Recon Outdoors Talon IR Spécifications télécharger pdf (Page 167)

Software

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4.3, a suitable filter is applied to reduce noise generated from electrical interference

and ADC inaccuracies. This is important because a small change in voltage represents

a large change in measured range, particularly at long ranges. Therefore it is

necessary to filter out noise before the voltage-to-range calculation is applied. A

number of different filtering techniques were considered including:

• Mean

• Weighted mean

• Sliding median

Mean

The mean or average of a group of samples is the most effective way of filtering small

amounts of noise. The function is easily implemented with the MATLAB function

mean and provides a fast response to change. The downside is extreme values in the

data set can significantly affect the result over the short term.

Equation 5.2

: i

sample

Ē: mean of samples

n: number of data samples

Weighted Mean

The weighted mean provides an extension to the standard averaging function by

allowing a different weighting factor to be applied to each data point. The sum of all

the weighting factors must equal 1 and a number of different methods can be used to

assign the weighting factors such as weights based on sample age or proximity to the

median. Although MATLAB does not have any weighted mean functions built the

algorithms can be generated very simply using basic arithmetic.

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Recon Outdoors Talon IR Spécifications Page 167