A system comprising a transmission apparatus and a receiving apparatus for receiving digital data transmitted from a transmission apparatus, wherein the transmission apparatus comprises: a data coding means (110, 120) for (i) converting digital data arriving during each of a plurality of successive symbol periods, into a respective symbol value representing the digital data for the duration of the respective symbol period, and (ii) converting the symbol value into a signal level, the data coding means being operative such that there is change in signal level between consecutive symbol periods whether or not the digital data changes; a first digital filter configured to operate with a first sampling cycle that is shorter than said symbol period, and allows only predetermined frequencies of the output from the data coding means to pass; a D/A conversion means for converting the digital data stream that has passed through the first digital filter, into an analogue signal; a low-pass filter for eliminating, from the analogue signal obtained by the D/A conversion means, frequencies at least twice as high as the frequencies that have passed through the first digital filter; and a differential driver for converting an output from the low-pass filter, into two signals having opposite polarities relative to a predetermined reference potential, and inputting the two signals into a twisted pair cable, wherein the first digital filter has frequency characteristics for cutting off at least those frequency components which are higher than a frequency band in which electromagnetic waves emitted from the respective signals that pass through the twisted pair cable cancel each other out, wherein the receiving apparatus comprises: a differential receiver for receiving transmission signals transmitted through a twisted pair cable, and converting a difference in potentials between two wires of the cable into a signal; an A/D conversion means for converting the signal outputted from the differential receiver into a digital signal value, the A/D conversion means being configured to operate with a predetermined sampling period; a second digital filter that allows only a predetermined frequency band of a digital data stream that has been obtained by sampling with the A/D conversion means, to pass; and a level evaluation means (250, 260; 510, 520) for evaluating a symbol value from the level of the digital signal value on the basis of the output from the second digital filter and converting the symbol value into corresponding digital data, wherein the second digital filter has low-pass characteristics, wherein the second digital filter has transmission characteristics such that, in use in combination with the first digital filter, the first and second digital filters (130, 240) together exhibit roll-off characteristics for a signal that is passed through said first digital filter and the second digital filter, and wherein the frequency characteristics of the first and second digital filters (130, 240) are set such that the combined characteristics of the first and second digital filters (130, 240) have roll-off characteristics relative to half of the symbol rate. a data coding means (110, 120) for (i) converting digital data arriving during each of a plurality of successive symbol periods, into a respective symbol value representing the digital data for the duration of the respective symbol period, and (ii) converting the symbol value into a signal level, the data coding means being operative such that there is change in signal level between consecutive symbol periods whether or not the digital data changes; a first digital filter configured to operate with a first sampling cycle that is shorter than said symbol period, and allows only predetermined frequencies of the output from the data coding means to pass; a D/A conversion means for converting the digital data stream that has passed through the first digital filter, into an analogue signal; a low-pass filter for eliminating, from the analogue signal obtained by the D/A conversion means, frequencies at least twice as high as the frequencies that have passed through the first digital filter; and a differential driver for converting an output from the low-pass filter, into two signals having opposite polarities relative to a predetermined reference potential, and inputting the two signals into a twisted pair cable, a differential receiver for receiving transmission signals transmitted through a twisted pair cable, and converting a difference in potentials between two wires of the cable into a signal; an A/D conversion means for converting the signal outputted from the differential receiver into a digital signal value, the A/D conversion means being configured to operate with a predetermined sampling period; a second digital filter that allows only a predetermined frequency band of a digital data stream that has been obtained by sampling with the A/D conversion means, to pass; and a level evaluation means (250, 260; 510, 520) for evaluating a symbol value from the level of the digital signal value on the basis of the output from the second digital filter and converting the symbol value into corresponding digital data,