HART sampling

An apparatus for processing an electrical signal comprising:

• a receiver arranged to receive an electrical signal comprising a frequency modulated signal encoding digital data;
• a sampler arranged to sample a first portion of the electrical signal to obtain a plurality of samples to obtain a first sample set, and to determine an index value from the first sample set by:
• comparing each sample in the first sample set to a threshold value;
• assigning a first value to each sample that is above the threshold value;
• and
• assigning a second value to each sample that is at or below the threshold value;
• outputting the assigned values for the first sample set as the index value;
• a memory storing a plurality of predetermined index values and a plurality of predetermined output values, each of the predetermined index values corresponding to one of the plurality of predetermined output values, each of the predetermined output values indicating a respective frequency modulation encoded value;
• and
• a processing module arranged to process the first sample set to:
• compare the determined index value with the predetermined index values to identify a first output value from the plurality of predetermined output values, the first output value indicating a frequency modulation encoded value within the first portion of the electrical signal;
• and
• output an indication of the first output value.