Olson Technology OTPN-MDN-870 - Manual (Page 9)

025-000556 Rev X4 31 Aug 2011 Page 9 of 11
2.2.2 RF Equalization Update Mode
When the unit is in the equalization update mode (the EQ: text will be flashing once per second), the UP and DOWN push
buttons will toggle the unit between the FLAT
and TILT modes. In FLAT mode, the RF output will be flat versus frequency
(assuming that the RF into the optical transmitter was flat). In the TILT mode, the RF output will be tilted upward by 10dB
over the full receiver bandwidth (again, assuming that the RF into the optical transmitter was flat).
2.2.3 RF Attenuation Adjust Mode
When the unit is in attenuation adjust mode (the ATN: text will flash once per second), the UP and DOWN push buttons are
used to adjust the internal digital RF attenuation. It may range from 0dB to 31dB. Each push of the UP and DOWN push but-
tons will increment or decrement the numerical value by one. Once a value of 0dB is reached, further pushes of the DOWN
button will cause the display to show MIN for two seconds. Once a value of 31dB is reached, further pushes of the UP button
will cause the display to show MAX for two seconds.
2.3 Optical Status LED
The optical status LED indicates the general status of the OTPN-MDN-870 Mini Digital Node. The presence of any color light
indicates that the unit is powered. If the light into the OTPN-MDN-870 Mini Digital Node exceeds +4.5dBm, the LED will turn
red, indicating that excessive optical power is being applied to the optical input. If the light into the OTPN-MDN-870 Mini
Digital Node is less than -8.0dBm, the LED will turn yellow indicating that insufficient light is being applied to the optical in-
put. If the light into the OTPN-MDN-870 Mini Digital Node is greater than or equal to -8.0dBm and less than or equal to
+4.5dBm, the LED will be green, indicating that the optical input is within the optimum range. Each transition has a hysteresis
of 0.2dB.
2.4 Measuring RF Input Levels at the Transmitter
Excessive RF input to a fiber optic CATV transmitter WILL destroy the laser even if the unit is not powered. Lasers can be
quickly destroyed by being overdriven. Therefore it is imperative that the RF level be within acceptable limits BEFORE the ca-
ble is attached to the transmitter. See the transmitter Data Sheet for the proper RF input level, and adjust as follows:
1) Using a spectrum analyzer, determine that the RF level input to the transmitter is within safety bounds.
2.5 Performance Verification
No user maintenance is required. The OTPN-MDN-870 Mini Digital Node CATV receiver contains no user-serviceable parts and
requires no routine service. Contact the factory if the unit requires warranty repair work. Once the units have been installed,
verify that the picture quality is good. If the picture quality is not good, there are several likely causes:
1) The optical fiber may have large back reflections. Use an OTDR to examine the fiber run.
2) There may be non-APC optical connectors somewhere in the system. These cause unacceptable levels of back reflection.
3) The RF input spectrum may not be flat. All Olson CATV products are designed to operate with a flat input spectrum.
4) There may be extraneous (i.e., non-video) signals in the input RF. Be sure to filter out all non-desirable signals.
5) The optical input power at the receiver may be too low. In this case, the optical status LED will be yellow. See the data
sheet for the expected CNR versus the channel loading and received optical power.