Optical differential delay tester

A device for measuring the difference in cable length comprising:

• a transmitter in a first location, having a first laser optically connected to a first end of a first cable and a second laser optically connected to a first end of a second cable;
• a receiver in a second location, having a first optical receiver optically connected to a second end of a first cable and a second optical receiver optically connected to a second end of a second cable;
• and
• a microprocessor responsive to executable instructions when executed on the microprocessor for calculating a differential delay between the first cable and the second cable in response to a travel time of a first light pulse along the first cable and a travel time of a second light pulse along the second cable,
• wherein the differential delay is first measured in cycles by the microprocessor and is then converted to a time.

A computer data system comprising:

• a first data center at a first location;
• a second data center at a second location;
• a first fiber optic cable coupled between the first data center and the second data center to transmit first data from the first data center to the second data center;
• a second fiber optic cable coupled between the second data center and the first data center to transmit second data from the second data center to the first data center;
• and
• a device for measuring a differential delay between the first fiber optic cable and the second fiber optic cable, the device having a transmitter associated with the first data center wherein a first laser is optically connected to a first end of the first fiber optic cable and a second laser is optically connected to a first end of the second fiber optic cable, the device also having a receiver associated with the second data center wherein a first optical receiver is optically connected to a second end of the first fiber optic cable and a second optical receiver is optically connected to a second end of the second fiber optic cable, the receiver having a microprocessor responsive to executable instructions when executed on the microprocessor for calculating the differential delay between the first fiber optic cable and the second fiber optic cable in response to a travel time of a first light pulse along the first fiber optic cable and a travel time of a second light pulse along the second fiber optic cable, wherein the differential delay is first measured in cycles by the microprocessor and is then converted to a time.