EP0122127A2 — Radio communication system

Claim 1

Independent Claim 233 words

A radio communication system operated under a quadrature amplitude modulation (QAM) method, including: a transmitter unit being operative to modulate a digital data signal clocked with a clock frequency f CL ,with a carrier having a frequency f 0 and to transmit the modulated wave signal to a radio transmission line; and a receiver unit being operative to receive, via said radio transmission line, the modulated wave signal, to extract the carrier therefrom and reproduce the original digital data signal with the use of the extracted carrier wave; characterized in that the transmitter unit contains therein an insertion means for inserting one or two signals for carrier recovery into the modulated wave signal, each said signal for carrier recovery having a frequency defined as (f O + k·f CL ), where an inequality of O < |k| < 1 is satisfied, the receiver unit contains therein an extraction means for extracting received frequency components (f O + k·f CL ), a separation means for separating the extracted frequency components (f O + k·f CL ) from each other i.e., f 0 from k·f CL , and a recovery means for recovering the original clock frequency component fCL and thereby operative to reproduce the original digital data signal, with the use of the recovered carrier frequency component f o and the recovered clock frequency component f CL , from the received modulated wave signal.

Claim 2

Dependent Claim 233 words

A radio communication system operated under a quadrature amplitude modulation (QAM) method, including: a transmitter unit being operative to modulate a digital data signal clocked with a clock frequency f CL ,with a carrier having a frequency f 0 and to transmit the modulated wave signal to a radio transmission line; and a receiver unit being operative to receive, via said radio transmission line, the modulated wave signal, to extract the carrier therefrom and reproduce the original digital data signal with the use of the extracted carrier wave; characterized in that the transmitter unit contains therein an insertion means for inserting one or two signals for carrier recovery into the modulated wave signal, each said signal for carrier recovery having a frequency defined as (f O + k·f CL ), where an inequality of O < |k| < 1 is satisfied, the receiver unit contains therein an extraction means for extracting received frequency components (f O + k·f CL ), a separation means for separating the extracted frequency components (f O + k·f CL ) from each other i.e., f 0 from k·f CL , and a recovery means for recovering the original clock frequency component fCL and thereby operative to reproduce the original digital data signal, with the use of the recovered carrier frequency component f o and the recovered clock frequency component f CL , from the received modulated wave signal.

Claim 3

Dependent Claim 67 words

A system as set forth in claim 1, wherein said insertion means is operative to first create either one or two zero nodes at either one side or both sides of said modulated wave signal at either one or both of frequencies (f O + k·f CL ) and (f O - k·f CL ), respectively, and then insert said one or two signals for carrier recovery.

Claim 4

Dependent Claim 24 words

A system as set forth in claim 2, wherein said insertion means includes therein a filter to create saidone or two / zero nodes.

Claim 5

Dependent Claim 28 words

A system as set forth in claim 3, wherein said filter is made of a cosine roll-off filter, the constant k being determined by a roll-off ratio thereof.

Claim 6

Dependent Claim 17 words

A system as set forth in claim 3, wherein said filter is made of a Gaussian-type filter.

Claim 7

Dependent Claim 32 words

A system as set forth in claim 3, wherein said filter is constructed as a partial response transmission line in which equalization is performed so as to discretely produce so-called inter-symbol interferences.

Claim 8

Dependent Claim 49 words

A system as set forth in claim 3 4, 5, or 6 , wherein said filter is operative to create at least one said zero node at either one or both of the frequencies (f 0 + k ·f CL ) and (f 0 - k ·f CL ).

Claim 9

Independent Claim 74 words

A system as set forth in any of claims 3 to 7, wherein said insertion means includes therein a hybrid circuit which is operative to receive, on one hand, an output signal from a modulator in which the filtered signal from said filter is modulated with said carrier of f 0 and receive, on the other hand, said signal for carrier recovery of (f + k·f CL ), thereby producing said modulated wave signal.

Claim 10

Independent Claim 28 words

A system as set forth in any previous claim, wherein the constant k is , where m and n are positive integers and m < n is satisfied.

Claim 11

Dependent Claim 92 words

A system as set forth in claim 9, wherein, in said transmitter unit, said insertion means is further comprised of a frequency divider having a dividing ratio and receiving a clock signal of f CL from a clock generator to produce a signal of .f CL , a mixer receiving both the signal of .f CL , and said carrier of f 0 from a carrier generator, and a band-pass filter to produce said signal for carrier recovery of (f 0 + ·f CL ) to be input to said hybrid circuit.

Claim 12

Dependent Claim 189 words

A system as set forth in claim 9 or 10,, wherein, in said receiver unit: said extraction means is comprised of a band-pass filter to filter said signal of (f 0 + ·f CL ) from the received modulated wave signal, which filter is tuned to the frequency (f 0 + .f CL ) ; said separation means and said recovery means are cooperatively coupled with each other and constructed by, as a whole, a bit timing recovery circuit receiving the received modulated wave signal and recovering the signal of f CL therefrom, a frequency divider having a dividing ratio which receives the recovered signal of f CL and then produces the signal of ·f CL , a modulator being operative to modulate the signal of (f 0 + f. CL ) from said band-pass filter of said extracting means with the signal of · fCL from said frequency divider of dividing ratio of and producing two modulation signals of f 0 and (f 0 + 2 .f CL ), and a band-pass filter to extract the modulation signal of f o , as said carrier, among the two.

