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# CRC (FEC 2/3 in Bluetooth) error correction

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#### godsosall

##### Newbie level 3
We have a course project to do the FEC 2/3 of Bluetooth in VHDL/MATLAB
I can find the syndrome vector after divisions but how I can build a lookup tables of syndromes to be able to correct to error bit.
it is a (15,10) hamming code, which can correct a single bit according to the specification

I don't know the partucularities of the code you are using, but anyway you can proceed as follows:
Introduce errors in bits, once at a time, and see the resulting syndrome in each case.
In that way yo construct the lookup table like this:

syndrome bit_in_error
0000 ... no error
0001 ... bit X
...
1111 ... bit Z

BTW: it is not a (15,11) code?
Regards

Z

V
Points: 2
According to the spec it is : FEC scheme (15,10) shortened Hamming code,
and this kind of code can correct all the possible single bit error plus some of double bit errors.
I though the same thing that you replied but it seams it is different.
Is there any function to calculate syndromes in MATLAB?

godsosall said:
Is there any function to calculate a syndromes in MATLAB?
There are several functions for error-control coding in the Matlab Communications Toolbox.
Probably the "syndtable" function is what you are looking for.
Regards

Z

### godsosall

Points: 2
I have used the syndtable, it generates the table of syndrome.
Now I have a problem in dividing the message by generator to find the syndrome, i have tried to use the outputlogic.com tool for CRC generator but I still can not get to correct answer, the reminder of VHDL is different than what I get with deconv in MATLAB

I have used the syndtable, it generates the table of syndrome.
Now I have a problem in dividing the message by generator to find the syndrome, i have tried to use the outputlogic.com tool for CRC generator but I still can not get to correct answer, the reminder of VHDL is different than what I get with deconv in MATLAB

I also meet this problem. The syndrome mapping is different between different decode method, one is use Matrix the other is using LSFR.

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