Grass Valley CopperHead Pro User Manual
Page 67
61
A Brief Guide to Measurement of Fiber Optic Signal Strength
A Brief Guide to Measurement of Fiber Optic Signal Strength
The CopperHead Pro operates within a defined fiber optic link margin, based on two
factors:
• Output (or "launch") power of the optical transmitter at each end of the link: typically -
7dBm* (pronounced as "minus seven dee-bee-em").
• Sensitivity of the optical detector at each end of the link: typically -22 dBm.
Fig. A-4: CopperHead Fiber Optic Link Margin
The overall link margin (or dynamic range) of the CopperHead Pro system (the difference
between the transmitter's output power and the receiver's sensitivity) is typically 15dB.
That margin is consumed by two main factors:
• Optical loss over the length of the fiber cable: typically 0.5dB per kilometer
• Optical loss at connection points: typically 1 dB per connector
Therefore, a CopperHead Pro system can optimally work over 24 kilometers of cable
(spending 12 dB of the link budget), and three connectors (spending 3 dB of the budget).
However, adding additional devices, such as the HDX or MPS power supply, or the camera-
mounted PowerPlus will add connectors to the path, and therefore contribute additional
connector loss.
The "SDI" indicator at the CopperHead Pro Base Station lights Green when the measured
optical power at Base Station is -20dBm or better, which is the minimum power
requirement for 3.0 Gb/s SDI data. See
on page 53 for the optical power
requirement for your particular SDI data signal.
*The unit "dBm" is an abbreviation for the optical power measured in decibels referenced to
one milliwatt (mW).