Re: F-SCAN II User Input Needed

I have posted here on this forum and extensively on the Yahoo FScan forum about the F-Scan2. I bought mine last year in April and have studied the electronic circuitry of the F-Scan2. The F-Scan2 has a design flaw since it does not limit the bandwidth before the ADC digitized the DC voltage that is picked up with the finger electrode.

There are some pictures of the older filter that I built for the F-Scan2 on this forum as well.

On the FScan forum you find several PDF documents that summarize my findings. In addition, I designed a filter that can be plugged into the F-Scan2 and no soldering or such is necessary. It will eliminate the so-called 'repeat pattern' that occurs every 1365Hz, which is the sampling freqeuncy of the ADC. This artifact can be understood as 'aliasing', which occurs because the bandwidth is not limited. The filter is a 5-pole Bessel filter with a -3dB point set at about 100Hz. Frequencies higher than 220Hz are suppressed while the DC voltage is not affected. The limited bandwidth does NOT mean that it will limit useable frequncies in DIRPs to below 200Hz!

You need to understand how the DIRP works. This is explained in detail in the PDF documents on the FScan forum.

With the filter I have had some interesting results, which I also posted on the FScan forum. I have uploaded several Excel spreadsheets on the FScan forum with these DIRP scans. However, for unknown reasons, I 'flatline' so I seem not to get any peaks during DIRPs. This is not because of the filter, since it works well with other test persons! I am puzzled about that and if anyone has an idea, please let me know. I am quite healthy and eat right.

If you want to contact me privately about the filter, e-mail me.

With best regards,

Stephan


PS: If you click on my name in this post 'All Stephan2's Messages', then you will find my past posts. There is one recent post (15 days old from the date of this one) that is about my new internal filter. Somehow it did not get posted correctly on this forum, maybe I made a mistake during the post.