set_dndt_k

Set filter coefficient for engine acceleration (dN/dt) measurement.

The set_dndt_k command sets or changes the value of the filter coefficient on the engine acceleration (dN/dt) measurement channel. The coefficient is used in an optional recursive filter on the analog input signal for the acceleration measurement to “smooth” the transient response. Filter values near 0.0 and 1.0 produce small and large filtering effects, respectively.

The command rejects any value for the filter coefficient that is less than 0.0 (no filter) or is greater than or equal to 1.0 (total filter).

Enter:

set_dndt_k [filter_coefficient]

or

set_dndt_k [frequency_cutoff in hz]

or

set_dndt_k [time_constant]

Where:

filter_coefficient	Specify the coefficient for the recursive filter on the engine acceleration measurement channel. Valid values are 0.0-1.0
frequency_cutoff	Specify the 1st order filter frequency.
time_constant	Specify the 1st order filter time constant.

Example:

set_dndt_k 0.10
specifies recursive filter coeff

set_dndt_k .5[ hz ]
specifies cutoff frequency

set_dndt_k .1[ sec ]
specifies time constant

Notes:

The recursive filter with coefficient k computes a filtered value Y(n) that is the contribution of the previous filtered value Y(n-1) and the current raw measurement X(n):

Y(n) = k * Y(n-1) + (1-k) * X(n)

See Also: