Explicit Control of Waterfall Bandwidth

I have seen mention that some observation types set the bandwidth to different from the default value. For example, those people who set up LRPT decoding have wider bandwidth than default. I understand this is linked to the GR block used.
My question is: how can this be done without setting up such a decoder? For example, suppose I wish to schedule an observation of Meteor m 2, using the default demodulator (no decoding to image), and then download the audio for decoding offline?
I’m happy hacking Python but still a GR novice and I don’t know the SatNOGS architecture…

Cheeers, and thanks in advance for ideas,