Manual - 8500A Series Peak Power Meter - Giga-tronics

Series 8500A Peak Power Meters
2.8.10 Marker Sub-Mode Functions
The Marker sub-mode is another completely independent way to read the time difference between user
defined points on the pulse waveform. It may, at first, seem redundant with the Pulse parameter mode.
The Marker sub-mode, however, treats the 100% power point differently, and reads the differences
between four user-defined points on the waveform. It is intended for use in specialized applications (such
as measuring the linearity of the leading edge skirt of a navigation pulse) where the user is interested in
something other than standard rise, fall, and width measurements. This Marker sub-mode is also most
similar to the Marker Mode offered in the original 8500 Peak Power Meter.
The Marker sub-mode uses the user-set REFerence PoWeR as the 100% power point of the pulse. This
allows the user to set the 100% point at other than the flat spot at the top of the pulse. For instance, the
100% point can be set at the top of the pulse overshoot. The 100% point can also be set 10 dB lower than
the top of the pulse to scale all the user-set marker percentages by 1/10. This is particularly useful to set
marker percentages to resolutions better than 0.1% of the peak power.
The default settings for marker sub-mode are set for the measurement of linearity on the leading edge of
a navigation pulse. In this particular measurement, the time between the 5%, 13.3%, 21.7%, and 30%
points on the voltage waveform are compared. Equal times indicate a linear voltage waveform between
the 5% and 30% point on the waveform. Because markers are entered in terms of % power, the
corresponding power percentages would be 0.25%, 1.78%, 4.69%, and 9.00%. Because markers can only
be entered to 0.1% resolution, the actual marker values are set 10 times greater or 2.5%, 17.8%, 46.9%
and 90.0%. Then, to get the maximum resolution from the markers the REFerence PoWeR is set to
exactly 10 dB less than the peak power of the pulse, effectively scaling all marker values by 1/10. (This
action must be done manually.)
Figure 2-10. Typical Marker Sub-Mode Digital Plot
To change a marker percentage setting:
1. In GRAPH mode, press [PULSE/CURSOR/MARKER] until you see a display on the right side
of the screen similar to:
∆CSR PWR = +0.91 dBm
MKR 2 - 1 = 4.9000 ns
MKR 3 - 2 = 5.4000 ns
MKR 4 - 3 = 10.5000 ns
2-28 Manual No. 20790, Rev C, November 1998
Superceded by Revision D, March 2009