General information

The radio is a subject which annoys the French ego, each time one evokes it in connection with the French Army of 1940. It is obvious that the High command saw it of an evil eye, was hostile even there.

In this file we wanted to point out the principles of the radio, so that one can have a clear idea of the possible problems which it was likely to generate. Then we stressed, with some examples, on the behavior of the Staffs of the time, vis-a-vis these recent means of communication.

Maurice_Gamelin (1872-1958) is chief of general staff French between 1935 and on May 19, 1940, date on which he is dismissed and replaced by the general Maxime_Weygand (1867-1965). Its error of judgments (to be made divide by many policies of the time) so much on the strategy to be adopted vis-a-vis in Germany than on the tactics to be implemented vis-a-vis the mechanized armies, belong to the causes of the French defeat of May 1940.

In connection with the radio transmissions (object of this document), let us recall that since its PC of the castle of Vincennes, Gamelin_ refuses to communicate by radio. Its messages in direction of the troops and its received information thus forward only by telephone or estafettes. The telephone is appropriate little for troops moving and the estafettes miss speed seriously.

Principles of the radio

(by Lionel_Cima, Lecturer in ENS_Cachan)

The principles of the radio impose the setting in cascade of a certain number of apparatuses installed in two stations:

- one, the transmitter, codes then sends information;

- the other, the receiver, receives information and decodes it.

Antennas

The central element of the TSF is the antenna. In the transmitter it transforms electrical energy into electromagnetic energy. The latter is propagated without palpable support and can be intercepted by the antenna of a receiver able to carry out opposite conversion. Electromagnetic energy is then retransformée in electrical energy.

Animation of the image?

Stop of animation?

Does explanations + advance step by step?

Does explanations + move back step by step?

It is to be noticed that, if the transmitting set has electric energy requirement to emit, in theory the receiving set does not need any to receive. Indeed, its antenna collects transformable electromagnetic energy in electrical energy. This is why, in the general diagram above, we did not put an electric energy source at the receiver whose lamp lights all the same with each reception of electromagnetic waves.

In practice, this would be only to amplify the received signal, the receiver has also its own electric energy source.

Radio telegraphy - Radiotelefony

In radio telegraphy a switch varies the electric current of the transmitter, which results in the emission (then reception) of a more or less long beep. Language Morse.

Into radiotelefony a microphone converts the sound emitted into electrical energy and, in the receiver, a loudspeaker (or ear-phones) carries out opposite conversion. Phonic or musical language.

Amplifier of power

As the electromagnetic waves lower intensity with the distance of the transmitter, this last will be all the more powerful as its signal will have been amplified at the beginning.

For the same reasons, the reception will be also improved by an amplifier of power on arrival.

The amplifier has energy requirement, which requires the installation of an energy source for each of the two stations.

Modulator and demodulator of amplitude

If there were not that a transmitter on Earth the problem of the radio would quickly be regulated. In theory (for the radiotelefony for example), it would be enough to directly connect its microphone to an antenna (after having amplified its signal). Further, each receiver would need only one loudspeaker connected on an antenna and the turn would be played. As it of it is nothing, one sees oneself obliged to transmit, in the same space, several signals coming from several transmitters which it is necessary to differentiate with the reception.

In the transmitter a modulator relocates the audible signal (i.e. located in the audio waveband being spread out 20Hz at 20kHz) in an inaudible signal located around an arbitrarily selected frequency FP.

Each transmitter is thus characterized by its FP (frequency of carrying). One has carrying 100kHz, the other carrying 200kHz etc

Of sound with dimensions the receiver must thus be equipped with a demodulator which carries out the opposite operation of the modulation and brings back the band of the frequencies collected to its initial place, i.e. between 20Hz and 20kHz. The signal, transmitted to an ear-phone, is then become again audible.

This double translation complicates a little the fitting of each station and requires, of course, a complement of electrical energy.

Selective filter of reception

The antenna, because inter alia its form and of its site, collects several wavelengths in a preferential way. A finer selection is ensured by a filter placed directly behind the antenna. This filter lets pass only the desired waveband. While operating this filter one is fixed thus on the transmitter of his choice.

Provided with the whole of the devices which we have just pointed out, the stations are then operational.

Note: it is noted that certain circuits and bodies (antenna) are found at the same time in the transmitter and the receiver. Some switchs, making it possible to use them in one or the other case, can then contribute to carry out at the same time transmitting and receiving stations. It is inter alia the case for station OTCF type 1939 for example.

Ministerial directive of November 7, 1936. (Extracts)

In 1939 this document was always of topicality since it was repeated in direction of the chiefs of Staffs.

Radio telegraphy

It makes it possible to communicate only in Morse (C-W communication).

§80.Avantages- the radiotelegraphic installations are not very visible and not very vulnerable. The radio telegraphy allows:

- to maintain the relations between two authorities, when the enemy distance, ground, shootings or any other reason prevent the establishment or the good performance of the other transmission resources;

- to make follow an authority in all its displacements by a station which can serve it within a short time.

