30M : My Stats and PM from Virgin

[pip08456]

Originally Posted by jb66

Probably because as I've been saying for years, a high downstream rarely causes an issue, it's the upstream that's the most important

Most houses that I go to when I swap a modem has a downstream of 10 etc. They all say worked fine for years

Yet there were a lot of VMNG300s that couldn't lock on above 7dB.

Yours look sweet now Diesel!

[Sephiroth]

Originally Posted by Masque

We get more issues above 11 thats why.

What's the formal spec for the SH in terms of max/min levels that make for intelligible communication?

[pip08456]

Originally Posted by Sephiroth

What's the formal spec for the SH in terms of max/min levels that make for intelligible communication?

Don't have one!

[craigj2k12]

mine was working.... alright-ish on 15db. it was cutting out about 4 times a day and speeds fluctuating, but a usable service

[Sephiroth]

Originally Posted by pip08456

Don't have one!

Not you. Masque.

[pip08456]

Originally Posted by Sephiroth

Not you. Masque.

You missed the point there Seph!

The formal spec for the SH which is easily understandable is Don't have one!!!!!!!!

[craigj2k12]

the spec for the superhub is

Downstream: VMNG
Upstream: 300

[Sephiroth]

Look - Simples. I'm asking Masque for a more scientific basis rather than observations.

For example, DOCSIS 3, states that a single DS 256QAM channel must be in the range -13 to +17 dBmv but that the total input power must be < 33 dBmv.

Upstream ATDMA, single channel 5120 Ksyms/sec in the range 23 dBmv to 56 dBmv.

Now we all know that modems are not that tolerant on the downstream side because of the aggregated power exceeding 33 dBmv. So is it that 11 dBmv is on average true for 3 channel systems but 8.25 dBmv is true for 4 channel systems?

[Sephiroth]

Has Masque got a view on on the SH's performance against the DOCSIS spec in the light of my analysis?

[Peter_]

We find that downstream now should not be above 11dBmv and not really below -7dBmv

The hubs seem to prefer to be below 8dBmv 0n the downstream though.

Upstream anything above 55dBmv can cause an issue.

With regards to upstream the Motorola BSR's do not show higher than 58.2dBmv whereas the Cisco uBR's can show a maximum of 61dBmv

[borrissey]

tartup Procedure
Procedure Status Comment
Acquire Downstream Channel 315000000 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 QAM256 87 55616000 Kbits/sec 315000000 Hz -5.0 dBmV 37.5 dB Hybrid
Locked QAM256 85 55616000 Kbits/sec 299000000 Hz -4.6 dBmV 38.0 dB Hybrid
Locked QAM256 86 55616000 Kbits/sec 307000000 Hz -4.7 dBmV 37.9 dB Hybrid
Locked QAM256 88 55616000 Kbits/sec 323000000 Hz -5.7 dBmV 37.5 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 3 20480 Kbits/sec 45800000 Hz 54.9 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 6003
Max Traffic Rate 102400000 bps
Max Traffic Burst 10000 bytes
Mix Traffic Rate 0 bps
Primary Upstream Service Flow
Upstream(0)
SFID 5602
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:Thu Jun 02 20:31:59 2011

Are mine ok?

Cheers.

[Peter_]

Originally Posted by borrissey

Are mine ok?

Cheers.

If it is running fine then the is nothing to worry about but I would keep an eye on the upstream.

[Sephiroth]

@ borrissey

You can't fault Masque for saying the near equivalent of if it aint broke don't fix it.

But there's an attenuation struggle happening there. The downstream is low (attenuated) and the upstream very high (to push through the attenuation).

Something's not good. We can't see the codewords corruption on the hub stats so don't know what's really happening. 2nd line can see what's happening or if the line's flapping. There would seem to be a common cause impairment - like you could do with a re-pull or something's not screwed in properly.

I wouldn't like these power levels and I wouldn't expect performance to be brilliant.

[Peter_]

Originally Posted by Sephiroth

@ borrissey

You can't fault Masque for saying the near equivalent of if it aint broke don't fix it.



I wouldn't like these power levels and I wouldn't expect performance to be brilliant.

They are not perfect and if the s an issue you would ring up but if it is running fine then you can leave it alone, I already said above that above 55 causes issues and this is borderline.

I would run checks with him if I took the call and if required book an engineer, but as I am not on the phone s we can only give generic advice.

[pip08456]

Originally Posted by Masque

We find that downstream now should not be above 11dBmv and not really below -7dBmv

The hubs seem to prefer to be below 8dBmv 0n the downstream though.

Upstream anything above 55dBmv can cause an issue.

With regards to upstream the Motorola BSR's do not show higher than 58.2dBmv whereas the Cisco uBR's can show a maximum of 61dBmv

If the hub prefers to be less than 8dB downstream and we know the VMNG300 doesn't like above 7dB downstream what is the rationale for 11dB being acceptable?