Wireless Telegraph Archives - Page 2 of 2 - Innovating in Combat

Category Archives: Wireless Telegraph
Prior to the outbreak of WW1 in August 1914 many of the techniques to be used in later years for radio communications had already been invented, although most were still at an early stage of practical application. Radio transmitters were predominantly using spark discharge from a high-voltage induction coil. The transmitted signal was noisy and rich in harmonics and spread widely over the radio spectrum.
The ideal transmission was a continuous wave (CW) and there were three ways of producing these: by an HF alternator, a Poulsen arc generator or a valve oscillator. The first two of these were high-power generators and not suitable for battlefield communication. Valve oscillators were eventually universally adopted. Several important circuits using valves had been produced by 1914. Predominant amongst these were the amplifier, detector and oscillator. The oscillator, apart from its use as a CW generator for radio transmitters, was also used in radio receivers in a heterodyne circuit and the resulting beat note produced an audible tone of the Morse signal in the headphones.
Valves at this time were still at a primitive state of development. Those available were: The Fleming diode, the de Forest audion triode and the C and T triodes designed by the Marconi engineer Henry Round. All these triode valves were gas-filled to improve their sensitivity but had erratic performance.
Both the C and T valves were used in the Marconi Short Distance Wireless Telephone Transmitter and Receiver. This radio, however, would not have been robust enough for use under battlefield conditions. The C valve, however, was used by the army in direction finding stations.
Early army radios
At the start of the war the only radios available were a few 500-watt and 1500-watt spark transmitters and their crystal-detector receivers. The 500-watt pack sets were used with Cavalry Brigades and the 1500-watt wagon sets with Cavalry Divisional Headquarters and General Headquarters.
The principal method of communication by the British army, up to late 1917, was by cable for speech and Morse transmission. Initially, a single cable was laid above ground and the earth used as the return. However, the cable was vulnerable to damage by enemy fire and by the passage of tanks across the battlefield, a problem not solved even when buried cable was used. Very often communication was not possible, particularly when troops were moving rapidly forward or in retreat. During the course of the war tens of thousand miles of cable was laid and, at times, there was an acute shortage of replacement cable.
It was found that the Germans were able to listen in by picking up earth currents or tapping into the cable. This was not realized at first but, when discovered, it was necessary to limit the number and content of the message and, where possible, to use codes or encryption. A solution to this was the Fullerphone, which made the signal immune from eavesdropping, but it could not be used for telephony.
Other non-wireless means of sending messages that were used with mixed success during the war was by runners, dispatch riders, pigeons, lamps and flags.
Up until the end of March 1918 the Royal Flying Corp was part of the army and experimental work on aircraft radio communication was carried out at Brooklands and later at Biggin Hill. The development group, headed by Major Charles Prince, also worked on the development of CW voice transmission. This culminated in mid-1916 with the successful demonstration of ground-to-air speech communication. However, it was to be a further two years before suitable equipment was incorporated in aircraft. Consequently all the early radios were spark transmitters fitted in the aeroplanes and crystal receivers on the ground.
No 1 Aircraft Spark
Amongst the earliest radios to be used in aeroplanes was the 30‑watt, No 1 Aircraft Spark (Figure 1), powered from an accumulator. The set was designed in 1914 and fitted to approximately 600 aircraft during 1915. It was used for spotting enemy artillery and reporting back to ground by Morse code. There were several variants of the set and, altogether, nearly 4000 of these were manufactured.
Unlike with the RFC there was a general lack of enthusiasm in the army for using radios, particularly during the first two years of the war. There were several reasons for this: the equipment was bulky; the accumulators needed frequent re-charging; and there was a genuine fear that the enemy would be able to intercept the messages.
This situation was to change later in the war when radio had proved to be the only reliable way to communicate, particularly when troops were on the move.
The BF Trench Set
One of the earliest radios to be used in the trenches was the 50-watt Trench Set, also known as the BF Set (Figure 2) which was used for communication from Brigade to Division. This went into action in the Battle of Loos in September 1915 and in the first Battle of the Somme on July 1st 1916. The transmitting portion of set was based on the design of the No 1 Aircraft Spark set. The receiving portion used a carborundum crystal detector. It was powered from an accumulator and also required dry-cell batteries for biasing the carborundum crystal and an internal test buzzer.
