3 illustrate aspects of embodiments as discussed above fig1 a illustrates a symbol of a system control unit or control panel 10 fig1 b illustrates a symbol of a type a device such as 12 a illustrated therein as discussed below a region r 1 or r 2 of interest can be populated with a plurality 12 a 12 b 12 c 12 m of the fixed devices such as device 12 a fig1 c illustrates symbols of movable type b units such as 14 a 14 b type a devices are fixedly installed in a respective region the control unit 10 communicates therewith and has a record of the fixed locations thereof type b units are mobile and readily moved in the respective region the type b units could be affixed to or incorporated into an article of interest initially various device locations are established by the central control unit 10 in a phase 1 learning process fig2 illustrates devices 12 i and a typical configuration in a secured premises such as region r 1 capabilities of each device are illustrated in fig1 b each security device 12 i is equipped with sensors to identify location these devices are located by the installer using a gps system to provide location of the respective detector such as 12 i with respect to a.