radio communications

radio communications. (Radio was an American term, the British more commonly using wireless.) During the Second World War radio communications revolutionized how the armed services fought, and they brought a new dimension to clandestine warfare, cryptology, battlefield intelligence, and even to the political conduct of the war as Churchill and Roosevelt were in regular contact by radio telephone (see alsoForschungsstelle), and from June 1944 Moscow and Washington were linked by a teleprinter service. Radio telephony (R/ T), pioneered as early as 1904, became crucial in controlling a battle on the ground and in the air. Wireless telegraphy (W/ T)—used with morse code—remained dominant at sea but was always a useful means of transmission when, because of noise and interference, speech was unintelligible. Field telephones and teleprinters (teletypewriters), using land lines or temporary wire, were also used extensively, especially in the rear areas.

Radio is defined in The Concise Oxford Dictionary as ‘the transmission and reception of sound messages etc. by electromagnetic waves of radio-frequency’. The first transmission took place in 1892 and by 1901 the Italian Guglielmo Marconi (1874–1937) was regularly transmitting morse code signals to ships at sea and even across the Atlantic. W/ T was employed effectively at sea during the Russo-Japanese war of 1904–5 and by the start of the First World War it had become part of land warfare for rear communications, the Germans being especially well advanced in its use. During the Second World War wireless, offering flexibility and mobility, became in its various forms (see Table) the most important method of military communications. The choice of technical parameters, such as frequency range and transmitter power output, for the different types of sets depended primarily on matching the users' operational requirements with the transmission characteristics of the various frequency bands (see Figures p. 724). The technology necessary for producing successful VHF and FM sets was not fully in place in 1939, but was established by the end of the war.

The size and weight of early equipment, as well as technical difficulties and financial restraints, inhibited the development of radio communications between the wars. The natural conservatism of the military hierarchy had also to be overcome. The chapter on ‘Command and Control’ in the British Field Service Regulations, published in 1935, did not even mention radio; and when, in 1934, the German tank specialist Colonel Guderian said that he proposed leading his panzer divisions ‘from the front—by wireless’, the chief of the German General Staff, Beck, replied ‘Nonsense! A divisional commander sits back with maps and a telephone. Anything else is Utopian!’ (quoted in K. Macksey, Guderian, London, 1975, p. 61).

Despite these obstacles, experimentation did continue. The first demonstration of controlling and manoeuvring a brigade of tanks by R/ T took place in the UK in 1931. In 1934 the British armoured warfare expert Brigadier Hobart was able to demonstrate that R/ T was, in principle, the most efficient means of controlling an armoured force down to individual tanks, and the following year a British scientist began developing a circuit which simplified the working of sets in a radio ‘net’. (The net consists of a control station working to a group of sub-stations on a common frequency. Net working, if it adheres to strict procedures, prevents excessive use of frequencies and ensures that each station hears all the messages passed over the net.)

However, it was the Germans who first exploited the full potential of radio communications in tank warfare. The first exercise by a panzer division controlled by R/ T was held in 1935. Guderian, who had commanded a radio unit during the First World War, encouraged the development of simple and reliable tank radio for the new type of warfare he was largely instrumental in developing, the blitzkrieg. Only R/ T—though supplemented by the more secure field telephone and teleprinter networks—could control the blitzkrieg effectively. But its essence was not only instant communication and control of forward armoured units but co-operation of all arms in a way never previously envisaged. Radio communications in armoured units were therefore paralleled in artillery and tactical aviation and allowed for intercommunication between them.

By contrast, French radio communications during the fall of France in May– June 1940 reflected the French Army's lack of preparation for blitzkrieg and the static state of mind with which it tried to counter it. Between the wars French planning had been almost entirely defensive (see Maginot line) and radio communications in all their forms were given a low priority. Between 1923 and 1939 only 0.15% of the military budget was spent on communications equipment and few resources were alloted to research and development. The French C-in-C, General Gamelin, ‘had nothing more than a telephone and an occasional courier’ ( A. Millett and W. Murray, Military Effectiveness, Vol. 2, London 1988, p. 58), and once the battle became fluid communications broke down.

The Japanese and Italian armies were even more poorly equipped when their countries entered the war, with Millett and Murray writing of ‘chronically poor’ communications in the Japanese Army and ‘the utter inadequacy of Italian equipment …Italian tank crews suffered without voice radios until 1941. Even after that, no long distance radio that could operate on the move existed’ (ibid., Vol. 3, pp. 34, 151–3).

The Red Army, too, lacked modern radio communications. Radio nets only extended down to company level in armoured units, so that company commanders had to communicate with their tanks by hand signal or motorcycle. In 1941 the infantry had to rely mostly on the civilian telephone network and it was not until Lend-Lease began supplementing what existed that the situation began to improve. Even when they had radios many Soviet commanders disliked using them as they knew that their transmissions could disclose their positions, and in 1943 Stalin had to issue an order which pointed out how essential radio communications were.

