I tried a bunch of
different variations of things, but the squidly line remains.)
Q2. The doc write up states that the pm_remez filter_types are one of:
bandpass, hilbert or differentiator. It seems like a natural for all these
filters to provide a lowpass option, what do you think? If I can get rid of
the squidly line, I would be able to test if "lowpass" works.
Thanks again for all your help.
Regards,
George
On Wed, Feb 23, 2022 at 2:02 AM Marcin Puchlik <m.puch...@is-wireless.com>
wrote:
> George,
> Running the below code:
>
>
>
>
>
>
>
>
>
>
>
>
> *#include <iostream>#include <gnuradio/filter/firdes.h>using namespace
> std;int main() { cout << "!!!Hello World!!!" << endl; // prints !!!Hello
> World!!! std::vector<float> taps = gr::filter::firdes::low_pass(1, 1, 0.3,
> 0.1); for(int i = 0; i < taps.size(); i++) cout << "tap " << i << ":" <<
> "\t" << taps[i] << "\n"; return 0;}*
>
> *I get the output:*
>
> !!!Hello World!!!
> tap 0: -0.00124749
> tap 1: 0.0026334
> tap 2: -3.313e-18
> tap 3: -0.00722382
> tap 4: 0.00725102
> tap 5: 0.0112526
> tap 6: -0.0272494
> tap 7: 1.54168e-17
> tap 8: 0.0582835
> tap 9: -0.0539706
> tap 10: -0.0877955
> tap 11: 0.298026
> tap 12: 0.600081
> tap 13: 0.298026
> tap 14: -0.0877955
> tap 15: -0.0539706
> tap 16: 0.0582835
> tap 17: 1.54168e-17
> tap 18: -0.0272494
> tap 19: 0.0112526
> tap 20: 0.00725102
> tap 21: -0.00722382
> tap 22: -3.313e-18
> tap 23: 0.0026334
> tap 24: -0.00124749
>
>
>
>
> śr., 23 lut 2022 o 02:39 George Edwards <gedwards....@gmail.com>
> napisał(a):
>
>> Hi Marcin and Vasil,
>>
>> Thank you guys very much!
>>
>> Marcin: I did as you suggested and left out win_type and beta.
>> Vasil: Based on the conversation exchanges between you Marcin, I followed
>> your suggestion to link in the gnuradio-filter library - in
>> lib/CMakeLists.txt in target_link_libraries() by adding gnuradio-filter.
>> Thus, the target_link_libraries in the original OOT lib/CMakeLists.txt
>> file was:
>> target_link_libraries(gnuradio-ge_filters gnuradio::gnuradio-runtime)
>> and I added to it as shown below:
>> target_link_libraries(gnuradio-ge_filters gnuradio::gnuradio-runtime
>> gnuradio-filter)
>> The OOT program compiles and makes the intended Gnuradio block for me to
>> load in a GRC flowgraph. For experimental purposes, I made the OOT block to
>> output the filter coefficients. When I run the grc, the lowpass filter
>> outputs all zeros, so something is wrong!
>> Marcin: You had written a piece of code to print "Hello World". Please
>> run your code to print out the returned filter coefficients and let me know
>> if it works well because mine is having some problems.
>>
>> This is how I invoked the filter method (all parameters are defined):
>> vector <float> lpfilter; //vector variable will contain the filter
>> coeff's
>> lpfilter = gr::filter::firdes::low_pass(gain, sampling_freq, cutoff_freq,
>> transition_bandwidth);
>>
>> Thank you guys!
>>
>> George
>>
>>
>> On Tue, Feb 22, 2022 at 3:41 PM Marcin Puchlik <m.puch...@is-wireless.com>
>> wrote:
>>
>>> Geroge,
>>> I posted the working code a few messages ago. Try to check this out. BTW
>>> as far as I can see those two arguments are optional (window type and
>>> beta). Try to run your code without them and check if it works.
>>>
>>>
>>> wt., 22 lut 2022 o 19:25 George Edwards <gedwards....@gmail.com>
>>> napisał(a):
>>>
>>>> Hello Vasil and Marcin,
>>>>
>>>> Thanks very much for your help.
>>>>
>>>> I have all the relevant #include header files and invoke the low_pass
>>>> filter as follows:
>>>> lpfilter = gr::filter::firdes::low_pass(gain, sampling_freq,
>>>> cutoff_freq, transition_bandwidth,
>>>> fft::window::win_type::WIN_HAMMING, beta);
>>>>
>>>> Observations:
>>>> Using the mouse to hover over WIN_HAMMING, I can see that it
>>>> interprets the win_type enum variable and correctly assigns it a value of
>>>> "0" (which is the value stated in the Gnuradio C++ API Reference manual).
>>>> However, there is a squidly under beta. Hovering over beta, the error
>>>> message is:
>>>> Argument of type "double" is incompatible with parameter of type
>>>> "gr::fft::window::win_type"
>>>>
>>>> If one of you has a working code fragment using one of the C++
>>>> Gnuradio filter methods that you can cut, paste and send in your next email
>>>> I would appreciate it.
>>>>
>>>> Thanks for your help.
>>>>
>>>> George
>>>>
>>>> On Tue, Feb 22, 2022 at 6:15 AM Vasil Velichkov <vvvelich...@gmail.com>
>>>> wrote:
>>>>
>>>>> Hi George,
>>>>>
>>>>> On 21/02/2022 18.31, George Edwards wrote:
>>>>> > lpfilter = gr::filter::firdes::low_pass(gain, sampling_freq,
>>>>> cutoff_freq, transition_bandwidth,
>>>>> > fft::window::win_type <
>>>>> https://www.gnuradio.org/doc/doxygen/classgr_1_1fft_1_1window.html#a599d7e9625d6cc77203a8b877c4911e2>window
>>>>> = fft::window::win_type::WIN_HAMMING, beta = 6.76);
>>>>> >
>>>>> > This failed and showed a squidly across the line with
>>>>> fft::window::win_type....!
>>>>>
>>>>> Try adding "gr::" before "fft::window" and make sure
>>>>> gnuradio/fft/window.h is included.
>>>>>
>>>>> #include <gnuradio/fft/window.h>
>>>>>
>>>>> lpfilter = gr::filter::firdes::low_pass(gain, sampling_freq,
>>>>> cutoff_freq, transition_bandwidth,
>>>>> gr::fft::window::win_type window =
>>>>> fft::window::win_type::WIN_HAMMING, beta = 6.76);
>>>>>
>>>>> If this does not fix it then provide the exact error you are getting.
>>>>>
>>>>> Regards,
>>>>> Vasil
>>>>>
>>>>
