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BMERS-Emergency Email System

BMERS portable station
The BHEPP MARS/WL2K Emergency Radio System (BMERS. Pronounced "beamers") was created 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. The purpose of BMERS is to supply the hospitals with a backup communications system that they can use when other communications resources such as cell phones, Internet access, and others, become unavailable over a large area around the hospitals, such as during a large disaster event.

What is BMERS, again?

BMERS is a combination of custom and open source software that, when combined with the proper hardware-- an amateur radio rig--, enables any ham to provide last-resort Internet email communications to a group of non-ham people when Internet service is not available at that location.

With BMERS, the radio operator completely delegates the responsibility of managing messages to the end users, and 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 work on what he/she can do best--operating the radio rig--and the end-users have access to a communications interface that is very familiar and requires almost no training to use. To access the BMERS email service, end-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, do not need to install any additional software, and only need a set of network credentials that are provided by the station operator.

The BMERS software is free and distributed as open source. BMERS supports any radio rigs that are compatible with Paclink, one of the 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 healthcare coalition. The expected outcomes of this project are the following:

  • A technical solution that provides the hospitals with access to long-haul email communications with minimum dependency on infrastructural services, such as regular 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 the hospitals' Command Centers in support of their Hospital Incident Command System.
  • Emergency communications support provided to the hospitals by experienced and dedicated volunteers from the ham and MARS communities.
  • A radio station design 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.

See "References" section below for additional material.

System Architecture

BMERS was implemented in two main versions, a "Base Station" that is always available to local hospitals, and a portable version. This diagram illustrates the main components of our Base Station" implementation:

BMERS Architecture

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' Hospital Command Centers (HCC), and it is intentionally not connected to the Internet for security and reliability reasons.
  • A computer server connected to BHEPPnet, hosting a webserver, customized electronic mail server software, and the software required to use the Winlink 2000 system.
  • The server is connected to our base radio station, which is equipped with an HF radio, SCS Pactor 3 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.
The portable version uses the same software, but 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 Highlights

  • A single radio station with one trained operator can serve many end-users simultaneously over a large local area.
  • End users do not require an FCC radio amateur license or any radio operating experience.
  • 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.
  • HCCs at the BHEPP hospitals 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.
  • 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.
  • Users can use a "chat" tool to exchange instant messages to 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.

However, when necessary, the operator has the power to enable specific accounts to send emails without these restrictions.

Software and Documentation

The BMERS software is open source and free-to use for non-commercial purposes. You can download the latest software and documentation from here [IMPORTANT: This is our latest ALPHA 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.