Method for detecting the presence of ice crystals in an environment
The invention relates to a method for detecting the presence of ice crystals in an environment, implemented by a detection device in relative motion with respect to said environment, said method comprising at least: an emission step, in which at least one optical radiation is emitted by the detection device into the environment; a reception step, in which at least a portion of the emitted optical radiation is received, a step of calculating a comparison signal, and a step of calculating the noise of the comparison signal, a thresholding step, in which the noise is compared to a defined threshold, a communication step, in which a signal indicating detection of the presence of ice crystals in the environment is transmitted when the noise is greater than the defined threshold.
1. Method for detecting the presence of ice crystals in an environment, implemented by a detection device in relative motion with respect to said environment, said method comprising at least:
an emission step, in which at least one optical radiation is emitted by the detection device into the environment;
a reception step, in which at least a portion of the emitted optical radiation is received by the detection device, said at least a portion of the received radiation including rays within a first wavelength band (λ 1 ) and rays within a second wavelength band (λ 2 );
characterized in that the detection method further comprises at least:
a calculation step, in which the detection device calculates a comparison signal (Comp(t)) representative of the contrast, said contrast being obtained from the following formula:
Comp
(
t
)
=
R
λ
2
(
t
)
-
R
λ
1
(
t
)
R
λ
2
(
t
)
+
R
λ
1
(
t
)
where R λ1 (t) is the intensity over time t of the rays within the first wavelength band (λ 1 ) and R λ2 (t) is the intensity over time of the rays within the second wavelength band (λ 2 ), and
a noise calculation step, in which a noise (B) of the comparison signal (Comp(t)) is calculated,
a thresholding step, in which the noise (B) is compared to a defined threshold (S),
a communication step, in which a signal indicating detection of the presence of ice crystals in the environment is transmitted when the noise (B) is greater than the defined threshold (S).
2. Detection method according to claim 1 , wherein the detection method further comprises at least:
a sampling step, in which a time window (FT i ) is defined.
3. Detection method according to claim 1 , wherein the detection method further comprises at least:
a continuation step, in which a next time window (FT i+1 ) shifted in time by a duration (D) with respect to time window (FT i ) is considered, and/or
a loop step, in which the noise calculation step and the thresholding step are repeated.
4. Detection method according to claim 3 , wherein the shift duration (D) is less than the duration of the time window.
5. Detection method according to claim 3 , wherein the detection method further comprises at least:
an incrementing step, in which a value (Cj) of a counter is incremented when the noise (B) is greater than the defined threshold (S), and/or
a confirmation step, in which the value (Cj) of the counter is compared to a triggering threshold (Sa).
6. Detection method according to claim 5 , wherein the communication step, is transmitted when the value (Cj) of the counter is greater than the triggering threshold (Sa).
7. Detection method according to claim 6 , wherein the detection method further comprises at least:
a reset step, in which the counter value (Cj) is initialized to zero.
8. Detection method according to claim 1 , wherein the noise calculation step comprises a step of calculating a standard deviation of the comparison signal (Comp(t)) in the time window considered.
9. Detection method according to claim 1 , wherein the noise calculation step comprises a step of calculating the Fourier transform of the comparison signal in the time window considered.