Its range was 3.7km with aerials mounted on masts but this reduced to 1.1km when the aerial was run close to the ground.
Careful planning of frequencies was required in order to minimize interference from neighbouring spark transmitters, a problem much simplified when CW sets came into use.
The BF set was used extensively during the second half of the war and approximately 1200 were manufactured.
130-watt Wilson Trench Set & Short Wave Tuner Mk. III
The Wilson Transmitter was used primarily for Division to Corps communication and Corps Directing Station. This set came into service about the same time as the BF Trench Set. It had a fixed spark gap with a motor-driven, high-speed interrupter rather than the slower magnetic interrupter. The greater number of sparks produced a musical note in the headphones, making the Morse signal more easy to hear through interference. The transmitter had the same frequencies as the BF set and the higher power meant that the range was up to 8.3km. The set was supplied by an accumulator.
Tuner Short Wave Mk. III*
The Mk. III version of this tuner was introduced in 1916 and the Mk. III* in 1918. Its prime purpose was to receive Morse messages from aircraft flying over the trenches but it was also used with the Wilson Set. The receiver used a crystal detector and there was a buzzer for calibrating and testing the tuner. Total production was 766 transmitters and 6595 receivers.
Later valve Developments
Towards the end of 1915 an entirely new type of valve was developed under Colonel (later General) Gustav Ferrié who was in charge of the French Military Telegraphic Service. The construction was very simple: it had a straight tungsten filament, a spiral grid and a cylindrical anode. It was evacuated to a low pressure and during the manufacturing process the glass and metal parts were heated to a sufficient temperature to release occluded gases. The valve, known as the TM, was immensely successful and widely used throughout the war, over 100,000 of which were made by the two French companies, Fotos and Métal. By 1916 it was being manufactured in Britain as the R-valve.
There were many variants, including the Air Force C and D, and the low-power transmitting valves B, F and AT25. Two higher power transmitting valves, introduced in late 1917, were the T2A and T2B which had 250 watt dissipations. These were used by the RFC (later RAF) in ground station CW transmitters.
One problem with the TM and R-valve was the high capacitance between the anode and grid. This made its use as an RF amplifier very difficult because energy fed back from the output of the valve to its input was liable to cause unwanted oscillation.
To overcome this Round of the Marconi Company developed the type Q in 1916 which featured small size and low capacitance. It had a straight tungsten filament terminated by the two pointed metal caps at each bend of the bulb. Both the anode and grid connections were taken to two further caps near one end of the tubular glass bulb. The Q was primarily intended as a detector but it was also used as both an amplifier. It overall length was 73mm and the bulb diameter 16mm. Later in the war Round designed the V24 which was better suited as an RF or AF amplifier.
Later army radios
Valve radios first made their appearance in 1916. One of the earliest was the Tuner Aircraft Valve Mk. I but this was not made in significant numbers.
W/T Set Forward Spark 20 watt “B”
This set came into service in 1917 and was also known as ‘The Loop Set’ and was used for forward communication. There were both Rear Stations and Front Stations sets, with two versions of each. There were also separate receivers for the Rear and Forward Stations. These receivers had two valves which were either the French TM or the British R.
The transmitter had a fixed spark gap powered directly from an induction coil operating in a similar way to the BF Trench Set. The power for the stations was supplied by an accumulator and a 32-volt HT battery.
Approximately 4000 of the transmitters and receivers were manufactured.
W/T Trench Set Mk. I 30-watt
The first CW sets for field use were made in 1916 and used a single valve for both the transmitter and receiver circuits and was used for forward communication by ICW. The Mark 1* version came into service in 1917 and incorporated a high-speed interrupter to modulate the transmission.
W/T Set Trench CW Mk. III*
This (CW) set comprised a transmitter and a heterodyne receiver in separate boxes. It came into service in 1917 and was used for forward area telegraphy.
