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OVER THE past two-and-a-half weeks 23 of the world’s fastest and most
expensive sailing boats have been completing the first half of a race round
the globe. Arriving in Auckland, New Zealand, at the end of the third leg
of the competition, they have travelled almost 17,500 nautical miles, about
32,500 kilometres, since the race began in September last year at Southampton.
The boats must complete another three legs, covering 15,565 nautical miles,
before they cross the finishing line back at Southampton some time in May.
Although the race is taking them across some of the loneliest and the most
treacherous stretches of ocean, the crews could hardly be less out of touch
with the rest of the world – the competitors are at the centre of one of
the most comprehensive telecommunications networks ever devised for an international
yachting race.

Several boats in the race are testing the latest generation of mobile
equipment for transmitting and receiving signals by satellite; this supplements
the standard high-frequency (HF), or short-wave, radio apparatus that the
craft carry. Other boats are experimenting with a system that sends still
colour pictures from their decks by HF radio to the race headquarters in
Portsmouth on the south coast of England. In addition, new computer software
uses data on the position of every boat in the competition, which satellites
regularly pick up and relay to the race headquarters, to present sailing
enthusiasts and the media all over the world with the most thorough race
summaries and form guide in the history of the event. Progress reports for
the fifth Whitbread Round the World Race, the longest of the 16-year series,
come in such graphic detailthat only live television coverage, if it were
possible, couldbetter them. Telecommunications companies, equipmentmanufacturers
and service agencies are using the eventto demonstrate how small and tame
the world is. The competitors might not agree.

After the start, the boats sped south in the Atlantic Ocean, skirting
the coast of Africa before swinging westwards to Punta del Este, Uruguay.
The second leg, the longest of the race at 7650 nautical miles, took the
competitors eastwards across the southern Atlantic and through the Roaring
Forties, the area between the 40-degree and 50-degree latitudes noted for
its gale-force winds. They had also to negotiate the fiercer winds further
south, ‘the screaming fifties and sixties’ as one race official put it,
before they reached the Indian Ocean port of Fremantle, Western Australia.
Two yachtsmen, members of the crew of Creighton’s Naturally, fell overboard
on that leg: both were recovered but only one survived. Earlier, the same
boat lost some rigging and had to return to Punta del Este for repairs;
another boat, Steinlager 2, sent back pictures of icebergs and a cold crew
on deck. Late last month, after several weeks’ rest and recuperation, the
boats began the short third leg to Auckland. This jaunt around southern
Australia was comparatively modest but it extracted a toll: the next phase
of the competition is the harshest of the race. Early next month, the boats
head out eastwards into the southern Pacific Ocean towards Cape Horn. Once
more they must sail through the ferocious winds between the 40-degree and
60-degree latitudes; again they must minimise the distance they cover by
keeping as close as they can to a great circle without coming so close to
the South Pole that they run the risk of hitting icebergs or suffering exposure
on deck; and in addition they must ride the 50-foot waves at the southernmost
tip of South America before they can seek some respite, again at Punta del
Este. The two final legs, from Punta del Este to Fort Lauderdale, Florida,
and from Florida back across the Atlantic to Southampton, will have been
hard won by the yachting crews.

Exceptional skills are needed to complete the second and fourth legs
of the race. This is recognised by the organisers, the Royal Naval Sailing
Association and Whitbread, a British brewing and leisure company, which
stipulate that no crew can enjoy the glory of the final dash across the
Atlantic unless it has completed one or other of the toughest stretches
of the competition. According to British Telecom, one of the sponsors of
the race, this also explains why the four competitors that accepted its
still picture transmission system – Steinlager 2, Liverpool Enterprise,
With Integrity and Union Bank of Finland – seem to have had little time
to experiment with the equipment. Even so the pictures that crews on these
boats have managed to despatch from the high seas by short-wave radio are
remarkably clear in view of the processes necessary to get images back to
the Portsmouth headquarters. British Telecom says the system is attracting
the interest of mineral exploration companies and the armed forces.

