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Re: What do you do to improve snr.

Hey Joe -

We hit our returns with 21dB @ reference level, however our modems hit at 16dB. We hit our CMTS +5dB rather than 0dB and we are using  1QPSK and 1QAM64. We see on the average 30-33dB upstream MER that the CMTS reports.

The other factor that we don't know when answering his question is how many nodes are being combined to 1 upstream port. If they are doing 3-8 nodes on one port you won't see high upstream MER reading, because of the funnel affect. We typically go 1upstream per node and over the past year moved to half of a node per upstream by segmentation. 

I agree with you on hitting the return @ anything higher than 17dB you could be asking for problems. I think there is confusion on modem TX level vs reference level. I guess it depends on which MSO you are working for too, since the plant managers have different ideas on how to optimize the return.



Another interesting article I read about analog DFB lasers vs digital returns back to headend/hub and DOCSIS3 channel bonding.

http://www.cable360.net/ct/news/ctreports/commentary/Why-DFB-Lasers-May-Be-Insufficient-in-DOCSIS-3-0-Upstreams_42451.html
This is CABL.com posting #313742. Tiny Link: cabl.co/mbtMw
Posted in reply to: Re: What do you do to improve snr. by Joe50
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