The transmitter was rated at 30-watts and had a range of 3.7km. It utilised two valves which were either the type B or AT25.
The receiver had two R valves. The first of these was used in a heterodyne circuit and the second as an audio frequency amplifier for the Morse signal.
The complete set also included a heterodyne wavemeter, Selector Unit and Rectifier Unit.
Total production was a little under 3000 for both the transmitter and the receiver and approximately 400 of the Selector Units.
Telephone Wireless Aircraft Mk. II
The Telephone Aircraft Mk. II came into service in 1917. It had two B or F valves, one being used for control and other an output valve. An accumulator was used to supply the valve’s filaments and the HT was derived from a wind-driven generator. It had a range of 3.2km to other aircraft and 2km to ground stations.
The aerial was a trailing wire of length 100–150ft with a lead weight at the end.
Earlier attempts to fit radio telephones in aircraft had been hampered by the high background noise from the aircraft’s engine. This problem was alleviated by the design of a helmet with built-in microphone and earphones to block much of the noise.
A typical receiver for use with this transmitter was the Tuner Aircraft Mk III which had three R valves, one for the detector and two for low-frequency amplification.
Conclusions
The army was very slow to adopt wireless for communication on the battlefield and relied too much on communication by cable. There was a genuine fear that wireless would be intercepted by the enemy but this was also true with cable. The cable used was being constantly severed by shell fire and the passage of tanks across the battlefield.
Apart from a few high-powered transmitters that played a minor role in the war, the first wireless transmitters were fitted in aircraft during 1915. These were used to communicate with crystal receivers on the ground to direct artillery fire.
The first trench sets went into service towards the end of 1915. From this time onward the army came slowly round to realizing that wireless communication was a more reliable way to communicate than by cable, particularly when troops were moving rapidly forwards or backwards.
The most significant technical breakthrough came following the development of the TM valve in France. This, and its many derivatives, enabled reliable valve transmitters and receivers to be produced from 1916 onwards. It now became possible to make CW transmitters, which were far superior to the spark sets.
By mid-1917 the army at last accepted that radios were the best way to communicate and increasing numbers of these came into service in the final year of the war.
Acknowledgements
I should like to thank Nick Kendall-Carpenter and his archive staff at the Royal Signal Museum, Blandford, Louis Meulstree and John Liffen of the Science Museum for their valuable assistance.
About the Author: Keith Thrower OBE is author of British Radio Valves: The Vintage Years – 1904-1925 and British Radio Valves: The Classic Years 1926-1946.
This article is based on the paper Keith gave at “Making Telecommunications in the First World War” in Oxford on 24 January 2014. See our events page for full details including the abstract, PowerPoint slides and full version of Keith’s paper.
Fig. 1 (left) Commercial version of Fleming diode; (right) BT-H version of the de Forest Audion triode, a ‘soft’ valve erratic in operation.
Fig. 2: Marconi-Round C and T valves of 1913. These were both ‘soft’ valves. The C was a receiver valve for use as a detector or RF amplifier. The T was a transmitter valve.
Fig 3: Marconi Short Distance Wireless Telephone Transmitter and Receiver. This set used a C valve in the receiver, connected as an RF amplifier with regenerative feedback to increase its gain and provide improved selectivity. Detection was by a carborundum crystal. For transmission there was a single T.N. valve (seen mounted in the frame) and this was connected as an oscillator. It is believed that Marconi used this set for CW voice trials in 1914.
Fig 9: Tuner Short Wave Mk. III*. This receiver has both a carborundum and a Perikon detector.
Fig. 10a & 10b: French TM and Osram F valve. The TM was a general-purpose valve used mainly as a detector or an AF amplifier. The F was a low-power transmitting valve similar in construction to the TM.
Fig. 10c & 10d: Top Q, bottom V24. The Q went into production at Edison Swan in 1916 and was used mainly as a detector. The V24 probably went into production at the end of 1917 or early in 1918. It was used as both an RF and an AF amplifier.
Second Lieutenant Basil Schonland R.E. Image available in the public domain.
