can anyone suggest me how to convert binary value to gray code value??

i would also like to know if you can provide me with the reverse conversion code of gray to binary value...thank you in advance.. :)

[Image Analyst]

Answer 1

[Guillaume]

The wikipedia article gives a very simple algorithm. I'm not sure what the difficulty is in converting it to matlab:

 function num = GrayToBinary(num)
    mask = bitshift(num, -1);
    while mask > 0
       num = bitxor(num, mask);
       mask = bitshift(mask, -1);
    end
  end

Answer 2

[Image Analyst]

In the Communications Systems Toolbox:

bin2gray

Convert positive integers into corresponding Gray-encoded integers

Syntax y = bin2gray(x,modulation,M) [y,map] = bin2gray(x,modulation,M)

Description y = bin2gray(x,modulation,M) generates a Gray-encoded vector or matrix output y with the same dimensions as its input parameter x. x can be a scalar, vector, or matrix. modulation is the modulation type and must be a string equal to 'qam', 'pam', 'fsk', 'dpsk', or 'psk'. M is the modulation order that can be an integer power of 2.

[Rezaur Rahman]

please do give the code...it will be a great help for me...and i dnt understand why the modulation is needed for the conversion...anyways, thanx... :)

[Image Analyst]

I don't have that toolbox. If you do, then in the help there is nearly always example code. You can ask for a trial version for a month if you want. It's free for a month. Good luck.

Answer 3

[Idin Motedayen-Aval]

bin2gray is no longer a MATLAB function, however, most of the digital modulation functions in Communication Toolbox (e.g. PAM, PSK, etc.) support gray coding directly. This example is a good reference:

https://www.mathworks.com/help/releases/R2025a/comm/ug/symbol-mapping-examples.html

If you really just want to convert binary mapping to gray (i.e. generate the table in the figure), you could either just write the lookup table manually, or do something like this:

M = 16; % Modulation order or 2^numBits
x = pskmod(0:M-1,M,0,"gray").';
y = pskdemod(x,16,0,"bin") % Will output the gray ordered integers
b = dec2bin(y) % Will output binary values

(I can't immediately think of why one might want to do this; other than as a teaching tool.)

Also note that binary-to-gray mapping is not unique. So the ordering you get from the code above may not match someone else's gray coding.

Answer 4

[David Goodmanson]

Here I used 'grey' instead of gray since Matlab has a function called gray.

n = 4
G = grey(n);
IG = igrey(n);
nbin = dec2bin(0:2^n-1);
[nbin blankss(2^n,2) G blankss(2^n,2) IG]

ans = 16×16 char array
'0000  0000  0000'
'0001  0001  0001'
'0010  0011  0011'
'0011  0010  0010'
'0100  0110  0111'
'0101  0111  0110'
'0110  0101  0100'
'0111  0100  0101'
'1000  1100  1111'
'1001  1101  1110'
'1010  1111  1100'
'1011  1110  1101'
'1100  1010  1000'
'1101  1011  1001'
'1110  1001  1011'
'1111  1000  1010'

fist column is binary 0:2^n-1, second column is grey code, third column is inverse grey code. example:

a = 12
abin = dec2bin(a)
  abin = '1100'

bbin = G(a+1,:)       % grey code; table is zero-based so add 1 to index
  bbin = '1010'
b = bin2dec(bbin)
  b = 10

cbin = IG(b+1,:)      % inverse grey, add 1 to index
  cbin = '1100'       % cbin = abin 
c = bin2dec(cbin)
  c = 12
  
%-----------------

function c = grey(n)
% n-digit gray code, 2^n row string matrix 
zero = '0';  one = '1';
c = [zero one]';
for k=2:n
    a = ones(2^(k-1),1);
    c = [zero(a), c; one(a), flipud(c)];
end
end

function c = igrey(n)
% n-digit inverse gray code, 2^n row string matrix 
zero = '0';  one = '1';
c = [zero one]';
for k=2:n
    a = ones(2^(k-1),1);
    d = flipud(c);
    d(:,2:2:end) = complement(d(:,2:2:end));
    c = [zero(a), c; one(a), d];
end
end

% a different way that bypasses explict construction of igrey

function c = igrey(n)
% n-digit inverse gray code, 2^n row string matrix 
% by simple inverse permutation of the grey code indices
a = bin2dec(grey(n));
[~, b] = sort(a);
c = dec2bin(b-1);
end

function xbar = complement(x)
xbar = char(97-abs(x));     %  '0' <-> '1'
end

function b = blankss(m,n)
% matrix of blanks, using Tony's trick!
% b = blankss(m,n)
space = ' ';
b = space(ones(m,n));
end

[Walter Roberson]

Did you intend to attach the code for grey and igrey ?

[David Goodmanson]

Hi Walter, I caught up and did that.