Method and device for measuring the current signal-to-noise ratio when decoding LDPC codes

A method for measuring the current signal-to-noise ratio when decoding Low Density Parity Check (LDPC) codes, the method comprising:

• receiving from an output of a demodulator an input code word;
• decoding the input code word in a LDPC decoder using a predetermined dependence of a law of distribution of a number of iterations on the signal-to-noise and a predetermined dependence of a law of distribution of a weight of the syndrome for a specified number of iterations;
• recording the weight of the syndrome for a specified number of iterations performed during the decoding of the input code word;
• constructing a histogram of distribution of the weight of the syndrome for a specified time interval;
• estimating a signal-to-noise ratio based on comparison of the histogram of distribution of the weight of the syndrome and on the dependence of the law of distribution of the weight of the syndrome for a specified number of iterations;
• and
• generating an output decoded code word.

A device for measuring a signal-to-noise ratio when decoding Low Density Parity Check (LDPC) codes, the device comprising:

• a decoder having an input and an output, wherein the input in an input to the device input and the output is a first output of the device;
• a signal-to-noise ratio estimating unit;
• an LDPC decoder;
• a synchronization unit having an input and a plurality of outputs, wherein the input is connected to the input of the device and the plurality of outputs are used to synchronize an operation of the device;
• and
• a unit for calculating the weight of the syndrome having an input and a plurality of outputs, wherein the input is connected to a third output of the LDPC decoder and the plurality of outputs are connected to corresponding inputs of the signal-to-noise ratio estimating unit having an output which is a second output of the device.