摘要:
The invention is related to a method and circuit arrangement for compensating for delayed components of a received transmission signal especially in a digital transmission system based on physical lines. The method and arrangement utilize a decision feedback equalizer, wherein the weighted sum of decisions based on earlier samples is subtracted from a sample. According to the invention, delayed components in the signal are measured in a measuring unit (11). The earlier decisions to be subtracted from a signal sample are selected from a predetermined group of consecutive decisions, and the strength of the delay component in the delay between each decision and the signal sample is used as a selection criterion. Advantageously, the equalizer according to the invention includes a selector (8) which connects some of the taps of the delay line (7) to multiplier units (9). By means of this method and arrangement it is possible to implement with a small number of multiplier units a equalizer capable of compensating for delayed components with long delays.
摘要:
The invention is related to a method and circuit arrangement for processing a received signal in a variable symbol rate system, such as a digital television system. In the method and arrangement according to the system, a received signal is sampled at a fixed sampling frequency (f f ) that is higher than the symbol frequency of any one of the received signals. The resulting sample sequence is converted to another sample sequence the sampling frequency of which equals the symbol frequency (f i ) of the received signal or its integer multiple. Then the samples are filtered (8) and signal value decisions are made (9) for the filtered samples. Conversion of the sampling frequency is advantageously performed using a so-called modified Farrow-type fractional delay filter (6) which is controlled using a control signal proportional to the delay of each sample. Using the method and arrangement according to the invention it is possible to process received signals the symbol frequencies of which are arbitrary within set limits.
摘要:
The invention is related to a method and circuit arrangement for compensating for delayed components of a received transmission signal especially in a digital transmission system based on physical lines. The method and arrangement utilize a decision feedback equalizer, wherein the weighted sum of decisions based on earlier samples is subtracted from a sample. According to the invention, delayed components in the signal are measured in a measuring unit (11). The earlier decisions to be subtracted from a signal sample are selected from a predetermined group of consecutive decisions, and the strength of the delay component in the delay between each decision and the signal sample is used as a selection criterion. Advantageously, the equalizer according to the invention includes a selector (8) which connects some of the taps of the delay line (7) to multiplier units (9). By means of this method and arrangement it is possible to implement with a small number of multiplier units a equalizer capable of compensating for delayed components with long delays.
摘要:
The invention is related to a method and circuit arrangement for processing a received signal in a variable symbol rate system, such as a digital television system. In the method and arrangement according to the system, a received signal is sampled at a fixed sampling frequency (f f ) that is higher than the symbol frequency of any one of the received signals. The resulting sample sequence is converted to another sample sequence the sampling frequency of which equals the symbol frequency (f i ) of the received signal or its integer multiple. Then the samples are filtered (8) and signal value decisions are made (9) for the filtered samples. Conversion of the sampling frequency is advantageously performed using a so-called modified Farrow-type fractional delay filter (6) which is controlled using a control signal proportional to the delay of each sample. Using the method and arrangement according to the invention it is possible to process received signals the symbol frequencies of which are arbitrary within set limits.