Change in channels
 

Recently my connection seems to have changed to 24 d/s channels and 4 u/s. Previously I was on 20 d/s 4 u/s, the latter was on 3 channels being 64qam and one 16qam.

Now the upstream modulation has changed to 16qam for all 4 channels, downstream albeit now with 24 is still 256qam.

I am wondering whether the changes to the upstream are better or worse?

I am connected to the Baguley range of UBRs, which I think will sooner or later be undergoing trials for possible future service options (going by the trialist signup at VM forums).

Anyone else had the same?

Re: Change in channels
 

@ Aye Up.

I am also under Baguley and now have 24 256qam downstream channels but my 4 upstream channels are 64 qam.

I have recently been invited to apply to be a trialist but not heard what for.

Re: Change in channels
 

your downstreams will always be qam256, they have been for years and need to be for the throughput. You will never see them drop to qam128. Keep an eye on your upstream channels, qam64 is better than qam16 (by 50%) and having qam16 on 4 channels is by no means the end of the world. It is possible you have been moved to a new bonding group (you would need to look at the channel numbers) or more than likely there is some noise on the line and if you check back tomorrow or the day after they will revert to qam64.

Re: Change in channels
 

As far as I know, when it comes to increasing bandwidth Virgin effectively has two choices:

1) Add more channels
2) Make existing channels "better" (cleaner signal)

It's not always cut and dry as to which choice is "better" as it can vary widely depending on what infrastructure currently exists in that area.

Re: Change in channels
 

I am still on 8 d/s 256 QAM channels and 4 u/s 16 QAM
why such a big difference?
My 200 is rock steady

Re: Change in channels
 

Have you got a shub 1 or 2?

Re: Change in channels
 

2 ac

Re: Change in channels
 

channels operate in bonding groups and you will have at least 16 channels in your bonding group for your area and probably 20. The problem is that shubs 1 and 2 can only use 8 downstream channels and 4 upstreams. It is to do with the limitations of the hardware and demands at the time. As an example, my first modem I had with VM back in 2001 could only use 1 channel which was more than sufficient for 512k, I think the second one could use 2 and then ambit 300 when I was on 50mbits could use 4.

In your case, at any one time you will use 8 of the 20 ish channels available. If for example your bonding group consists of channels 120-139, you might be using channels 120-127 now and if you reboot your shub you can move to 131-139 or a random mix of in between. I was the same pre-August when I was on 200mbits with a shub2 and I never had any problems getting full speed. It was only when I got a shub 3 that I realised there were 20 channels in my group and that increased to 24 last week.

Re: Change in channels
 

Thanks for that

Re: Change in channels
 

Same for me here in Timperley (so Baguely headend also):

1 298750000 0.5 40 256 qam 21
2 322750000 0 40 256 qam 24
3 314750000 0.2 40 256 qam 23
4 306750000 0.5 40 256 qam 22
5 290750000 0.2 40 256 qam 20
6 282750000 0.2 40 256 qam 19
7 274750000 0 40 256 qam 18
8 266750000 0.2 40 256 qam 17
9 258750000 0.2 40 256 qam 16
10 250750000 0.4 40 256 qam 15
11 242750000 0.4 40 256 qam 14
12 234750000 0.2 40 256 qam 13
13 226750000 0 40 256 qam 12
14 218750000 0 40 256 qam 11
15 210750000 0 40 256 qam 10
16 202750000 0.2 40 256 qam 9
17 194750000 0.4 40 256 qam 8
18 186750000 0.5 40 256 qam 7
19 178750000 0.2 40 256 qam 6
20 170750000 0.2 40 256 qam 5
21 162750000 0 40 256 qam 4
22 154750000 -0.2 40 256 qam 3
23 146750000 -0.2 40 256 qam 2
24 138750000 0 40 256 qam 1

1 25800000 44 5120 16 qam 12
2 32600000 44 5120 16 qam 11
3 39400000 44 5120 16 qam 10
4 46200000 44 5120 16 qam 9

JG

Re: Change in channels
 

I am literally round thee corner from you in Brooklands :wavey:

Still on 16qam for upload though.

Re: Change in channels
 

Just checked and I'm on 24 channels too. Probably have been on 24 channels when the .603 firmware was downloaded, but my downstream has a lot of "Pre RS Errors" errors. What does that mean?

Also, yesterday I could barely get 5-10mbit when it should be close to 390mbit and upload was barely 1-3mbit. There was some T3 timeouts too. It was weird so I left it and checked today and it seems fine now.

1 323000000 3 34 256 qam 24
2 315000000 3 35 256 qam 23
3 299000000 3.5 35 256 qam 21
4 291000000 3.7 35 256 qam 20
5 283000000 3.9 35 256 qam 19
6 275000000 4 36 256 qam 18
7 267000000 4.3 36 256 qam 17
8 251000000 4.5 35 256 qam 15
9 243000000 4.6 36 256 qam 14
10 227000000 5.4 36 256 qam 12
11 219000000 5.5 36 256 qam 11
12 307000000 3.2 35 256 qam 22
13 259000000 4.4 36 256 qam 16
14 235000000 5 36 256 qam 13
15 211000000 5.9 36 256 qam 10
16 203000000 6 36 256 qam 9
17 195000000 6.5 37 256 qam 8
18 187000000 6.6 36 256 qam 7
19 179000000 7 37 256 qam 6
20 171000000 7.5 37 256 qam 5
21 163000000 8.1 37 256 qam 4
22 155000000 8.8 36 256 qam 3
23 147000000 9.1 37 256 qam 2
24 139000000 9.4 37 256 qam 1

1 Locked 34.9 364582 0
2 Locked 35 291739 0
3 Locked 35 179101 0
4 Locked 35.5 134333 0
5 Locked 35.5 105005 0
6 Locked 36.6 72075 0
7 Locked 36.3 58855 0
8 Locked 35.7 38885 0
9 Locked 36.3 31530 0
10 Locked 36.3 22722 0
11 Locked 36.3 20335 0
12 Locked 35 218938 0
13 Locked 36.3 49514 0
14 Locked 36.3 27980 0
15 Locked 36.6 15600 0
16 Locked 36.6 13233 0
17 Locked 37.3 10484 0
18 Locked 36.6 8570 0
19 Locked 37.3 6398 0
20 Locked 37.3 4290 0
21 Locked 37.3 4248 0
22 Locked 36.3 1347 0
23 Locked 37 499 0
24 Locked 37.6 130 0

1 25800000 41.8 5120 32 qam 84
2 39400000 42.5 5120 64 qam 82

1 ATDMA 0 0 0 0
2 ATDMA 0 0 0 0

Re: Change in channels
 

RS stands for reed Solomon and is a coding that includes strong error checking and correction. The initial connection negotiation is done without this encoding so on occasion errors occur. So long as there are no post RS errors the connection is sound.