Radio receiver

Claim 2

A radio receiver for receiving an input signal, comprising: equalization means (3) for equalizing a received signal corresponding to the input signal and for reducing distortion which is included in the received signal; clock regeneration means (7) for regenerating a clock from the input signal; and abnormal receiving condition detection means (9) for detecting an abnormal condition in the received signal; characterized by variable phase shift means (10), operatively connected to said clock regeneration means (7), for variably phase shifting the regenerated clock when said abnormal receiving condition detection means (9) detects an abnormal receiving condition.

Claim 3

A receiver according to claim 1, further comprising: an input terminal (1) for receiving the input signal; and detection means (2), operatively connected between said input terminal (1) and said equalization means (3), for detecting the input signal and for providing the received signal to said equalization means (3).

Claim 4

A receiver according to claim 1, further comprising an input terminal (1) for receiving the input signal, wherein said clock regeneration means (7) is operatively connected to the input terminal (1) for regenerating the clock from the input signal.

Claim 5

A receiver according to any one of claims 1 to 3, wherein said variable phase shift means (10) includes means for sweeping the regenerated clock so as to determine a clock phase at which said equalization means (3) can be operated.

Claim 6

5 . A radio receiver for receiving an intermediate frequency signal, comprising: input terminal means (1) for receiving the intermediate frequency signal; detector means (2), operatively connected to said input terminal means (1), for detecting the intermediate frequency signal and for providing a baseband frequency signal; equalization means (3), operatively connected to said detector means (2), for equalizing the baseband frequency signal which is provided by said detector means, and for reducing distortion in the baseband frequency signal; discrimination means (4), operatively connected to said equalization means (3), for discriminating the equalized signal, and for outputting a data signal; carrier recovery means (6), operatively connected to said discrimination means (4) and said detector means (2), for recovering a carrier signal from the data signal, and for providing the recovered carrier signal to said detector means (2), said detector means (2) detecting the intermediate frequency signal based on the recovered carrier signal; abnormal receiving condition detection means (9), operatively connected to said discrimination means (4), for detecting an abnormal receiving condition based on the data signal; and clock regeneration means (7), operatively connected to said input terminal means (1), for regenerating a clock signal from the intermediate frequency signal; characterized by variable phase shift means (10), operatively connected to said clock regeneration means (7), and said abnormal receiving condition detection means (9), for variably phase shifting the regenerated clock signal when said abnormal receiving condition detection means (9) detects an abnormal receiving condition.

Claim 7

5 . A radio receiver for receiving an intermediate frequency signal, comprising: input terminal means (1) for receiving the intermediate frequency signal; detector means (2), operatively connected to said input terminal means (1), for detecting the intermediate frequency signal and for providing a baseband frequency signal; equalization means (3), operatively connected to said detector means (2), for equalizing the baseband frequency signal which is provided by said detector means, and for reducing distortion in the baseband frequency signal; discrimination means (4), operatively connected to said equalization means (3), for discriminating the equalized signal, and for outputting a data signal; carrier recovery means (6), operatively connected to said discrimination means (4) and said detector means (2), for recovering a carrier signal from the data signal, and for providing the recovered carrier signal to said detector means (2), said detector means (2) detecting the intermediate frequency signal based on the recovered carrier signal; abnormal receiving condition detection means (9), operatively connected to said discrimination means (4), for detecting an abnormal receiving condition based on the data signal; and clock regeneration means (7), operatively connected to said input terminal means (1), for regenerating a clock signal from the intermediate frequency signal; characterized by variable phase shift means (10), operatively connected to said clock regeneration means (7), and said abnormal receiving condition detection means (9), for variably phase shifting the regenerated clock signal when said abnormal receiving condition detection means (9) detects an abnormal receiving condition.

