PowerXpert™ Help : Using USB Power Sensors with PowerXpert : Time Slot Mode
 
Time Slot Mode
Time Slot mode is available with power sensor models MA24x08A, MA24x18A, and MA24126A and is used for performing measurements on TDMA waveforms like GSM/EDGE. The Time Slot mode breaks up the measurement into equal time slots and displays the calculated average power reading for each individual slot as shown in Figure: Time Slot Mode Graphical Display Area.
Time Slot Mode Graphical Display Area
Index
Description
1
The vertical scale displays the power level in dBm.
2
Trigger Delay Time: Shows the current trigger delay position. The trigger delay is set via the Trigger Settings area. Note that the trigger marker will not be visible for positive trigger delays. See Trigger Settings.
3
Trigger Level Marker: Shows the current trigger level position. The trigger level is set via the Trigger Settings area. See Trigger Settings.
4
Graphical slot display showing the slot power level as a function of time slot number.
5
Marker showing as a vertical blue line with an x on the marker point and numerical values for the time slot number and power level (in dBm). The marker is available for reading power at an instant of time. It can be dragged with the mouse and can be centered in the display via the Center marker button.
6
The horizontal scale displays the time slots and may be increased or decreased from the Time Slot mode settings window.
7
Graticule Settings:
Number of Slots: Displays the current number of slots setting. This setting is changed via the Time Slot mode settings area.
Power Max (dBm): Sets the upper power level for the vertical scale.
Power Min (dBm): Sets the lower power level for the vertical scale.
• Power Max (dBm) and Power Min (dBm) settings are not available when set to Automatic.
Scale Mode: Sets the vertical scaling to Automatic or Manual.
Changes to these settings are applied by pressing the Enter key.
Settings
The measurements need to be triggered. Unwanted portions in the transition from one time slot to the next can be masked by user-definable exclusion periods. It is necessary that the waveform under test consists of equally spaced time slots and that the settings match the waveform. Time Slot mode settings are shown in Figure: Time Slot Mode Settings.
Time Slot Mode Settings
Index
Description
1
Continuous mode location on Task Bar
2
Apply above settings.
Number of Slots
The number of time slots that make a single frame. PowerXpert can support up to 128 slots. A single marker can be set on a particular slot to read average power in that slot. The power reading is the average power of all the samples falling within that slot.
Slot Width
Slot width is the width of each slot in milliseconds. All slots in a single frame should have the same width.
Start and End Exclusion
Start exclusion is the time in milliseconds to be excluded from the beginning of each slot for power calculation. End exclusion is the time in milliseconds to be excluded at the end of each slot for power calculation. This feature is generally used to define spacing between slots, although it may not be evident from the Time Slot mode graph. the following are general guidelines for Time Slot mode settings:
• The exclusions should not eclipse the entire slot width:
Start Exclusion + End exclusion < Slot width
• The maximum capture time is limited by the sensor:
Slot width x Number of slots = Total capture time
Apply Above Settings Button
The Apply above settings button applies all changes made to the Time Slot Mode settings. Changes to these settings do not take effect until clicking this button.