6 digital filtering, 1 digflx parameters, 2 dfsens and dfthrh parameters – Rice Lake Tracer AV User Manual

Page 41: Digfl x, Dfsens and dfthrh parameters

Advertising
background image

Tracer AV Installation Manual - Appendix

37

6.6

Digital Filtering

The

Tracer AV

uses averaged digital filtering to reduce the effect of vibration on weight readings. Adjustable

threshold and sensitivity functions allow quick settling by suspending filter averaging, allowing the weight
reading to jump to the new value. Figure 6-3 shows the digital filter parameters on the CONFIG menu.

Figure 6-3. Digital Filtering Parameters on the Configuration (CONFIG) Menu

Figure 6-4. Flow Diagram for

Tracer AV Digital Filters

6.6.1

DIGFLx Parameters

The first three digital filtering parameters, DIGFL1,
DIGFL2, and DIGFL3, are configurable filter stages
that control the effect of a single A/D reading on the
displayed weight. The value assigned to each
parameter sets the number of readings received from
the preceding filter stage before averaging (see
Figure 6-4).

The overall filtering effect can be expressed by adding
the values assigned to the three filter stages:

DIGFL1 + DIGFL2 + DIGFL3

F o r e x a m p l e , i f t h e f il t e r s a r e c o n f i g u r e d a s
DIGFL1=4, DIGFL2=8, DIGFL3=8, the overall
f i l t e r i n g e f f e c t i s 2 0 ( 4 + 8 + 8 ) . Wi t h t h i s
configuration, each A/D reading has a 1-in-20 effect
on the displayed weight value. Setting the filters to 1
effectively disables digital filtering.

6.6.2

DFSENS and DFTHRH Parameters

The three digital filters can be used by themselves to
eliminate vibration effects, but heavy filtering also
increases settling time. The DFSENS (digital filter
sensitivity) and DFTHRH (digital filter threshold)
parameters can be used to temporarily override filter
averaging and improve settling time:

DFSENS specifies the number of consecutive
scale readings that must fall outside the filter
threshold (DFTHRH) before digital filtering
is suspended.

DFTHRH sets a threshold value, in display
divisions. When a specified number of
consecutive scale readings (DFSENS) fall
outside of this threshold, digital filtering is
suspended. Set DFTHRH to NONE to turn off
the filter override.

1

4

2

8

DIGFL1

32

16

64

1

4

2

8

DIGFL2

32

16

64

1

4

2

8

DIGFL3

32

16

64

8OUT

32OUT

16OUT

64OUT

DFSENS

DFTHRH

2OUT

128OUT

4OUT

2DD

NONE

5DD

20DD

10DD

50DD

200DD

100DD

250DD

DIGFL1= n1

DIGFL2= n2

DIGFL3= n3

3rd Stage

Filter A verage

2nd Stage

Filter A verage

1st Stage

Filter A verage

Displayed

Value

n3

2nd Stage

Filter A verages

n2

1st Stage

Filter A verages

n1

A/D Readings

Advertising
This manual is related to the following products: