Dec 20, 2010 Replies: 79 A new B4X FFT library does exits, the library in this thread is only valid for B4A. The ownership of this post has been changed by Erel from agraham to klaus, with agrahams agreement, to allow me to edit this post with the update of the FFT library. agrahams original text. About nine months ago Klaus and I collaborated on a Basic4ppc library and demonstration program to perform forward and inverse Fast Fourier Transforms. We have collaborated once again to port the library and demo to Basic4android. Update 2014.08.03 The library has been updated after the bug report here. The demo program has been 'rewritten' to take advantage of the B4A improvements since december 2010. Attachments FFT_lib_V1_2.zip FFT_lib_V1_2.zip 4.7 KB · Views: 1,457 FFTDemoV1_2.zip FFTDemoV1_2.zip 25 KB · Views: 1,383 Time1.png 51.7 KB · Views: 1,708 FFT1.png 47.4 KB · Views: 1,725 List.png 72.8 KB · Views: 1,536 Last edited: Feb 27, 2020 Click to expand...
A new B4X FFT library does exits, the library in this thread is only valid for B4A. The ownership of this post has been changed by Erel from agraham to klaus, with agrahams agreement, to allow me to edit this post with the update of the FFT library. agrahams original text. About nine months ago Klaus and I collaborated on a Basic4ppc library and demonstration program to perform forward and inverse Fast Fourier Transforms. We have collaborated once again to port the library and demo to Basic4android. Update 2014.08.03 The library has been updated after the bug report here. The demo program has been 'rewritten' to take advantage of the B4A improvements since december 2010.
maso1975 Member Licensed User Longtime User Mar 21, 2014 #41 Now that you mention it I'm not sure, I have made a modification to the code to add the Thread.Start, but I get the same results. Code: Sub Button1_Click AR.Initialize(AudioSource,SampleRate,ChannelConfig,AudioFormat,BufferSize) AR.StartRecording StartTime = DateTime.Now Record.Start(Record,"FreqDetect",Null) ' FreqDetect End Sub Attachments FreqDetect.zip FreqDetect.zip 454.7 KB · Views: 656
Now that you mention it I'm not sure, I have made a modification to the code to add the Thread.Start, but I get the same results. Code: Sub Button1_Click AR.Initialize(AudioSource,SampleRate,ChannelConfig,AudioFormat,BufferSize) AR.StartRecording StartTime = DateTime.Now Record.Start(Record,"FreqDetect",Null) ' FreqDetect End Sub
klaus Expert Licensed User Longtime User Mar 23, 2014 #42 Attached you find a small test project. It is based on your FreqDetect program. I had never used the AudioRecord library, so I had to learn and it took some time. In the attached program you can : - Record record a sound with the mic, it shows the time signal. - Calc calculate a theroretical 'sound', I needed this to make sure that the time signal is well known and the peak detector works. - Time display the time signal - FFT display the frequency signal - Moving the finger on the diplay shows a cursor and displays the values. - The first Spinner holds the peaks found. - The second Spinner allows to change the threashold for peak detection. The display doesn't show all the time and frequency samples but only the first which fit into the display. The red vertical line shows the cursor position. The red horizontal line shows the threashold level. The signal in the display is just wistling. The problems in your code were: - You converted Bytes into Doubles, but the sample size is 2 Bytes so Shorts. - Buffersize too small, you read only 4096 samples. Attachments FFT_Freq_Detect1.png 41.4 KB · Views: 955 FFT_Freq_Detect2.png 27.9 KB · Views: 892 FFT_Freq_Detect.zip FFT_Freq_Detect.zip 14.6 KB · Views: 760 Last edited: Mar 23, 2014
Attached you find a small test project. It is based on your FreqDetect program. I had never used the AudioRecord library, so I had to learn and it took some time. In the attached program you can : - Record record a sound with the mic, it shows the time signal. - Calc calculate a theroretical 'sound', I needed this to make sure that the time signal is well known and the peak detector works. - Time display the time signal - FFT display the frequency signal - Moving the finger on the diplay shows a cursor and displays the values. - The first Spinner holds the peaks found. - The second Spinner allows to change the threashold for peak detection. The display doesn't show all the time and frequency samples but only the first which fit into the display. The red vertical line shows the cursor position. The red horizontal line shows the threashold level. The signal in the display is just wistling. The problems in your code were: - You converted Bytes into Doubles, but the sample size is 2 Bytes so Shorts. - Buffersize too small, you read only 4096 samples.
maso1975 Member Licensed User Longtime User Mar 24, 2014 #43 Hi Klaus, thank you for your help, and I'm sure other users will thank also, seemed easier than it is, I'll experiment a bit with his example. Regards, and thanks again for your time.
