Campbell Scientific SDM-INT8 8-Channel Interval Timer User Manual
Page 21
SDM-INT8 8 Channel Interval Timer
TABLE 4. Sampling Interval (Seconds) to Accumulate
8000 Unprocessed Events for Functions 1,2,6,7
Input
Number of Channels
Freq. kHz
3
4
5
6
7
8
1.1
5.26
1.3
7.97
2.84
1.48
1.5
4.21
1.81
1.00
1.7
2.67
1.26
.73
1.9
5.62
1.87.
.93
.55
2.1
3.68
1.38
.72
.43
2.3
2.64
1.07
.57
.35
2.5
2.00 .86 .47 .29
2.7
6.55 1.57 .7 .39 .24
2.9
4.64 1.27 .58 .33 .20
3.1
3.50 1.05 .49 .28 .18
3.3
2.76 .88 .42 .24 .15
3.5
2.24 .75 .37 .21 .13
3.7
1.86 .65 .32 .19 .12
3.9
1.57 .57 .28 .17 .11
4.1
1.35 .50 .25 .15 .10
4.3
8.91 1.17 .45 .23 .13 .09
4.5
6.73 1.03 .40 .20 .12 .08
4.7 5.33
.91 .36 .19 .11 .07
4.9 4.36
.81 .33 .17 .1 .06
5.1 3.65
.73 .30 .15 .09 .06
Sampling intervals shown in Table 4 are for "worst case"
conditions. Longer sampling intervals are possible
depending on channel phase relationships. See Appendix B
to calculate maximum intervals for other Functions.
When the low resolution frequency function is used, summing is not required;
an average over the full interval is always available.
In all options that do averaging, the functions that involve time or count
differences between different channels (time since channel 1, counts on 2 since
1, and time since previous channel) behave as follows: if there are multiple
beginning edges and/or ending edges, i.e., more than 1 beginning edge per
ending edge or visa versa, then only the last of the beginning edges and the
first of the ending edges are used in the average. For example, assume all
detection is on rising edges, and the function is counts on channel 2 since 1 for
channel 3. A diagram of this example is presented in Figure 4. Multiple
beginning edges are shown on channel 1, and multiple ending edges on
channel 3. In this example, only 2 edges are used in the average.
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