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    Perfect Livio. You understand very well. Solo 3 electrodes, no switch. We must reinvent an ECG that would need calibration systems and appropriate filters to eliminate spurious frequencies and pulse. It's fine Theremino the ECG. It's a great monitor the heart activity. A system for the measurement of HRV is really interesting for a number of domestic applications and for biofeedback. Work could implement the plugin in the future if the soft runs well.


    Allow me to disagree, of course, only from a personal point of view. If someone wants to take new paths to reach the same end because stop him?
    Lots of inventions have started with this spirit.
    Then maybe it reveals a hole in it, if you can find a new and more efficient method?
    It will always valid the old definitely efficient and effective method.
    So why complicate life?
    It would be so even if someone in order to show that the earth was not flat had not discovered the Americas, who made him do it to experience at its diametrically opposite theory to practice.
    Having said this, I repeat that this is only my personal opinion and everyone is free to do and think about what feels right.
    It is understood that I follow the discussion but, merely from the standpoint of general culture, I have no expertise in this field.


    Amilcare you're right.
    In looking straight ahead I did not think to look sideways.
    I agree with what you write.


    I think as often happens, the right is in the middle.

    This discussion was created for the measurement of HRV, and then the intervention of Lorenzo is formally correct, when it advised to limit the choice and placement of functionally for that purpose electrodes.
    However, I believe that a deepening electrodes on the subject, mainly done by Lorenzo, who is well informed, It has been invaluable.
    As far as I'm concerned, well be simplified positioning lil, because ultimately what we want to achieve is just a simple system for everyone.
    I therefore propose to continue in this direction, and possibly open a separate discussion with regard to the ECG reading 'classical'.
    Before use in the direction of the electrodes in contact, there, however I would like to expose my point of view the use of relatively low-resistance electrodes towards the skin to make measurements.
    The low resistance, if on the one hand allows to acquire very weak signals while limiting losses, the other opens the way to the risk of electrocution, when the device connected to the person under examination is not built according to strict safety and safeguard criteria.
    As I have written in the past regarding the e-meter made Theremino, also here I would recommend the use of a laptop exclusively battery powered which also supplies the interface, so you do not have any links with the 220V power line.
    Livio in the past had also experienced non-contact electrodes, which were quite promising and solved some problems, as the conductivity of the skin and the isolation of the subject from the measurement system.

    Said this, I would say that the next step is that each experimenter must have an interface between the body and the system Theremino.
    The card AD8232 is cheap enough to be able to have all, does not require to be specially built and allows low so that a common basis for comparing the results.
    Once acquired (and I do not talk about Lawrence, obviously, but mostly me) sufficient ability to place the electrodes and to obtain reliable readings, we can begin to put his hand to the program, which unfortunately I can not do myself, It will be a burden that will fall on the shoulders of Livio, when you have time.
    I can act as beta testers independently, and exhibit in this case the views and impressions of a non-expert user.

    Lorenzo, could you tell us what you'd expect to see in the program, and how to calculate it?
    In your opinion, It simply makes small works of adaptation to the existing program graphic, or is it better to create a different graphics?

    Thanks for your help


    Given that Amilcare is indeed right in its observation I think the focus should be on the calculation of the HRV. I would leave the Theremino ECG program so as not to touch anything. It's just perfect and hardly perfectible. I believe that Livio could use it as a template for a new program for the calculation of the HRV according to the mathematical analysis presented by Maurizio in the post opening and by Fourier analysis on only one parameter RR. Livy does not need my advice knows what to do. I want to better think and then I could give some suggestions. I need a few days because they are pretty messed up with work. If I send someone a sample image as I do? Images can be posted here? No thanks to me! I really enjoy! I wish I had your talents I worked in VBasic but now are too distracted by other things demanding. However, I also want to buy the AD8232 module. Tomorrow I order.


    To post pictures the easiest way is upload them to a hosting site, Once loaded copy the direct link that return you.
    What you can safely use here using the function img present in the top box you use to write messages.
    Simply click on the box [ img ] and paste the link there.
    I use usually but that's great any other hosting you prefer


    This morning I cut a little’ time for this search.
    First of all, I found a site Lorenzo intervention Theremino, and report here some salient passages (Here is the full discussion

    “I see that the system allows to measure the average heart rate calculated on 1 minute (Heart Rate), but in the soft Theremino ECG screen appears (between a heartbeat and the other) the number of the given time elapsed in milliseconds. This is a very important measure because it allows you to measure Heart Rate Variability (ENG).
    Looking at the circuit diagram published in your site the HRV would be measured as well:
    In practice, it returns the square of the difference in milliseconds of the time elapsed between a beat and the next. It is now understood that the heartbeat (as the average rate per minute) can not change (or change little) between one minute and the next (in the published image HR = 82 / min), but the variability of the duration between the various beats varies greatly (64, 4096 e 1764) !!!. I think the trick of squaring the result to be done to get more positive numbers HRV.”
    “I wish you would read this and other reference which carry the link (but there are many others on the web):
    Good, once you obtained a long series of values ​​of HRV (one for each pair of beats) these are facts "digest" by a soft which makes the analysis in time and so you get the maximum expressiveness of the data obtained.”

    Livio responds with some tips on how to achieve the desired readings, and notes that the spectrum analysis is already implemented in some applications Theremino, such as WaveAnalyzer.

    Well, This morning I re-read the information in the link Lorenzo, and then I downloaded WaveAnalyzer, with the intention of doing some proof.
    In fact, I thought I had found a way quite simple:
    – a small change to Theremino ECG, which calculates the HRV with the square, as suggested by Lorenzo, and he writes the values ​​obtained on a slot. The transmission frequency would be the same as the heart rate, so it should not exceed, normally, i 150 Hz, well below the 800 fps del sistema Theremino.
    – a small change to Theremino WaveAnalyzer, HRV values ​​that reads directly from the slot and makes the spectral analysis.
    Unfortunately, I saw that in WaveAnalyzer there is a minimum attendance analyzable, equal to 0,1 Hz, which is the minimum acceptable value the box Min Freq dell'FHT spectrum.
    In the link posted by Lorenzo, They are defined as three frequency range:
    VLF = 0.0033-0.03
    LF = 0.03-0.15
    HF = 0.15-0.40
    Practically, WaveAnalyzer as it is written at the time, It can only analyze the values ​​in the HF range.
    I opened the source of WaveAnalyzer and I changed the properties of the box because they also agree to the values ​​needed for this analysis, but the spectrum displayed starts in each case from just above 0,1 Hz.
    Then, before proceeding with any changes to the software, I ask Livio, author program, which is the reason for this limitation, and whether it is possible to modify it for the analysis of HRV.

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