Manual

C HAPTER F OUR : Understanding and Managing Waveforms
WM-RCM-E Rev D ISSUED: February 2005 59
Sequence waveforms: are really many independent acquisitions, so each segment will have its own horizontal
offset. These can be found in the TRIGTIME array.
For the nth segment:
x[i,n] = HORIZ_INTERVAL x i + TRIGGER_OFFSET[n].
The TRIGTIME array can contain up to 200 segments of timing information with two eight-byte double
precision floating point numbers for each segment.
RIS (Random Interleaved Sampling) waveforms: are composed of many acquisitions interleaved together.
The descriptor parameter, RIS_SWEEPS gives the number of acquisitions. The i
th
point will belong to the m
th
segment where:
m = i modulo (RIS_SWEEPS) will have a value between 0 and RIS_SWEEPS -1.
Then with: j = i - m
x[i] = x[j,m] = HORIZ_INTERVAL x j + RIS_OFFSET[m],
where the RIS_OFFSETs can be found in the RISTIME array. There can be up to 100 eight
- byte double
precision floating point numbers in this block. The instrument tries to get segments with times such that:
RIS_OFFSET[i] ≅ PIXEL_OFFSET + (i - 0.5) x HORIZ_INTERVAL.
Thus, taking as an example a RIS with RIS_SWEEPS = 10, HORIZ_INTERVAL = 1 ns, and
PIXEL_OFFSET = 0.0, we might find for a particular event that:
RIS_OFFSET[0] = -0.5 ns RIS_OFFSET[1] = 0.4 ns
RIS_OFFSET[2] = 1.6 ns RIS_OFFSET[3] = 2.6 ns
RIS_OFFSET[4] = 3.4 ns RIS_OFFSET[5] = 4.5 ns
RIS_OFFSET[6] = 5.6 ns RIS_OFFSET[7] = 6.4 ns
RIS_OFFSET[8] = 7.6 ns RIS_OFFSET[9] = 8.5 ns
and therefore:
x[0] = RIS_OFFSET[0] = -0.5 ns
x[1] = RIS_OFFSET[1] = 0.4 ns
...
x[9] = RIS_OFFSET[9] = 8.5 ns
x[10] = 1 ns x 10 + (-0.5) = 9.5 ns
x[11] = 1 ns x 10 + 0.4 = 10.4 ns
...
x[19] = 1 ns ´ 10 + 8.5 = 18.5 ns
x[20] = 1 ns ´ 20 + (-0.5) = 19.5 ns.
...