Oscillogramme indiquant les effets de la manipulation de clé sans charge en arrière.

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13

GERMAN PROPOSAL CONCERNING TOPIC 15 OF THE PROGRAM1 LIMITATION OF THE RANGE OF BROADCASTING STATIONS

We must unfortunately admit that in the course of the last few years the conditions under which the reception of emissions from broadcasting station is made in the band of 550 to 1,500 kc/s have become considerably worse. This unfortunate situation does not only result from the fact that a certain number of stations are using irregular waves or cannot obtain a sufficient stability on account of carrier waves.

Another very important reason lies in the fact that a very great power is given to new stations, the emissions of which cover those of smaller stations. In short, any increase in the power should be welcomed, since the proportion between the field intensity of the transmitter and the field intensity of the disturbances becomes more favorable for receiving stations, which is equivalent to a decrease in the influence of electric disturbances. Furthermore, it is rational to use more efficient means in the transmitters, since they permit the reduction in cost of a great number of receiving stations.

However, a great increase in the transmitter power would be in the interest of European broadcasting only when it would be applied simultaneously, as far as possible, to all broadcasting transmitters. The present competition between the various countries, in order to possess the most powerful transmitters, is creating for broadcasting a state of affairs which can not go on, since only listeners of the most powerful and the most recent stations alone can profit by them, while the other listeners, according to circumstances, encounter strong and unsurmountable interferences. As there is no limit with regard to the transmission power-mention is already made nowadays of the use of an antenna power of 60 and 100 kw and we are wondering without doubt who will protect us against the emissions of stations which might increase their power to 1,000 kw and above-it will not be possible, unless an understanding is arrived at with regard to the fixing of a maximum power, to reach the ideal condition of an equal power for all European transmitters.

The GERMAN DELEGATION therefore proposes:

1. To fix provisionally, in the band 550 to 1,500 kc/s, a maximum power for all European transmitters, i. e., 60 kw sent in the antenna.

1

[Enclosed with Circular Letter No. R 30/72, dated July 25, 1929, of the International Bureau of the Telegraph Union. Radiotelegraph Service.H. F. W.]

2. To request all European administrations to undertake not to install, in the course of the next few years, any transmitter exceeding the above-mentioned power.

14

PRELIMINARY DANISH STATEMENT CONCERNING TOPIC 16 OF

THE PROGRAM1

RADIOTELEPHONE COMMUNICATION BETWEEN MOBILE AND LAND

STATIONS

This topic has been studied in Denmark since 1926. At that time, the steamboat Aalborghus belonging to "Forenede Dampskibsselskab" and plying between Copenhagen and Aalborg (230 km) was fitted for experimental purposes with the necessary installation for radiotelephony so that passengers on board could carry on telephone communications with subscribers on land. The connection with the telephone network was established by the radiotelephone stations of Sorø (transmitter) and of Amager (receiver) near Copenhagen. The latter is fitted with a radiotelephone device for communications with the Island of Bornholm in the Baltic Sea. The result of these experiments was satisfactory. Since that time the telephone service has been maintained and in the last few years telephone conversations have been carried on daily between the ship and the subscribers of the various sections of the country. The percentage of unsatisfactory conversations on account of trouble, defects in apparatus, etc., amounted to about four in 1928. The connection. with the telephone system is made at the land station through a bridge device similar to that which is used with the telephone amplifiers to connect an arbitrary subscriber with the telephone system. On board ship, conversations are carried on only from one apparatus fitted in one cabin.

The ship transmits on an 870 m wave-length, while the land station transmits on a 2,150 m wave-length. The main characteristics of the ship station and of the land stations are indicated in the following description:

DESCRIPTION OF THE SHIP STATION

In principle, the station is built as shown on the attached sketch. The telegraph transmitter of the ship is used as transmitter and, for that purpose, has been fitted with a modulation tube and a spe

[Enclosed with Circular Letter No. R 30/72, dated July 25, 1929, of the International Bureau of the Telegraph Union, Radiotelegraph Service.— H. F. W.]

118275-3010

cial amplifier. The transmitting antenna is made up of four wires suspended between the ends of the masts. When the transmitter is used for telephony, the power of the antenna is approximately 34 kw.

The receiving antenna is made up of two wires suspended between the stack of the ship and the bow mast. The receiver is fitted in the office of the ship (for the sale of tickets). The office is also used as a telephone booth.

The receiving apparatuses consist of an amplifier with two highfrequency sets coupled by resistance and followed by a detector and by three low-frequency sets coupled by resistance. Two filtering circuits are inserted in front of the receiver to hold the transmission wave of the ship while permitting the transmission wave of the land station to go through.

The handling is effected in the room where the transmitter is fitted. In this room are also found the starters, the adjustment devices for the transmitter and a device for the switching on or off of the current of the receiver installed in the cabin. A microphone and a telephone are installed in the cabin, as in the telegraph office. The operator, by means of the switch shown in the sketch, may obtain the following combinations between the microphones, telephones, transmitter and receiver:

Position I: The microphone of the telegraph office connected with the transmitter; the telephone of the telegraph office connected with the receiver.

Position II: The microphone of the telegraph office connected with the telephone in the cabin; the microphone of the cabin connected with the telephone of the telegraph office.

Position III: The microphone of the cabin connected with the trans

mitter; the telephone of the cabin connected with the receiver. In position III the telephone of the telegraph office is parallel with the telephone of the cabin.

The sending of a telephone conversation from the ship is carried out as follows:

The passenger enters the cabin and takes the receiver off the telephone. At the same time, the bell of the telegraph office of the ship is ringing. The operator switches on to position II and may thus speak with the passenger. The latter asks for his number, after which the operator switches to position I, starts the transmitter, and calls the land station. When communication is established, the operator switches to position II, informs the subscriber that the communication is established, switches to position III, and the communication between the passenger on board ship and the subscriber on land is established.