The key to the transmission of pictures from the race, as it is in other
systems for relaying images electronically, is the method of reducing the
volume of data in the picture to essential ingredients, a process known
as image compression. Researchers at British Telecom chose to modify a picture-coding
algorithm (a logical sequence of instructions for, in this case, compressing
an image) that they had helped to develop under Esprit, the European Community’s
programme of research into information technology. The Esprit work, which
ended a year ago and was known as the Photovideotex (later termed Photographic)
Image Compression Algorithm project, defined a sequence of instructions
suitable for use as an international standard for still picture transmission.
Over three years, a team of researchers from Britain, the Netherlands, Denmark,
France, West Germany and Italy drew on existing algorithms to produce a
standard that combines high compression and minimum impairment of picture
quality with the capability of delivering a signal that can be decoded as
it is received, in real time.

According to Chris Dawkins, the head of Videotex research at British
Telecom, the company’s main modification to the standard, which is due to
be endorsed by the International Standards Organisation (ISO) this year,
doubles the degree of compression. This means there is 50 per cent less
information in the picture so the HF radio can transmit the signal reliably
in a reasonable time. The difference between the two systems is considerable.
The ISO algorithm reduces the information in a picture by a ratio of 20
to 1 for transmission at the rate of 64 000 bits per second, which is standard
for the Integrated Services Digital Network (ISDN), a growing data transmission
network. Dawkins says the British Telecom algorithm for the Whitbread race
slashes 800 000 bits of picture information to just 20,000 bits, a ratio
of 40 to 1. Inevitably this means some loss of picture quality. Only 2.5
per cent of the original data is left for the HF radio to transmit at 300
bits per second – the speed of the slowest form of electronic data transmission
– by bouncing the information off the ionosphere .

Operating the system on deck is straightforward, at least, in ideal
conditions. The crew plugs a standard video recorder into the boat’s personal
computer, now as common a feature of modern yachts as the mast, and selects
the frame it wants to transmit. The computer is fitted with extra circuitry
to convert the analogue signal from the video recorder into digital code
and with extra solid-state memory to store the selected frame from the video
sequence. British Telecom’s software then compresses the frame and a modem
converts the data for the picture’s essential ingredients, which are now
in digital code, back into analogue form for transmission. (A modem consists
of a modulator that converts computer signals in digital code into audio
signals in analogue form, and a demodulator that does the reverse.) HF radio,
which operates in a frequency range of 3 to 30 megahertz, does the rest.

The sky’s the limit

Problems arise from the natural unpredictability of shortwave communications.
For instance, the signals for pictures of the second leg in the southern
Atlantic, about 12 000 kilometres from British Telecom’s receiving station
at Portishead in the southwest of England, will have bounced between the
Earth and the ionosphere at least three times before being picked up by
the station’s antennas. The best frequency to use depends on a number of
factors including the location of the boat, the time of day and the season
of the year. Other difficulties arise from the sensitivity of transmissions
to corruption from interference by extraneous signals, or noise. A transmission
must be completely free of errors in order for the picture to be received
successfully at Portishead. If even one section of the data stream is corrupted
or gets lost, the rest of the stream shifts out of position and makes a
nonsense of the message, unless the error is close to the end of transmission.

The unpredictability of HF radio encouraged the owners of maritime vessels
to seek alternative communications links. This led to the establishment,
10 years ago, of Inmarsat, the International Maritime Satellite Organisation,
which began to provide satellite communications for operators at sea. Compared
with the multiple reflections of an HF-radio link, satellites offer the
equivalent of direct communication by transmitting the signal from space.
Inmarsat’s original system, known as Standard-A, is bulky: it consists of
a large antenna, which is a parabolic dish of about 1.2 metres diameter,
for attachment to the vessel’s superstructure, and a terminal as big as
a hefty office cabinet below deck. The equipment is also expensive at around
Pounds sterling 30 000. It is not suitable for sailing boats, let alone
racing yachts, although one competitor in the Whitbread race, Union Bank
of Finland, is said to have the equipment on board.

