Communication system for coexistent base band and broad band signals

A broad band communication system comprising:

• a plurality of information devices for performing broad band communication with each other connected to a transmission path along which modulated signals having a plurality of mutually different frequency ranges, each of said frequency ranges being previously allocated according to kinds of said information devices;
• a plurality of data processing units for performing base band communication with each other, each having means for outputting digital data in the form of a base band signal having a frequency range, a higher part of which is overlapped with one of said frequency ranges of said modulated signals;
• and
• a plurality of branch connecting means, each being provided for an associated one of said data processing units for connecting the associated data processing unit to said transmissional path,
• each of said branch connecting means including filter means for limiting the frequency range of the base band signal communicated between said associated data processing unit and said transmission path as being within a range outside of the frequency ranges of the broad band signal used by said information devices.

A communication network comprising:

• a transmission path;
• a plurality of first data processing units for performing base band communication with each other by outputting digital data onto said transmission path in the form of a base band signal,
• branch connecting means provided between each of said first data processing units and said transmission path for limiting the frequency range of said base band signal inputted/outputted to/from said first data processing unit to a frequency range not higher than a predetermined cut-off frequency, but passing the broad band signal through said transmission path;
• and
• a plurality of second data processing units for performing broad band communication by outputting data to be transmitted onto said transmission path after modulation to a predetermined frequency range which is higher than said cutoff frequency.
• whereby both said base band communication and said broad band communication are performed individually on said transmission path.