Wartime Advances in Equipment to Be Reflected in Peacetime Applications

MILITARY needs have brought such advanced developments in radio communication that firemen and policemen in the postwar period may be equipped with walkie-talkies to fight fire and crime with radio.

And through the same medium doctors may keep in touch with offices and hospitals, and operators of trains, busses, taxis and trucks would receive their instructions from headquarters while on the move.

H. F. Mickel, manager of the Police and Emergency Communications Section of RCA Victor, Camden, outlined the foregoing possibilities at a recent conference of the International Municipal Signal Association in Philadelphia.

Although he declared the possibilities almost limitless in communications and industrial electronics, Mr. Mickel emphasized there would be no sudden transition from the present status. Rather, he said, existing equipments and methods would be improved and expanded instead of being rendered obsolete overnight.

As an early possibility in the public safety field, the RCA engineer suggested that firemen carrying walkie-talkie sets small enough not to hamper their movements could be directed inside a blazing building by a superior officer on the outside who would be supplied the necessary information by the men throughout the structure. The same technique, be said, could he employed in combatting forest fires.

Higher Frequencies Probable

“It is probable that future emergency communications systems will tend toward the use of higher frequencies in the radio spectrum,” Mr. Mickel said. “Again let me point out that this is the result of gradual evolution rather than the application of a radically new principle. The first police and fire department radio systems operated on medium frequencies just above the standard broadcast band. A few years later a gradual swing to the use of channels in the 30 to 40-megacycle band began. However, this transition did not render the original systems obsolete and unusable.

“The first automatic radio relaying systems in the emergency communications service were in the 30 to 40 MC portion of the spectrum, hut just prior to the war, a group of channels in the 110 to 119 MC band was allocated for such use. It can be seen, therefore, that the gradual tendency is toward higher frequencies and it is believed that the trend will continue.

“The use of higher frequencies will result in lower-powered transmitting equipment, smaller-sized apparatus and highly efficient antenna systems. Higher frequency systems may be more readily controlled to cover the exact areas desired, thus making more efficient use of available power. Higher frequencies will also result in the availability of a

large number of additional channels. Perhaps this will open the way for many new radio applications and services.”

Higher frequencies also will lead to the more common application of automatic relaying units. Mr. Mickel said. Where great distances are to be covered and direct transmission is beyond the range of available equipment, automatic relaying or repeater units may be interposed to pick up the transmitted signal and pass it along to the receiving point.

Automatic Relaying

“An example of automatic relaying is found in the radio system in operation on the Pennsylvania Turnpike,” he continued. “Here, unattended relay stations pick up and pass along transmissions from one end of the turnpike to the other. A message originating at any point on the turnpike is clearly heard by all the cars patrolling the road, by all the toll office personnel, by Pennsylvania State Police headquarters in Harrisburg and Bedford and in all maintenance buildings along the right-ofway.

“This system has been in operation for more than two years and effectively proves the practicability of such apparatus. The use of higher frequencies will make such systems more common and easier of accomplishment.”

As a development of the present-day fire alarm system, Mr. Mickel visualized a standard radio receiver which, when switched off at night, would maintain in operation a tiny receiver which would connect the loudspeaker and permit transmission of any desired message when actuated by a specific signal from headquarters. Such a device would have wide application in police and fire systems for calling out reserves or off-duty members, he said.

“We will also see electronic heat indicators for actuating fire alarms,” the engineer said, “and the burglar alarm of tomorrow may readily use invisible light rays to prevent any visible indication that such a detection device is in operation.”

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