On Sun, May 24, 2020 at 11:27:57PM +0200, Pavel Machek wrote: > > > The SNR seems to be most universal value, when it comes to comparing > > > different situations (different links and different PHYs). The > > > resolution of BER is not that detailed, for the NXP PHY is says only > > > "BER below 1e-10" or not. > > > > The point I was trying to make is that SQI is intentionally called SQI and > > NOT SNR, because it is not a measure for SNR. The standard only suggest a > > mapping of SNR to SQI, but vendors do not need to comply to that or report > > that. The only mandatory requirement is linking to BER. BER is also what > > would be required by a user, as this is the metric that determines what > > happens to your traffic, not the SNR. > > > > So when it comes to KAPI parameters, I see the following options > > - SQI only > > - SQI + plus indication of SQI level at which BER<10^-10 (this is the only > > required and standardized information) > > - SQI + BER range (best for users, but requires input from the silicon > > vendors) > > Last option looks best to me... and it will mean that hopefully silicon > vendors standartize > something in future.
It already has been for > 1G PHYs, but whether they implement it is another question altogether. It's a 22-bit limiting counter in the PCS. There's also indications of "high BER". -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC for 0.8m (est. 1762m) line in suburbia: sync at 13.1Mbps down 424kbps up