No Corps of Signals existed in those days. Signalling was very much the province of the Royal Engineers and specifically its Telegraph Battalion and it was they who attempted to use wireless for the first time in a military conflict during the Boer War in South Africa. But it was not equal to the task and it was left to the Royal Navy to show the way. And show it they did during the blockade operation they were mounting in Delagoa Bay, Portuguese East Africa. Wireless proved itself at sea; it was still to do so on land.
In 1908 the Royal Engineer Signal Service came into being and it was this body of men, plus their horses, cable carts and much other paraphernalia of war that provided the British Army with its signalling capability during conflict that broke out in 1914.
By now wireless equipment suitable for use by soldiers and rugged enough to be hauled about on carts and on the backs of men was slowly becoming part of the Army’s inventory of equipment. And the officers and men were being trained to use it. Amongst that group was a young South African by the name of Basil Schonland. During the summer of 1915 he completed Part 1 of the Mathematical Tripos at Cambridge and immediately set his sights on serving his adopted country. Even whilst a schoolboy, and then an undergraduate in his home town of Grahamstown in South Africa’s Eastern Cape province, Schonland was a loyal subject of the King and, along with many of his fellow South Africans, he saw it as his duty to fight for King and Country.
Schonland was commissioned as a second lieutenant in August 1915 and immediately began training at the Signal Depot in Bletchley. In October he was given command of 43 Airline Section with 40 men, their horses and their cable carts and in January 1916 he led them into France where they joined the Fourth Army then being formed under Sir Henry Rawlinson.
It was the Battle of the Somme that saw wireless equipment pressed into service in earnest. Though hundreds of miles of telephone and telegraph cables had been laid only those buried at considerable depth had any hope of surviving the onslaught of almost incessant artillery barrages. Visual signalling by flag, heliograph and lamp was perilous in the extreme for the operator who raised himself mere inches above the parapet of a trench: wireless became almost obligatory. And Schonland, whose skills had already been noted, was soon to become a W/T officer in the Cavalry Corps. None was more enthusiastic.
Map showing the deployment of the wireless sets near the front line in September 1916. Image available in the public domain.
This new technology caught the imagination of a young man for whom science, and especially physics, was of almost overwhelming interest. He threw himself into mastering the wireless equipment and of passing on his knowledge to his men. The three trench sets with which Schonland became so familiar were the BF Set, the Wilson Set and the Loop Set. The ‘BF’ presumably meant “British Field” but to those who used it in earnest its eponymous letters had another meaning entirely! Like most of the equipment in use at that time the BF set had a spark transmitter and carborundum crystal detector. It radiated signals over a band of frequencies between about 540 and 860 kHz at a power of some 50 watts. The Wilson set was more powerful and used a more sophisticated method of generating its spark. The frequencies (or wavelengths in those days) that it covered were similar to the BF Set. Both were used extensively from within the trenches during First Battle of the Somme in September 1916.
In 1917 a new wireless set was introduced. Called the W/T Set Forward Spark 20 Watt B it soon became rather more familiar by the less wordy name of the Loop Set. The loop in question was its peculiar aerial (or antenna) which consisted of a square loop of brass tubing 1m per side that was mounted vertically on a bayonet stuck into ground. The Loop Set’s other great claim to fame was that it was extremely simple to use even for an inexperienced operator. Morse code was the mode of transmission and that skill was fundamental to all who served in the R.E. Signal Service, officers included. Of particular importance, especially to the technically-minded such as Schonland, was the much higher frequency on which the Loop Set worked. It could be tuned to transmit and receive between 3.8 and 4.6 MHz and was claimed to have an effective range of 2000 yards. And though the transmitter still used a spark, the receiver contained two thermionic valves – an astounding technological leap at that time.
By then Schonland had left the front line and was instructing at the GHQ Central Wireless School at Montreux where he was also promoted to lieutenant. It was there that he and another South African by the name of Spencer Humby conducted their own ‘researches into wireless’ which they published in a scientific journal soon after the end of the war. “The wavelengths radiated by oscillating valve circuits” became an important paper in the field of wireless communications that flowered in the 1920s.
