[Homer-users] Data acquisition via Homer2

[Hörmetjan Yiltiz]

Hi,

We are using CW6 devices by Techen for our studies using fNIRS in China.
The agent company in China provided us with some compiled executables which
can be used to configure the source/detector probe maps (SD files) and
another one with similar GUI with Homer2 to acquire the fNIRS raw data.

I think this should be a standard way of acquiring the data from CW6 using
Homer2. However, they told us that the executable used for acquiring the
data is not open sourced (nor free software as in freedom) so that I am
unable to inspect the code to understand exactly what happens for the *raw*
data just after it is acquired by the detectors.

Suppose we have a simple probe as below, with detectors D1, D2 and source
SA and SB with 3cm distance between each adjacent combination. The line
indicates a channel defined by the SD file.

D1 ---  SA   D2 -- SB
    CHN1        CHN2

So, detector D2 not only receives light emitted form source SB as expected,
it is also able to and will receive light emitted form source SA. So how
exactly (it is just said via *intensity modulation* in the User Manual,
without the specific parameters and exact algorithm).

This question is not trivial since we are using a probe such as this:

D1    D2
  \    /
   \  /
    x
   /  \
  /    \
S1   S2

And we are worried whether signals that goes through the same location of
the brain will get corrupted by each other. The technician assured us that
they won't, yet I still would love to understand how exactly is that
achieved.

Is it that the sources emits lasers with different intensity or pulses with
different frequencies so that after the detectors receive the lights, the
signals are decomposed using Fourier transformation or alike?


​Best
，
========================
He who is worthy to receive his days and nights is worthy to receive* all
else* from you (and me).
                                                 The Prophet, Gibran Kahlil
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