Easter Island/Salas y Gomez 1-22 September 1995
Cordell Expeditions

Radio Science and Amateur Radio

  • Radio Science
  • The TCS/AC System

  • Radio Science

    A team of approximately 25 radio amateurs will set up and operate four independent radio stations on Easter Island and two on Salas y Gomez. The goals include implementation of a computer-based system for logging and confirming contacts; logging stations who want a contact with these islands for their records; operation of a beacon for recording propagation; moon-bounce radio contacts; digital radio operation including RTTY, AMTOR, and PACKET; and operation of slow-scan TV. Much of the motivation is to advance the art and science of amateur radio in remote locations, both for calling stations and the expedition stations.

    It is planned to operate all legal digital modes, including via satellites. Thus, this operation will provide contacts for many amateurs primarily interested in developing and field-testing their equipment and software, as well as those interested in collecting DX contacts for certificates. Salas y Gómez will provide a new island for the Islands-on-the-Air (IOTA) program, administered by G3KMA for the Radio Society of Great Britain.

    The expedition team will establish a base camp on Easter Island from which the scientific and radio operations will be conducted. This team will concentrate on providing contacts with amateurs on digital modes, and will provide the link to the team at Salas y Gómez. The Salas y Gómez team will establish 2 stations for about a week. The Easter Island stations will use the callsign XRØY, and the Salas y Gómez stations will use the callsign XRØZ.

    A central goal for this project is to implement a variety of innovations that have not previously been used for radio DXpeditions. The following items have been implemented for the 1995 EI/SyG expedition.

    1. Internet connection: The campsite on Easter Island will have a computer that is a node on the Internet. The IP address is not publically available, but the expedition can be reached through several internet relays.
    2. Anchor stations: A network of amateur radio stations with additional digital capability will receive data and pass it into local communication channels.
    3. Public radio logs: A WWW site provides access to the logs. The user can log in, enter a callsign or date/time, and view the corresponding log entries.
    4. e-QSLs: Within 24 hours after any logged QSO, an internet message to the calling station is automatically generated.
    5. Next-day QSLs: Within 24-hours after a station's first QSO with the expedition, a QSL card is automatically printed and placed in the U. S. mail
    6. Barcode: A barcode representing the essential data about the contact is printed on the QSL card.
    7. Reflector: A discussion group called Easter-Island@the-courtyard is available for anyone to read and send comments about the expedition or EI/SyG in general.
    The efficient interconnection of many thousands of radio operators to a single remote site provides an exceptional opportunity for conducting research on radio science. During late 1995, the sunspot activity will be minimum, providing the motivation for investigating propagation of radio waves during such normally poor conditions. We expect to be able to test models and software predictions of propagation, especially on the low bands.

    The greatest effect of this project, however, will be to help change the DXpedition from a performance/spectator event to a participatory event, and to increase the efficiency and enjoyment of the sport for as many persons as possible.

  • Return to Radio Menu
  • Return to Home Page

    The TCS/AC System

    The expedition seeks to implement a system for enhancing temporary radio communications from remote sites, called Temporary Communications Structure/Auxiliary Channel (TCS/AC). The TCS/AC is shown schematically in the following figure.

    The TCS/AC is designed as follows: We desire to carry out communication across a link between a remote station R and a set of local stations L. This link is very poor quality, perhaps due to weak signals, interference, unknown schedules, unknown transmission and reception frequencies, etc. Furthermore, the RL link is in place for only a limited period of time. At the low rates of communication over this link, it is unlikely that a successful exchange will be made before the link is broken, or that the link cannot be established in time. Although it is possible to improve the quality of the RL link by adjusting it operating parameters (e.g., selecting transmit/receive speeds, frequencies, etc.), it is not possible to pass enough information over the link to effect this improvement before the link is broken.

    The TCS/AC strategy is to establish an auxiliary channel AC which is of very high quality but which has very limited capacity. The auxiliary channel carries information that can improve the operation of the RL link, but it cannot carry the communications itself. Thus, the auxiliary channel will assist in improving the RL link, but that is all.

    We apply this to the typical problem faced by an amateur radio expedition ("DXpedition") as follows: A DXpedition involves communications between a single remote site (typically an island) and many individual local sites (amateur radio stations). The goal is to make a confirmed contact with each station, by which is meant two-way communication between the remote and local sites. The problem is that propagation of radio waves through the ionosphere between the two sites is noisy, subject to interference, and occurs for only a few hours each day. Typically there is no capacity to test the propagation paths and optimize the operation of the stations, e.g., by selecting frequencies, mode, and data rates. Often, the greatest challenge is just finding the correct frequency on which to listen or transmit, and being on frequency at the right time.

    In operation, the island station sends data through the AC, providing the local amateur stations with information about the operations and guidance for adjusting their operations. The local stations in turn feed information on quality of their contact back through the AC to the island station, which adjusts its operations accordingly. Thus, the contacts made directly between the island and the amateur stations are enhanced by means of the auxiliary channel.

  • Return to Radio Menu
  • Return to Home Page
    Last Update: 23 August 1995
    Prepared and maintained by Robert Schmieder, cordell@ccnet.com and Gunthar Hartwig, Gunthar_A._Hartwig@bmug.org