Hi Klaus, thank you for your help, and I'm sure other users will thank also, seemed easier than it is, I'll experiment a bit with his example. Regards, and thanks again for your time.
T T0mee Member Licensed User Longtime User Apr 26, 2014 #44 I got an array containing values received from my heart-rate-sensor. It contains the time measured between every heart beat (i.e. 700 - 1100 [ms]). Now I would like to calculate the LF (< 0,15 hz) and the HF (> 0,15 hz - 0,4 hz) of the spectrum ...can anybody help me out ?
I got an array containing values received from my heart-rate-sensor. It contains the time measured between every heart beat (i.e. 700 - 1100 [ms]). Now I would like to calculate the LF (< 0,15 hz) and the HF (> 0,15 hz - 0,4 hz) of the spectrum ...can anybody help me out ?
klaus Expert Licensed User Longtime User Apr 26, 2014 #45 Could you post a sample file ? And I'll have a look at it. Not sur if the FFT library is of any help here.
Could you post a sample file ? And I'll have a look at it. Not sur if the FFT library is of any help here.
T T0mee Member Licensed User Longtime User Apr 26, 2014 #46 klaus said: Could you post a sample file ? And I'll have a look at it. Not sur if the FFT library is of any help here. Click to expand... I used File.WriteList to create the file ...it contains 400 of the time spaces between my heart-beats. Attachments Intervals.txt Intervals.txt 1.6 KB · Views: 590
klaus said: Could you post a sample file ? And I'll have a look at it. Not sur if the FFT library is of any help here. Click to expand... I used File.WriteList to create the file ...it contains 400 of the time spaces between my heart-beats.
T T0mee Member Licensed User Longtime User Apr 26, 2014 #47 I attached a screenshot of the results calculated by Kubios (a HRV Software) ...i used the 400 intervals from the 'Intervals.txt'-file. Attachments Intervals.jpg 302.7 KB · Views: 822
I attached a screenshot of the results calculated by Kubios (a HRV Software) ...i used the 400 intervals from the 'Intervals.txt'-file.
klaus Expert Licensed User Longtime User Apr 26, 2014 #48 Well, You say: It contains the time measured between every heart beat (i.e. 700 - 1100 [ms]). Click to expand... - What exactly do the values in the file represent ? The time between the beats ? Or some other value with a given time interval between the values ? If the signal is a time signal, with a constant time interval between samples, the FFT could be used, otherwise it is more a statistics probelm.
Well, You say: It contains the time measured between every heart beat (i.e. 700 - 1100 [ms]). Click to expand... - What exactly do the values in the file represent ? The time between the beats ? Or some other value with a given time interval between the values ? If the signal is a time signal, with a constant time interval between samples, the FFT could be used, otherwise it is more a statistics probelm.
T T0mee Member Licensed User Longtime User Apr 26, 2014 #49 The values represent the time between the beats.
klaus Expert Licensed User Longtime User Apr 26, 2014 #50 Please leave me some time to look at it, I have some other problems to solve before.
klaus Expert Licensed User Longtime User Apr 29, 2014 #51 Below you see a screenshot on what I get til now. The top diagram shows the rate intervals, the data from your file. The middle diagram shows the heart rates. The botton diagram shows the FFT of the rate intervals. This is an attempt to generate diagrams similar to the ones in your post. The FFT doesn't look exactly like in your screenshot, but is relatively close, and I don't know either how the LF and HF values are extracted from the FFT. Do you have any information on how the FFT is calculated and how to define LF and HF ? Attached you find the test program in its current stage. Attachments Screenshot.png 18.1 KB · Views: 772 HeartRate.zip HeartRate.zip 13.7 KB · Views: 615
Below you see a screenshot on what I get til now. The top diagram shows the rate intervals, the data from your file. The middle diagram shows the heart rates. The botton diagram shows the FFT of the rate intervals. This is an attempt to generate diagrams similar to the ones in your post. The FFT doesn't look exactly like in your screenshot, but is relatively close, and I don't know either how the LF and HF values are extracted from the FFT. Do you have any information on how the FFT is calculated and how to define LF and HF ? Attached you find the test program in its current stage.