Claim 8

A receiver according to claim 5, for receiving a baseband frequency signal including channel signals, wherein said equalization means (3) comprises a transversal filter which includes: sets of delay circuits (301,302,303,304) connected to each detector means (2), each of the delay circuits within a set being connected in series and each having an input an output, each of said sets of delay circuits for delaying a respective one of the channel signals; multipliers (305 to 310), connected to said delay circuits (301 to 304), for multiplying respective coefficients by the signals at the respective inputs and outputs of said delay circuits; adders (317,318) connected to said multipliers (305 to 310) and to predetermined ones of said delay circuits (301 to 304), for adding predetermined ones of the output signals of said delay circuits and the output of said multipliers; and a coefficient control circuit (319), connected to said discrimination means (4) and said multipliers (305 to 310), for controlling the coefficients in a manner such as to reduce intersymbol interference and interchannel interference.

Claim 9

A receiver according to claim 5, wherein said abnormal receiving condition detection means (9) comprises: a discriminate (91), connected to said equalization means (3), for discriminating the equalized signal at a timing which is offset from the discrimination timing of said discrimination means (4). a judging circuit (92), connected to said discriminator (91) and to said discrimination means (4), for determining that an abnormal receiving condition exists by measuring the frequency at which the output of said discriminator (91) is different from the output of said discrimination means (4); and a low frequency oscillator (93), connected to said judging circuit (92), for generating a low frequency sawtooth wave to gradually vary the phase shift of said variable phase shift means (10) when the judging circuit (92) determines that an abnormal receiving condition exists.

Claim 10

A receiver according to claim 7, wherein said variable phase shift means (10) comprises an LC circuit having a variable capacitance element.

Claim 11

A receiver according to claim 7, wherein said variable phase shift means (10) comprises a one-shot multivibrator having a variable hold time.

Claim 12

A receiver according to claim 5, for receiving an equalized signal which is a multi-level signal, wherein said discrimination means (4) includes analog-to-digital conversion means for sampling the multi-level signal with an accuracy greater than the accuracy at which the multi-level signal was converted from data by a transmitter and for producing, as the data signal, data and error detection data, and wherein said abnormal receiving condition detection means (9') includes: EXCLUSIVE OR circuits (94,95) operatively connected to said analog-to-digital conversion means; a NAND circuit (96) connected to said EXCLUSIVE OR circuits (94,95); an integrator circuit (97), connected to said NAND circuit (96), for integrating the output of said NAN D circuit (96); a comparator circuit (98), connected to said integrator circuit (97), for comparing the integrated output with a reference voltage, and for determining whether abnormal receiving condition exists; and an oscillator (99), connected to said comparator circuit (98) and said variable phase shift means (10), for generating an oscillating control signal for said variable phase shift means (10) when an abnormal receiving condition exists.

Claim 13

A receiver according to claim 10, wherein said oscillator (99), is arranged to generate a sine wave signal and a cosine wave signal as the oscillating control signal, and wherein said variable phase shift means (10) comprises: a first hybrid circuit (1 0 3 ), operatively connected to said clock regeneration means (7), for dividing the regenerating clock provided by said clock regeneration means (7) into two output signals having a phase difference of 90°; mixers (101,102), operatively connected to said oscillator (99) and said first hybrid circuit (103), for respectively multiplying the sine wave signal and the cosine wave signal by the two output signals of said first hybrid circuit (103); and a second hybrid circuit (104), operatively connected to said mixers (101,102), for combining the multiplied signals and for outputting the phase shifted regenerated clock.

Claim 14

A radio receiver for receiving an input signal having distortion, comprising: first means (2,3) for detecting the input signal, for equalizing the input signal to reduce the distortion, and for providing an equalized signal; second means (7) for regenerating a clock based on the input signal; third means (4), operatively connected to said first means (2), for discriminating the equalized signal and for generating a data signal; and fourth means (9,9'), operatively connected to said third means (4), for detecting an abnormal condition in the input signal based on the data signal; characterized by: fifth means (10,10'), operatively connected to said first means (2), said second means (7) and said fourth means (9,9') for variably phase shifting the regenerated clock when said fourth means (9,9') detects an abnmormal condition and for providing the variably phase shifted regenerated clock to said first means (2).

Claim 15

A radio receiver for receiving an input signal having distortion, comprising: first means (2,3) for detecting the input signal, for equalizing the input signal to reduce the distortion, and for providing an equalized signal; second means (7) for regenerating a clock based on the input signal; third means (4), operatively connected to said first means (2), for discriminating the equalized signal and for generating a data signal; and fourth means (9,9'), operatively connected to said third means (4), for detecting an abnormal condition in the input signal based on the data signal; characterized by: fifth means (10,10'), operatively connected to said first means (2), said second means (7) and said fourth means (9,9') for variably phase shifting the regenerated clock when said fourth means (9,9') detects an abnmormal condition and for providing the variably phase shifted regenerated clock to said first means (2).

