Hi Daniel,
From my understanding, you want to generate a random signal with varying frequncy but constant rms value.
For generation the random frequencies, you can use the rand function-
r = minVal + (maxVal-minVal)*rand(sampleSize)
Then you can use these frequencies to create a sine wave.
The signal generated will then have to be normalized to have rms value of 1. You can do this by dividing the signal by its own rms value -
signal = signal/rms(signal)
You can read more about these functions, from the following documentations -
