AT5000 1310 nm F3ST Optical Transmitter
Solutions Provider for FTTx, RFoG, and HFC
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The total RF analog input level depends on the number of analog channels in your system and
is identical for the type of system (NTSC, PAL, CENELEC) used. Use the following equation to
determine the optimum RF input level per channel when the rated channel loading is not
being used:
Analog Input Level (dBmV) = A+10log(N/M)+10log(W1/W2)
A: Manufacturer's recommended nominal drive level for optical transmitter/module;
N: The number of channels corresponding to A;
M: Actual number of loaded channels
W1: The bandwidth corresponding to A;
W2: The actual bandwidth
For example, if the product datasheet give the following parameters:
75 dBµv @ 59 PAL channels
If the customer actually has: 40 NTSC channels, the drive level will be:
Actual drive level=75+10log(59/40)+10log(8/7)=75+10*1.69+10*0.06=75+1.7+0.6=77.3(dBµV)
For digital channels, if the digital signal level is 6 dB lower than the analog signal level, then 4
digital channels are equal to 1 analog channel; If the digital signal level is 10 dB lower than the
analog signal level, then 10 digital channels are equal to 1 analog channel. In the actual
calculation, first calculate the number of digital channels as the number of analog channels,
and then use the above formula. For example, with 20 analog channels, 20 digital channels,
and with the digital channel being 6 dB lower than the analog channel level, then the total
number of channels is:
20 + 20/4 = 25 (channels)
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