Radio message

“ Broadcasts by Radio Free Europe and Radio Liberty to these countries should be increased both in air time and in quality. They should also be broadcast in FM frequency, not short-wave, in order to reach the largest percentage of the population. ”

“ Written matter could be transmitted with even greater safety than messages which are sent in the ordinary way in Morse Code, as the signals received in the receiver {36}of an hostile installation would be but a meaningless jumble of sounds, and even were they possessed of radio-photographic apparatus the received message would be unintelligible, unless they knew the exact speed at which the machines were running and could synchronise accurately. ”

“ Just the same, only in radio telephony we are confronted by a problem not met with in wireless telegraphy. We have not only to transmit sound, such as isolated dots and dashes, but to send through the air every rise and fall and inflection of the human voice just as it is recorded in the minute lines of a phonographic record. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ Nearly all the big wireless companies have great stations fitted with powerful telephone transmitters and at given hours of the day and night they send out songs by popular singers, dance music by jazz orchestras, fashion talks by and for the ladies, agricultural reports, government weather forecasts and other interesting features. Then by simply shifting the slide on your tuning coil you can often tune-in someone who is sending Morse, that is, messages in the dot and dash code, or, perhaps a friend who has a wireless telephone transmitter and is talking. ”

“ If a telephone-receiver diaphragm can be made to vibrate in accordance with the variations in signal intensity then the air adjacent to that diaphragm will be set into vibration and these vibrations will be just like those which the human voice set up in the air molecules near the mouth of the speaker. All the different systems of receiving radio-telephone signals are merely different methods of getting a current which will affect the telephone receiver in conformity with the variations in signal strength. ”

“ 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. ”

“ Perhaps the next time the radio set begins to howl as if a dozen cat fights were mewling inside of the loud speaker, it is not static that is interfering with the reception from the broadcasting station, but a newspaper photograph which is being sent through the air. ”

“ 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. ”

“ The signal which radiates out from the transmitting antenna carries all the little variations in pitch and loudness of the human voice. When this signal reaches the distant antenna it establishes in that antenna circuit a current of high frequency which has just the same variations as did the current in the antenna at the sending station. The human voice isn’t there. ”

“ 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. ”

“ We'll try to contact phone stations wherever possible for this program we have in mind. Most of the stuff will be put on tape, and Dad will probably want you to prepare typed copies, too. You can do enough to take a big load off the rest of us."
"I'll be happy to try."
They spent the rest of the day in the radio room of the science shack. Ken taught Maria the simple operations of turning on the transmitter and receiver, of handling the tuning controls, and the proper procedure for making and receiving calls. ”

“ A single receiver can be used but a pair of receivers connected with a head-band gives far better results. Then again the higher the resistance of the receivers the more sensitive they often are and those wound to as high a resistance as 3,200 ohms are made for use with the best sets. To make the incoming signals, conversation or music, audible to a room full of people instead of to just yourself you must use what is called a loud speaker. In its simplest form this consists of a metal cone like a megaphone to which is fitted a telephone receiver. ”

“ Bill explained. "It will be all right in the morning. If you want to listen to the radio, you can use the portable radio directional finder. That always works."
"I want to catch the 5 o'clock news and hear the latest on our satellite," Carol replied. She went to the RDF and switched it on to the standard broadcast channel. "Anyhow, I'd feel better if we could put out a signal. The way we're limping along with water in our gas is no fun. ”

“ They’re coming into the ranks by thousands every day. Nobody can keep count of them, but they must run into the millions.
“And they’re great in quality as well as quantity,” he continued, warming to his favorite subject. “The President of the United States has a radio receiving set on his desk. There’s one in the office of every one of the ten Cabinet members. The Secretary of the Navy is sending out wireless messages every day to vessels scattered in all parts of the globe. The head of the army is keeping in touch by radio with every fort and garrison and corps area in the United States. ”

“ Every time a signal reaches the receiving station the current in the telephone receiver is sudden reduced; and in the time between signals the leak across the grid condenser brings the tube back to a condition where it can receive the next signal. While the sending key is depressed the current in the receiver is decreasing and increasing once for every signal which is being transmitted. For each decrease and increase in current the diaphragm of the telephone receiver makes one vibration. ”

“ By keying the transmitter tube, meters in the receiver tube were made to read in accordance. Then they had another conclave.
"Nothing brilliant," said Jim. "We could use super-output voice amplifiers and yell halfway across the planet if we didn't have radio. We can radio far better than this cockeyed system of signaling." ”

“ The remarkable growth of the radio-phone has, of course, been due to the radio broadcasting stations which have been established in all parts of the country, and from which concerts, speeches, market reports, baseball reports, news reports, children's stories and religious services are sent out. ”

“ Electromechanical protection circuits ensure that a transmitter can only be connected to an antenna that is tuned to the same frequency. The change of antennas and transmitting frequencies is made during the ten-minute interval between programmes, which always begin on the hour, preceded by the now familiar signature tune of a shepherd playing his flute with the tinkling of sheep-bells in the background, recorded in 1936, followed by the Greek National Anthem. ”

“ 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. ”

“ Tom wanted to know.
"Because, up to the present, no way has been found of utilizing in radio telephony the entire energy of the electric waves sent out," replied Professor Chadwick. "Only the variations in the waves can be detected, or transformed into sound at the receiving end of a radio telephone system. Therefore an immense amount of electrical energy has to be manufactured in order that the voice vibrations may register their variations as powerfully as possible." ”

“ 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 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. ”

“ The Additional signals and phrases contained in paragraph 4 of this Section may also be used.
3.
Whenever aircraft of the parties come into visual contact with each other, their aircrews shall monitor the frequency 121.g MHz or 243.0 MHz. If it is necessary to exchange information, but communication is a common language are not possible, attempts shall be made to convey essential information and acknowledgment of instructions by using phrases referred to in paragraphs 2 and 4 of this Section. If radio communication is not possible, then visual signals shall be used. ”

“ Don unwrapped something that looked like a flat cigarette case with two appendages, one a disk of perforated hard rubber the size of a half dollar, and the other a three-quarter-inch-wide ribbon of opaque plastic. "I've got it, sir."
"Good. What you see is a highly advanced radio transmitter and receiver. You can imagine its value in the field. It's a pilot model you were bringing back from the contractor for tests here. ”

“ The propagation media, including the Earth, atmosphere, and ionosphere, as well as physical and electrical characteristics of transmitters and receivers, influence the stability and accuracy of received radio signals, dependent upon the frequency of the transmission and length of signal path. ”

“ 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. ”