Claim 16

A receiver according to claim 12, wherein said fifth means (10) includes means for sweeping the regenerated clock so as to determine a clock phase at which said first means (2,3) can be operated.

Claim 17

A receiver according to claim 12, wherein said fifth means (10) comprises an LC circuit having a variable capacitance element.

Claim 18

A receiver according to claim 14, wherein said fourth means (9) comprises: a discriminator (91), operatively connected to said first means (2,3) and said third means (4), for discriminating the equalized signal at a timing which is offset from the timing of said third means (4); a judging circuit (92), operatively connected to said dicriminator (91) and said third means (4), for determining whether an abnormal condition exists by measuring the frequency with which the output of said discriminator (91) is different from the data signal generated by said third means (4); and a low frequency oscillator (93), operatively connected to said judging circuit (92) and said LC circuit, for generating a low frequency sawtooth wave to gradually vary the phase shift of said LC circuit when said judging circuit (92) determines that an abnormal condition exists.

Claim 19

A receiver according to claim 12, wherein said fifth means (10) comprises a one-shot multivibrator having a variable hold time.

Claim 20

A receiver according to claim 16., wherein said fourth means (9) comprises: a discriminator (91), operatively connected to said first means (2,3) and said third means (4), for discriminating the equalized signal at a timing which is offset fromthe timing of said third means (4); a judging circuit (92), operatively connected to said discriminator (91) and said third means (4), for determining whether an abnormal condition exists by measuring the frequency with which the output of said discriminator (91) is different from the data signal generated by said third means (4); and a low frequency oscillator (93), operatively connected to said judging circuit (92) and said one-shot multivibrator, for generating a low frequency sawtooth wave to gradually vary the phase shift of said one-shot multivibrator when said judging circuit (92) determines that an abnormal condition exists.

Claim 21

A receiver according to claim 12, wherein said fifth means (10') comprises: a first hybrid circuit (103), operatively connected to said second means (7), for dividing the regenerated clock into two output signals having a phase difference of 90°; first and second mixers (101,102), operatively connected to said fourth means (9') and said first hybrid circuit (103), for multiplying the abnormal condition detection signal by the two output signals of said first hybrid circuit (103); and a second hybrid circuit (104), operatively connected to said first and second mixers (101,102) and said first means (2,3), for combining the multiplied signals and for outputting the variably phase shifted regenerated clock.

Claim 22

A receiver according to claim 18, for receiving an equalized signal which is a multi-level signal, wherein said third means (4) includes analog-to-digital conversion means for sampling the multi-level signal with an accuracy greater than the accuracy at which the multi-level signal was converted from data by a transmitter and for producing, as the data signal, data and error detection data, and wherein said fourth means (9') includes: first and second EXCLUSIVE OR circuits (94,95) operatively connected to said analog-to-digital conversion means; a NAND circuit (96) connected to said first and second EXCLUSIVE OR circuits (94,95); an integrator circuit (97), connected to said NAND circuit (96), for integrating the output of said NAND circuit (96); a comparator circuit (98), connected to said integrator circuit (97), for comparing the integrated output with a reference voltage and for determining whether an abnormal condition exists; and an oscillator (99), connected to said comparator circuit (98) and said first and second mixers (101,102), for generating an oscillating control signal as the abnormal condition detection signal for said first and second mixers (101,102) when an abnormal condition exists.

Claim 23

A radio receiver according to claim 12, wherein said first means comprises: a detector (2), operatively connected to receive the input signal, for detecting the input signal; and a transversal filter (3), operatively connected to said detector (2), said third means (4) and said fifth means (10), for equalizing the input signal to reduce distortion and for providing the equalized signal as an output, said fifth means (10) providing the variably phase shifted regenerated clock to said transversal filter so as to provide a phase shifted regenerated clock with a clock phase at which transversal filter can be operated.