Moving median filter based on FIFO buffer.
input
+
|
+--+--+
| S/H | <-----------------+ sampling time
+--+--+
|
v
+------------------+--------------------+
index +-->+ DEMUX |
+----+------+------+----------------+---+
| | | |
+--+-+ +--+-+ +--+-+ +--+-+
| B0 | | B1 | | B3 | . . . . . | Bn | <+ buffer
+-+--+ +-+--+ +-+--+ +-+--+ n is size+1
| | | |
+---+------+------+----------------+----+
| SORT |
+----+------+------+----------------+---+
| | | |
+--+-+ +--+-+ +--+-+ +--+-+
| S0 | | S1 | | S2 | . . . . . | Sn | <+ sorted list
+-+--+ +-+--+ +-+--+ +-+--+
| | | |
+------+------++---------------+
|
+--------+--------+
| Fill index / 2 | <+ list
+--------+--------+ med value
|
v
filtered
/* Include library */
#include "moving-median.h"
/* Filter objects */
movingMedian_t med_filter;
movingMedian_t med_filter_2;
void main()
{
/* Initialization of filters */
moving_median_create(&med_filter, 11, 100); /* filter size 11, sample time 100ms */
moving_median_create(&med_filter_2, 29, 150); /* filter size 29, 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_median_filter(&med_filter, signal);
moving_median_filter(&med_filter_2, signal);
process_or_print = med_filter.filtered;
process_or_print = med_filter_2.filtered;
}
}- channel 0 - signal + noise (+/- 20)
- channel 1 - filter size 9, sample time 100ms
- channel 2 - filter size 29, sample time 100ms
- channel 3 - filter size 49, sample time 100ms
