Radio telegraphy

“ This mysterious signal is on eleven hundred mètres—a continuous wave—above the ships and the Air Ministry.”
“And nobody else hears it except yourself?” asked the lean, deep-eyed old man, who possessed such wide scientific knowledge, though he admitted that wireless was a branch with which he was not familiar. Radio-telegraphy was a new science, fresh discoveries being made daily by those who, like his son, were engaged in active research work.
“Not so far as I can learn. I’ve asked our people at Poldhu, Carnarvon, and Witham, and I’ve listened myself at Chelmsford, but nobody hears it.” ”

“ CHAPTER THREE THE RADIO AMATEUR MOVEMENT From the turn of the century enthusiastic young men who built their own items of electrical and wireless apparatus were known as "Wireless Experimenters". Many of them were later granted licences for the use of "Wireless Telegraphy for experimental purposes" (in the United Kingdom) by the Postmaster General under the terms of the 1904 Wireless Telegraphy Act. ”

“ The essential element in wireless telegraphy—above all others—is, indeed, a discriminating or selective method. For the main purposes of radio-telegraphy, immunity from interference by syntony is essential. Thus a selective system in time of war would be invaluable; a non-selective system almost worse than useless. Syntonic wireless telegraphy entails in the first place, a similar rate of oscillation, or time—i. ”

“ It is a matter of common knowledge that a large part of the important inventions in connection with wireless telegraphy have been the work of amateurs and private research and not the outcome of official brains or the handiwork of military or naval organisations. In fact we may say that wireless telegraphy itself in its inception was an amateur product. Numerous important inventions such as the crystal detector, the oscillating valve, the triode valve—have been due to private or amateur work. ”

“ The aerial wire is precisely the same for either wireless telegraphy or wireless telephony. The transmitter of a wireless telegraph set generally uses a spark gap for setting up the electric oscillations, while usually for wireless telephony a vacuum tube is employed for this purpose. The receptor for wireless telegraphy and telephony is the same and may include either a crystal detector or a vacuum tube detector, as will be explained presently. ”

“ Eleftheriou issued three licences 'for experimental research in connection with the propagation of short waves' on the basis of earlier legislation governing the use of wireless telegraphy which really had nothing to do with amateur radio. ”

“ In a subsequent letter to the Editor Marconi wrote:
"In my opinion it would be a mistaken policy to introduce legislation to prevent amateurs experimenting with wireless telegraphy (which the authorities were contemplating) . Had it not been for amateurs, wireless telegraphy as a great world-fact might not have existed at all. A great deal of the development and progress of wireless telegraphy is due to the efforts of amateurs." ”

“ The two sets are connected to the terminals of a spark gap and induction coil. This apparatus acts as a huge reflector and sends out waves in one direction only, but however interesting and ingenious it may be is not entirely practical.
FIG. 97.—Bellini-Tosi radio-goniometer for directive wireless telegraphy.
Another method devised by Braun employs two or more aerials at certain distances apart. The alternating currents used to excite the oscillations differ in phase, i. e. are so arranged that they have different comparative values at the same moment. ”

“ Millions of messages going in all directions, crossing and recrossing one another, as is done every day by wire, are probably an impossibility by wireless telephony. Weird and little-understood conditions of the ether, static electricity, radio disturbances, make wireless work uncertain, and such a thing as twenty-four-hour service, seven days in the week, can probably never be guaranteed. In radio communication all must use a common medium, and as its use increases, so also do the difficulties. The privacy of the wire is also lacking with the wireless telephone. ”

“ In that way, a single pair of wires can be used for transmitting, simultaneously and without any interference, several different telephone conversations. It takes very much less power than would radio transmission and the conversations are secret. The ordinary telephone conversation can go on at the same time without any interference with those which are being carried by the modulations in high-frequency currents. ”

“ You can see that very few telephone messages can be sent in the long-wave-length part of the radio range and many more, although not very many after all, in the short wave-length part of the radio range. You can also see why it is desirable to keep amateurs in the short wave-length part of the range where more of them can transmit simultaneously without interfering with each other or with commercial radio stations. ”

“ As the waves shoot out and reach the distant station, the filings in the tube cohere and the current passing through them draws up the armature of the relay magnet. This closes the circuit of the recording instrument. It is broken constantly [156] by the tapper and instantly re-established by receiving waves.
The towers employed in 1920 for the transmission of wireless messages were very high. The manifest advantages of the system were apparent and long before 1930 wireless telegraphy came into general use. The new system proved the death-knell of telegraph poles, as well as ocean cables. ”

“ A wireless telegraph transmitter is less costly than a wireless telephone transmitter and it is a very good scheme for you to learn to send and receive telegraphic messages.
At the present time, however, there are fifteen amateur receiving stations in the United States to every sending station, so you can see that the majority of wireless folks care more for listening in to the broadcasting of news and music than to sending out messages on their own account. The easiest way to begin wireless, then, is to put up an aerial and hook up a receiving set to it. ”

“ Wireless telephony, like wireless telegraphy, but to an even greater extent, is peculiarly suited for the conveyance of marine intelligence. Wireless telephony occupies a unique position in this regard-no operator is required. The additional expense of an operator is an objection to the wireless telegraph in many cases, and forbids its installation. Anybody can operate the wireless telephone. It is also much quicker-words can be spoken more rapidly than they can be put into Morse signals and translated. ”

