be aware, if you are looking for a low-cost, DIY system that you can install yourself in a couple of hours, there are people who will try to scare you with unquantified allegations.
See if you can get Bernard to tell you how many such alarms in ordinary domestic houses, in ordinary residential streets, he estimates have failed to operature during a burglary due to RF interference (he won't because there is no evidence to support his tale)
He does like to trot out his vague smears whenever he sees the word "Yale" on this forum. He is always very offended when I point it out.