User's Manual

APPENDIX 2 - Microwave Leakage Measurements
a. Microwave ovens can be a major source of interference in the 2.450 GHz range and may cause loss of
data between the bedside and central stations or remote views. This loss of data will be seen as “holes”
in waveform data, or if the interference is of a long duration, complete loss of a channel at the central
station. In the event microwave ovens are located in the wireless coverage area anywhere within about
300 feet of either the WNI or wireless bedside, then these microwave ovens must be tested for possible
interference. If in doubt about interference “potential” setup a network using central station, WNI and one
bedside. Place a glass of water into the center of the microwave (NEVER TURN ON A MICROWAVE
OVEN WITHOUT A “LOAD” PLACED INSIDE OF IT) and turn it on at it’s highest power setting. Watch
the central station and verify that NO data dropouts occur while the oven is turned on ( a test duration of
30 seconds to a minute is adequate, be sure to change water if a longer test is desired as water should
not be boiling for this test).
b. A simple measuring device has been released for use in determining oven leakage (Spacelabs part
number 149-0002-00, "Meter, Microwave Leakage Detector"), and assist you in finding offending oven
noise sources. Both EPA and FCC have limits concerning emission levels for these ovens and published
the following as guidelines (excerpt):
• Power density of microwave ovens shall not exceed one milliwatt per square centimeter at any
point 5 centimeters (2 inches) or more from the external surface of the oven, measured prior to
acquisition by a purchaser, and thereafter, 5 milliwatts per square centimeter at any point 5
centimeters (2 inches) or more from the external surface of the oven.
• Leakage testing – Microwave should be operating at it’s maximum output and containing a load of
275 ±15 milliliters of tap water placed within the cavity of the center of the load carrying surface
provided by the manufacturer.
c. Refer to the operator's instructions for the microwave oven emission meter that you are using.
d. Emission measurement
- With the oven set for maximum power output, operational, and water placed
into it, test for leakage as indicated in the figure above. Readings above 5 mW/cm
2
are unacceptable and
the oven should be removed from service. To co-exist with Spacelabs wireless networks, emission levels
should be no greater then 1.5 mW/cm
2
(Federal safety standards allow higher leakage levels for safety
purposes, but an emission level exceeding 1.5 mW/cm
2
may cause wireless network problems). If
emissions are greater, the hospital responsible party must service the unit. Cleaning the door and mating
surfaces in some cases may resolve the issue.
e. MD-2000 MICROWAVE DETECTOR OPERATING INSTRUCTIONS
A Microwave Detector (part number 149-0002-00) is available for use by Customer Service
Representatives to determine the emissions level of microwave ovens in areas where wireless
products are in use. Proper use of the microwave detector enables the CSR to find sources of
wireless communications interference and prevent signal drop-offs.
To use the MD-2000:
1. Place a cup of water inside the microwave oven.
2. Press and hold the orange button on the microwave detector MD-2000. The unit’s display will show
a count-up sequence, the warning light will briefly turn on, and a beeping tone will be generated for
1 second. When the tone stops, the display will show a 0.00 reading. This numeric value is
measured in mW/cm
2
.
Part Number 062-0983-01 Rev C page 3 - 36