The Wireless Medical Telemetry Service (WMTS) is in the 608 – 614, 1395 – 1400, and 1427 – 1432 MHz range. WMTS spectrum is used for remote monitoring of a patient’s health. Wireless medical telemetry systems include devices to measure patients' vital signs and other important health parameters (e.g., pulse and respiration rates) and devices that transport the data via a radio link to a remote location, such as a nurses' station, equipped with a specialized radio receiver. For example, wireless cardiac monitors are often used to monitor patients following surgery.
Similar services include the Medical Device Radiocommunications Service (MedRadio).
Prior to establishing the Wireless Medical Telemetry Service (WMTS), medical telemetry devices operated on an unlicensed basis on vacant television channels 7-13 (174-216 MHz) and 14-46 (470-668 MHz) or on a licensed, but secondary basis to private land mobile devices in the 450-470 MHz band. This meant that wireless telemetry devices had to accept interference from the television broadcasters and private land mobile licensees.
Concerns over additional interference to medical telemetry devices became a greater issue as the transition from analog to digital television began. To help alleviate additional interference to wireless medical telemetry devices, the FCC took action to establish the Wireless Medical Telemetry Service (WMTS) in 2002 by allocating 14 MHz of spectrum for wireless medical telemetry.
There are four Wireless Medical Telemetry Service (WMTS) channels in the 608-614 MHz band. No specific WMTS channels are specified in the 1395-1400 MHz and 1427-1432 MHz bands. The WMTS spectrum is divided into three spectrum blocks:
- 608 – 614 MHz: This spectrum band corresponds to television channel 37, but it is not used by any TV station because it is used for radio astronomy.
- 1395 – 1400 MHz.
- 1427 – 1432 MHz: The channels in this spectrum band are shared by WMTS devices and non-WMTS devices such as utility telemetry devices. Generally, WMTS devices have primary status in the 1427 – 1429.5 MHz segment and non-WMTS devices have primary status in the 1429.5-1432 MHz segment, but there are seven geographical areas where WMTS and non-WMTS statuses are “flipped” and WMTS devices have primary status in the 1429-1431.5 MHz segment and non-WMTS devices have primary status in the other segments of the band:
- Pittsburgh, PA
- Washington, D.C.
- Richmond/Norfolk, VA
- Austin/Georgetown, TX
- Battle Creek, MI
- Detroit, MI
- Spokane, WA
The Wireless Medical Telemetry Service (WMTS) is licensed by rule. Licensed by rule means an individual license is not required to operate a WMTS device.
The FCC service rules for the Wireless Medical Telemetry Service (WMTS) are located in 47 C.F.R. Part 95.
Operating a Wireless Medical Telemetry (WMTS) Device
Only authorized health care providers are eligible to operate Wireless Medical Telemetry Service (WMTS) devices and WMTS devices may be used only within a health care facility. WMTS devices must be registered with the FCC’s designated frequency coordinator, the American Society for Healthcare Engineering of the American Hospital Association (ASHE/AHA).
An authorized health care provider is:
- A physician or other individual authorized under state or federal law to provide health care services.
- A health care facility operated by or employing individuals authorized under state or federal law to provide health care services.
- Any trained technician operating under the supervision and control of an individual or health care facility authorized under state or federal law to provide health care services.
A health care facility is defined as a hospital or other establishment that offers services, facilities and beds for use beyond a 24-hour period in rendering medical treatment, or an organization regularly engaged in providing medical services through clinics, public health facilities and similar establishments, including government entities and agencies such as Veterans Administration hospitals and health care facilities on tribal lands.
Manufacturers of wireless medical telemetry devices and their representatives are authorized to operate such devices only for the purpose of demonstrating, installing and maintaining the equipment for the benefit of duly authorized health care providers.
Radiation Testing of Wireless Medical Telemetry (WMTS) Devices
All Wireless Medical Telemetry Service (WMTS) devices that operate within 20 centimeters of a person's body must be routinely evaluated to demonstrate compliance with the FCC's radiofrequency (RF) radiation exposure guidelines. Portable WMTS devices are those designed to be used with a separation distance of less than 20 centimeters from the radiating structures of a device and a person's body. WMTS devices that operate at 20 centimeters or more from a person's body are not required to undergo routine evaluation to demonstrate RF exposure compliance. Mobile WMTS devices are those designed to normally operate with a separation distance of at least 20 centimeters from the radiating structures of a device and a person's body.
Since medical telemetry devices are typically worn on the body of the patient, it is expected that most WMTS devices will be classified as portable transmitters and will therefore be required to demonstrate RF exposure compliance with respect to the SAR (Specific Absorption Rate) limit (specified in 47 C.F.R. 2.1093). Nonetheless, there may be situations in which the WMTS device is mounted on a patient bed or incorporated within a separate device that is more than 20 centimeters away from the patient and nearby persons. In those cases, the WMTS device will not be required to undergo routine evaluation to demonstrate RF exposure compliance because, as a consequence of the relatively low power at which the devices must operate (i.e., less than 1.5 watts effective radiated power) and the separation distance between the device and the body of persons, the potential for mobile WMTS devices to exceed RF exposure limits is substantially remote.