Radio Communications: Representative list of military radio sets

Type	Frequency range MHz	Frequency band	Rated transmitter output (watts)	Type of emission	Expected range in kilometres (miles)	Remarks
a Line-of-sight range for standard conditions of atmosphere is approximately 160 km (100 mi) between a ground station and an aircraft at 3,048 m(10,000 ft)
Source: Dr Sean Swords.
American
AN/MRG-1	2.0 to 13.0	HF	2,000	W/T	1,600 (1,000)	Portable. Facilities
(incorporating						for high power high
SCR-399)						speed automatic
	W/T transmission
SCR-399	2.0 to 18.0	HF	400 (W/T)	W/T	1,600 (1,000)	Army mobile high
			300 (R/T)	R/T		power station
SCR-508	20.0 to 27.9	HF	30	R/T	24 (15)	FM set. Installed in tanks,
	scout cars, and trucks
SCR-511	2.0 to 6.0	HF	0.75	R/T	4.8 (3)	Manpack and vehicular set
SCR-300	40 to 48	VHF	0.5	R/T	1.6 (1)	FM walkie-talkie
SCR-536	3.5 to 6.0	HF	0.02	R/T	800 m (1/2)	Light weight handie-talkie
SCR-522	100 to 156	VHF	6	R/T	Line-of-sighta	Airborne transmitter
	receiver 4 pre-set
	channels
AN/ARC-3	100 to 156	VHF	6	R/T	Line-of-sighta	Airborne transmitter
TBS-3	60 to 80	VHF	50	R/T	32 (20)	Surface craft or submarine
	vessel to vessel inter-communication
TBY-1	28 to 80	VHF	0.5	R/T	1.6 (1)	For use by Marines
British
Marconi Sender	3.0 to 22.2	HF	3,500	W/T	8,000	RN and RAF fixed
SWB 8					(5,000)	service transmitter
No. 5 HP	0.2 to 0.6	LF/MF	2,000	W/T	World-wide	Army fixed station
	3.0 to 20.0	HF
No. 33	1.2 to 17.5	MF/HF	250 (W/T)	W/T	1,600 (1,000) (for W/T)	Army fixed or mobile
			65 (R/T)	R/T	100 (60) (for R/T)	station
No. 19 (A Set)	2.0 to 8.0	HF	12	W/T		Armoured Fighting
				R/T		Vehicle set
No. 46	3.6 to 4.3	HF	1.5	W/T	6.5 (4)	Commando and
	5.0 to 6.0	HF		R/T		paratroop set
	6.4 to 7.6	HF
	7.9 to 9.1	HF
No. 38	7.3 to 8.8	HF	0.5	R/T	1.2 (3/4)	Infantry manpack set
T1083	0.136 to 0.50	LF/MF	30	W/T	Line-of-sighta	Airborne transmitter
	3.0 to 15.0	HF		R/T	(at least)
R1082	0.111 to 15.0	LF/MF/HF		W/T		Airborne receiver used in
				R/T		conjunction with T1083
T1143	100 to 124	VHF	5	R/T	Line-of-sighta	Airborne transmitter receiver
T1131	99 to 126	VHF	50	R/T	Line-of-sighta	RAF ground station transmitter
German
1.5-kW-LK	0.1 to 0.6	LF/MF	1,500	W/T	1,000 (600)	Army high power mobile
Sender a						station
1.0-kW-KW	1.090 to 6.70	MF/HF	1,000	W/T	1,000 (600)	Army high power
Sender b				R/T		mobile station
Fu5 SE 10	27.2 to 33.3	HF/VHF	10	W/T	6.5 (4)	Armoured Fighting
(includes 10-W-S.c)				R/T		Vehicle set
Feldfu.a1	120 to 156	VHF	0.15	R/T	1.2 (3/4)	Infantry manpack set
Feldfu.h	23.1 to 25.0	HF	0.15	R/T	1.6 (1)	Infantry manpack set
FuG10	3 to 6	HF	40	R/T	Line-of-sighta (at least)	Airborne transmitter-receiver
T200 FK 39	3 to 23	HF	200	W/T 100	(60) with special	Communications
				R/T	‘eel’ antenna	transmitter for submarine use

The USA, as with so many other technological developments, was quick to put its enormous financial and scientific resources behind the development of all aspects of radio communications. It produced some remarkable portable radio sets, the 2.26 kg. (5 lb.) walkie-talkie (the SCR-536, known then as the handie-talkie), the Gibson Girl, and the radiosonde, used to obtain meteorological intelligence, being three examples. Other developments included automatic teleprinters which could transmit messages at a rate of 100 words a minute, and facsimile facilities which could transmit war photographers' prints halfway round the world in seven minutes.

