Receiver and signal processing method

A receiver, comprising:

• a first frequency mixer, configured to perform frequency mixing on a first received signal by using a first square wave signal to obtain a first frequency-mixed signal, wherein the first square wave signal is based on a carrier frequency estimation value of the first received signal;
• a first low-pass filter, configured to receive the first frequency-mixed signal from the first frequency mixer and perform low-pass filtering on the first frequency-mixed signal to obtain a first filtered signal;
• a first analog-to-digital converter, configured to receive the first filtered signal from the first low-pass filter and perform analog-to-digital conversion on the first filtered signal to obtain a first sampled signal;
• a second frequency mixer, configured to perform frequency mixing on the first received signal by using the first square wave signal to obtain a second frequency-mixed signal;
• a second low-pass filter, configured to receive the second frequency-mixed signal from the second frequency mixer and perform low-pass filtering on the second frequency-mixed signal to obtain a second filtered signal;
• a second analog-to-digital converter, configured to receive the second filtered signal from the second low-pass filter and perform analog-to-digital conversion on the second filtered signal to obtain a second sampled signal;
• a third frequency mixer, configured to perform frequency mixing on the first received signal by using a second square wave signal to obtain a third frequency-mixed signal;
• a third low-pass filter, configured to receive the third frequency-mixed signal from the third frequency mixer and perform low-pass filtering on the third frequency-mixed signal to obtain a third filtered signal;
• and
• a third analog-to-digital converter, configured to receive the third filtered signal from the third low-pass filter and perform analog-to-digital conversion on the third filtered signal to obtain a third sampled signal;
• a fourth frequency mixer, configured to perform frequency mixing on the first received signal by using the second square wave signal to obtain a fourth frequency-mixed signal;
• a fourth low-pass filter, configured to receive the fourth frequency-mixed signal from the fourth frequency mixer and perform low-pass filtering on the fourth frequency-mixed signal to obtain a fourth filtered signal;
• a fourth analog-to-digital converter, configured to receive the fourth filtered signal from the fourth low-pass filter and perform analog-to-digital conversion on the fourth filtered signal to obtain a fourth sampled signal;
• and
• a processor configured to receive the first sampled signal from the first analog-to-digital converter, the second sampled signal from the second analog-to-digital converter, receive the third sampled signal from the third analog-to-digital converter, and receive the fourth sampled signal from the fourth analog-to-digital converter, and estimate, according to the first sampled signal, the second sampled signal, the third sampled signal, and the fourth sampled signal, an information symbol transmitted by a transmit end.

A signal processing method, comprising:

• performing frequency mixing on a first received signal by using a first square wave signal to obtain a first frequency-mixed signal, wherein the first received signal comprises a narrowband signal whose carrier frequency is fi and wherein the first square wave signal is based on a carrier frequency estimation value of the first received signal;
• performing low-pass filtering on the first frequency-mixed signal to obtain a first filtered signal;
• performing analog-to-digital conversion on the first filtered signal to obtain a first sampled signal;
• performing frequency mixing on the first received signal by using a second square wave signal to obtain a second frequency-mixed signal, wherein the second square wave signal is based on the carrier frequency estimation value of the first received signal;
• performing low-pass filtering on the second frequency-mixed signal to obtain a second filtered signal;
• performing analog-to-digital conversion on the second filtered signal to obtain a second sampled signal;
• and
• estimating, according to the first sampled signal and the second sampled signal, an information symbol transmitted by a transmit end,
• wherein:
• the first square wave signal is sign{ sin(f1×2π×t)+sin((f3+fp) ×2π×t)}, and the second square wave signal is sign{ cos(f1×2π×t)+cos((f3+fp) ×2π×t)};
• or
• the first square wave signal is sign{ sin(f1×2π×t)+sin((f−fp) ×2π×t)}, and the second square wave signal is sign{ cos(f1×2π×t) +cos((f3−fp) ×2π×t)};
• or
• the first square wave signal is sign{ sin((f1+fp) ×2π×t) +sin(f3×2π×t)}, and the second square wave signal is sign{ cos((f1+fp) ×2π×t) +cos(f3×2π×t)};
• or
• the first square wave signal is sign{ sin((f1−fp) ×2π×t)+sin(f3×2π×t)}, and the second square wave signal is sign{ cos((f1−fp) ×2π×t)+cos(f3×2π×t)};
• or
• the first square wave signal is sign{ sin(f1×2π×t)}+sign{ sin((f3+fp) ×2π×t)}, and the second square wave signal is sign{ cos(f1×2π×t)}+sign{ cos((f3+fp) ×2π×t)};
• or
• the first square wave signal is sign{ sin(f1×2π×t)}+sign{ sin((f3−fp) ×2π×t)}, and the second square wave signal is sign{ cos(f1×2π×t)}+sign{ cos((f3−fp) ×2π×t)};
• or
• the first square wave signal is sign{ sin((f1+fp) ×2π×t)}+sign{ sin(f3×2π×t)}, and the second square wave signal is sign{ cos((f1+fp) ×2π×t)} +sign{ cos(f3×2π×t)};
• or
• the first square wave signal is sign{ sin((f1−fp) ×2π×t)}+sign{ sin(f3×2π×t)}, and the second square wave signal is sign{ cos((f1−fp) ×2π×t)}+sign{ cos(f3×2π×t)};
• or
• the first square wave signal is sign{ cos(f1×2π×t)}+cos((f3+fp) ×2π×t)}, and the second square wave signal is sign{ sin(f1×2π×t)}+sin((f3+fp) ×2π×t)};
• or
• the first square wave signal is sign{ cos(f1×2π×t)}+cos((f3−fp) ×2π×t)}, and the second square wave signal is sign{ sin(f1×2π×t) +sin((f3−fp) ×2π×t)};
• or
• the first square wave signal is sign{ cos((f1+fp) ×2π×t)}+cos(f3×2π×t)}, and the second square wave signal is sign{ sin((f1+fp) ×2π×t)}+sin(f3 ×2π×t)};
• or
• the first square wave signal is sign{ cos((f1−fp) ×2π×t)}+cos(f3×2π×t)}, and the second square wave signal is sign{ sin((f1−fp) ×2π×t)}+sin(f3×2π×t)};
• or
• the first square wave signal is sign{ cos(f1×2π×t)}+sign{ cos((f3+fp) ×2π×t)}, and the second square wave signal is sign{ sin(f1×2π×t)}+sign{ sin((f3+fp) ×2πt)};
• or
• the first square wave signal is sign{ cos(f1×2π×t)}+sign{ cos((f3−fp) ×2π×t)}, and the second square wave signal is sign{ sin(f1×2π×t)}+sign{ sin((f3−fp) ×2π×t)};
• or
• the first square wave signal is sign{ cos((f1+fp) ×2π×t)}+sign{ cos(f3×2π×t)}, and the second square wave signal is sign{ sin((f1+fp) ×2π×t)}+sign{ sin(f3×2π×t)};
• or
• the first square wave signal is sign{ cos((f1−fp) ×2π×t)}+sign{ cos(f3×2π×t)}, and the second square wave signal is sign{ sin((f1−fp) ×2π×t)}+sign{ sin(f3×2π×t)},
• wherein sign is a sign function, t represents a time, fp is a minimum frequency or a fundamental frequency of the first square wave signal or the second square wave signal, f1and f3are the carrier frequency estimation values of the first received signal, and fi is not equal to f3.