But Schonland was not only a competent physicist; he also wielded an educated pen and his most lasting contribution to wireless communications during WW1 was his four-part series of articles published in 1919 in The Wireless World. They appeared under the title of this article and described the use of wireless in the trenches and were possibly the first such articles to tell how wireless was used during the war by the R.E. Signals Section. The Boy’s Own Paper had nothing on them for verve and excitement! Take this passage in which the young Schonland describes an attack during the battle of Arras in which a key hilltop position had been captured by the British Army. However, the enemy was re-grouping below and a counter-attack was imminent.
Owing, however, to the speed of their advance our troops were out of touch with the higher command, and the guns behind them. Out of touch, did I say? What is this queer mast affair some sappers are rigging up in the garden of what was once a pretty cottage? Up go the small steel masts in spite of the shells streaming into the village … The aerial up, it is not long before they have installed their tiny set in the cellar and are ‘through’. R9 signals each way. Just in time too, for the Boche at the foot of the hill shows signs of counter-attack. “Get at the guns, Sparks, get at the guns!”. And Sparks bends to his key …
By the war’s end Basil Schonland had been promoted captain and was in charge of all wireless communications of the British First Army. Under him he had thirty officers and more than 900 hundred men, along with over 300 wireless sets. And soon, after the end of hostilities, strenuous efforts were made to retain his services as Chief Instructor in Wireless in the British Army. But Schonland was intent on following a career as a scientist and he returned to Cambridge to work under Lord Rutherford at the famous Cavendish Laboratory. However he was not lost entirely to the colours for a mere twenty years later he was back in uniform and served throughout the second great conflict with distinction, ultimately as scientific adviser to Field Marshal Montgomery’s 21st Army Group.
About the author
Dr Brian Austin is a retired engineering academic from the University of Liverpool’s Department of Electrical Engineering and Electronics. Before that he spent some years on the academic staff of his alma mater, the University of the Witwatersrand in Johannesburg, South Africa. He also had a spell, a decade in fact, in industry where he led the team that developed an underground radio system for use in South Africa’s very deep gold mines.
He also has a great interest in the history of his subject and especially the military applications of radio and electronics. This has seen him publish a number of articles on topics from the first use of wireless in warfare during the Boer War (1899 – 1902) and South Africa’s wartime radar in WW2, to others dealing with the communications problems during the Battle of Arnhem and, most recently, on wireless in the trenches in WW1. He is also the author of the biography of Sir Basil Schonland, the South African pioneer in the study of lightning, scientific adviser to Field Marshall Mongomery’s 21 Army Group and director of the Atomic Energy Research Establishment at Harwell.
Ahead of next year’s centenary, Elizabeth Bruton and Graeme Gooday ask what were the different motivations of scientists, the military and industry in terms of World War One innovation and research – patriotism, profit, or both?
Should innovators profit from warfare? Is it reasonable instead to ask scientists and engineers to act from pure patriotism alone? As Scientists for Global Responsibility has recently voiced alarm about UK science’s reliance on military funding, it is revealing to look back to a time before science entered a Faustian pact with armed conflict.
Prior to World War One, Britain did not have a military-industrial complex in which scientists routinely participated with industry to facilitate ever more warfare. Even in the first year of the war, rather than safely researching in a laboratory, a brilliant scientist such as Henry Moseley could die at Gallipoli, shot by a sniper while serving as a signals engineer. Reflecting on such tales, we think we know about the Great War: the patriotism and sacrifice of those in the armed forces and the terrible and pointless loss of life – especially on the Western Front – throughout the four long years of war.
But numerous historians have recently rethought these stereotypes. How was it that the war continued for four years, with 16 million dying while millions more of pounds and dollars were spent on armaments and the routine expense of war? Who was manufacturing such weaponry and ammunition, and who developed the infrastructure of scientific research that helped to win the ‘Great War’? More importantly, what were their motives: patriotic altruism, private profit – or an uneasy mixture of both?
