The aim of this project is to demonstrate the feasibility of providing automatic data and facsimile services for remote users via MF, HF and VHF radio systems. In this context, remote users are those who can only be reliably linked through long-range (HF or MF) radio systems, as they are located in remote areas away from national communications facilities or are travelling by land, sea or air.
Existing remote users employing MF and HF radio communications to access the public networks are mainly those using the maritime mobile service. The systems available are generally limited to the transmission of telephony, telegraphy and telex which, apart from telex, are operated manually, requiring operators at coast stations to connect calls to and from the public networks. Such users may alternatively employ mobile satellite communication systems (such as INMARSAT), which provide automatic access to numerous radio communications services including data and facsimile.
The project consists of four main areas:
- Specification of remote user and system interfaces to allow fully automatic two-way access between remote users and the public network for long-range radio.
- Definition and development of a remote user system that will register a link request and automatically set up a link with the required network user. The process used for setting up the link will use predefined information about the intended network user's location and facilities to select the path, and will also select the frequency and data bit-rate to use.
- Definition and development of a public network gateway that will detect and route calls from remote users to the required network user and set up a link with the required remote user. The setting up of a link to the remote user will require prior knowledge of that user's facilities, location and monitoring or some means of acquiring this information.
- Development of new techniques to enhance and optimise the performance of data communications over long-range HF radio links. This involves investigating techniques to provide real-time channel evaluation and computation of optimum transmission parameters such as bit-rate.
EC1A 7AJ London