Cleber Borges

Thank you for the informations I have no problem with R. That's why I use it. I don't understand this diagram in SDK Ref Man. I don't know what calculations this diagram represents. By general formula I want to say the numerical way of making these modulations. Is there an online version (links) of this manual? I tried with those notes and got the coefficients shown in the graph. const test = "CCCBBB ||||||"; play (test); But the combination of the coefficients with the carrier is still a mystery. thanks Cleber Borges ########################################################## > res$rgAM [1] 1.0000000 1.0000000 1.0000000 1.0000000 1.0000000 1.0000000 0.8000000 0.6200000 0.4580000 [10] 0.3122000 0.1809800 0.0628820 -0.0434062 -0.1390656 -0.2251590 -0.3026431 -0.3723788 -0.4351409 [19] -0.4916268 -0.5424642 -0.5882177 -0.6293960 -0.6664564 -0.6998107 -0.7298297 -0.7568467 -0.7811620 [28] -0.8030458 -0.8227412 -0.8404671 -0.8564204 -0.8707784 > > res$rgFM [1] -0.7026982 -0.7026982 -0.7026982 -0.4387690 -0.4387690 -0.4387690 -0.4387690 -0.4387690 -0.4387690 [10] -0.4387690 -0.4387690 -0.4387690 -0.4387690 -0.4387690 -0.4387690 -0.4387690 -0.4387690 -0.4387690 [19] -0.4387690 -0.4387690 -0.4387690 -0.4387690 -0.4387690 -0.4387690 -0.4387690 -0.4387690 -0.4387690 [28] -0.4387690 -0.4387690 -0.4387690 -0.4387690 -0.4387690 ##########################################################

I would like to reproduce the script: "Wavegen Piano Script" in R language for learning purposes. The WaveForms script is on the Script => Example tab. ( It's a demonstration of how to use FM / AM ). I studied the script and I can see the coefficients given in the arrays: rgFM and rgAM in the "Custom" tab and I can export them to Clipboard. In R, I created the carrier signal like this: rate <- 44100 # the sampling rate dur <- 5.333 # duration time in seconds # Generate the carrier signal_carrier <- sin( seq( 0, 1760*dur*2*pi, length=rate*dur ) ) This way I can produce the sinusoidal signal with 235186 points. In R, I matched the size of rgAM and rgFM with the size of signal_carrier: coef_am <- approx( rgAM, n=length(signal_carrier) )$y coef_fm <- approx( rgFM, n=length(signal_carrier) )$y But my question is how to produce the resulting signal, that is, how to apply these coefficients. In my test, I simply multiplied both and made a graph. output <- signal_carrier * coef_am plot( output, t='l' ) The appearance of my graph is quite different from that generated by WaveForms (when I temporarily disabled the FM option). >--- PNG (bitmap) Graphic ---< As I have not yet understood the application of the rgAM coefficients, I have not applied the rgFM. (I also have doubts about this). So I ask questions: 1) Is there a general formula for doing both modulations in this example? 2) In WaveForms, do I have any option to export the output signal that is generated? I apologize for being such basic questions, but the goal is to learn. I thank you immediately for the information and attention. Thank you very much! Cleber Borges ps.: In R, I can test the signal directly to the speakers and compare the audios.

Hello @Andras ... Very cool your results ... This case study is very interesting! Have you considered putting all this information on a blog too? (It can be an inspiration and starting point for others).

Hello @Andras ... I think bubble formation is critical ... 1- Is CO2 forming? 2 - Just some other gas coming out? 3 - Yes, temperature is a critical parameter in measurements that require a lot of accuracy ... But I don't know how much temperature variation can affect a preliminary study that doesn't need as much precision and accuracy. Cleaning the electrodes I think is a good idea ... It would be nice to check how much influence on the results ...

Hello @Andras ... Actually, two parallel plates are enough as electrodes ... But always make sure that they are well fixed and constant as any change in geometry adjustment will cause a lot of variation in measurement. The arrangement would only need more sophistication if the electrode itself developed a chemical potential at its interface! Which is not the case here ... So I think your scheme is satisfactory. [ 1 ] I would like to know the results with your yeasts ... if you can post the results. Very good to see a case study. Thank you very much Cleber [ 1 ] - page 2 = *Two electrode setup* ( www.ecochemie.nl/download/Applicationnotes/Autolab_Application_Note_EC08.pdf ) ((( The two-electrode configuration can therefore be used whenever precise control of the interfacial potential across the WE electrochemical interface is not critical and the behavior of the whole cell is under investigation. )))

Hello @Andras ... Could you show how your electrode scheme looks? I think it is also geometry / electrode setup is a very important parameter. Very cool the results of your experiments ... In electrochemical impedance spectroscopy (EIS), I see that the voltage amplitudes are much smaller than you are using ... In general, the articles show that they are 100mV amplitudes due to problems with linearities in Nerst's law ... Have you tested at lower amplitudes? Thank you very much. Best regards, Cleber

hello @Andras ... My IA board (impedance analyzer) arrived a few days ago, but I did not even test it ... But now I have the AI board in my hands. Thanks for your attention. The IA board does not allow a reference electrode (RE) such as figure-item B. Such a scheme would be to not pass current between the working electrode (WE) and a reference electrode (RE). It would be to measure more accurately and discount several other effects in a more automated way. This scheme is not necessarily mandatory. You can use the scheme of just two electrodes as you mention. I am a chemist and I do not have much knowledge of the electrical / electronic part. I imagine that your measurements reflect well the salinity of the water tested. Actually, I think this device - AD2 - could provide a lot of chemical information of Impedance measurement, but I just started reading about it. It's great to know that more people are interested in AD2 and EIS ... so we can build a source of information. Regards, Cleber