“ If the electricity with which any conducting body is charged be suddenly disturbed, electrical waves are generated which travel outwards in all directions with the velocity of light. The problem of wireless telegraphy is the problem of producing these waves by means of an instrument called a transmitter, and of recording their impact at a distance by means of an instrument called a receiver. ”

“ I told him about my visitor and the repair job. "What I did was add a modulator-oscillator-power amplifier, and a few feet of wire for an antenna, coiled around inside the case."
"So what does that make it?"
"Simple. It makes it a radio transmitter. Not only will he hear what the horses are saying, but anyone in town with a radio tuned to that frequency will, too."
"And where does that get you?" The sergeant was still puzzled but not bored now. ”

“ The lack of know-how and equipment may keep many from the air, but only a tiny fraction of those with resources and intelligence can hope to communicate by radio at the same time if intelligible communication is to be had, even if the entire radio spectrum is utilized in the present state of commercially acceptable technology. ”

“ Discovery may need to intervene, to enable invention to restimulate.
In both telegraphy and telephony, the longer the line the weaker the current which is received at the distant end. In both telegraphy and telephony, there is a length of line with a given kind and size of wire and method of construction over which it is just possible to send intelligible speech or intelligible signals. A repeater, in telegraphy, is a device in the form of a relay which is adapted to receive these highly attenuated signal impulses and to re-transmit them with fresh power over a new length of line. ”

“ The radio-telephone does not transmit the human voice. It reproduces near the ears of the listener similar motions of the air molecules and hence causes in the ears of the listener the same sensations of sound as if he were listening directly to the speaker. This reproduction takes place almost instantaneously so great is the speed with which the electrical effects travel outward from the sending antenna. If you wish to understand radio-telephony you must know something of the mechanism by which the voice is produced and something of the peculiar or characteristic properties of voice sounds. ”

“ An LRS team that can see everything and report nothing is useless. LRSUs normally use high-frequent radios to report information and receive instructions. Because of the complex nature of using the HF radio spectrum, a LRSU radio operator must have an in-depth knowledge of radios, antennas, and radio wave propagation.
D-1. HIGH-FREQUENCY RADIO FUNDAMENTALS For successful communication, HF radio performance depends on the type of emission (voice or burst device) , transmitter power output, and type of antenna. The challenge facing HF radio operators is tremendous. ”

“ No such trouble can occur with wireless telegraphy, and if it becomes necessary to move a wireless station with great rapidity, as for instance on an unexpected advance of the enemy, it is an advantage to have no wire to bother about. ”

“ When a sub is heard and located, the listeners call the net-layers by radio, and they go to the spot at a thirty-knot speed. As they approach they soon drown out the sound of the sub, but their speed and number enables them to surround the area in which she is known to be, for she won’t have time to go far from where she was last heard. Paying out their nets, they hem her in and keep the ring of nets closed round her till the area is raked with trailing wires and other electromagnetic detectors which will enable the chasers to concentrate their depth charges with the certainty of a kill. ”

“ At present wireless messages are chiefly of service where secrecy is not of such importance as speed; but an enormous number of experiments are being conducted upon beam wireless, directional wireless, and in the combination of the Radio oscillation with some other oscillations such as those of visible or invisible light. By these means secrecy will be obtained when we discover how to use small powers for long distance, but at present Radio is chiefly of value as a time-saver. ”

“ One of the greatest disadvantages of most systems of wireless telegraphy lies in the fact that no arrangement is provided for simultaneously transmitting and receiving wireless signals. It is usually necessary for one operator listening to another to have to wait until the finish signal is given before he can reply or interrupt in case he cannot understand part of the message, because the receiving apparatus of the transmitting station is necessarily disconnected from the aerial and the ground during the period a message is being sent. ”

“ Wireless telegraphy is part of the established order of things. The wireless telephone is practical for limited distance, but is not a commercial rival of the telegraph. Great distances are claimed, but they are matters for proof and speculation.
There is no immediate possibility that wireless telephony will take the place of local exchanges. If the time ever does come that it in any way tends to supplant the line telephone for some uses, it is more than probable that each subscriber must have his own generating station and call up direct. ”

“ Although a war invention, its peacetime service will be to save lives. It is a very simple matter to rig up a wireless-telegraph system that will send messages to a considerable distance, and simpler still to rig up a receiving-set. European governments have always discouraged amateur radiotelegraphy, but in this country restrictions used to be so slight that almost any one could set up and use a radio set, both for receiving and for transmitting. ”

“ The range of intermediate wave receptors is such that they will receive amateur, broadcasting, ship and shore Navy, commercial, Arlington's time and all other stations using spark telegraph damped waves or arc or vacuum tube telephone continuous waves but not continuous wave telegraph signals, unless these have been broken up into groups at the transmitting station. ”

“ The Marconi station at Glacé Bay, Cape Breton, is now receiving messages for cableless transmission to England at the rate of ten cents a word—newspaper matter at five cents a word. Transatlantic wireless telegraphy is an everyday occurrence, and the common practical uses are almost beyond mention. ”

“ FIG. 153.—The aerial system of a transatlantic station.
The wireless telephone enables a passenger on board ship to communicate direct with his home by relaying the message over the line wires. By the same means the captain of a ship can call his home office and communicate with the owner of the vessel.
Telegraphs and telephones are the nerves of the world, carrying swift messages from its brain centers to its hands, annihilating distance in thought. All differences between men as individuals and people as nations can be traced to the lack of close contact. ”