power limits

[markie1966]

guys...whats the upper power limit for downstream channels these days for the superhub?

ive been keeping an eye on mine the last month aand its slowly rising...its ranging between 11.9dBmV to 12.4dBmV on the 5 downstream channels in modem mode

funnily enough the connection seems stable for surfing...downloads and playing games

any reason for concern or should i get a 10dB fpa from ebay?

[Sephiroth]

You should get a 10 dB FPA from ebay in order to remove worry.

The DOCSIS spec says the SH should be able to perform OK at between -13 & +17 dBmv. I've seen some on forums that perform just about down at the -12 level and a few that work OK at the +11/12 dBmv level.

If you had 8 downstream channels (which I believe is coming with 200 meg), then anything above 10 dBmv would bust the total input power lijit of the modem.

But cheap components speak a greater truth, IMO, than the DOCSIS spec. So, VM recommend an optimal power range of -3 to +7 dBmv.

[markie1966]

cheers seph :)

[General Maximus]

But cheap components speak a greater truth, IMO, than the DOCSIS spec. So, VM recommend an optimal power range of -3 to +7 dBmv.

and bearing that in mind I would make a phone call because if anything above 7 is unacceptable for VM then they will want to get it looked at

[Nopanic]

Why would you buy anything ? Get a tech out to drop it .. You could technically be charged £70 if a tech comes out and a fault is caused by equipment you have purchased and added the the network ..

[Ignitionnet]

if you had 8 downstream channels (which i believe is coming with 200 meg), then anything above 10 dbmv would bust the total input power lijit of the modem.

10 + 3 + 3 + 3 = > 33 ?

[Sephiroth]

11+3+3+3+3+3+3+3 -> 33

[Ignitionnet]

11+3+3+3+3+3+3+3 -> 33

I see.

You add 3 each time you double the bandwidth, not each time you add a channel.

[Sephiroth]

Oh yeah. I forgot that basic principle. Demn.

[Ignitionnet]

Oddly my service is running just fine despite the below:

Downstream Channels
Lock Status Modulation Channel ID Max Raw Bit Rate Frequency Power SNR Docsis/EuroDocsis locked
Locked QAM256 74 55616000 Kbits/sec 307000000 Hz 17.8 dBmV 41.7 dB Hybrid
Locked QAM256 73 55616000 Kbits/sec 299000000 Hz 18.0 dBmV 41.9 dB Hybrid
Locked QAM256 75 55616000 Kbits/sec 315000000 Hz 17.3 dBmV 41.9 dB Hybrid
Locked QAM256 76 55616000 Kbits/sec 323000000 Hz 16.9 dBmV 41.4 dB Hybrid

[craigj2k12]

the superhub copes with higher levels, mine runs at 16db without the attenuator, and with the exception of a few disconnections, it copes fine. obviously i keep the attenuator on though

[RB2004]

Why would you buy anything ? Get a tech out to drop it .. You could technically be charged £70 if a tech comes out and a fault is caused by equipment you have purchased and added the the network ..

From past experience sometimes its hard to get a tech to do anything usefull.

The techs on here, are the most helpfull ive come accross so thank you all of you who have helped me previously, and apoligies when ive criticised engineers.. it is aimed at the lack of trust I have with those visiting my house.. not those online who have been great :)

But the ones who came to my house when I had signal problems either fobbed me off with excuses and lied to me, or did nothing.

If it wasnt for me buying my own equipment (which is exactly the same stuff VM use anyway) and the help I recieved from the engineers here online. I would not of been able to resolve my signal problems... that tied with persistence constantly reporting a fault getting 1 engineer down after the next.

I had signal levels of -6 on the superhub, occasionally dropping to -7 but engineers wouldnt do anything about it. As they kept tellling me it was perfectly acceptable.

But since I increased my levels to +2 ive noticed a more reliable service, and no errors logged on the superhub.

So have to agree with the spec that has been posted in various places -3 to +7 is the spec that should be accepted as being the most optimal. Despite what is on paper, as what is on paper is in a perfect scenario using good quality components in perfect conditions. In reality they may not necessarily apply.

As like in my case, even with a working service of -6 I was recieving lots of errors in the superhub and previously VMNG300 log, and fluctuating internet speeds... which seem to of dissappeared now, with a more consistent speed.. especially since the new VM configuration file always get 100+ Mbit now :)

Although the latter could of also been a line card upgrade as my downstream channel ID numbers went from in the 70 or 80 range, to the 190 range. Although still have 4 channels.

But back on topic, that is why I feel now sometimes.. waiting aside also, it is the only way to get things resolved.. despite being against vm terms and conditions. So as long as it is done properly thats the most important thing.