Optical transceivers (SFP's, optical transmitter-receiver) have a few important optical characteristics that dictate the amount of optical loss (aka insertion loss or attenuation) permitted between two (2) interconnected transceivers. These optical characteristics are:
- TX min launch power: minimum amount of light out of transmitter
- TX max launch power: maximum amount of light out of transmitter
- RX saturation level: maximum amount of light allowed into a receiver
- RX sensitivity level: minimum amount of light required into a receiver
In an Optigo Connect Spectra system, the transceivers are ONS-SX-SFP and ONS-CX-SFP. All communications happen between ONS-SX-SFP and ONS-CX-SFP. That is, ONS-CX-SFP never communicate directly to eachother.
To calculate the minimum required insertion loss, we look at the lower of the following pairing:
ONS-SX-SFP(TX_max_launch) - ONS-CX-SFP(RX_saturation) = 7.0dBm - -3.0dBm = 10.0dB
ONS-CX-SFP(TX_max_launch) - ONS-SX-SFP(RX_saturation) = 4.0dBm - -6.0dBm = 10.0dB
To calculate the maximum allowed insertion loss, we look at the lower of the following pairing:
ONS-SX-SFP(TX_min_launch) - ONS-CX-SFP(RX_sensitivity) = 2.5dBm - -27.0dBm = 29.5dB
ONS-CX-SFP(TX_min_launch) - ONS-SX-SFP(RX_sensitivity) = 0.0dBm - -30.0dBm = 30.0dB
Therefore the
Minimum insertion loss (attenuation): 10.0dB
Maximum insertion loss (attenuation): 29.5dB
Optigo Networks recommends the range to be [10dB — 26dB]. The margin is to account for unexpected air gaps, dirt, bends and other uncertainties.
The range of insertion loss can be used to split the light using Optigo's Passive Optical Splitters (ONS-Yx). Each splitter adds attenuation. The amount depends on the split ratios. The minimum insertion loss means ONS-SX-SFP and ONS-CX-SFP connect be directly connected (e.g. via a patch cable) without any splitter or attenuator.
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