Most of the frequencies are licensed to multiple users in the county, so it may be hard to isolate just DBU. Also, I have no idea whether they have started their spring break yet, or not.
I've plugged all the licensed frequencies into a system on my 536HP, running off an ST2 on the roof. I'm maybe five miles from the campus, tough they are below my horizon (the same ridge line you encounter on I20 descending down to Mountain Creek Pkwy, or west on either Kiest Blvd. or Illinois in western Oak Cliff. I have the scanner set to hold on the system, as well as record activity. I'll give it a day or two & see what I hear.
I am hearing what sounds like a control channel at times on 461.875, but that is also licensed to DFW Communications for trunk usage.