# getPercentileRelativePower

System object: comm.CCDF
Package: comm

Get relative power value for a given probability

## Syntax

`R = getPercentileRelativePower(H,P)`

## Description

`R = getPercentileRelativePower(H,P)` finds the relative power values, `R`. The power of the signal of interest is above its average power by `R` dB (if PowerUnits equals 'dBW', or 'dBm') or by a factor of `R` (in linear scale if PowerUnits equals 'Watts') with a probability `P`.

The method output `R`, is a column vector with the i-th element corresponding to the relative power for the i-th input channel. The method input `P` can be a double precision scalar, or a vector with a number of elements equal to the number of input channels. If `P` is a scalar, then all the relative powers in `R` correspond to the same probability value specified in `P`. If `P` is a vector, then the i-th element of `R` corresponds to a power value that occurs in the i-th input channel, with a probability specified in the i-th element of `P`.

For the i-th input channel, this method evaluates the inverse CCDF curve at probability value P(i).

## Examples

Obtain CCDF curves for a unit variance AWGN signal and a dual- one signal. The AWGN signal is RPW1 dB above its average power one percent of the time, and the dual-tone signal is RPW2 dB above its average power 10 percent of the time. This example finds the values of RPW1 and RPW2.

``` n = [0:5e3-1].'; s1 = randn(5e3,1); % AWGN signal s2 = sin(0.01*pi*n)+sin(0.03*pi*n); % dual-tone signal hCCDF = comm.CCDF; % create a CCDF object step(hCCDF,[s1 s2]); % step the CCDF measurements plot(hCCDF) % plot CCDF curves legend('AWGN','Dual-tone') RPW = getPercentileRelativePower(hCCDF,[1 10]); RPW1 = RPW(1) RPW2 = RPW(2) ```