Olson Technology OTPN-400C - Manual (Page 5)

is lowered, the RF input level to the transmitter can be raised. This results in
increased RF levels at the OTPN receiver and improves the carrier-to-noise ratio
over the link. Links should be designed and transmitters should be set up using
values that represent the maximum number of channels likely to be carried.
Chart 1 assumes approximately 77 channels from 50MHz to 550MHz and digital
loading from 550MHz to 1,000MHz at -6dB.
-8dBm 0.16V +14dBmV
-6dBm 0.25V +18dBmV
-4dBm 0.40V +22dBmV
-2dBm 0.63V +26dBmV
-1dBm 0.79V +28dBmV
0dBm 1.00V +30dBmV
Although the node will operate at optical input levels as high as +0dBm, there is
little improvement in the CNR performance of the node at optical input levels
above 0dBm. For optimum distortion performance it is recommended that the
optical input to the node be kept at or below -1dBm. At -1dBm, the DC test point
voltage will be 0.79 Volts.
Unlike many optical nodes, the OTPN-400C is designed to perform down to an
optical input of -8dBm. Figure 2 shows the approximate CNR performance at
various receiver optical input levels and transmitter equivalent RF channel
loading. This performance may vary considerably depending upon fiber and laser
performance so it is presented as a design aid only.
Chart 1 - Test Point Voltage and RF Output Level vs. Optical Input
Optical Input Received Power TP Approx. RF Output Level