telecommunications switches; pulse code modulation multiplexers and higher order multiplexers; digital transmitters, receivers and transceivers; cryptographic units; telephone sets, facsimile terminals, videotex and telex machines, modems, fire and pollution detectors; radiotelephones, radio base stations; switching stations, namely, local or transit telephone switching base units; digital cross connect switching stations, namely, devices installed in digital transmission systems for performing automatic restoration switching using facility rerouting; identification of friend or foe machines, namely, machines for land, sea or airborne application able to meet identification requirements of long and short range radar systems; avionic machines, namely, airborne terminals for performing radio communications in the nature of data and voice transmission; private digital branch exchanges, namely, private telephone switching units capable of switching a predetermined number of external lines to a predetermined number of extensions; plant safety controllers, namely, machines for monitoring the correct operation of all technical devices in a building including anti-fire devices, and lifting devices; automatic vehicle monitoring apparatus, namely, apparatus for centralized collection of information concerning the location of a single vehicle in a public transportation system as well as the number of passengers transported by a predetermined vehicle; (base transceiver stations (BTS's), local switching center (LSC), main switching center (MSC), location registers (LS), and operation and maintenance centers (OMC), for switching, control and management of cellular and digital cordless telephones; and apparatus in the nature of a video signal broadcasting station, interactive terminals, namely, machines suitable for capturing the data superimposed on video signals and to display them on a television screen, data processing centers for interactive like television systems, and apparatus in the nature of audio video servers, broadband switching centers and set top terminals for interactive television through existing broadcast communications systems enabling the user to participate actively in television programs such as quiz shows, commercials, opinion polls, sports events, and telemarketing