Despite these advances, radio communications had their disadvantages. In the heat of battle orders given over R/T could be confused or misheard, and technical difficulties were numerous. For instance, not until operational research scientists in Australia investigated the effect of a tropical climate on the operational life of dry batteries was the constant failure of radios in the New Guinea campaign eradicated.

Security was also a problem. ‘Wireless is still untrustworthy and entirely unsecret,’ Dorman-Smith wrote in July 1942 during the Western Desert campaigns. ‘Speak in clear and you give the enemy your plans. Speak in code and you slow everything down. Use cypher and it takes hours encoding and decoding. You pay your penny and you choose your inconvenience’ ( L. Greacen, Chink, London, 1989, p. 215). Even the increasing use of cipher machines, which also speeded up the process of transmission and decipherment, did not guarantee security, as the Allied gathering of ULTRA intelligence showed. In the Pacific war US forces overcame the problem to a certain extent by employing Navajo Indian ‘codetalkers’.

Radio communications at sea also suffered from security problems as the relative slowness of ships made them, and their operational intentions, vulnerable to an opponent. This meant that radio silence was imperative until contact with the enemy had been made, though systems were devised of transmitting W/T signals from shore stations which did not entail revealing the position of the receiving ship. However, Allied direction-finding equipment could often pinpoint the position of U-boats, even though the Germans devised a method for abbreviating transmissions to a few seconds (see huff-duff).

W/T at sea increased in scale during the war years without undergoing any radical changes. In September 1939 the British Admiralty had a world-wide network of seventeen high-frequency radio stations which relayed W/T messages to British warships. By 1945 it had 65, and also scattered across the world were some 20 stations for intercepting enemy signals (see Far East Combined Bureau, for example) and 69 direction-finding stations. In 1939 a battleship had, typically, eight transmitters and nine receivers; by 1945 it had 16 transmitters and 23 receivers.

R/T became widespread in the western Allied surface navies, though it had been practically unknown at sea before the war, the properties of VHF making it comparatively safe from interception by the enemy. It was the basis for controlling aircraft operating from carriers, and was also used by convoy escorts during the battle of the Atlantic, as it was not possible for distant U-boats to intercept VHF transmissions. To prevent a nearby one picking up a conversation, escort groups used a simple voice code which disguised vessels' names, changes of courses, and so on.

In the air the lack of security from which R/T suffered was not usually relevant as the speed of aerial warfare made the information gleaned by the opposing side largely obsolete within minutes (butsee Philippine Sea). Apart from the blitzkrieg, the earliest example of the paramount importance of radio communications in the air was the battle of Britain. Encouraged by Dowding (who in 1917 had almost certainly become the first person to be in ground–air voice communication with an aircraft) the basic system for intercepting incoming enemy bombers had been developed during the 1930s. The bombers were tracked by radar and the intercepting fighters by high-frequency direction finders which locked on to the fighters' ‘pip-squeak’ transmissions. The bearings of both groups of aircraft were plotted in the sector control room and the fighters were then guided on to the bombers by R/T. The bombers were recognized as enemy aircraft because they did not transmit the correct IFF signals.

However, by 1937 the HF (high-frequency) wavebands fighter R/T used for ground–air transmission had become unsatisfactory—they were overcrowded and were subject to distortion and interference—and it was decided to develop a VHF (very high frequency) set with air-to-air range of 160 km. (100 mi.) and an air–ground range of 225 km. (140 mi.) at a height of 3,000 m. (10,000 ft.). But the delivery of these sets was delayed and though, by September 1940, sixteen fighter squadrons had been equipped with it the battle of Britain was fought largely with HF sets. The British VHF set, the TR-1143, was copied for US aircraft, and designated the SCR-522.

Air co-operation with ground forces was another sphere in which radio communications played a central role, and as the war progressed, and R/T became more reliable and more portable, radio communications enabled both artillery and aircraft to give close support to infantry and armour. Beginning during the Italian campaign forward air controllers equipped with SCR-522 radios fed information to artillery fire direction centres from light aircraft while new procedural systems enabled controllers on the ground to call down accurate fighter-bomber air strikes, a form of support quickly adapted by the US Marine Corps in the Pacific war when the limitations of naval gunfire became apparent. It was brought to a fine art by Lt-General Pete Quesada's Twelfth Tactical Air Force, which supported Bradley's Twelfth Army Group in north-west Europe, with tanks being specially converted for air–ground co-operation.

Finally, the development of smaller and more powerful radios influenced clandestine warfare as spies were able to use suitcase-sized transceivers and resistance groups special ground to air R/T sets such as the S-phone.

Bibliography

Devereux, A. , Messenger Gods of Battle (London, 1991).
Hallion, P. , Strike from the Sky (Shrewsbury, 1989).
Hezlet, A. , The Electron and Sea Power (London, 1975).