Wireless Medical Telemetry Systems
Wireless medical telemetry is generally used to monitor a patient’s vital signs (e.g. pulse, and respiration) using radio frequency (RF) communication. These devices have the advantage of allowing patient movement without restricting patients to a bedside monitor with a hard-wired connection.
The Federal Communications Commission (FCC) established the Wireless Medical Telemetry Service (WMTS) by allocating specific frequency bands exclusively for wireless medical telemetry. The WMTS set aside 14 MHz of spectrum in three defined frequency bands of: 608-614 MHz, 1395-1400 MHz, and 1427-1432 MHz for primary or co-primary use by eligible wireless medical telemetry users. The WMTS creates frequencies where medical telemetry is protected against interference from other RF sources. A key feature of WMTS is the provision for establishment of a Frequency Coordinator to maintain a database of user and equipment information to facilitate sharing of the spectrum and to help prevent interference among users of the WMTS. Operating these devices within the specific frequency bands allocated exclusively for WMTS should reduce the risk of electromagnetic interference (EMI) with vital medical telemetry signals
The FDA encourages manufacturers and users of medical telemetry devices to use this spectrum because of its protections against interference from other intentional transmitters and because frequency coordination will be provided.
FCC service rules for the Wireless Medical Telemetry Service (WMTS) are located in 47 C.F.R. Part 95 Subpart H
Eligible WMTS users are limited to authorized health care providers, which include licensed physicians, health care facilities, and certain trained and supervised technicians. The healthcare facilities eligible for the WMTS are defined as those where services are offered for use beyond 24 hours, including hospitals and other medical providers. Ambulances and other moving vehicles are not included within this definition.
The service rules for the equipment and use of the WMTS include limitations on transmitter output power, out-of-band emissions, and protection of other services. Users of the WMTS are co-primary with the radio astronomy service operating in the 608 614 MHz frequency range and must not disrupt radio astronomy operations. WMTS users are required to obtain written permission to transmit within 80 km (50 miles) of some radio astronomy facilities and within 32 km (20 miles) of other radio astronomy facilities. The Frequency Coordinator maintains information to help the WMTS co-primary users avoid conflicts.