Creating Fm Markers - LeCroy PXA125 User Manual

Creating FM
Markers
3-102 ArbConnection
Frequency markers are available at the SYNC output when the
instrument is placed in either sweep or arbitrary FM modes. Unlike the
normal SYNC operation where a SYNC bit is placed only once on a
specific waveform segment, multiple frequency markers can be
placed along the modulation curve thus, every time a specific
frequency is hit, the SYNC outputs a marker pulse.
Marker position is programmed using the FM Markers Table, as
shown in Figure 3-30. To program marker positions create your
modulating waveform curve first and then, from the Edit menu select
FM Markers...command. The FM Markers Table dialog box will show
and will let you enter values in the edit field, on top of the markers list.
Makers are entered in sample clock frequency units (SA/s) and
should be within your deviation range. If you want to compute marker
position in output frequency, then you should convert the units using
the following equation:
Frequency = Sample clock frequency / n
where n = number of points of the modulating curve.
For example, if you look at Figure 3-30, the first marker position is
7.2006 MSa/s and the number of point on the horizontal axis is 1000
points (0 to 999 = 1000). The actual marker frequency is:
7.2006 MSa/s / 1000 = 7.2006 KHz
After you complete writing maker positions and if the specified
markers are within the selected deviation range, the markers will be
shown on the modulating curve as little blue dots. The various
controls in the FM Markers Table are described below.
Sort – will automatically sort your markers in an ascending or
descending order as you add them to the list.
Add – will add a marker to the list after you type it in the Enter Marker
Value field.
Delete – will delete a highlighted marker from the markers list.
Remove All – will remove all marker positions from the list and will
clear the entire table.
Store & Update – will save your table and will update the program so
you can close it safely without loosing table data.
Close – will remove the FM Markers Table from the screen and will
User Manual PXA125