Spreading technique applied to broadband mobile communications by satelite relying on DVB-RCS

A system for DVB-RCS type satellite communication comprising:

• a first device comprising:
• a buffer for temporarily storing a sequence of digital samples of an analog input signal according to a first sampling frequency and in a manner synchronized with respect to starts of periodic time slots, and
• a digital-to-analog converter operative to generate, during each time slot and according to a second sampling frequency equal to N times the first sampling frequency, where N is an integer strictly greater than 1, an analog output signal representative of N repetitions of the sequence of digital samples that is stored in the buffer during the time slot concerned, transmitted according to a symbol rate equal to N times a reference symbol rate;
• a second device, operative to process the analog signals output by the first device, including at least:
• an analog-to-digital converter operative to sample an analog input signal representing N repetitions of sequences of digital samples, where N is an integer strictly greater than 1, to produce N identical sequences of digital samples at a third sampling frequency equal to N times a fourth sampling frequency in sequence with beginnings of periodic time slots,
• a buffer operative to temporarily store the N identical sequences of digital samples delivered by analog-to-digital converter during each time slot, and
• a combination processor, operative to combine in phase during each time slot the N identical sequences of digital samples stored in the buffer so as to deliver a sequence of digital samples combined at a reference symbol rate;
• and
• a demodulator,
• wherein the demodulator includes at least:
• a digital-to-analog converter operative to generate from the output of the combination processor, in each time slot, and at a fourth sampling frequency, an analog output signal representing a combined sequence of digital signals,
• a frequency conversion processor operative to convert to a primary frequency a secondary frequency of each analog output signal of the digital-to-analog converter, and
• a carrier demodulation processor operative to demodulate the analog output of the frequency conversion processor.

A method for transmitting signals using a DVB-RCS type satellite communication standard comprising:

• storing temporarily in a first buffer, in a first device, a sequence of digital samples of an analog input signal according to a first sampling frequency and in a manner synchronized with respect to starts of periodic time slots;
• generating with a digital-to-analog converter, in a first device, during each time slot and according to a second sampling frequency equal to N times the first sampling frequency, where N is an integer strictly greater than 1, an analog output signal representative of N repetitions of the sequence of digital samples that is stored in the buffer during the time slot concerned, transmitted according to a symbol rate equal to N times a reference symbol rate;
• sampling with an analog-to-digital converter, in a second device, an analog input signal representing N repetitions of sequences of digital samples, where N is an integer strictly greater than 1, to produce N identical sequences of digital samples at a third sampling frequency equal to N times a fourth sampling frequency in sequence with beginnings of periodic time slots;
• temporarily storing in a second buffer, in a second device, the N identical sequences of digital samples delivered by analog-to-digital converter during each time slot;
• combining with a combination processor, in a second device, in phase during each time slot, the N identical sequences of digital samples stored in the buffer so as to deliver a sequence of digital samples combined at a reference symbol rate;
• generating with a digital-to-analog converter, in a demodulator, the output of the combination processor, in each time slot, and at a fourth sampling frequency, an analog output signal representing a combined sequence of digital signals;
• converting with a frequency conversion processor, in a demodulator, to a primary frequency a secondary frequency of each analog output signal of the digital-to-analog converter;
• and,
• demodulating with a carrier demodulation processor, in a demodulator, the analog output of the frequency conversion processor.