Bluetooth Devices; Other Transient Devices; Continuous Noise In The 2.4 Ghz Spectrum; Wifi Devices - Philips IntelliVue Telemetry System Infrastructure Installation And Service Manual

Chapter 2: Planning Your ITS Deployment
located between an Access Point and wireless beside monitors or patient-worn
transceivers.
Avoidance: Physical separation of at least 20 feet. Microwave level at 2.4 GHz ITS
AP shall be < -25dBm. Use insufficient spectrum alert on APC web interface to
determine if microwave source will be a problem at selected AP location.
Microwaves that operate on ½ sine wave can be avoided by the 2.4 GHz ITS with its
frequency agility & retry mechanism. If a patient-worn transceiver is in close
proximity to a microwave source, then data loss > 90sec/day may be experienced.
Although originally designed and deployed for short distance, low power Personal
Bluetooth
Devices Area Network (PAN) deployments, full power (100mW) devices are now being
produced and deployed.
A Bluetooth device may operate as a frequency hopper or as a device emitting
energy on several narrow band channels. Fortunately, Bluetooth devices are usually
very low powered and have interference avoidance algorithms built into them. When
a Bluetooth device encounters a fixed channel system like the 2.4 GHz ITS, it should
avoid conflict. Unfortunately, Bluetooth devices are typically non-hospital owned
"walk-in" devices and thus are difficult to control. For this reason, they are treated
as transient noise sources.
Avoidance: Possibly none needed. Provide physical separation if possible. Refer to
hospital policy on Bluetooth use in care areas. 2.4 GHz ITS can tolerate Bluetooth
piconet systems with seven Bluetooth 2.0 devices communicating.
Increasingly, the 2.4GHz space is being used for other non-communication or non-
Other Transient
Devices computer related devices. Various remote controls and children's toys are using
2.4GHz radios. Be sure to consider these as possible interference sources. If
persistent, a noise source like this would be discovered by a spectrum analysis,
typically appearing as a narrow band, continuous emitter with nearly a 100% duty
cycle.
Avoidance: Physical separation.

Continuous Noise in the 2.4 GHz Spectrum

We refer to "Continuous" RF emitters as devices that emit energy constantly,
although seldom at a 100% duty cycle.
Devices which "beacon" when in low use may not be thought of as continuous noise
sources, but because they often appear in short-term (5 to 20 minute) spectra
captures, they are treated as such.
Noise attributed to 802.11 devices will vary in duration/duty cycle. It can range from
802.11/WiFi
Devices short, intermittent "beaconing" bursts to near steady state, broad spectrum energy
from heavily loaded, systems. Fortunately, device keep-alive and beaconing
2-20
20 feet (6 m) (Consumer-grade Oven)
Figure 2-16: Recommended Minimum AP Distance from Microwave Ovens