Making Fast and Accurate Power Measurements with Absolute Confidence
Application Notes

Making Fast and Accurate Power Measurements with Absolute Confidence

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This application brief introduces the PowerSuite measurements and explains why they are important in your device characterization.

Table of contents 

  • Channel Power 
  • Adjacent Channel Power (ACP) 
  • Occupied Bandwidth 
  • Complementary Cumulative Distribution Function (CCDF) 
  • Burst Power 
  • Spurious Emissions 
  • Spectrum Emission Mask 
  • Third Order Intercept (TOI) 
  • Harmonic Distortion 

Channel Power  

This measures the total power present in the channel bandwidth. Unlike a continuous-wave (CW) signal, the power of a modulated signal is spread across a wide bandwidth. As a result, a complex integration is needed to calculate the total power of the channel.  

The PowerSuite channel power measurement can do this correctly, accurately, and quickly. With the Keysight X-Series signal analyzers, it only takes two touches to set the center frequency and the bandwidth of the measurement—and the PowerSuite will perform the test automatically. When testing communication and wireless signals of specific formats, PowerSuite offers embedded presets, making measurement setup even easier.  

As part of this measurement, the analyzer reports the power spectral density, which is the power in the signal normalized to a 1 Hz bandwidth. The channel-power measurement can use either the traditional integration bandwidth (IBW) method or the root-raised cosine (RRC) weighted method to calculate the power.  

Power measurements are essential to the characterization of any wireless device or system, whether you are creating a new design, verifying its performance, or testing it on the production line. In modern wireless communications, the ability to accurately measure the power of digitally modulated signals will enable you to maximize the capacity of a system and improve the quality of communication. 

For broadband signals, typical power measurements include adjacent channel power (ACP), occupied bandwidth (OBW), harmonics, spurious emissions, spectrum emission mask (SEM), burst power, and the complementary cumulative distribution function (CCDF). When performed manually, these measurements can be very complicated and time-consuming because they are format-specific and must account for the increasingly complex multi-carrier nature of today’s digitally modulated signals.  

Keysight’s PowerSuite is a collection of these measurements and is a standard feature of the X-Series signal analyzers. With an intuitive multi-touch display, the X-Series simplifies PowerSuite measurements with a streamlined menu structure, fewer keystrokes, and preset values for many cellular and wireless-connectivity standards. Built-in, format-based setups include LTE, W-CDMA, GSM/EDGE, cdma2000®, IS-95, Bluetooth®, and WLAN. 

Complementary Cumulative Distribution Function (CCDF) 

Many digitally modulated signals are noise-like in both the time and frequency domains. As a result, statistical measurements of these signals can provide useful information. The PowerSuite CCDF measurement can characterize the higher-level power statistics of a digitally modulated signal.  

A CCDF curve is defined by how much time the waveform spends at or above a given power level. The percent of the time the signal spends in that region defines the probability for that particular power level. This is of great value to design engineers when testing and troubleshooting the nonlinearity of power amplifiers.  

The PowerSuite performs this complicated CCDF measurement automatically and can support four-carrier W-CDMA signal measurements. In the test results, the analyzer displays the distribution of peak-to-average-power ratios versus probability. The CCDF curve is displayed on a semi-log graph along with a convenient measurement summary table and a range of useful marker functions.