70M How to change downstream channel ID?

JPAC · 17-08-2018, 13:37

Major Pre and post RS errors. Currently on Ch 1-8, seems better on 9-16. How to change downstream channel ID? Tried switching CM off 30 mins and back on again, no difference.

Sephiroth · 17-08-2018, 16:03

Always best to post the downstream and upstream stats in full.

Your locale and thus your modem will be on a given set of downstream channels although VM can change that back at their end. You should check with your neighbours. If they have the same, then there is an area fault which VM will deal with when reported.

JPAC · 17-08-2018, 17:43

Over time I've noticed the DS Ch ID changes and 9-16 have the least errors.
These are over a couple of hours, but usually have millions of errors, both pre and post.

Sephiroth · 17-08-2018, 18:05

I can only comment on what I see in the stats right now.

The power levels are exemplary and the SNR (RxMER) is better than just satisfactory.

What I've seen in the RS-Error data is that the Post-RS Errors are almost certainly down to what happens when you reboot the modem. For the initial moments, it is in a chaotic state where unsynchronised data enters the modem and, if, unintelligible, yield Post-RS Errors.

As to the millions, you'd need to catch that and post the stats again. The ones you've posted are channels 1-8 and they are excellent. If you see 9-16 in the stats, then VM have changed them because there were SNR problems on 1-8 (or at least parts of that range); but it's not common for changes like that to occur.

Another point of interest to nerds like me, your current channels are at a lowish end of the downstream frequency spectrum. The lower frequencies are more noise prone than the higher frequencies. Provided that VM have cleaned up their cabinets and amplifiers, then those channels should not be problematic.

HTH.

JPAC · 17-08-2018, 18:16

All points noted thanks. I've reset the counters, see what happens next. I saw on some days the BQM had several red zones, don't know if this matters.

Sephiroth · 17-08-2018, 18:22

The red zones on the BQM are likely to have been outages. If VM induced, that might be when the DS channels change.