When the Federal Communications Commission (FCC) established the wireless medical telemetry service (WMTS) in response to concerns about interference resulting from television stations, paging stations and private land mobile radio (PLMR) equipment, they also appointed the
American Society for Healthcare Engineering (ASHE) as the WMTS frequency coordinator.
The FCC charged ASHE with developing a frequency coordination database, and mandated that all WMTS users register their deployments in the database maintained by ASHE.
Now is the time to register your WMTS deployment with ASHE. Failing to do so is illegal and could also put patients at risk.
Why use WMTS?
The WMTS frequency coordination database has been available for some time now. However, the notion of frequency coordination may be foreign to most WMTS users. In addition, hospitals may not be aware of all the reasons to move to WMTS.
Because equipment is still under development for the two 1.4 GHz bands (i.e., 1395-1400 MHz and 1427-1432 MHz) and there are still a few technical issues to be cleared up for those bands, this article focuses on WMTS deployments in the 608-614 MHz band.
The FCC established the WMTS and allocated frequencies because of the impending encroachment on medical telemetry use in the other bands. It is important to note that medical telemetry users in these other bands are referred to by the FCC as secondary. This means that there are other users who enjoy primary operation in bands to the extent that they can cause interference to medical telemetry users with impunity. Medical telemetry users' only recourse to these licensed primary users is to retune to another frequency (preferably WMTS).
The table accompanying this article lists the bands available for medical telemetry and provides a few statistics on the number of current users. It's easy to see that the interference potential to medical telemetry users in the non-WMTS bands is quite high. Considering the number of licensees currently in the non-WMTS bands, and the number of annual license grants, interference to medical telemetry systems in these bands is not a matter of if, but when.
Register with ASHE
By contrast, there is inherent protection to medical telemetry operations in the WMTS bands. In fact, systems in these bands are licensed. The FCC refers to services such as WMTS as licensed by rule, requiring that "prior to operation, authorized health care providers who desire to use wireless medical telemetry devices must register all devices with a designated frequency coordinator." It is through this registration process that WMTS systems become licensed.
Since ASHE is the exclusive FCC-designated frequency coordinator, all operating WMTS systems must be entered into ASHE's WMTS frequency coordination database. Failure to do so will not only leave these systems unprotected from interference, but will also mean that these systems are operating illegally and could be shut down by the FCC and even fined. In addition, the FCC requires that frequency use in the WMTS bands be coordinated, meaning that other WMTS users must search the database and select frequencies that will minimize the potential for interference into any pre-existing systems. The FCC leaves the determination of interference up to the end user, not ASHE.
Because WMTS is the only designated frequency spectrum for medical telemetry systems, users are protected against interference from other wireless devices, provided the WMTS deployments are properly coordinated and entered into the database. Thus, the sooner devices are registered in the database, the sooner they receive this protection. Because of this protection, the Food and Drug Administration has strongly encouraged the use of the WMTS bands by the medical telemetry community.
In case the legal reasons are not enough, here are a few other reasons to register your WMTS deployments:
- Risk management. You can protect patients' telemetry data from being corrupted due to interference. Interference has caused entire telemetry systems to fail, leaving critically ill patients with no monitoring at all. Registration with ASHE helps ensure that telemetry units are protected from this type of harmful interference.
- Wireless planning. Registration is a key part of wireless planning, which is essential for proper interference-free operation of any wireless investment, especially a WMTS system.
- Protection. The operating frequencies of registered telemetry units will be considered in other hospitals' analyses, thus providing a greater margin of interference protection.
- Inventory management. The database can help you keep an inventory of your WMTS deployments. It can also help manage electromagnetic interference and compliance (EMI/EMC) issues throughout the hospital.
- Monitor other WMTS activity. Users can get equipment manufacturer and model information as well as hospital contact information for any WMTS system that could affect a deployment.
- Support. Users get immediate access to specialists who can help to better understand the FCC rules and explain this process.
Using the database
To use the WMTS frequency coordination database, users must first contact ASHE to establish an account either by phone at (312) 422-3805 or by logging on to www.ashe.org/currentevent/ wmts.html.
The simple online process involves providing information on the hospital or main facility where medical telemetry will be installed. Users must also pay a one-time administrative fee to establish their account.
When contacting ASHE, have the following information ready: Contact name; hospital department; hospital address, zip code, phone and fax numbers, and e-mail address; and data for up to 10 facilities, including addresses and zip codes.
Once ASHE receives the registration information and processes the payment, they will set up an account to use the WMTS frequency coordination database. ASHE will contact the hospital with the appropriate account information including login and password. ASHE uses the facility information to prepopulate the facility data in the coordination database. This helps to streamline the deployment registration.
After an account is established, enter your login and password to access the WMTS frequency coordination database. You can access the database from the ASHE Web site, or by entering www.wmtssearch.com in your browser.
