Radio relay

“ 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 an emergency, any wire of sufficient length can be used for an antenna; for example, barbed wire, electrical wire, fence wire, and metal-cored clothesline. Communication has been successful using metal house gutters and even metal bed springs. A radio operator's mission is not completed until communication is established. f. Grounding. A good electrical ground is needed for two reasons: first, to protect the operator and his equipment; and second, as a radio frequency ground needed by some antennas to function properly. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ We have been so often told that power can be transmitted by Radio that we are apt to look upon this statement with contempt. This is quite wrong: power will one day be transmitted by wireless; power can at present be inductively sent over quite [Pg 73] a large air gap, though the energy available quite close to any wireless station is practically negligible to-day.
When motor-cars and ships are controlled or stopped by wireless, it is not the wireless which does the work; the therial oscillation merely sends signals to the ordinary operative mechanism. ”

“ In any system of radio-telephony you will always find that there is produced at the transmitting station a high-frequency alternating current and that this current flows in a tuned circuit one part of which is the condenser formed by the antenna and the ground (or something which acts like a ground) . This high-frequency current, or radio-current, as we usually say, is varied in its strength. It is varied in conformity with the human voice. If the human 147voice speaking into the transmitter is low pitched there are slow variations in the intensity of the radio current. ”

“ Truly the science of radio-telegraphy has made rapid strides since the days of the “coherer,” until now, after the war, it is the most advanced in our human civilisation, and at the same time full of romance. Not a month passes but something new is discovered in that high-built, well-knit laboratory, where daily the keenest brains of wireless experimenters are at work devising, testing, and too often scrapping new instruments, new circuits, and new devices in order to improve and render less complicated both the ordinary wireless by Morse, and that modern marvel, the wireless telephone. ”

“ 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. ”

“ If an interfering station butts in, just decrease the coupling between primary and secondary and then tune again the two circuits. You can feel pretty sure of cutting out the interference and getting clearly just the station that you want.”
“That’s mighty good dope,” said Bob. “I’ve had that trouble more than once and haven’t been quite clear as to the best way of getting around it.”
“Then too,” went on the radio expert, “you must be careful in adjusting the tickler that gives the regenerative effect. Start in slowly by turning the control knob toward the maximum. ”

“ This coherer is connected in between the aerial and the earth, and is also in circuit with a battery and the electromagnet of a telegraphic relay. When this relay operates it closes the circuit of another battery which is placed in series with the telephone coil. The moment the current passes through the telephone coil it attracts, and therefore vibrates, the diaphragm and shakes up the metallic filings. If an observer, therefore, places the telephone to his ear, he hears a sound corresponding to every train of waves incident upon the aerial. ”

“ Inside was a complete radio receiving set, with vacuum tube detector and batteries in perfect working order. Between the roots of the tree an 182 iron pipe had been driven into the earth to act as a ground. The antenna was strung from top to bottom of the tree on the side away from the path, and there was nothing to differentiate the box from an ordinary wire telephone set, except that it was slightly larger. ”

“ If the radio signal having a frequency above the critical frequency is sent at an angle, the signal is bent back to earth instead of passing through the region. This can be compared to skipping stones across a pond. If a stone is thrown straight down at the water, it penetrates the surface. If a stone is thrown at an angle to the pond, the stone skips across the pond. For every circuit, there is an optimum angle above the horizon called the takeoff angle. It produces the strongest signal at the receiving station. This optimum takeoff angle is used to select the antenna for a specific circuit. ”

“ If you follow directions carefully. And with the new outfit a loop is just as effective an antenna as an outside aerial. They say, too, that to catch broadcasting for not more than twenty-five miles, not even a loop is needed, the circuits themselves acting as the absorbers of energy.”
“I’m going to try it,” declared Jessie, with more confidence. “But I feel that I understand so little about the various forms of radio, after all.”
“You have nothing on me there,” laughed the operator. “I am learning something new all the time. ”

