Here’s my collection of discovered and written useful reference material.
FRS/GMRS Privacy Codes Demystified
Does your FRS or GMRS radio have privacy codes, sub codes, or interference eliminator codes? They are all kind of the same thing, except different. What if you want to use your Cobra GMRS radio with your Motorola TalkAbout? I’ve got answers for all these questions, plus a short tutorial on squelch, which is really what these privacy codes are.