Radio Communication

Wheelhouse Project - Radio

It seems hard to imagine that little over 100 years ago there was no such thing as radio communication, or 'wireless' as it was called. Indeed, even the telegraphs with wire conductors between railway signal boxes, and Post Offices used code and not voice communication.

'Wireless' came to these shores with the young Italian Marconi, and the first signals transmitted over water were between Lavernock Point near Penarth to the island of Flat Holm in the Bristol Channel, a distance of three and a half miles.

A bronze plaque commemorating the event was erected on the wall of St Lawrence Church, Glamorgan in 1947, 51 years later.

From the outset it was realised that radio would make all the difference to the safety of shipping, and Lloyds had operational wireless stations on several sites around the coast by 1898. It must also be remembered that, at that date, thermionic valves had yet to be invented, thus receivers were inherently insensitive. A good reference to these very early days is 'Wireless at Sea' by H E Hancock 1950 pub MIMCO.

There were thousands of vessels of all kinds across the world and clearly there would be advantages for improved safety, and purely commercial considerations, for every one fitted with radio equipment. As there were no radio stations it took some time before the fishing fleet began to fit receivers. There were many reasons for this, not least because there was no electrical supply system on fishing vessels that used steam for propulsion.

Invention of the radio valve by John Ambrose Fleming in 1904 unleashed a flood of related inventions that in the first decade of the twentieth century laid the foundations for things that changed the world. Not least, in 1924 the BBC was founded and broadcasting mushroomed from nothing. The Museum has a receiver (pic right) from that period, strange as it may seem they could only be purchased in kit form, the radio industry did not exist! The two battery operated valves can be seen mounted horizontally near the top. In a few years such valves were used in a battery operated echo-sounder design and the steady evolution of electronics into the fishing fleet began.

The radiotelephone (top) dates from the 1960s when technical specifications for both the transmitter and its associated receiver were laid down by the Radio Services Dept of the General Post Office in the UK. Prototypes were submitted to them for test and if they complied, the equipment would be given Type Approval. This transmitter produced 100 watts of RF power in the marine bands from 1.4 to 4.0 MHz and when fed into the kind of aerials shown between the masts of 'Pioner' see Brooke Marine page, gave a range of 200-300 miles. Communication was of a high standard both to other ships, often within the same fleet, and for emergency services. They could also communicate with the network of Coastal Stations that used common frequencies for calling and distress including quiet periods of 5 minutes after the hour to listen for distress calls on 2182 kHz. It was possible to make 'link calls' through these stations into the public telephone service, a facility widely used in the fishing industry by the skipper and owner to optimise landing places and times for the catch. Many of these coastal stations around the world have now closed down, but thankfully the history of this aspect of marine communication is on record, see www.qsl.net/gm3zdh/coast/uk/index.htm and www.gka.btinternet.co.uk/history.htm

After WW2, radio technology improved and higher frequencies came into use. VHF port and inter-ship communication could use these new bands effectively because performance is optimal in line of sight short range conditions. Interference within the long range medium frequency bands was also reduced by transferred usage. Typical output power was in the range of 10 to 25 Watts and using a marine end-fed dipole aerial, see side mounted aerials on the 'Spirit of Lowestoft' on RNLI page. Range would be up to about 20 miles and the equipment is simpler to use than an MF radiotelephone as there is no tuning, all the channels are preset and easy to select.