Using an Average Detector rather than a Peak, you can estimate the average Power (dBm or mW) by taking the mean or average detected level;
Pt =P{dBm} + 10log (BW/RBW) or
Pt =P{mW} * 10log (BW/RBW)
Pt =total rms power of spread spectrum signal
P= mean Power integrated or avg. in RBW
BW= Signal BW @-10dB approx.
RBW=Resolution BW or Noise BW
Also you can dump all the power data, Pk in mW and compute the Product Sum of k points
for k= number of data points
SPAN = BW of Data for all k data points
RBW=Resolution BW or Noise BW