System for controlling signal level at both ends of a transmission link, based upon a detected value

A dynamic range enhancing system for enhancing performance of a digital transmission link by controlling a transmit signal adapted to be transmitted over said digital transmission link within a communication path, said digital transmission link extending from a first location to a second location remote from the first location, said system comprising:

• control means for detecting, at an initial position along the communication path, a level of the transmit signal, and for controlling first signal level adjusting means and second signal level adjusting means in response to the detected level;
• said first signal level adjusting means comprising means for adjusting the signal level of said transmit signal before transmission over said digital link, and said second signal level adjusting means comprising means for adjusting the level of said transmit signal after transmission over said digital link, said control means controlling said first and second signal level adjusting means to adjust the signal level of said transmit signal in a coordinated fashion based on the detected level;
• said first and second signal level adjusting means respectively comprising first and second outputs and means for adjusting the level of the transmit signal present at said first and second outputs;
• and
• said control means comprising means for controlling said first and second signal level adjusting means so that:
• the transmit signal level is decreased at the first output and increased at the second output when the detected transmit signal level increases, and
• the transmit signal level is increased at the first output and decreased at the second output when the detected transmit signal level decreases.

A dynamic range enhancing system for enhancing performance of a transmission link by controlling a transmit signal to be transmitted along a communication path comprising said transmission link, said transmission link extending from a first location to a second location remote from said first location, said system comprising:

• a pre-processing unit, provided at said first location, that receives, as input, said transmit signal, said pre-processing unit comprising a first signal level changing device which changes a signal level of said transmit signal to be transmitted over said transmission link, and a transmitter which transmits said adjusted transmit signal over said transmission link;
• and
• a post-processing unit provided at said second location that receives, as input, said adjusted transmit signal transmitted over said communication link, said post-processing unit comprising a second signal level changing device which changes a signal level of said adjusted transmit signal transmitted over said transmission link, and a controller which controls said first signal level changing device and said second signal level changing device, such that the overall system gain is substantially constant, said controller comprising:
• a detector which detects the signal level of said transmit signal at an input of said pre-processing unit;
• a first generating device which generates a first control signal for controlling said first signal level changing device based on the signal level detected by said detector;
• a second generating device which generates a second control signal which controls said second signal level changing device based on the signal level detected by said detector, said second control signal comprising a constant amplitude signal;
• a signal combiner which combines said transmit signal and said second control signal before said transmit signal has been adjusted by said first signal level changing device, wherein said transmitter transmits said second control signal with said adjusted transmit signal over said transmission link to said post-processing unit.