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View Full Version : 100M dodgy 100meg upgrade


imaxtec
27-01-2012, 05:25
QAM64 wont support 100meg stable connection.looks like my 100mb connection linked with qam 64 which means i think my connection sever shared with 30 and 50 meg connection users in my area.

its complete rubbish

my connection upgraded from 50meg to 100meg

but i am only geting 35meg to 45meg all the time.its a complete cheat by virgin#

they should supply 100meg after the local infrastructure upgrade into 256QAM



i am getting this connection without any attenuator attached



A better question would be who thought it was smart to release 100Mbit in an area running on 64QAM.

There's less than 150Mbit/s available total for every device in this area sharing those 4 downstreams, in other words whenever the area is running at over 33% utilisation OP won't be able to get 100Mb.

Hopefully when this gets picked up on questions will be asked and the necessary work to get 256QAM running done sooner rather than later. This will increase the available bandwidth to a shade under 200Mbit and, if capacity is the problem, give OP his missing 50Mbit overnight.



Connection
Startup Procedure
Procedure Status Comment
Acquire Downstream Channel 435000000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Configuration File OK
Security Enabled BPI+
Downstream Channels
Lock Status Modulation Channel ID Max Raw Bit Rate Frequency Power SNR Docsis/EuroDocsis locked
Locked QAM64 236 41712000 Kbits/sec 435000000 Hz 5.7 dBmV 40.3 dB Hybrid
Locked QAM64 237 41712000 Kbits/sec 443000000 Hz 4.7 dBmV 39.4 dB Hybrid
Locked QAM64 238 41712000 Kbits/sec 451000000 Hz 4.1 dBmV 38.6 dB Hybrid
Locked QAM64 239 41712000 Kbits/sec 459000000 Hz 3.2 dBmV 37.6 dB Hybrid
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV 0.0 dB Unknown
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV 0.0 dB Unknown
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV 0.0 dB Unknown
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV 0.0 dB Unknown
Upstream Channels
Lock Status Modulation Channel ID Max Raw Bit Rate Frequency Power
Locked ATDMA 2 20480 Kbits/sec 35800000 Hz 44.0 dBmV
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV

Primary Downstream Service Flow
Downstream(0)
SFID 4264
Max Traffic Rate 110000000 bps
Max Traffic Burst 10000 bytes
Mix Traffic Rate 0 bps
Primary Upstream Service Flow
Upstream(0)
SFID 4263
Max Traffic Rate 10250000 bps
Max Traffic Burst 16320 bytes
Mix Traffic Rate 0 bps
Max Concatenated Burst 16320 bytes
Scheduling Type Best Effort
Current System Time:Fri Jan 27 04:14:14 2012

General Maximus
27-01-2012, 07:44
Power levels are fine but I'll be honest and admit that I don't understand the difference between QAM modulations and the impact it has on throughput (and I am too tired to read atm), we need Seph to grace us with some words of wisdom

Scratch that, I see you have already made another post which he has replied to, you don't need to start another thread dude.

qasdfdsaq
27-01-2012, 09:46
64-QAM = 6 bits per symbol, 256-QAM = 8 bits per symbol

8/6 = 25% extra data being transferred over the same period of time, = 25% more capacity.

General Maximus
27-01-2012, 15:28
But how do bits and symbols correspond to your overall throughput though and what is the 64 and 256 for?

qasdfdsaq
27-01-2012, 19:37
You have a channel, a channel transfers a fixed number of symbols per second, more data per symbol = more throughput.

64 and 256 are simply the size of the constellation required to carry X bits per symbol. Oversimplified, it means instead of each symbol being a 0 or 1, it can be anything from 0 to 63 (or 0 to 255).

General Maximus
27-01-2012, 20:35
why have symbols though? We know 8 bits make a byte etc and each channel runs at 55mbit (or whatever it is) so why are saying we have got a 55mbit/sec channel which is pressumably something like 7 million symbols per sec at 6 bits each. It is like introducing a new measure, instead of saying we have got a 55mbit channels, we have now got a 7megasymbol channel. I can remember Igni saying a while back that there was only a fraction of a difference in speed between QAM256 and 1024 so why the massive jump in numbers?

qasdfdsaq
28-01-2012, 05:05
Because that's how it works.

There's 256 different combinations any given sequence of 8 bits can take, there's 1024 different combinations any given sequence of 10 bits can take.

General Maximus
28-01-2012, 09:54
gotcha, which is why if we looked at QAM2048 we would only be looking at a 10% increase in soeed over QAM 1024 because it is 11bits per symbol and not 10?

qasdfdsaq
28-01-2012, 15:02
Yes.

General Maximus
28-01-2012, 15:17
Super, i just need to do some reading now to understand how symbols come into because i have always understood data to be transmitted as segments, packets, frames and bits and not segments, packets, framed, bits and symbols