Average filter based on FIFO buffer
input
+
|
+-----+
| S/H | <------------------ sampling time
+-----+
|
v
+------------------+--------------------+
index +-->+ DEMUX |
+----+------+------+----------------+---+
| | | |
+--+-+ +--+-+ +--+-+ +--+-+
| B0 | | B1 | | B3 | . . . . . | Bn | <- buffer
+-+--+ +-+--+ +-+--+ +-+--+ n is size-1
| | | |
+---+------+------+----------------+----+
| ACCUMULATOR |
+------------------+--------------------+
| <---------------------- sum
v
+--------+--------+
| divided by fill |
+--------+--------+
|
v
filtered
result
/* Include library */
#include "moving-average.h"
/* Filter objects */
movingAverage_t avg_filter;
movingAverage_t avg_filter_2;
void main()
{
/* Initialization of filters */
moving_average_create(&avg_filter, 10, 100); /* filter size 10, sample time 100ms */
moving_average_create(&avg_filter_2, 30, 150); /* filter size 30, sample time 150ms */
/* wait for 1 maximum sample time */
delay(150);
while(1)
{
signal = signal_source(); /* signal source function may ADC, Capture count, sensor data*/
/* Filter process
*
* call this function maximum passible short time
*/
moving_average_filter(&avg_filter, signal);
moving_average_filter(&avg_filter_2, signal);
process_or_print = avg_filter.filtered;
process_or_print = avg_filter_2.filtered;
}
}- channel 0 - signal + noise (+/- 20)
- channel 1 - filter size 10, sample time 100ms
- channel 2 - filter size 30, sample time 100ms
- channel 3 - filter size 50, sample time 100ms
Thank to Graph - serial plot tool