Instrument Function > RF Block > RF Level > NRP-Z Level Control
NRP-Z Level Control

With the NRP-Z Level Control function, you can achieve a very stable and accurate RF power supplied to your DUT. With the aid of a downstream control circuit, a CLPC (Closed Loop Power Control), you can detect frequency response characteristics of the used components, such as losses due to cables, modules or components like power amplifiers, and compensate these effects accordingly.

Example: How to set up a closed loop power control
Example of a test setup with NRP-Z Level Control

As shown in the example, the sensor measures a proportional power in defined time intervals, derivated from a coupler. It considers optionally given S-parameters and returns the results to the generator. The signal generator compares the measured level with the set value and adjusts its output level accordingly.

This allows you to control the external signal level continuously and reliably reach a constant input level at the DUT in real time.

Impact of the NRP-Z Level Control and the Operating Modes

Since the frequency and level of the RF output signal are continuously adjusted during "NRP-Z Level Control", this operating mode interferes those with varying frequency and level values.

The reason is, that the generator regularly transmits the output frequency to the connected R&S NRP-Zxx power sensor, which in turn requests the signal generator to adjust the output level according to its measurement. In contrast to this real time control loop, for example the list operating mode already generates the RF output signal on previously optimized frequency and level value pairs. In this case, the "NRP-Z Level Control" as a second control loop would impact the already determined RF signal values and also considerably slow down the measurement. Similar impacts occur in sweep mode, and also the "NRP-Z Power Viewer" and "NRP-Z Level Control" affect each other's functionality.

Hence, the operating modes exclude each other as follows:
  • "NRP-Z Level Control" automatically disables "NRP-Z Power Viewer" and "NRP-Z Power Analysis", and vice versa.
  • Activating the RF frequency sweep, RF level sweep or the list mode instantly deactivates a running "NRP-Z Level Control".
  • A running list or RF sweep mode blocks "NRP-Z Level Control". It can not be activated.

Also keep in mind that modulated signals may differ from CW signals regarding mean power and peak power. This affects the operation of "NRP-Z Level Control".

 


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