I'm running on a RPi v1 B.
I'm using a USB scope to view the generated frequency signal and all my timings.
I modified control_dune_warrior.py to work with my requirements and found the usec values I specified produced timings that were 10 times longer.
So for example where you have:
if bit_pattern[-1] == 0:
useconds = 127
That would output the frequency for 1270 microseconds.
I wasn't able to understand the cause, so I divided my desired timings by 10 and the output is better.
I'm concerned I might still have some underlying issue I should address though.

Timings from other applications, old and new, are correct on my scope, so I think it's pi-rc, control_dune_warrior.py, or maybe some OS/hardware setting related to DMA?
Any idea what would cause this?
Thanks
Ion