Grass Valley 3050 CopperHead - Manual (Page 60)

54
Operation of the System
Using Digital Displays
Using Digital Displays
Measuring Fiber Optic Signal Strength
The decibel (dB) is a logarithmic unit of measurement that expresses the magnitude of a
physical quantity (usually power or intensity) relative to a specified or implied reference
level. Since it expresses a ratio of two quantities with the same unit, it is a dimensionless,
relative unit. A decibel is one tenth of a bel, a seldom-used unit. Typically dB has been
employed in Audio Measurement and Fiber Optics among many uses.
Proper measurement of signal strength requires an absolute measurement and the dBm
provides this measurement. Since it is referenced to the milliwatt, it is an absolute unit,
used when measuring absolute power. By comparison, the decibel (dB) is used for
quantifying the ratio between two values, such as signal-to-noise ratio
The CopperHead 3050 Transceiver System operates within a defined range of Fiber Optic
Link signal strength. The minimum recommended signal strength is -22 dBm or better.
Typically the system should operate at levels between -8 dBm and -20 dBm. The standard
CopperHead 3050 laser output strength is -6 dBm. Cable length affects signal strength as
does the number of connections between the Camera Unit and the Base Station. For
example, using a Power Supply such as the MPS or HDX produces a minimal signal loss
through each connection.
The digital readouts on both the CopperHead 3050 Base Station and Camera Unit provide
direct signal strength measurements in dBm. These readouts also provide a wide range of
diagnostic information (below).
The CopperHead 3050 Base Station Digital Display
The Base Station digital display has three functions selected by the Display Mode Selector
(see #14 on the diagram in
CopperHead 3050 Transceiver System Base Station Back Panel
on page 83). These functions are indicated by the Display Mode LEDs.
• BASE RX – Base Station Optical Power or Signal Strength that is being received at the
Base Station. Displayed in units of –dBm. The acceptable range for operation is -7dBm
down to -22dBm. *
• CAM RX – Optical Power or Signal Strength being received at the Camera Unit.
Displayed in units of –dBm. The acceptable range for operation is -7dBm down to -
22dBm. *
• DIAG – One of four diagnostics modes:
• TEMP – displays operating temperature in degrees Centigrade of each circuit board
that reports temperature
• POWR – displays power level from monitored circuit boards
• REV – displays microcontroller firmware version from each circuit board with a
microcontroller
• CAM – displays the error status reported by the Camera Unit
To select the different display modes, push the Display Mode Selector. The transition from
one mode to another may take a moment with the transition into the Diagnostic mode
taking slightly longer. The Selector is cyclical rotating through each of the modes. Once in