Digital transmission apparatus

A digital transmission apparatus having a base unit for receiving n-bit digital signals from a plurality of (N) remote units, synthesizing said digital signals, and transmitting the digital synthesized signals,

• wherein said base unit comprises:
• a plurality of (N) bit extending units each for extending the digital signal from each of said remote units from n bits to (n+log2N) bits;
• an adding unit for adding signals from said bit extending units;
• a gain arithmetic operating unit for executing an arithmetic operation of (2n−1−1)/|addition result| by using an addition result added by said adding unit, setting the arithmetic operation result into a gain coefficient when an arithmetic operation result is smaller than “1”, and setting “1” into the gain coefficient when said arithmetic operation result is equal to or larger than “1”;
• a multiplying unit for multiplying said addition result by the gain coefficient obtained by said gain arithmetic operating unit;
• a bit contracting unit for discarding upper log2N bits excluding a sign bit with respect to data multiplied by said multiplying unit and returning the data to n bits;
• a D/A converting unit for converting a signal from said bit contracting unit from the digital signal into an analog signal;
• and
• a wireless unit for frequency converting the signal from said D/A converting unit and amplifying the frequency converted signal.