History of the Arabic alphabet the same. After all this, there were only 17 letters that were different in shape. One letter-shape represented 5 phonemes ("b t th n" and sometimes "y"), one represented 3 phonemes ("j ħ kh"), and 5 each represented 2 phonemes. Compare the Hebrew alphabet, as in the table at . A similar ambiguity occurs in the German Fraktur font, in which the Roman alphabet uppercase letters I and J look the same but are officially different letters. The Arabic alphabet is first attested in its classical form in the 7th century. See PERF 558 for the first surviving Islamic Arabic
Morse code and Channel Coding comparisons, the word "PARIS" is used to determine Morse Code's properties because it has an even number of dots and dashes. Morse Code, when transmitted essentially, creates an AM signal (even in on/off keying mode), assumptions about signal can be made with respect to similarly timed RTTY signalling. Because Morse code transmissions employ an on-off keyed radio signal, it requires less complex transmission equipment than other forms of radio communication. Morse code also requires less signal bandwidth than voice communication, typically , compared to the roughly 2400 Hz used by single-sideband voice, although at a lower data