Multichannel Optical Transport Network Time Domain Reflectometry Calibration

A system for controlling time delay in a multichannel optical transport network (OTN) transmission device using time delay reflectometry measurements, the system comprising:

• an Ix skew module having an input to accept an Ix signal from a pair of 2n-phase shift keying (2n-PSK) modulated signals, where n>1, the Ix skew module having a control port and an output to supply the Ix signal delayed in time in response to signals received at the control port;
• a Qx skew module having an input to accept an Qx signal from the pair of 2n-PSK modulated signals, the Qx skew module having a control port and an output to supply the Qx signal delayed in time in response to signals received at the control port;
• an Iy skew module having an input to accept an Iy signal from a pair of 2p-PSK modulated signals, where p>1, the Iy skew module having a control port and an output to supply the Iy signal delayed in time in response to signals received at the control port;
• a Qy skew module having an input to accept an Qy signal from the pair of 2p-PSK modulated signals, the Qy skew module having a control port and an output to supply the Qy signal delayed in time in response to signals received at the control port;
• a first time domain reflectometry (TDR) module having an input coupled to the delayed Ix signal for measuring signal reflections from an output port, and an output to supply an Ix reflection measurement signal;
• a second TDR module having an input coupled to the delayed Qx signal for measuring signal reflections from an output port, and an output to supply a Qx reflection measurement signal;
• a third TDR module having an input coupled to the delayed Iy signal for measuring signal reflections from an output port, and an output to supply an Iy reflection measurement signal;
• a fourth TDR module having an input coupled to the delayed Qy signal for measuring signal reflections from an output port, and an output to supply a Qy reflection measurement signal;
• and,
• a delay control module having an input to accept the Ix, Qx, Iy, and Qy reflection measurement signals, and an output to supply signals to the Ix, Qx, Iy, and Qy skew module control ports, the delay control module minimizing time delay differences in the signal reflections for the Ix, Qx, Iy, and Qy signals paths by adjusting time delay modules in each signal path.