Build a wav file with multiple frequencies

[peterstivin]

We would like to build a wav file with multiple frequencies for a specified duration for each frequency.

I'll try to explain the use case

Say we need to build a wav file with frequency ranging from 150MHz to 200MHz for the first 5 secs( the whole wave file from frequency 150MHz, 150.1MHz, 150.2MHz, etc up to 200MHz should end in 5 secs time)
The next 10 secs should be from 200MHz to 300MHz
The next 15 secs should be from 300MHz to 400MHz
Once all the 3 wav files are generated, we need to combine/concat all these 3 into a single wav file of 30 secs (5+10+15)

Can you please let us know how can we achieve this using this code base?