Demand for a more compact system has led Inmarsat to produce its Standard-C
equipment. (Standard-B, an improved version of Standard-A, is still in the
early stages of development.) According to Neil Teller, head of the Standard-C
project at Inmarsat, the latest equipment is being designed to serve any
operator on the move, whether at sea, on land or in the air. The antenna
weighs a few kilograms and ‘looks a bit like a flower pot’, he says, adding
that the terminal takes up less room than a personal computer. The equipment
needs to draw just 20 watts of power to transmit signals, and the antenna
can detect such weak signals that Teller describes the performance as ‘like
picking up heat from a 1-kilowatt fire on the Moon’. The basic Standard-C
package costs about Pounds sterling 4000.

Trials started last March after three years of development work. Inmarsat
is now serving between 300 and 400 lorries, trains and ships in the Atlantic
and Pacific regions, as well as three boats in the Whitbread race, Martela
OF, Gatorade and Equity & Law II. The organisation operates two distinct
networks: the ground station for the Atlantic region is at Goonhilly, in
the southwest of England and that for the Pacific region is in Singapore.
The satellite footprint in the Atlantic region extends from the Midwest
of the US to Kuwait and from Greenland to Antarctica; the one in the Pacific
region extends from Malaysia to the west coast of the US and from Alaska
to Antarctica. The stations transfer the signals to Inmarsat’s London headquarters:
from Goonhilly, the organisation leases a line from British Telecom; from
Singapore, it uses a link provided by Mercury, the other telecommunications
company based in Britain. Inmarsat staff in London process the calls and
redirect the messages using one of British Telecom’s standard services;
either the telex network or the data transmission service, known as the
X-25 network.

Although Standard-C equipment can transmit only data at a rate of 600
bits per second, unlike Standard-A equipment that can transmit speech or
data at a rate of 9600 bits per second, the smallness and cheapness of the
new system, which Inmarsat says might be described as a mobile telex terminal,
seems to be attracting considerable interest. The way things are going,
says Teller, a commercial service will begin inJune: he hopes to have half
a million customers before the endof the decade.

The trials of the Standard-C equipment demonstrated the demand for the
service – Inmarsat was soon transferring 600 calls a day via its main switching
system in London. They also revealed some of the problems that the organisation
would have to overcome to make the service successful. Chief among these
was the difficulty of minimising errors in messages that are transmitted
at such low power. (Transmissions at higher power are better able to swamp
extraneous noise.) Inmarsat uses three standard methods to keep its messages
clean. ‘Parity checking’ enables the system to detect when there are errors
in the signal received. As the message is transmitted, the sum of the digits
in the binary data, or bits, that make up a packet of information is always
made odd or even by adding the appropriate extra digit, either ‘0’ or ‘1’;
this assigned parity is verified at the receiver. In ‘forward error correction’,
extra bits of information are added ahead of the transmission. When errors
are detected, these bits let the system perform calculations to reconstruct
correct data from garbled passages. As an added precaution, ‘interleaving’
spreads out the bits in time to dilute the effect of a sudden burst of noise.
The bits are not transmitted in their natural sequence; they are scrambled
like shuffled cards and reassembled on reception. The overall result is
a ‘coding overhead’, says Teller: for every 100 bits transmitted, only 50
bits carry useful information.

On another level, Inmarsat has not yet found a way of modifying its
equipment to compensate for the doppler effect so that aircraft can use
the new system. The change in the perceived frequency of a signal, as an
aeroplane flies towards or away from a transmitter or a receiver, means
that only comparatively slow-moving motor vehicles or sailing boats can
take advantage of the lightweight mobile satellite link.

