Using multiple channels to increase overall instantaneous bandwidth

[MSybrant]

I'm sure this isn't a new problem, but something I'm trying to work through and figure out how to work around, which is the instantaneous bandwidth limit. I've looked around the forums and haven't quite found what I'm looking for (but there are a lot of topics to read through and I could easily be missing it).

I am trying to build an FMCW radar that can sweep through frequencies from 300MHz-1GHz.  (I plan on it being adjustable depending on the situation and the range will most likely be narrower, but still wider than the instantaneous limits set by the radio. My question is a more high-level understanding anyways on where the limit actually exists within the system).

I haven't bought any hardware yet, but have been looking at the USRP-2974 due to it essentially being an "all-in-one" system. 

Anyways, if I programmed the radio in such a way that the TX outputs from each channel to each take a portion of the bandwidth and alternate channels to ultimately get the continuous sweep I want (ie: CH1 300MHz-400MHz, CH2 400MHz-500MHz, CH1 500MHz-600MHz....etc), would the system be able to process the data or am I just trying to trick it into subverting the bandwidth limits when the limit still exists somewhere else? 

With the thought that I'm a beginner and still trying to grasp how to put it all together, is there any documentation or explanations which will help me with this? I plan on using a sawtooth modulation signal which doesn't seem possible with the built-in LO so I plan on using an external signal to stream in to be modulated inside the radio. (I haven't figure out if I can pump in an FMCW signal into the radio and have it still work, or if two signals have to be pumped in and modulated within the radio to create the FMCW output before it'll work).

I would appreciate any help even if it's in video or pdf or friendly advice form pointing me in the right direction. 

Thanks for the time,

Matt