| 摘要 |
<p>An audience response system, an audience response keypad detection system and an audience response alert system. The audience response system comprises a master unit (10) and a plurality of RF linked keypads (12), (1012). The master unit (10) comprises a circuit controller (20) that has a plurality of channel sets (13) each of which comprises two RF receiver channels (14, 16), and a RF transmitter channel (18). Each of the keypads (12, 1012) has a single channel set (13) comprising two RF receivers (22, 24), and a single RF transmitter (26). The detection system is arranged for detecting keypads (12, 1012) and the alert system is arranged to issue alerts if the keypads (12, 1012) pass into, through or out of a controlled area (1050). The alert system can be used as a sentry system.</p> |