Certain stations are even able to emit and receive moving. They make it possible the command to ensure the continuity of its relations during the movements. Only, among all the processes of transmission, the radio telegraphy allows the simultaneous diffusion, with an unlimited number of correspondents, of the same telegram.

§81.Inconvénients- the capital disadvantage of the radio telegraphy is its indiscretion.

- The enemy can listen, far with the back (the sensitivity of the specialized apparatuses of listening is much larger than that of the receivers of the bodies of troop, so that the enemy radiotélégrammes can be collected at a distance notably exceeding the official range of the transmitting sets), under very good conditions, the unfavourable emissions, which obliges to quantify in theory the telegrams dispatched by radio telegraphy, and even it can, by radiogoniometry, to determine the sites of the heard stations and, consequently, the sites of the headquarters. The whole of the information collected by enemy listenings can provide to the adversary important data on the battle order and, to a certain extent, the intentions of the command. Also, in certain circumstances, the command it is led to prohibit partially or completely the use of the radio telegraphy.

In spite of the high number realizable wavelengths at present, the need for avoiding jammings limits the number of the networks which can be made up in a unit.

The reception of the radiotelegraphic stations can be scrambled:
- by normal emissions of the enemy;
- by systematic emissions of this last - if he agree to support itself the consequences of this jamming;
- by atmospheric parasites.

The relations established by radio telegraphy are, compared to telephone relation, of poor yield, in consequence of the need:
- to make, generally, work the network terminals, which implies that only one station can emit at a given moment;
- to quantify in theory the telegrams;
- to exchange for the corresponding stations of the communications of service before and after the transmission of the telegram itself (Call of the station shipper, indication which the recipient is ready to receive, signal of end of telegram, acknowledgement of delivery of the recipient, etc)

The whole of these contingencies can reduce the productive flow of a radiotelegraphic station for less than 100 groups (of 5 letters or figures) per hour.

Consequently, any telegram to be dispatched by radio telegraphy will have to be as condensed as possible and written using special documents benches for this purpose.

The radiotelegraphic stations cannot be usefully implemented that by a carefully educated personnel.

Lastly, the material not comprising apparatuses of call, it is necessary to ensure a permanence of listening each station.

Radiotelefony

It makes it possible to communicate by Morse and the voice (phone).

§85. Generally, the radiotelefony has the same above mention characteristics of employment as those for the radio telegraphy. However first presents, by comparison with the second, the following advantages and disadvantages:

Favour the stations of radiotelefony can be exploited by a personnel not knowing to read with the sound (To include/understand the Morse). Possibly, this process makes it possible two authorities to converse between them;

Disadvantages All equal things besides:
- the range of the stations of radiotelefony is in the actual position of two to three times less large than that of the stations of radio telegraphy;
- the number the wavelengths available is twice weaker than in radio telegraphy;
- the reception can be more easily scrambled;
- the risks of indiscretions are even greater, especially if the stations are used for conversations.

The discipline of exploitation must thus be very strict. It is very difficult to ensure. It must be carefully controlled by the obligatory organization of a system of listening of the friendly transmissions. The conversation should in theory be practised only in station-with-station.

As it is noted, the radio does not seem to have the favours of the ministry for the war [spokesperson here of the French High-Command].

Radio not very brilliant Frenchwoman

In connection with the use of the transmissions in shift, in the ministerial directive of November 7, 1936, repeated in 1939, the “radioelectric means” seem to have well little comparative advantages with their disadvantages! It is undoubtedly the reason for which the French radio operator apparatuses were of doubtful quality, inter alia compared to those of the other countries.

Besides Colonel Philippe_Truttmann has a sentence which seems to summarize the situation:

One touches an aspect there rather little brilliance of our fortification, although it did not have exclusiveness in it.

Lieutenant Cinto_Kohenoff (chief of the transmissions of the 58eDBAF in 1940 - SFAM-) entrusted to us that with the radio operator material it had it had had large difficulties in establish reliable communications, for example, between Mont_Agel and Cap_Martin distant of 5km hardly as the crow flies and separated one from the other by any serious obstacle!

The problems with which we were confronted [he added] were the lack of power of the stations and the difficulty in insulating the antennas at the time of their passage through the often wet concrete. Later, in North Africa, I was impressed by high efficiencies of the American radio operator materials at side of which ours made pale figure! But it was already another time and technologies had had time to evolve/move!

Secrecy. Until where?

In fact the problem of evolution of the radio operator materials [or others] is closely related to the will to use them or not to use them. However in 1940 the modern information means are proscribed under pretext which they could be intercepted by the enemy.

Ultrasecret in France

The 1e Brigade of Spahis_, ordered by the Colonel Paul_Jouffrault, fact part of the units having taken contact with the Germans, in Luxembourg, as of the morning of May 10, 1940.