Once in the system, you can enter site and equipment information, perform a frequency search, select frequencies, and download a coordination certificate. There is no charge to perform a frequency search. However, once you select frequencies and commit the deployment to the database, you will be charged a coordination fee. The fee will be charged for each deployment.
Performing the search and selecting frequencies is simple. Based upon your login information, the software knows your associated hospitals. Then, using a utility called the "facility finder," you can display all hospitals registered under your login. Select the hospital where the deployment is to be installed, and the software will return the hospital's address.
From there, you provide specific information regarding the deployment including the following: Clinical unit; deployment type--permanent or trial; radius of the deployment (i.e., how far from the geographic coordinates the deployment will reach); highest floor with WMTS transmitters; total number of transmitters; equipment manufacturer and model (this is a pick-list of all WMTS vendors' equipment); and search radius.
Assuming all the information is correct, you can then click a button to perform the frequency search. The results of the search will indicate what other systems are operating within the search radius. The search results return information on other WMTS systems, adjacent-channel TV stations (channels 36 and 38), and radio astronomy receivers. You can change search parameters if you like and rerun the search.
When ready to select frequencies, you can click a button that takes you to a list of frequencies. The frequencies are labeled as being available or having potential conflicts. In most cases, all frequencies will be available; however, in some instances, some of the frequencies may be indicated as having potential conflicts. This will happen if any of the following are found within the search radius:
- There are other WMTS users;
- There are TV stations on channels 36 or 38; or
- The WMTS deployment is within a specified distance of a radio astronomy site.
In the unlikely event that there are potential conflicts, you can select those frequencies that are not conflicted. If all frequencies show conflicts, you can still select a conflicted frequency, but you should also contact your equipment vendor or another third party to perform a thorough assessment of the interference potential. However, if the conflicts result from proximity to radio astronomy sites, there's one more step.
The 608-614 MHz band is shared by radio astronomy in several remote areas of the country. Radio astronomy sites are used to map the radio energy coming from the distant reaches of the universe. Consequently, these sites are highly sensitive to energy that could come from a nearby transmitter such as those used for WMTS.
Thus, the FCC requires that ASHE coordinate WMTS usage with radio astronomy for deployments that fall within these areas. The map accompanying this article shows the locations of the 13 radio astronomy sites in the United States, as well as a protected area around each site. There is an additional fee for this coordination, and it is charged only if the deployment falls within one of these protected areas. This type of coordination requires acknowledgment from the radio astronomy site that there will be no interference from the proposed WMTS deployment. Therefore, no such WMTS deployments are allowed to proceed without approval from the spectrum manager at the radio astronomy site. ASHE performs this coordination with the appropriate spectrum manager and will let you know immediately once approval is received.
Once you're satisfied with the frequencies you've selected, the next steps are to commit the frequencies to the database, pay the coordination fees and generate the coordination certificate. The coordination certificate contains all the specific information for the deployment, including the specific deployment data and the frequencies selected.
The certificate confirms that you have used the WMTS frequency coordination database to select frequencies for the WMTS deployment, and that those frequencies have been entered into the database. Please note that the FCC requires you to have the coordination certificate before you activate the system.
Need help?
The WMTS frequency coordination database was designed to be quick to learn and easy to use. However, if you run into trouble or have questions, ASHE has developed several resources to help you better understand how to use the system, as well as how to better understand your registration obligations.
All of these resources are available on the ASHE Web site or on the www.wmtssearch.com Web site. There is a downloadable self-paced training presentation that takes you step-by-step through the process of registering your medical telemetry deployment and answers many questions about the information required to register medical telemetry systems.
In addition, there is a User Information Guide available that also gives the basic detail on how to register a WMTS deployment. You can also refer to the Web sites for frequently asked questions.
A requirement, not an option
Registering your WMTS deployment is not optional. Even if you were operating in the 608-614 MHz band before the new rules were adopted, you still are required to register. So, be sure to register every deployment as soon as you can.
H. Mark Gibson is senior director in charge of health care engineering services at Comsearch, Ashburn, Va. Comsearch, which provides total-solution offerings for wireless engineering design, is ASHE's technical partner for WMTS frequency coordination, database development and related issues.
Primary users of the medical telemetry spectrum
| Band | Primary users | Nationwide statistics (as of July 2002) |
| 174-216 MHz, 470-608 MHz & 614-668 MHz |
TV channels 736 & 3846 PLMR Paging |
483 licensed DTV stations 1205 potential future DTV stations 28,000 PLMR licenses |
| 450-460 MHz | PLMR Paging Auxiliary broadcast Maritime mobile Personal radio Air-ground |
230,000 PLMR licenses Note: The average number of PLMR license grants per year is 41,000 |
| 460-470 MHz | PLMR Personal radio |
622,000 PLMR licenses Note: The average number of PLMR license grants per year is 102,000. |
| 608-614 MHz | WMTS Radio astronomy |
13 radio astronomy sites |
| 13951400 MHz | WMTS Military radar |
17 radar sites |
| 1427-1432 MHz | WMTS Military radar |
14 radar sites |
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