Tx Power Control (Uplink)

This topic describes the parameters of the uplink Transmit Power Control setup table, which is accessible when you click Tx Power Control in the tree view.

 

Tx Power Control determines how the transmit power of the receiving base station will vary. The Up/Down Pattern, whether from an external trigger or from a user defined bit sequence, directs the receiving base station to increase or decrease its transmit power by an amount specified in the Power Step parameter. This parameter adjusts the total Tx power of all active channels.

The Min Power and Init Power parameters are linked to the Power Step parameter. The values will automatically round to a lower value if the selected Power Step value requires such an adjustment.

State

Choice: On, Off
Default: Off

Double-click or use the drop-down menu to turn the uplink transmit power control On or Off. When set to On, the TPC control is enabled from the first connection frame number timeslot (CFN = 0).

Compressed mode cannot be active when using Transmit Power Control.

Max Power

Default: 0.0 dB

This cell displays the maximum power of Tx Power Control, in dB. (Read only).

The value displayed is relative to the maximum amplitude set for the E4438C. For example, if the amplitude for the E4438C is set to –20 dBm, Min Power is set to –40 dB, and Init Power is set to –10 dB, then the absolute initial power level will be –30 dBm (10 dBm below the E4438C amplitude) and the absolute minimum power will be –60 dBm (40 dBm below the E4438C amplitude).

Max Power (dBm)

This cell displays the maximum power, in dBm, which is the same value as Amplitude (dBm) set in the Project Property node. (Read only).

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Min Power

Range: –40.0 to 0.0 dB
Default: –40.0 dB

This cell sets the minimum power for Tx Power Control, in dB. The value must be smaller than or equal to the value set in Init Power. The minimum power is decreased in increments determined by the value set for Power Step, but is also limited by the amplitude set on the E4438C. To achieve a minimum power of  –40.0 dBm, the E4438C must be set to –96.0 dBm or lower. See Max Power for more information.

Press the Apply button to make changes to this parameter while the signal is active.

The power difference between Min Power and Max Power should be a multiple value of Power Step.

Min Power (dBm)

This cell displays the minimum power, in dBm. (Read only).

Init Power

Range: –40.0 to 0.0 dB
Default: 0.0 dB

This cell sets the initial power of Tx Power Control, in dB. The value must be smaller than or equal to the value set in Min Power.

After clicking the Apply button in the tool bar, or selecting Signal > Apply from the menu bar, the start power is always set to the Init Power value.

The power difference between Init Power and Max Power should be a multiple value of Power Step.

Init Power (dBm)

This cell displays the initial power, in dBm. (Read-only).

Power Step

Choice: 0.5 dB, 1.0 dB, 2.0 dB, 3.0 dB
Default: 0.5 dB

Double-click or use the drop-down menu to set the power step size. Press the Apply button to make changes to this parameter while the signal is active.

Up/Down Pattern

Choice: EXTERNAL, USER
Default: EXTERNAL

Double-click or use the drop-down menu to display the Data Type Entry window and select an External trigger to play the Up/Down Pattern, or select a user defined Up/Down Pattern. See TPC Pattern (Uplink).

 

External allows you to choose the trigger polarity and the trigger source:

For more information about external trigger connections, see Signal IO (Uplink).

 

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