T T0mee Member Licensed User Longtime User May 1, 2014 #52 Hello Klaus, thank you very much for helping me. I am really happy about this result! Unfortunately, I got no information how the FFT is calculated or how the LF/HF values are extracted - and I can't find more information in the internet. All I got is the 'Analysis Options' you have seen in the Kubios-Screenshot and this part of a publication: The spectral components were obtained by harmonic Fourier analysis in the 0.0033–0.5 Hz frequency range, with the power reflecting the square of the amplitudes (Luczak and Laurig, 1973). LF and HF power were calculated by integrating the spectra over the 0.04–0.15 Hz and 0.15–0.40 Hz ranges, respectively (Bigger et al., 1992), and corrected for the square of the mean heart rate (Baharav et al., 1995). Thus, the resulting power was unitless. I want the software to calculate the LF/HF ratio to get more (+better) information about the vns and stress. Again, thank you very much for your help! I could not have done this... If I am right, I can now take the output of your test-program and integrate the values to calculate the LF/HF ratio.
Hello Klaus, thank you very much for helping me. I am really happy about this result! Unfortunately, I got no information how the FFT is calculated or how the LF/HF values are extracted - and I can't find more information in the internet. All I got is the 'Analysis Options' you have seen in the Kubios-Screenshot and this part of a publication: The spectral components were obtained by harmonic Fourier analysis in the 0.0033–0.5 Hz frequency range, with the power reflecting the square of the amplitudes (Luczak and Laurig, 1973). LF and HF power were calculated by integrating the spectra over the 0.04–0.15 Hz and 0.15–0.40 Hz ranges, respectively (Bigger et al., 1992), and corrected for the square of the mean heart rate (Baharav et al., 1995). Thus, the resulting power was unitless. I want the software to calculate the LF/HF ratio to get more (+better) information about the vns and stress. Again, thank you very much for your help! I could not have done this... If I am right, I can now take the output of your test-program and integrate the values to calculate the LF/HF ratio.
klaus Expert Licensed User Longtime User May 1, 2014 #53 If I am right, I can now take the output of your test-program and integrate the values to calculate the LF/HF ratio. Click to expand... I think so. In FFTAmpl you have the amplitudes and with i / NbSamples * RateMean you get the x axis unit.
If I am right, I can now take the output of your test-program and integrate the values to calculate the LF/HF ratio. Click to expand... I think so. In FFTAmpl you have the amplitudes and with i / NbSamples * RateMean you get the x axis unit.
PhilipK Member Licensed User Longtime User Dec 4, 2014 #54 Hi, I am in the process of implementing your fantastic FFT routine. I'm passing an array of data which is a stream of single values (as doubles) called DataFFT Successive streams are of different lengths (by design). So when the DataFFT max array index is an odd number, I adjust the index to (index-1) and then divide by 2 to get and set the array size for FFTReal and FFTImag. OK? On execution, I'm getting an error on the line: FFT.Transform2(DataFFT, FFTReal, FFTImag) "FFT: Real and Imaginary arrays are incorrect length!' Any ideas? Many thanks.
Hi, I am in the process of implementing your fantastic FFT routine. I'm passing an array of data which is a stream of single values (as doubles) called DataFFT Successive streams are of different lengths (by design). So when the DataFFT max array index is an odd number, I adjust the index to (index-1) and then divide by 2 to get and set the array size for FFTReal and FFTImag. OK? On execution, I'm getting an error on the line: FFT.Transform2(DataFFT, FFTReal, FFTImag) "FFT: Real and Imaginary arrays are incorrect length!' Any ideas? Many thanks.
klaus Expert Licensed User Longtime User Dec 4, 2014 #55 The size N of DataFFT must be a power of 2 (128, 256, 512, 1024 etc)! Then, the size of FFTReal and FFTImag must be N/2 + 1.
The size N of DataFFT must be a power of 2 (128, 256, 512, 1024 etc)! Then, the size of FFTReal and FFTImag must be N/2 + 1.
