Procedures Profile Operation Mode
ML2437A/38A OM/PM PN: 10585-00001 Rev. P 6-13
Control of x-axis - Width of Profile - Sample Time
The control of the time-frames over which the PROFILE is gathered is very precise, but there
are certain restrictions. With care it can be used to display the profile of signals down to
typically 100 ns or better.
1. Select SYSTEM > PROFILE. The first two items in the menus have already been
covered (selection of channel 1 or 2, and the method of display, min max). The last two
selections control the data collection PERIOD (the time span of the window). The
default period is 10 ms, and it can be adjusted down to 100 ns and below. If you are still
displaying the 1 kHz square wave, enter a period of 3 ms. The display will zoom in to
show more detail of the pulses.
2. Note that the cursors have remained at their set positions in time, that is, when altering
the time axis the cursors stay at their set positions in terms of time - NOT POSITION
ON THE SCREEN. This is very important when measuring specific points or peaks in a
signal.
3. By altering the DELAY parameter, the PROFILE can be made to look at a segment of
time long after or very close to the trigger point. That is, by setting the DELAY to
100 ms, the PROFILE will show the 100th pulse (and onwards) of a 1 kHz square wave.
By setting to ZERO, the profile will show data immediately after the trigger has
occurred. This is the DISPLAY TRIGGER DELAY and is denoted by a small ‘x’ on the
PROFILE display. This marks the point on the display where data is taken at the time
DISPLAY TRIGGER DELAY is placed. For example, for the 1 kHz square wave, the
pulse edge would occur at the ‘x’ point whenever the DISPLAY TRIGGER DELAY is a
multiple of 1 ms. The x-axis nomenclature always denotes this point with a time of
ZERO (t=0), this allows the user to always consider time intervals relative to the
display trigger which is usually the point of interest.
4. As well as the CURSOR readouts described above, the POWER AVERAGE method can
be used to display the average power between the two cursors. This is performed as a
TRUE AVERAGE and is the actual average of all the data points between and
Note
Thermal sensors have rise and fall times of <15 ms. Do not use a thermal sensor
for fast signal profiles. Typical MA2470A and MA2440A Series sensors have rise
times of <4 µs. Fall time is typically <10 µs, except at low power levels. Consider
this when looking at fast signals.
Note
For smaller values of display trigger delay, it is possible that the display will cover
time intervals (on the left of the display) for which there is no data. In these
conditions, the cursors are normally prevented from displaying data taken there as
it will be in error (there is no data). The position of ‘x’ is nominally 10 % of the
screen. This can be altered to any percentage the user requires in the
SYSTEM > more > more > GRAPHICS preferences menu as the PRETRIGGER
percentage. It can also be set to ZERO to remove pretrigger data and prevent
confusion in cases of small display trigger delays.
Profile can display A, B, or A–B measurements. Note that in the case of a ratioed
measurement (A–B), the data is calculated as a straight dB difference (not a
LINEAR mw difference). This is not the same as a MODULATED POWER
AVERAGE measurement.
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