On the design and assessment of a 2.45 GHz radio telecommand system for remote patient monitoring

This paper discusses the design and operational assessment of a minimum-pow er, 2.45 GHz portable pulse receiver and associated base transmitter compri sing the interrogation link in a duplex, cross-band RF transponder designed for short-range, remote patient monitoring. A tangential receiver sensitiv ity of - 53 dBm was achieved using a 50 Omega mitrostrip stub-matched zero- bias diode detector and a CMOS baseband amplifier consuming 20 mu A from 3 V. The base transmitter generated an on-off keyed peak output of 0.5 W in to 50 Omega. Both linear and right-hand circularly-polarised antennas were employed in system evaluations carried out within an operational Coronary C are Unit ward. For transmitting antenna heights of between 0.3 and 2.2 m ab ove floor level, transponder interrogations Here 95% reliable within the 82 m(2) area of the ward, falling to an average of 46% in the surrounding roo ms and corridors. Separating the polarisation modes, using the circular ant enna set gave the higher overall reliability. (C) 1999 IPEM. Published by E lsevier Science Ltd. All rights reserved.