Radio Codes
The codes you hear are ones used as a type of automated dispatching system. They are similar to the codes used for EMS Emergency Medical Dispatching, an automated system of determining the resources needed for dispatching.
There has been a lot of controversy with these codes. The codes have confused many volunteers. Instead of saying a "House Trailer Fire", it is now a "Structure Fire, a 69 - Delta - 9". Any type of emergency is now coded along with the severity.
This system will take some time to shake out. Whether it will be a help or not remains to be seen.
A 52 Bravo 1 is a Structure Fire, Residental, Multiple dwelling.
Jeff