The dynamotor took from 1/10 to 1/4 of a second to 'spin up' to full power. Radios in the 1930s were based on vacuum tubes powered by a small motor-generator called a dynamotor. Experienced radio operators knew the first syllable of a transmission was frequently not understood because of quirks in early electronics technology. Hopper had been involved in radio for years and realized there was a need to abbreviate transmissions on State Police bands. Credit for inventing the codes goes to Charles 'Charlie' Hopper, communications director for the Illinois State Police, District 10 in Pesotum, Illinois. The development of the APCO Ten Signals began in 1937 to reduce use of speech on the radio at a time when police radio channels were limited.

Other important records in accordance with the uniform crime reporting system sponsored by the International Association of Chiefs of Police.

A standard record system for logging the operation of the station.

W 2605 Ford S 35 blue red wheels 2345678 may go to Indiana). This information would actually be transmitted in the text of the message as follows: John Brown 28-5-9-165 medium build brown eyes dark hair dark suit light hat Mich.

A standard arrangement of the context of messages, (for example, name and description of missing person might be transmitted as follows: Name, age, height, weight, physical characteristics, clothing if car used, the license, make, description and motor number.

A simple code for service dispatches relating to corrections, repetitions, etc.

A standard message form for use by all police departments.

In August 1935, the APCO Bulletin published a recommendation that the organization issue a handbook that described standard operating procedures, including:

Navy, though these procedures were for communications in Morse code, not voice. APCO first proposed Morse code brevity codes in the June 1935 issue of The APCO Bulletin, which were adapted from the procedure symbols of the U.S.

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