Claim 13

Dependent Claim 78 words

A system as set forth in claim 7, wherein said insertion means includes therein a hybrid circuit which is operative to receive, on one hand, an output signal from a modulator in which the filtered signal from said filter is modulated with said carrier of f 0 and receive, on the other hand, said signals for carrier recovery of (f 0 + k·f CL ) and (f 0 - k·f CL ), thereby producing said modulated wave signal.

Claim 14

Dependent Claim 29 words

A system as set forth in claim 12 , wherein the constant k is m n, where m and n are positive integers and m < n is satisfied.

Claim 15

Dependent Claim 102 words

A system as set forth in claim 13, wherein, in said transmitter unit, said insertion means is further comprised of a frequency divider having a dividing ratio and receiving a clock signal of f CL from a clock generator to produce a signal of ·f CL , a mixer receiving both the signal of ·f CL and said carrier of f 0 from a carrier generator, and first and second band-pass filters to produce said signals for carrier recovery of (f + ·f CL ) and (f 0 - .f CL ), respectively to be input to said hybrid circuit. or 14

Claim 16

Dependent Claim 212 words

A system as set forth in claim 13 , wherein, in said receiver unit: said extraction means is comprised of first and second band-pass filters to filter said signals of (f O + m n·f CL ) and (f O - m n.f CL ), respectively from the received modulated wave signal, which filters are tuned to the frequencies (f O + m n.f CL ) and (f O - m n.f CL ), respectively; said separation means and said recovery means are cooperatively coupled with each other and constructed by, as a whole, a modulator receiving both filtered signals of (f O + m n.f CL ) and (f O - m n.f CL from said first and second band-pass filters and producing two modulation signals of 2f 0 and 2mn·f CL , first and second band-pass filters to extract the two modulation signals of 2f O and 2mn.f CL respectively independently from each other, a frequency divider having a dividing ratio of 1 2 receiving the filtered signal of 2f o and recovering said carrier of f 0 , and a frequency divider having a dividing ratio of n' m' (= n 2m) receiving the filtered signal of 2m n.f CL and recovering said clock signal of f CL .

Claim 17

Dependent Claim 64 words

A system as set forth in claim 1, wherein said insertion means inserts two signals for carrier recovery simultaneously, a first signal thereof having a frequency (f 0 + k·f CL ) and a second signal thereof having a fre- quenc y (f 0 - k·f CL ), where the constant k is determined as 1 N (N is positive number larger than 1).

Claim 18

Dependent Claim 164 words

A system as set forth in claim 16, wherein, in the transmitter unit, said insertion means is comprised of a frequency divider having a dividing ratio 1 N and receiving a clock signal of f CL from a clock generator to produce a signal of 1 N·f CL , a mixer receiving both the signal of 1 N.F CL and said carrier from a carrier generator and producing two signals for carrier recovery of (f O + 1 N.f CL ) and (f O - 1 N.f CL ) simul- taneously, a modulator receiving, on one hand, said carrier of f 0 from said carrier generator and receiving, on the other hand, said digital data signal converted into analog form and producing said modulated wave signal, and a hybrid circuit being operative to insert said signals of (f O + 1 N.f CL ) and (f O - 1 Nf CL ) in the modulated wave signal and transmitting them to said receiver unit.

Claim 19

Dependent Claim 243 words

A system as set forth in claim 17, wherein, in said receiver unit, said extraction means is comprised of first and second band-pass filters to filter said signals of (f O + 1 N.f CL ) and (f O - 1 N.f CL ) from the received modulated wave signal, which filters are tuned to the frequencies (f + 1 N.f CL ) and (f O - 1 N.f CL ), respectively; said separation means and said recovery means are cooperatively coupled with each other and constructed by, as a whole, a modulator receiving output signals of (f O + 1 N.f CL ) and (f O - 1 N.f CL ) from said first and second band-pass filters and producing two modulation signals of 2f O and 21 N.f CL , first and second band-pass filters to filter said signals of 2f O and 21 N.f CL from each other, which filters are tuned to the frequencies 2f 0 and 21 N.f CL , respectively, a frequency divider having a dividing ratio 1 2 receiving the filtered signal of 2f 0 and recovering said carrier of f o , an N 2 multiplier receiving the filtered signal of 2N.f CL and recovering the clock signal of f CL , and thereby operative to reproduce the original digital data signal, using the received carrier frequency component f 0 and the recovered clock frequency component f CL , from the received modulated wave signal.

Claim 20

Dependent Claim 140 words

A system as set forth in claim 18, wherein a modulator, a frequency divider having a dividing ratio 1 2, and a subtractor are further employed, the modulator receiving both the received modulated wave signal and said recovered carrier of f 0 and producing a modulated output signal therefrom, the frequency divider receiving the filtered signal of 21 N.f CL from said band-pass filter and producing an offset frequency signal of 1 N.f CL the subtractor receiving both the modulated output signal from the modulator and the offset frequency signal and being operative to subtractively combine these two signals with each other so as to produce the original digital data signal in analog form, which analog-form original digital data signal is transformed, with the use of the recovered clock signal of f CL ' into the original digital data signal.

Claim 21

Dependent Claim 17 words

A system as set forth in claim 19, wherein said subtractor is constructed as a ring modulator.

Claim 22

Dependent Claim 14 words

A transmitter unit for a radio communication system as claimed in any preceding claim.

Claim 23

Dependent Claim 18 words

A receiver unit for a radio communication system as claimed in any one of claims 1 to 20.

Radio communication system

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