While Inmarsat is trying to establish its Standard-C network, the organisation
has set an 8-kilobyte limit as the maximum length of a message. (One byte
is equivalent to one character of text.) This is to avoid congestion of
the network while it is using only two channels to carry the bulk of the
communications traffic: one for transmitting messages from the ground stations
to the mobile operators and the other for transmitting messages from the
operators to the stations. The organisation uses two other, ‘signal’ and
‘coordination’, channels for short packets of information, up to 25 bytes
long: operators use the signal channel to let the stations know that they
want to send a message; the stations use the coordination channel to respond.
The channels are in the so-called L band, towards the top end of the ultra
high frequency (UHF) band, at frequencies between 1500 and 1700 megahertz.
According to Teller, the average message is 300 bytes long, which takes
about five seconds to transmit at 600 bits per second. As more operators
join the network, Inmarsat plans to increase the limit on the length of
a message to 16 kilobytes and possibly to 32 kilobytes, and to open other
channels.

Besides the clever electronics equipment that is beingtested in the
Whitbread race, there is the information servicebased at Portsmouth that
is telling the rest of the world inmore detail than ever before what is
happening on the highseas. The raw data come from the CLS/Service Argos
satellitesystem and its beacons, which are attached to all the boats inthe
race. The information is collected from Argos’s headquarters at Toulouse
via the International Packet SwitchedService, an established data transmission
network, under an agreement with the Royal Naval Sailing Association. The
main function of the Argos system is to gather environmental data. The system
is operated by the National Centre for Space Studies in France and by NASA
and the National Oceanic and Atmospheric Administration in the US. NOAA
satellites, of the Tiros polar-orbiting series, receive and relay climatic
information from automatic transmitters in balloons, buoys and fixed platforms
around the world. In the case of the Whitbread race, the satellites send
information about the location of competing boats, which the beacons supply
in bursts about every 60 seconds, and the time of the transmission. Race
positions are derived from this data.

A feast of information

During the fourth Whitbread race in 1985/86, when the rules stipulated
for the first time that contenders had to install Argos beacons on their
boats as a safety measure, that was all the information that followers of
the competition got. British Telecom has taken a leap forward. It provides
more than a regular update on the speed and the course of competitors and
the distances they have travelled and still have to cover. For instance,
the company’s researchers have designed software that calculates how fast
trailing boats must go if they want to contest the race leadership and that
stores the positions of boats in an electronic carousel, which can display
the information in sequence on a screen. This allows followers of the race
to plot the up-to-date routes of six boats at a time, in different colours,
superimposed on a map of the world. Most of the development work for the
information system for the Whitbread race has been done in British Telecom’s
research laboratories at Martlesham Heath, Suffolk. The softwaremay not
be revolutionary but it has transformed the wayan expected six million people
can keep up with a racehappening many thousands of kilometres away in theremotest
stretches of water.

British Telecom has established a private communications network that
links the race headquarters in Portsmouth to the four ports of call in Uruguay,
Australia, New Zealand and the US. The service leases lines on the standard
international communications system to transmit voice or data, via satellite,
land or subsea cables and microwave links. The publicsystem provides a backup
in the event of problems with theprivate lines.

News about the race is distributed to the widest audience by feeding
information from the private network into five public services: electronic
mail, facsimile transmission, the telephone network and the teletext and
viewdata systems. The syndicates sponsoring boats in the race, some of which
have cost as much as Pounds sterling 5 million to build and sail, have access
to mailboxes in British Telecom’s electronic-mail service, Telecom Gold.
The media’s main source of news is a facsimile database: journalists can
dial the database from their own facsimile machines to retrieve a print-out
of the latest race information. According to British Telecom, using facsimile
machines to poll a database in this way is a little known asset of the Group
3 standard terminals, which were introduced in 1980. People can keep track
of the race by using a Supercall telephone service, which has charge rates
well above the standard ones. They can also scan a proprietary teletext
system on their televisions, such as Ceefax or Oracle, or they can subscribe
to a viewdata service, such as Prestel. There is simply no excuse now for
not knowing what’s going on in the middle of the Pacific Ocean and around
Cape Horn.

* * *

Short-wave radio and the state of the ionosphere

WE USE high-frequency (HF), or short-wave, radio to communicate over
long distances because it is convenient, although distorted at times. Transmitters
can send signals all the way round the globe if they need to by bouncing
them off the ionosphere, the portion of atmosphere between 50 and 1000 kilometres
above the Earth that is ionised by radiation and particles from the Sun.
HF signals need 10 bounces and less than one-seventh of a second to circle
the world once.