“ In radio communication it is advantageous and has long been the practice to use a directive antenna by which the waves of radio activity emanating from it are projected as a beam in the direction of the receiving station. In practice the beam is directed at an angle from the earth's surface toward the ionized layer of the stratosphere, or Heaviside layer, from which the beam is deflected toward the earth's surface in the compass direction of the receiving station. In more recent years it has been the practice to use relatively short wave lengths for radio communication. ”

“ Here was the powerful short-wave sending and receiving set, an intermediate wave set for communication with near-by cities and other ships of both air and sea, and a radio direction finder. Within this room, a group of mining scouts was carefully taking apart and putting back together one of the Renaud portables, under the watchful eye of Lee. These men must know their radio mechanism. For when the great dirigible dropped these men for scouting in various parts of the Arctic waste, radio would be their only means of communication with the rest of the party. ”

“ And new means for modulating electric current by changing light values may be expected when the American boy starts to play with this new toy.
There has been a veritable army of engineers engaged in the development of radio as a service to the ear, while relatively few engineers have been developing radio as a service to the eye.
It is believed that the distant electric modulation of light for many purposes will soon become a common phenomena and eventually of inestimable service in science, in engineering, in industry, and in the home. ”

“ It is not possible to predict the exact duration of our absence in the depths, but it will not, in any case, exceed about twenty hours.
"Once arrived at the bottom, nearly six miles down, we shall attach the cable to some secure anchorage, by means of a radio-control, operated from within the bell, and then, with the bell free, we shall make explorations, as extensive as possible. The radio-control of which I have spoken governs also the attachment of the cable to the bell. This appliance has been prepared and tested with such care that we have no doubt of its entire efficiency. ”

“ Don't--no never--connect one side of the spark gap to the aerial wire and the other side of the spark gap to the ground. The Government won't have it--that's all.
Don't try to tune your transmitter to send out waves of given length by guesswork. Use a wavemeter.
Don't use hard fiber for panels. It is a very poor insulator where high frequency currents are used.
Don't think you are the only one who doesn't know all about wireless. Wireless is a very complex art and there are many things that those experienced have still to learn. ”

“ RADIATION RESISTANCE—The resistance, which if inserted in place of an antenna, would consume the same amount of power as that radiated by the antenna.
RADIO FREQUENCIES—Electromagnetic frequencies that fall between 3 kilohertz and 300 gigahertz and are used for radio communications.
RADIO HORIZON—The boundary beyond the natural horizon in which radio waves cannot be propagated over the earth’s surface.
RADIO WAVE— (1) A form of radiant energy that can neither be seen nor felt; (2) An electromagnetic wave generated by a transmitter. ”

“ Operators thus know when and where to expect degraded performance. Of course, strong solar activity can virtually make over-the-horizon HF radar unusable.
A Spectrum Analyser display shows all the frequencies between 5 and 28 MHz. In order to avoid possible interference to other services, those frequencies which are known to be permanently allocated to fixed broadcasting and telecommunication stations are locked out, as well as frequencies which happen to be used at any instant so that they can also be avoided by the OTHR transmitter. ”

“ 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 alteration of sensibility in the ordinary contact form of relay is the pressure that is necessary to bring the platinum points of the circuit closer together, so as to pass the minimum current which will work the telegraph printer.
The important matter, however, in connection with the use of the relay in Hertzian wave telegraphy, is that it should be capable of adjustment without extraordinary skill. It is no use to put into the hands of an operator a relay which requires abnormal dexterity to make it work at all. ”

“ The antenna system is designed to provide reliable above-ground communication. A variable attenuator is connected to the above-ground antenna coax to limit above-ground RTMN radiation to a minimum of 2,000 feet without interfering with RTMN transmissions at other launch complexes. The below-ground antenna branch is a continuous coaxial slotted cable which is routed from the base station radio equipment bay in the control center throughout the under-ground launch complex. ”