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README improved.
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antirez committed Dec 30, 2022
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Expand Up @@ -29,13 +29,17 @@ how things work just grepping inside.
In order to show unknown signals, the application attempts to understand if
the samples obtained by the Flipper API (a series of pulses that are high
or low, and with different duration in microseconds) look like belonging to
a legitimate signal, and aren't just noise. We can't make assumptions about
a legitimate signal, and aren't just noise.

We can't make assumptions about
the encoding and the data rate of the communication, so we use a simple
but relatively effective algorithm. As we check the signal, we try to detect
long parts of it that are composed of pulses roughly classifiable into
a maximum of three different classes of lengths, plus or minus 10%. Most
encodings are somewhat self-clocked, so they tend to have just two or
three classes of pulse lengths. However often pulses of the same theoretical
three classes of pulse lengths.

However often pulses of the same theoretical
length have slightly different lenghts in the case of high and low level
(RF on or off), so we classify them separately for robustness.

Expand All @@ -51,6 +55,14 @@ Under the detected sequence, you will see a small triangle marking a
specific sample. This mark means that the sequence looked coherent up
to that point, and starting from there it could be just noise.

In the bottom-right corner the application displays an amount of time
in microseconds. This is the average length of the shortest pulse length
detected among the three classes. Usually the *data rate* of the protocol
is something like `1000000/this-number*2`, but it depends on the encoding
and could actually be `1000000/this-number*N` with `N > 2` (here 1000000
is the number of microseconds in one second, and N is the number of clock
cycles needed to represent a bit).

Things to investigate:

* Many cheap remotes (gate openers, remotes, ...) are on the 433.92Mhz or nearby and use OOK modulation.
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