Unlike satellite communications, or satcoms, standard HF transmitters
and receivers can be cheap, light and compact, and require little power
to operate. Small HF sets are also more versatile than miniature satcoms.
They can transmit speech, data and now still pictures, and they are suitable
for people on the move: for the operators of trains, boats and planes, and
for mineral prospectors in remote locations. The armed forces are particularly
keen on HF radio because the ionosphere is more resilient to attack than
a satellite.

HF radio operates in the waveband from 3 to 30 megahertz: the upper
limit is about the maximum frequency that is influenced by the ionosphere.
This mixture of ions and electrons, or plasma, has its most significant
effect on HF radio waves between altitudes of about 80 kilometres and 300
kilometres, where the concentration of free electrons is greatest. Radio
scientists label regions, or layers, of the ionosphere with letters. The
D Region, at around 80 kilometres, attenuates HF signals that pass through
it. The E Region, at around 110 kilometres, is more helpful; during the
day it may be able to reflect HF transmissions. The F Region, which is subdivided
into the F1 and F2 Regions between 200 and 300 kilometres, reflects waves
that manage to pass through the lower layers. The plasma fizzles out above
300 kilometres.

The ionosphere tends to trap waves with frequencies less than 30 megahertz.
Besides the HF band, these are waves in the medium frequency (MF), or medium
wave (MW), band from 300 to 3000 kilohertz; in the low frequency (LF), or
long wave (LW), band from 30 to 300 kilohertz; in the very low frequency
(VLF) band from 3 to 30 kilohertz; and in the extremely low frequency (ELF)
band from 300 to 3000 hertz. Waves in the ELF band can penetrate water,
which make them ideal carriers of messages to submarines. The trouble is
that low frequency waves cannot carry very much data because you cannot
impress fine information on a long wavelength: an ELF wave can transmit
only a few bits of information per second. (The higher the frequency of
a wave, the shorter the wavelength is. You can divide the speed of light,
300 000 kilometres per second, by the frequency of a wave to determine the
same band position as a wavelength.) Waves with frequencies greater than
30 megahertz tend to pass through the ionosphere. These are waves in the
very high frequency (VHF) band from 30 to 300 megahertz; in the ultra high
frequency band (UHF), which is used for transmitting TV signals, from 300
to 3000 megahertz; and in the super high frequency (SHF), or microwave,
band from 3000 to 30 000 megahertz.

The structure of the ionosphere is variable and this means that the
frequency limits for HF radio communications fluctuate. Its composition
changes with the time of day, the season of the year and the sunspot cycle.
The distance between terminals and the type of equipment being used also
influence the limits. If radio scientists are to exploit the ionosphere
fully for HF communications they need to be able to alter easily the frequency
at which their equipment operates. Civil and military communicators use
forecasts of the state of the global ionosphere to help them to select the
best frequency to use at a particular time. For instance, the D and E Regions
are hardly present at all after sunset and so waves absorbed during the
day are reflected at night. However, it is the frequent changes in the composition
of the F Region that present the greatest challenge; these demand skilled
radio operators or the most up-to-date equipment, which emits signals to
probe the ionosphere to determine its state.

Broadcasters still transmit signals on shortwave radio although they
prefer to use the MW and VHF bands. VHF transmissions are largely immune
to ionospheric interference and MW signals propagate locally by diffraction
over the ground. During the day, MW signals are too heavily absorbed by
the D Region to be heard over long distances; during the night, however,
when the D Region rapidly subsides, listeners must battle with foreign radio
transmissions, which are reaching and rebounding from the F Region, as they
try to tune into their favourite local station in the MW band.

Current research in the field of HF communications is concerned with
improving forecasts of the state of the ionosphere, especially in high latitudes
where thecomposition of the ionosphere varies considerably. Equipment manufacturers
arealso developing radios that automaticallycompensate for changes in the
ionosphereand for interference from other users.