## Methods of communication

### Binary signalling

#### ### Binary signalling using a single cable #### Here the transmission rate is determined by how fast the voltage (or other symbol type) can be varied on the channel, before the frequency content (as predicted by the Fourier Series expansion) is so high that the inevitable filtering of the channel attenuates and hence distorts too much of the signal. In other words, it is limited by the bandwidth of the link. |
#### ### Binary signalling using many parallel cables #### By using multiple cables, the throughput over the link can be increased in proportion to the number of cables (channels) used. Alternatively, the throughput can be maintained at that of the single binary link, allowing lower bandwidth (probably lower cost) links to be substituted. |