which is the longer of the two signals used in the morse code
Morse code Each Morse code symbol represents either a text character (letter or numeral) or a prosign and is represented by a unique sequence of dots and dashes. The duration of a dash is three times the duration of a dot. Each dot or dash is followed by a short silence, equal to the dot duration. The letters of a word are separated by a space equal to three dots (one dash), and the words are separated by a space equal to seven dots. The dot duration is the basic unit of time measurement in code transmission.[1] To increase the speed of the communication, the code was designed so that the length of each character in Morse varies approximately inversely to its frequency of occurrence in English. Thus the most common letter in English, the letter "E", has the shortest code, a single dot.
Ten-code 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. Credit for inventing the codes goes to Charles "Charlie" Hopper, communications director for the Illinois State Police, District 10 in Pesotum, Illinois. Hopper had been involved in radio for years and realized there was a need to abbreviate transmissions on State Police bands.[3] Experienced radio operators knew the first syllable of a transmission was frequently not understood because of quirks in early electronics technology. Radios in the 1930s were based on vacuum tubes powered by a small motor-generator called a dynamotor. The dynamotor took from 1/10 to 1/4 of a second to "spin up" to full power. Police officers were trained to push the microphone button, then pause briefly before speaking; however, sometimes they would forget to wait. Preceding each code with "ten-" gave the radio transmitter time to reach full power. An APCO Bulletin of January 1940 lists codes assigned as part of standardization;[4]