A card may detect variations (e.g., position, velocity, acceleration and direction) of a read head in relation to the card. Based on certain parameters (e.g., card length, initially detected read head position, and read head velocity) the card may change communicated bit parameters (e.g., bit period) so that a total number of data bits may be communicated by the card to the read head while the read head remains within a communication distance of the card.