In connection with the transmissions on the battle field, which one suspects that the precision and the speed were factors all the more dominating as the Germans were found where they were not supposed to be, written Jouffrault_:

It is necessary to acknowledge here that the only transmissions which function outside of the civil network [Luxembourg] - are the transmissions by car, motor bikes or estafettes assembled. The regulation to quantify all the messages of TSF removes the use of the waves in the course of active operations. The 1e Brigade wanted, as the Germans did it, to try to speak in light, then in pidgin [North-African dialect]: she was immediately and severely recalled to the order by the monitoring services of the army.

In the event of unforeseen, and it of it badly this May 10, 1940 ago, it is undoubtedly more effective of being able to launch on the waves of the precise information [even in light] immediately usable, to wait tens of minutes, even hours, an obsolete circulation of protected information.

Clearly in Italy

The Italian mobile units have radiophonic stations which they use during their attacks. The conversations are listened and exploited by the French stations. Here some significant examples of collected messages, on June 22, 1940, in full Italian attack:

14:05. Colonel Bernini_, PC. Major Serres_, Battalion 42e, still of firm footing with Colla_Bassa. Column of right-hand side led to Passo_di_Cuore. My advance is prevented by shootings coming from Basso_Vina [Cuore_]. Action for Passa_Vacca [southern 500m of Grammondo_] will start before long. Let us try to act by surprise. Signed Falconieri_.

14:10. Here Colonel. The Battalion is going up to turn obstacle of Colla_Bassa. The 1e Bataillon goes towards Castellar.

18:00. Colonel Bernini_. 5.CP continuation 1CP CCNN exceeded the peak of Butetta and seeks to go down to circumvent the Colla network Based. 7th Company joined Mont_Razet. One is in critical condition and request ammunition.

It is obvious that, each time, the French artillery benefitted from this information (exact) to direct its shootings.

A happy medium

Between the two attitudes (Frenchwoman and Italian) there is a happy medium all the same. One could, for example, to plan to use the radio in light to indicate where was the enemy, or if one needed reinforcements or material and to use the radio quantified to indicate its own sites.

Source of the document: work strengthened of Chesnois_, 2nd army (SHAT_Vincennes)

Transmissions of orders in the French Army in May 1940

When the histories of certain French units are consulted one is sometimes surprised by the slownesses noted in the chain of command.

Here we do not refer to May 10, 1940, day special during which one could think that French learned with their depend that the speed of the transmissions was a determining factor in the success of the battles. It would be too easy. We chose a document produced on May 13, 1940 by the General Gamelin_, General-in-chief French who had proscribed the radio of his PC. On May 13, 1940 thus, it enacts its general order [important and urgent] according to:

It is now necessary to hold head with the rush of the mechanical forces and motorized of the enemy. The hour had just fought thoroughly on the positions fixed by the High-Command. There is not any more the right to move back. If the enemy makes locally breach, not only to clog, but counter-attack and begin again. Signed: GAMELIN_

We can note that this order, of which we will not analyze the contents, arrives after May 19 in the majority of the combat units [it arrives whereas Gamelin was dismissed and thus does not order any more!]. The least which one can say is that the order was any more neither of the first freshness, nor of topicality, unless one recognizes a certain gift of anticipation to the Gamelin General.

The personal history of this document in addition is very animated. After receivebeing received by its recipient, the work of Chesnois_ (SF_Montmedy), following the French defeat it is taken along to Germany with many of other files. Then, at the end of the second world war, it is taken by Soviet who classifies it in their files - French Army. And in 1995 the Russians resell it with the SHAT_. 55 years after its drafting it returns thus to France. The loop is buckled.

Without them, would there be a radio?

Heinrich_Hertz

Heinrich_Hertz (1857-1894), is a German physicist. In 1887 it highlights the existence of the electromagnetic waves imagined by James_Maxwell in 1873.

Édouard_Branly

Édouard_Branly (1844-1940), is a French physicist pioneer of the radio. Without work of Branly_ on its coherer (1890), Guglielmo_Marconi could not have carried out into 1895 the first radiotelegraphic connections. Branly_ also created the prototype of the radio controls currently used to operate our domestic apparatuses as well (television set, etc) as on the space probes.

Alexandre_Popov

Alexandre_Popov (1859-1906) is a Russian physicist. He studies the electromagnetic emissions of the storms when he with the idea to improve the sensitivity of the receiver equipped with a coherer with Branly_ by connecting the wire with a lightning conductor to it. He has just invented the antenna.

Nikola_Tesla

Nikola_Tesla (1856-1943) is a Croatian physicist. In 1893, before even as Marconi_ the possibility did not show of transmitting telegraphic messages by Hertzian waves, Tesla written on the transmission of electrical energy without wire. It can be regarded as one of the pioneers of the radio.

Guglielmo_Marconi

Guglielmo_Marconi (1874-1937) is an Italian physicist. In 1895 it makes experiments on the Hertzian waves. It reproduces the material used by Hertz by improving it with a coherer of Branly_ and the antenna of Popov_. In 1895 it carries out in the Swiss Alps a radio contact on 1,5km. In 1897 it carries out the first communication in Morse on more than 13 km between Lavernock_ (Wales) and Brean_ (England) over the Channel of Bristol_.