PhilipK Member Licensed User Longtime User Dec 4, 2014 #56 Klaus AAArrrgh, so ridiculously obvious it's embarrassing! I was thinking it was more complex..... Wood and Trees come to mind. I won't be getting any stars for that!!! As usual, many thanks, PhilipK
Klaus AAArrrgh, so ridiculously obvious it's embarrassing! I was thinking it was more complex..... Wood and Trees come to mind. I won't be getting any stars for that!!! As usual, many thanks, PhilipK
freedom2000 Well-Known Member Licensed User Longtime User Dec 11, 2014 #57 klaus said: Attached you find a small test project. It is based on your FreqDetect program. I had never used the AudioRecord library, so I had to learn and it took some time. In the attached program you can : - Record record a sound with the mic, it shows the time signal. - Calc calculate a theroretical 'sound', I needed this to make sure that the time signal is well known and the peak detector works. - Time display the time signal - FFT display the frequency signal - Moving the finger on the diplay shows a cursor and displays the values. - The first Spinner holds the peaks found. - The second Spinner allows to change the threashold for peak detection. The display doesn't show all the time and frequency samples but only the first which fit into the display. The red vertical line shows the cursor position. The red horizontal line shows the threashold level. The signal in the display is just wistling. The problems in your code were: - You converted Bytes into Doubles, but the sample size is 2 Bytes so Shorts. - Buffersize too small, you read only 4096 samples. Click to expand... HI Klaus, I am looking for the audiorecord library. I found one here https://www.b4x.com/android/forum/threads/audiorecord-library.13993/#content But it is not working with your code (not the same arguments) Please could you tell me which is the right one ? Thanks
klaus said: Attached you find a small test project. It is based on your FreqDetect program. I had never used the AudioRecord library, so I had to learn and it took some time. In the attached program you can : - Record record a sound with the mic, it shows the time signal. - Calc calculate a theroretical 'sound', I needed this to make sure that the time signal is well known and the peak detector works. - Time display the time signal - FFT display the frequency signal - Moving the finger on the diplay shows a cursor and displays the values. - The first Spinner holds the peaks found. - The second Spinner allows to change the threashold for peak detection. The display doesn't show all the time and frequency samples but only the first which fit into the display. The red vertical line shows the cursor position. The red horizontal line shows the threashold level. The signal in the display is just wistling. The problems in your code were: - You converted Bytes into Doubles, but the sample size is 2 Bytes so Shorts. - Buffersize too small, you read only 4096 samples. Click to expand... HI Klaus, I am looking for the audiorecord library. I found one here https://www.b4x.com/android/forum/threads/audiorecord-library.13993/#content But it is not working with your code (not the same arguments) Please could you tell me which is the right one ? Thanks
freedom2000 Well-Known Member Licensed User Longtime User Dec 11, 2014 #58 freedom2000 said: HI Klaus, I am looking for the audiorecord library. I found one here https://www.b4x.com/android/forum/threads/audiorecord-library.13993/#content But it is not working with your code (not the same arguments) Please could you tell me which is the right one ? Thanks Click to expand... Ok I found that the threading lib had been updated...
freedom2000 said: HI Klaus, I am looking for the audiorecord library. I found one here https://www.b4x.com/android/forum/threads/audiorecord-library.13993/#content But it is not working with your code (not the same arguments) Please could you tell me which is the right one ? Thanks Click to expand... Ok I found that the threading lib had been updated...
daniel69 Member Licensed User Longtime User Feb 7, 2015 #59 Hi Klaus! Any ios version of your FFT lib?
klaus Expert Licensed User Longtime User Feb 9, 2015 #60 Not in a near future. I will look to make a Class, no time schedule, I don't have the knowledge to write libraries. Just to be clear, the library was written by Andrew Graham (agraham). I made a small change in the library, and as Andrew is now less active in the forum Erel changed the ownership of the first post from agraham to mine (with Andrews agreement) to let me update the first post. I wrote the demo program.
Not in a near future. I will look to make a Class, no time schedule, I don't have the knowledge to write libraries. Just to be clear, the library was written by Andrew Graham (agraham). I made a small change in the library, and as Andrew is now less active in the forum Erel changed the ownership of the first post from agraham to mine (with Andrews agreement) to let me update the first post. I wrote the demo program.
