Download getSymbol.m and put it in your code folder.

In the editor in MATLAB (or Octave-online) open a new file and write the function tokensToMessage(tokens, unittime) which takes a set of tokens and outputs a message. Each element in tokens represents a dot, dash, short-space, long-space, or long-long-space.

Save the file as tokensToMessage.m.

The table in Figure 1 has been implemented in a getSymbol function that will translate a string of dits and dashes to a character. For example:

>> getSymbol('...')

ans =

S

>> getSymbol('---')

ans =

O

Your function tokensToMessage should loop through all of the tokens and accumulate a symbol with dots and dashes. The matrix token is a 2D matrix with two columns. The first column represents the duration of the token and the second column represents the value of the token. Implement the general algorithm presented here:

message initialized to an empty string

symbol initialized to an empty string

for each row in tokens

if token's duration > 2 * timeunit and value == 0

concatenate getSymbol(symbol) to message

if token's duration > 4 * timeunit

concatenate ' ' to message

reset symbol to empty string

else if token's duration > 2*timeunit and value == 1

concatenate '-' to symbol

else if token's duration > timeunit/2 and value == 1

concatenate '.' to symbol

else

do nothing (it is either a character separator or too short)

%after the loop check to see if there is a last symbol

if not isempty(symbol)

concatenate getSymbol(symbol) to message

Submit your function to the quiz server for grading.

getSymbol.m:

function symbol = getSymbol( morse_string ) persistent code; if isempty(code) code{1} = '.-'; code{2} = '-...'; code{3} = '-.-.'; code{4} = '-..'; code{5} = '.'; code{6} = '..-.'; code{7} = '--.'; code{8} = '....'; code{9} = '..'; code{10} = '.---'; code{11} = '-.-'; code{12} = '.-..'; code{13} = '--'; code{14} = '-.'; code{15} = '---'; code{16} = '.--.'; code{17} = '--.-'; code{18} = '.-.'; code{19} = '...'; code{20} = '-'; code{21} = '..-'; code{22} = '...-'; code{23} = '.--'; code{24} = '-..-'; code{25} = '-.--'; code{26} = '--..'; % punct code{27} = '.-.-.-'; code{28} = '--..--'; code{29} = '..--..'; code{30} = '-..-.'; % numbers code{31} = '.----'; code{32} = '..---'; code{33} = '...--'; code{34} = '....-'; code{35} = '.....'; code{36} = '-....'; code{37} = '--...'; code{38} = '---..'; code{39} = '----.'; code{40} = '-----'; end symbols = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ.,?/1234567890'; symbol = symbols(strcmp(code,morse_string)); end