The incidence of radio-frequency impulsive noise within hospital buildings: initial measurements in the 450 MHz band.
This paper reports on the incidence and level of man-made electrical impulse noise capable of causing interference to low-power, ASK and FSK radio biotelemetry links. Measurements were made at two acute hospitals, one in a residential area of Belfast, Northern Ireland and the other in an industrial part of Berlin, Germany. Monitoring was effected in the 450 MHz band using a communications receiver with its AGC line disabled and AM-detector AM output fed to a PC-based logger. The RF bandwidth was 20 kHz and a rotatable folded-dipole receiving antenna was used. Seven-day impulse counts were recorded at each location, for separate RF input thresholds of -100, -110 and -120 dBm and a common trigger window of 10 micros-10 ms. Histograms depicting the average pulse count per minute are presented; values range from a maximum of 55x10(3)/min for -120 dBm sensitivity in Berlin, to a minimum of 1.2/min for -100 dBm sensitivity in Belfast, both with vertical polarisation.
Riemann
A I
AI
N. Ireland Bio-Engineering Centre and School of Electrical and Mechanical Engineering, University of Ulster, Newtownabbey, UK.
Evans
N E
NE
D016477:Artifacts; D004562:Electrocardiography; D004868:Equipment Failure; D006761:Hospitals; D011846:Radio Waves; D013686:Telemetry