In light of the impending centenary of this global catastrophe, we find that patriotism was not always the sole or indeed the main rationale for industrial activity in wartime. Indeed, afterwards the financial rewards for war-winning innovation were treated somewhat differently to equivalent creative acts during peacetime.
When Britain entered the war on 4 August 1914 the Marconi Company, with evident patriotic fervour, offered its wireless operators and training to facilitate the armed services’ use of wireless communications. It did so without any initial upfront demand for payment. The Company also allowed government ‘censors’ to monitor all communications through their long-distance wireless stations. Suspicious communications were intercepted and passed onto code-breakers in the Admiralty’s secret ‘Room 40’. During the war, the Company apparently received no compensation or out-of-pocket expenses for this work: in summer 1915 Marconi’s General Manager complained that “not one penny-piece has yet been refunded to us.”
By now, it was clear that the German model of state investment in research could win wars more decisively than uncoordinated private industry, laissez-faire invention, and British heroism. Stung into action by German innovations in poison gas warfare and devastatingly effective interception of French and British telecommunications, in 1915 the UK government established its own national Department of Scientific Industrial Research (DSIR).
Supported initially by the ‘Million Fund’ – approximately £45 million today – the DSIR both hired scientists for laboratory research and encouraged private industrial firms to establish co-operative industrial research associations. Unlike the Marconi Company, however, many companies did not willingly offer their services to the state. This is evident from the 1915 extension to the Defence of the Realm Act (1914): now key British industries were compelled to prioritise government and military orders.
The production of armaments and industrial infrastructure was thereby raised to a level that, when combined with American input from 1917, could support a military force capable of winning the war. By then increased state support for science and industry was having a noticeable effect. For example, the aeroplane invented just over a decade previously was adapted dexterously to the purposes of aerial combat and the ‘tank’ changed the nature of battle when first introduced in France in 1916.
Soon after the so-called ‘Great War’ was concluded in November 1918, a Royal Commission on Awards to Inventors rewarded hundreds such wartime innovations. It eventually handed out £1.5 million (about £75 million today) in a Britain nearly bankrupted by the cost of conflict. The distribution indicates just how much the British establishment acknowledged national inventiveness, crediting tanks and aeroplanes as crucial to the recent victory. The Commission rejected claims about other inventions it deemed to lack genuine novelty or life-saving significance.
Telecommunications had been of great importance during wartime, especially when threatened by interception. The catastrophic interception of British and French forward communication by Germans early in the war resulted in the development and widespread deployment of an interception-proof alternative. This was the so-called Fullerphone, invented and patented by a serving military officer Captain Algernon Clement Fuller in 1916. When Fuller took his device to the Commission soon after the war ended, however he was offered much less than he requested: not only did his device rely heavily on the work of others, his patent rights would reap him further international rewards. Fuller perhaps took comfort from his post-war promotion eventually reaching the rank of Major-General.
A young Henry Moseley, taken in the Balliol-Trinity Laboratory, Oxford, c.1910. Source: Wikimedia Commons.
In contrast, the Marconi Company’s wartime contribution was more richly rewarded than that of Fuller. This was due in part to the eventual recognition of the Company’s important role in supporting the British government and the Admiralty. Not only had Marconi intercepted hostile communications, but its “direction finders” had tracked German navy and airships in the open sea.
Despite this, the Marconi Company entered into an extraordinary post-war dispute with the British government, demanding large rewards for its wartime contributions. Marconi’s lawyers actually accused the government of infringing the Company’s wireless patents: exploiting its intellectual property without due payment. So difficult did the discussions become on the six-figure royalty claims that the matter was devolved to a private adjudication. Although the final amount paid was never publicized, the Marconi Company was soon able to buy up telegraph companies to fulfil its long-held ambition to become a telecommunications giant – later known as Cable and Wireless.
So how then shall we commemorate Fuller and Marconi and indeed their industrial production teams for their wartime innovations? Were they like Moseley nobly donating their all to the cause, seeking only recompense to endure the hardships of war? Or to rephrase Clausewitz’s old dictum, was warfare for them just profit by other means…?
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