Patent ID: 8107628

Claim:
A data transmitting apparatus for multi-leveling information data by using predetermined key information and for performing secret communication with a receiving apparatus, the data transmitting apparatus comprising: a plurality of pseudo random number generators for respectively generating random numbers, each generated random number of the generated random numbers being a multi-level pseudo random number composed of a binary number, and each generated random number being generated using the predetermined key information; and a multi-level signal modulation section including: a multi-level code setting section including a plurality of first XOR circuits performing exclusive OR operations between a first random number and remaining random numbers of a multi-level sequence composed of a combination of values of the random numbers generated by the plurality of pseudo random number generators, so as to output a multi-level code sequence in which (i) the first random number is set as a lowest order bit and (ii) outputs from the plurality of first XOR circuits are set as remaining order bits; a multi-level processing section including a second XOR circuit performing an exclusive OR operation between the information data and a bit of the multi-level code sequence, and including a D/A converter to which an output from the second XOR circuit is inputted as a highest order bit and to which the multi-level code sequence is inputted as the remaining order bits, the multi-level processing section outputting a D/A conversion result of the D/A converter as a multi-level signal; and a modulator for modulating the multi-level signal to generate a multi-level modulated signal, wherein the multi-level signal modulation section is configured to select, from among multi levels previously prepared, a level corresponding to the information data and the multi-level sequence composed of the combination of values of the random numbers generated by the plurality of pseudo random number generators, and configured to generate, by using the selected level, the multi-level modulated signal including a noise having a predetermined noise level, and wherein a plurality of levels of the multi-level modulated signal is in a predetermined range of an amplitude or an intensity, and a plurality of multi-level sequences corresponding to the plurality of levels of the multi-level modulated signal includes, as values composing respective digits thereof, all of the values of the random numbers respectively generated by the plurality of pseudo random number generators.