@Andras I ordered the IA card and it took six months to arrive in Brazil. (Digilent-USA did not want to sell me direct for having representatives in Brazil) ... So I left the project temporarily ? I'm sorry you can not contribute information Cleber

Hello @attila, Good Morning, I imagined that using the reference resistors (such as the impedance analyzer extension board) could have been used the I-V method, since it would be easy to calculate the current value (I) ... But, given your explanation, I understand that the AI tool still uses the same method: Transfer Function Analysis (or the same as FRA - Frequency Response Analysis) ... [I needed this information to report] Thank you very much for your response and dedicated attention to this issue. Cleber Borges

Hello @attila Thank you for your consideration and for your response. My question is more about the theory itself. Since I have the Magnitude and Phase experimental measure, the rest of the properties are reasonably easy to calculate by a CAD (algebra software) My concern is to know what are the real limitations involved in measuring when I ask about fundamental differences.

Hello everyone, Reading about the EIS area - Electrochemcical Impedance Spectroscopy - I found that currently commercial potentiostats implement Impedance analysis by the method: FRA - Frequency Response Analyzer, also referred to as Transfer Function Analysis. As far as I understand, this method would be the same as the one implemented by the Network Analyzer tool in AD2 (am I right? ? ), since in its description it consists of: "The Network Analyzer is used to analyze transfer functions (the ratio between an output function and an input function)" If I can have the Impedance Analysis (measurement) implemented by the two tools: (i) Network Analyzer and (ii) Impedance Analyzer; with differences observed between the two tools, for example, in the frequency range: Network Analyzer = 2 mHz up to 10 MHz - and no "open" and "short" compensation option Impedance Analyzer = 200 uHz up to 25 MHz - and with "open" and "short" compensation option Which made me have the following doubts: [1] - What is the fundamental difference between them? [2] - I saw that the Impedance Analyzer tool forces the current calculation while the Network Analyzer emphasizes the voltage attenuation. But what is the implication of this? In the literature, I saw the defense of the FRA method based on measurement accuracy. The source signal is multiplied by the attenuated signal and the result is given from this combination. [3] - Does the Network Analyzer tool algorithm follow this form? [4] - In the WaveForm examples, there is the use of reference resistors for use of the Network Analyzer tool. Is it mandatory to use them or can you close the circuit by connecting to Ground-GND? Many thanks for your attention and patience! These details may be basic to those trained in electronics, but it is difficult to find them in referrals from other areas. And it certainly makes all the difference trying to do the measurement correctly. Once again: thank you! Cleber Borges

Hello @attila, I'm seeing the updates now ... Thank you very much for the new limits and Nyquist Plot. :-) the item: 1) - Wavegen, Network/Impedance Analyzer: external Amplification option Will it be possible to have tips in the future? the item: 2) Sound Card device CPU usage: I'm still looking for where to see this feature! ... :-) The AWG for my sound card worked fine in the line-in (Scope) thank you so much Cleber Borges

Ok, I got it. :-) @attila Very cool. A voltage divider is a really a simple solution. Some more questions: 1 - For amplification would a very well specified OpAmp be needed? Is transistor amplification n 2 - Some details of the sound card appear in the image: is 32bits or float more advantageous? 3 - In "WaveForms - Network" there is option of Nyquist Plot as visualization mode. Is it possible to access this view also in "Impedance"? Many thanks Cleber Borges

in addition: In the Biology and Food Sciences, the 1MHz to 20MHz region is widely used for viable cell counts - VCC [2] [2] - Electrical impedance spectroscopy (EIS) for biological analysis and food characterization: a review J. Sens. Sens. Syst., 6, 303-325, 2017 https://doi.org/10.5194/jsss-6-303-2017

Hello @attila Good Morning Thanks for your response and patience :-) I am a Professor of Chemistry (University Researcher in Brazil) and I am interested in the area of: EIS - Electrochemical Impedance Spectroscopy ( below SITE reference in [1] ). In an EIS study, the frequency region of 100kHz to 1uHz is very common. It is the current practice of this area. The amplitude of the signal is a few millivolts. Usually it's 10mV. So my interest in low frequencies and low amplitudes In WaveForms Help - AD2 (item 5: AWG) says: The resolution is ~0.7 mV for amplitudes above 1 V, and ~0.18 mV for amplitudes of 1 V and lower. Does the AD2 and sound card achieve a higher resolution than this? Because I see that the low frequency is not limiting but the signal resolution at 10mV seems to me to be near the limit. I am a layman in the subject and I am still starting in EIS but I think that the hardware and the software could also be very useful in this field :-) !!! Thanks again for your dedication! Cleber Borges [1] - https://en.wikipedia.org/wiki/Dielectric_spectroscopy

In the AWG tool it is possible to set a wave with a minimum frequency of 100 uHz. In the Impedance tool it is only possible to set a wave with a minimum frequency of 1 mHz. What is the reason for this limitation for the generated wave in Impedance? Thank you for your attention Cleber Borges