Transmission system for digital signals, and transmitter and receiver therefor
First Claim
Patent Images
1. A transmission system for a digital signal (sr) which, encoded in symbols (Si), is transmitted from a transmitter (T) to a receiver (R) by quadrature modulation, wherein:
- said transmitter comprises means for delaying one of the two quadrature signal components (ki, kq) before the quadrature modulation by a given time interval (td) substantially equal to one quarter of a symbol period Tsymb or by one quarter of the period of the quadrature carrier (tr) in the transmitter (T); and
,said receiver (R) comprises;
clock recovery means;
an analog-to-digital converter coupled to said clock recovery means;
said analog-to-digital converter for forming a sampled signal (sd) from a received signal (s(t)), and utilizing a sampling frequency fs being substantially equal to four times the symbol frequency fsymb ;
a demultiplexer coupled to said clock recovery means;
said demultiplexor for separating the sampled signal (sd) into an in-phase component (ki) for an I data path (I) and a quadrature component (kq) for a Q data path (Q) which are each filtered by means of a respective pulse-shaping filter (FI2, FQ2) with an IIR filter structure; and
a quadrature mixer coupled to said clock recovery means.
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Abstract
Transmission system with a transmitter (T), a receiver (R), and a filter combination (FI1, FI2; FQ1, FQ2) for transmitting a digital signal (sr), encoded in symbols (Si), from the transmitter (T) to the receiver (R) at any frequency position by quadrature modulation, wherein one of the two quadrature signal components (ki, kq) in the transmitter is delayed before the quadrature modulation by a time interval td, particularly by td=Tsymb/4. (FIG. 7)
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Citations
10 Claims
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1. A transmission system for a digital signal (sr) which, encoded in symbols (Si), is transmitted from a transmitter (T) to a receiver (R) by quadrature modulation, wherein:
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said transmitter comprises means for delaying one of the two quadrature signal components (ki, kq) before the quadrature modulation by a given time interval (td) substantially equal to one quarter of a symbol period Tsymb or by one quarter of the period of the quadrature carrier (tr) in the transmitter (T); and
,said receiver (R) comprises; clock recovery means; an analog-to-digital converter coupled to said clock recovery means; said analog-to-digital converter for forming a sampled signal (sd) from a received signal (s(t)), and utilizing a sampling frequency fs being substantially equal to four times the symbol frequency fsymb ; a demultiplexer coupled to said clock recovery means;
said demultiplexor for separating the sampled signal (sd) into an in-phase component (ki) for an I data path (I) and a quadrature component (kq) for a Q data path (Q) which are each filtered by means of a respective pulse-shaping filter (FI2, FQ2) with an IIR filter structure; anda quadrature mixer coupled to said clock recovery means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A receiver (R) for receiving a digital signal (sr) which, encoded in symbols (Si), is transmitted from a transmitter (T), said transmitter (T) comprising means for delaying one of the two quadrature signal components (ki, kq) before quadrature modulation, said receiver comprising:
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clock recovery means; an analog-to-digital converter coupled to said clock recovery means;
said analog-to-digital converter for forming a sampled signal (sd) from a received signal (s(t)), and utilizing a sampling frequency fs being substantially equal to four times the symbol frequency fsymb ;a demultiplexor coupled to said clock recovery means;
said demultiplexor for separating the sampled signal (sd) into an in-phase component (ki) for an I data path (I) and a quadrature component (kq) for a Q data path (Q) which are each filtered by means of a respective pulse-shaping filter (FI2, FQ2) with an IIR filter structure; anda quadrature mixer coupled to said clock recovery means.
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Specification