BRUEL & KJAER 1617 - Use of Variable Averaging Time Programs

Writ i ng speed (mm/s)
4
8 - 16 31,5 - 50 80 - 125
200 - 2000
(100
mm paper)
Paper speed for AC
0,1 0,3 1 3
10
recording (mm/s)
770410
Table 4.3. Paper speeds for AC recording
ing speeds available. Once again these may be increased by one step when the spec-
trum is known to be relatively flat.
4.4. USE OF VARIABLE AVERAGING TIME PROGRAMS
44
In the Band Pass Filter Type 1617, the AVERAGING CONTROL programs are able to re-
duce the averaging time of the Measuring Amplifier (Type 2607) in tempo with the in-
creasing frequency during the scan. Table 4 .4 indicates the programs available, while
Fig . 4.3 gives a chart showing the variation of selected averaging times indicating the fre-
quencies at which the Band Pass Filter selects the next time constant, in the different
programs .
Minimum Av. Time (s)
Program 0,1
1,0
10
Slow Random
C
F
J
Fast Random
B E
H
Si ne
A D
(G)
770411
Table 4.4 . Programs that can be chosen by the two AVERAGING
CONTROL switches
Averaging Ti me
(5)
100 C. F ,J Slow Random
30
10
10 5
G,H.J
0.3
L 1,0 5
L----,==-D_..,L, __ ~~~~~~~~~ .... B:~~--F--~~:L ----- - ------- C --: ', :....~- '~
A,B ,C
0, 1
, ! , ! , ! I , !
2
5
10 20
50 100 2
00 500 1 k 2 k
5 k
10 k 20 k
Sw it ch ove r Fr eque ncy ( Hz) 76 1041
Fig.4 .3. Variation of selected averaging time with frequency