BMERS-Emergency Email System

BMERS portable station

In the late 2000's and early 2010's, NIHRAC was invited by the National Library of Medicine to help develop an innovative solution to help hospitals remain "connected" during extraordinary disaster events. As a result, NIHRAC and other collaborators created a new concept in amateur radio emergency communications support. This concept modifies the traditional role of hams that usually consists on passing individual messages through radio to assist emergency practitioners or other served individuals into one of maintaining a reliable electronic communications services, with ham radio at the core, for many emergency practitioners to handle their own messaging needs. The concept was materialized on a prototype technology called BMERS:

The purpose of the "BHEPP MARS/Winlink Emergency Radio System" (BMERS--pronounced  "beamers") is to supply medical facilities with a backup Internet email system for disaster situations. Emergency managers in the EOC can use BMERS when other communications resources such as cell phones, Internet access, and others, are affected by the emergency. This is particularly important when telecommunications become unavailable over a large area around the facility, potentially in a radius of tens or thousands of miles. 

BMERS acts roughly as a very-long-distance wireless Wi-Fi connection to the Internet, but only for email because the bandwidth is limited. Although BMERS cannot provide web browsing capabilities to end users, it supplies enough communications capacity to transfer hundreds of brief emails per day during a disaster situation. Since BMERS connects wirelessly to the Internet outside the disaster zone, the email recipients at the other end do not need any special equipment or software to communicate with BMERS users other than their regular email service. Typically, BMERS stations can be powered by a car battery, grid power or other sources.

BMERS  was developed as a research collaboration between the NIH Radio Amateur Club (NIHRAC), the US National Library of Medicine (NLM), and the Bethesda Hospitals' Emergency Preparedness Partnership (BHEPP), a local healthcare coalition. The project also benefits from contributions from Army-MARS, MARC members, and other hams.

I'm a ham. What is BMERS, again?

BMERS integrates customized and open-source software that, when combined with the an amateur radio rig compatible with the Winlink 2000 system, enables any ham to provide emergency Internet email communications to a group of non-ham people when Internet service is reduced or not available at that location.

In contrast to more traditional ham radio services, BMERS allows end-users to handle their own email. With BMERS, the radio operator becomes an almost-transparent component of the email service enabled by this application. This has many advantages, for example: the radio operator can focus his efforts on making sure the radio links are established and not on handling messages. The end-users have access to a familiar email communications interface that requires almost no training to use. Since local users can access BMERS via Wi-Fi at a distance, BMERS allow local users to communicate among themselves or with the radio operator via instant messaging or local email. The radio operator has access to an easy-to-use management interface to control most functions.

End-user requirements

Local users do not need to have a ham radio license or interact with the radio equipment at all. To access the BMERS email service, local users can use any Wi-Fi or Ethernet capable device (such as a PC, laptop, tablet or smart phone) that can run a standard web browser. No additional software is required. The radio station operator supplies local users with email credentials and Wi-Fi configuration data required to access the service. 

Email users at the other end, on the Internet side, do not need any special software to communicate with BMERS users. They simply include in their emails some special addressing data included in emails from BMERS users.


After the objective of the project was achieved, the project itself was sunset in 2019. The BMERS software can still be downloaded from our website (click HERE for a direct link), but it is not been actively maintained and therefore it's probably not compatible with new version of operating systems and other required software anymore. BMERS integrates custom software with several free and open source products. BMERS was designed to support any radio rigs that are compatible with Winlink Express or Paclink, two software tools used to access the Winlink 2000 service (see

If you want to learn more about BMERS, keep reading.

Project Goals

BMERS was born of a R&D project for a local healthcare coalition (BHEPP). The expected outcomes of this project are the following:

More details about this project and the implemented system can be found in these articles:

Cid V, Mitz A. "Optimizing Amateur Radio Resources for Major Disasters". ARRL QST Magazine, September 2011 issue, pages 30-34.

VH Cid, AR Mitz, SJ Arnesen, "Keeping communications flowing during large-scale disasters: leveraging amateur radio innovations for disaster medicine".  Disaster medicine and public health preparedness 12 (2), 257-264

System Architecture

BMERS has been tested in two operating modalities, as a portable version that can be easily deployed, and as a "Base Station" that is permanently available to local facility staff. 

As a portable version, BMERS implements its own LAN (wired and wireless) around the radio station and, via a Wi-Fi bridge, can extend the LAN access to the system to users located up to a mile away. This portable version can use a variety of power sources and antenna systems, and operate on HF and VHF amateur and MARS frequency bands.

BMERS portable station diagram

BMERS can also be connected to a pre-existing LAN, which makes this service available to users through that local network. The following diagram illustrates the main components of our "Base Station" implementation in the NIH Bethesda campus:

BMERS Architecture

As the diagram suggests, a single BMERS station is shared by three EOCs in three different medical facilities (note: as of September 2017, the BHEPP network was discontinued, but other mechanisms are being explored to provide this multi-facility service). In the above example, BMERS has the following high-level components:

BMERS Highlights

BMERS Portable Station deployed

Bandwidth Control

The bandwidth provided by a HF (or even VHF) radio link for sending email over Winlink 2000 is very limited. It's very easy to completely choke the link with a single large email. The radio operator can potentially remove a large email from a queue on the local radio station side to unclog the system, but it can be difficult to remove a large email coming from the other side that can be clogging the available downstream bandwidth. While the radio link is busy receiving an email, no email can be sent. This situation is what we call "Winlink jam" (or "bandwidth catastrophe", depending on the severity).

There are no limitations when sending emails within the BHEPPnet LAN, but to reduce the chances of a "Winlink jam" in the radio link to the Internet, we implemented a number of features in the software:

When necessary, the operator has the power to enable specific accounts to send emails without size or attachment restrictions.

Software and Documentation

The BMERS software is free-to use for non-commercial purposes. You can download the latest software and documentation from here [IMPORTANT: BMERS Is not being actively maintained anymore]. You can find older versions and other related files in our "Documents and Software" page.


VH Cid, AR Mitz, SJ Arnesen, "Keeping communications flowing during large-scale disasters: leveraging amateur radio innovations for disaster medicine".  Disaster medicine and public health preparedness 12 (2), 257-264

Cid V., Mitz A. ‘Optimizing Amateur Radio Resources for Major Disasters”. QST, September 2011, pp. 30-34. Available from

NIHRAC. “BMERS-Emergency Email System”. On the Web at

Conuel T. “Emergency Backup Communications: The Old Meets the New”. NLM In Focus, January 10, 2013. Available from

Cid V., Mitz, A. “Radio E-Mail Service for Back-up Hospital Communications. Poster, updated January 2015. Available from