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BMERS-Emergency Email System

BMERS portable station
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-MARSMARC 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.


The BMERS software is openly available for download and use free of charge (see download instructions in the Documents and Software page on this website-BMERS Software and Docs section, or click HERE for a direct link), and is distributed as an installable Windows application. BMERS integrates custom software with several free and open source products. NLM cannot provide hardware, but BMERS supports any radio rigs that are compatible with Winlink Express or Paclink, two software tools used to access the Winlink 2000 service (see www.winlink.org). We will soon make available on this website the technical specifications of the rigs we have used during development, but many others, including rigs with software modems, should work just fine.

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:

  • A technical solution that provides medical facilities (and others) with access to long-haul email communications with minimum dependency on infrastructural services, such as local telecommunications, power, etc.
  • A communication system that is fast to deploy-activate, simple to use, and as simple as possible to manage and maintain during an emergency situation and emergency communications exercises.
  • A system that provides electronic mail communications between Incident Command Centers (or EOCs) in support of their Hospital Incident Command System or equivalent.
  • Emergency communications support provided to the hospitals by experienced and dedicated volunteers from the ham and MARS communities.
  • Radio station rig designs that can be reproduced by others, and software that can be freely used by anyone interested.

More details about this project and the implemented system can be found in this QST article:

Cid V, Mitz A. "Optimizing Amateur Radio Resources for Major Disasters". ARRL QST Magazine, September 2011 issue, pages 30-34.
You can temporarily acess a copy of this article in our Resources page. At this location you can also find a presentation about the project, and a BMERS poster that depicts the main components of our portable station.

A much updated article will be published in 2017 (check here for the link).

See "References" section below for additional material.

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:

  • A high-speed, private Local Area Network between the hospitals. This network (called BHEPPnet) was implemented via a separate BHEPP project. This LAN interconnects the hospitals' Incident Command Centers (ICC or EOC), and it is intentionally not connected to the Internet for security and reliability reasons.
  • A computer server connected to BHEPPnet, running the BMERS software.
  • The server is connected to our base radio station, which is equipped with an HF radio, SCS Pactor 3/4 radio modem, and a variety of HF antennas.
  • The system makes use of the Amateur Radio Safety Foundation, Inc's (ARSFI) Winlink 2000 system to allow for emergency email service via ham and MARS radio.

BMERS Highlights

  • A single radio station with one trained operator can serve many end-users simultaneously over a potentially large local area.
  • End users do not require an FCC radio amateur license or any radio operating experience.
  • BMERS users can use any available computer (or tablet or smartphone) with a standard web browser to access the email service. No special software is required on users' computers, just a web browser and Wi-Fi.
  • BMERS has pre-defined user accounts based on HICS roles, but the user accounts can be easily reconfigured as needed.
  • Local users can exchange full-featured emails with attachments among them (and communicate via text messaging) at full LAN speed.
  • BMERS implements a number of features aimed to manage the use of the radio link's limited bandwidth (see "Bandwidth Control" below).
  • Users' email accounts in BMERS are all role-based and follow the staffing positions defined in the Incident Command System.
  • Local users can see which other users on BHEPPnet are using BMERS at any given time. The available email address in the LAN are predefined in an address book for quick access.
  • Local users can use a "chat" tool to exchange instant messages with each other and with the radio operator. This tool also allow users to know who is available via the local area network around a BMERS station.
  • The Radio operator has access to a Graphical User Interface (GUI) for managing all the aspects of the system. This tool allows the operator to monitor the email queues, quickly switch between ham and MARS operation, manage user accounts, and much more.

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:
  • Users need to use a texting interface to compose email messages going to the Internet. This interface has a message size limit (currently 1000 characters). It displays a character counter that tells the user how many characters are left when typing a message.
  • Users can only send an email to a single Internet destination (no copies), to reduce the chances of multiple users replying at the same time and clogging the link on the way back.
  • Emails include instructions for replying, which include a request to keep replies small.
  • The body of the message is stripped of unnecessary characters before sending.
  • Headers and other control information is kept to a minimum.
  • Regular emails cannot include attachments.
  • Under certain circumstances, trained operators can also use Winlink 2000 tools to remove the traffic jam at the remote end.

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: This is our latest BETA software version that is still in active development. Please report any issues to us]. You can find older versions and other related files in our "Documents and Software" page. You can contact  vcid @ nih.gov for more details or to report problems.


Cid V., Mitz A. ‘Optimizing Amateur Radio Resources for Major Disasters”. QST, September 2011, pp. 30-34. Available from http://docs.google.com/viewer?a=v&pid=sites&srcid=bmlocmFjLm9yZ3x3d3d8Z3g6NzI1M2I0NWFlODY5NDg3OA.

NIHRAC. “BMERS-Emergency Email System”. On the Web at http://www.nihrac.org/home/bmers.

Conuel T. “Emergency Backup Communications: The Old Meets the New”. NLM In Focus, January 10, 2013. Available from http://infocus.nlm.nih.gov/2013/01/10/emergency_backup_communication/.

Cid V., Mitz, A. “Radio E-Mail Service for Back-up Hospital Communications. Poster, updated January 2015. Available from https://docs.google.com/a/nihrac.org/viewer?a=v&pid=sites&srcid=bmlocmFjLm9yZ3x3d3d8Z3g6NTc0YTYwNzQ3ZTYxODA0NQ.