Digital signal processor, transmitter, and system

A digital signal processing method, comprising the following steps:

• generating a first digital signal and a second digital signal;
• modulating the first digital signal to obtain a third digital signal;
• modulating the second digital signal to obtain a fourth digital signal;
• performing phase shifting on the third digital signal, to output the third digital signal and a fifth digital signal, wherein the fifth digital signal is a signal obtained after phase shifting is performed on the third digital signal;
• performing phase shifting on the fourth digital signal, to output the fourth digital signal and a sixth digital signal, wherein the sixth digital signal is a signal obtained after phase shifting is performed on the fourth digital signal;
• calculating a sum of the third digital signal and the fourth digital signal, to obtain a seventh digital signal, wherein the seventh digital signal is a first drive signal used to drive a single sideband modulator;
• and
• subtracting the sixth digital signal from the fifth digital signal, to obtain an eighth digital signal, wherein the eighth digital signal is a second drive signal used to drive the single sideband modulator.

A data communications apparatus, wherein the apparatus comprises a processor, a memory, and a bus system, the processor and the memory are connected by using the bus system, the memory is configured to store an instruction, and the processor is configured to execute the instruction stored in the memory, wherein

• the processor is configured to:
• modulate a first digital signal to obtain a third digital signal;
• and
• modulate a second digital signal to obtain a fourth digital signal;
• perform phase shifting on the third digital signal, to output the third digital signal and a fifth digital signal, wherein the fifth digital signal is a signal obtained after phase shifting is performed on the third digital signal;
• perform phase shifting on the fourth digital signal, to output the fourth digital signal and a sixth digital signal, wherein the sixth digital signal is a signal obtained after phase shifting is performed on the fourth digital signal;
• calculate a sum of the third digital signal and the fourth digital signal, to obtain a seventh digital signal, wherein the seventh digital signal is a first drive signal used to drive a single sideband modulator;
• and subtract the sixth digital signal from the fifth digital signal, to obtain an eighth digital signal, wherein the eighth digital signal is a second drive signal used to drive the single sideband modulator.

A transmitter, comprising a digital signal processor, a first digital-to-analog converter, a second digital-to-analog converter, a light source, and a single sideband modulator, wherein

• the digital signal processor is configured to:
• generate a first digital signal and a second digital signal;
• modulate the first digital signal to obtain a third digital signal;
• modulate the second digital signal to obtain a fourth digital signal;
• perform phase shifting on the third digital signal, to output the third digital signal and a fifth digital signal, wherein the fifth digital signal is a signal obtained after phase shifting is performed on the third digital signal;
• perform phase shifting on the fourth digital signal, to output the fourth digital signal and a sixth digital signal, wherein the sixth digital signal is a signal obtained after phase shifting is performed on the fourth digital signal;
• calculate a sum of the third digital signal and the fourth digital signal, to obtain a seventh digital signal, wherein the seventh digital signal is a first drive signal used to drive a single sideband modulator;
• and
• subtract the sixth digital signal from the fifth digital signal, to obtain an eighth digital signal, wherein the eighth digital signal is a second drive signal used to drive the single sideband modulator;
• the first digital-to-analog converter is configured to convert the seventh digital signal into an analog signal, the second digital-to-analog converter is configured to convert the eighth digital signal into an analog signal, the light source is configured to generate contiguous optical carriers, and the single sideband modulator is configured to modulate the optical carriers according to the analog signal of the seventh digital signal and the analog signal of the eighth digital signal, to generate an optical signal on a left sideband and an optical signal on a right sideband that are independent from each other.