Web Site for Demonstrating Browsing over HF Radio

It can be important for Mobile Units (e.g., Ships and Planes) to access information over HF Radio to complement "push" services such as messaging and XMPP. Access to a Web site is a natural way to achieve such a "pull" service. HF Radio is a difficult transmission medium, with slow speeds, very high latency, variable and error-prone transmission.

One part of providing Web Service over HF is to address protocol issues using products such as Isode's Icon-PEP. This solution is discussed in the Isode white paper "Measuring and Analysing HF-PEP for TCP communication and Web Browsing over HF", which is also available on this web site HERE.

While general purpose Web sites can be accessed using new Wideband HF (WBHF) technologies, the user experience is quite slow. To provide good user Web experience at WBHF speeds and to enable useful service over narrowband HF (which is widely deployed) it is important that the Web site is designed with HF in mind. Key considerations:

  1. Keep all elements of the Web sites small, because of download speeds.
  2. Do not use TLS. This improves performance due to reduced hand-shaking, and allows cached pages to be shared between users on a Mobile Unit.
  3. Keep the number of files on the Web site small. (most general purpose Web sites have lots of files)
  4. Do not reference additional domains. Domain lookups add considerable delays.
  5. Structure pages to be small.
  6. When a large graphic or picture is important, provide as separate object, which size of object noted (to help user estimate download time).

This Web site is constructed to follow these principles. It is intended to support demonstration and testing of access over HF Radio, while being available on the Internet to any interested users.

There are two types of page on this site. The first are intended for access with WBHF and the top-end speeds of Narrowband HF (4800-9600 bps) with low error rates. This is information taken from the Isode Web site, to show that it is practical to provide good looking Web material in a way that can be accessed over HF. These pages are:

The second type of page is to demonstrate that Web access is possible at mid-range HF speeds (down to 1200 bps). This home page is designed for this, as is STANAG 4406 Military Messaging, showing how information from the Isode web site can be structured in a way that enables basic information to be accessed at these low speeds, using a highly structured approach and simple presentation to limit page size.

Further details of this Web site, including performance measurements, videos and analysis will be given in the upcoming Isode whitepaper "Building a Web Site for Access over HF Radio", which will be made available on this website.