NTL power levels???

[Pana]

Hi guys,

ntl are coming out to increase the power on my cable line on wedensday.

i just wanted to know what power levels a "working" ntl line should have so they can't fob me off with any excuses this time.


cheers

[Chas]

Well my downstream power level is 13 dBmV with a Signal to Noise Ratio of 32 dB, upstream power level 37 dBmV and everything is running sweet.

Cheers,

Chas

[Pana]

is that a "sweet" sweet or a sweet sweet??? :)

is it running ok with those levels??

mine is signal to noise ratio is 27db,downstream is -15, upstream is 51?? yet i have packet loss,programs wont open(irc,icq etc) and net is slow.

[Edited by Pana on 16-01-2001 at 01:49 PM]

[Chas]

I tend to find sweet sweets clog up the cooling grilles on the modem;)

The only problems I've had are occasional "Connection timed out" messages when browsing, but it doesn't happen often enough for me to be unduly concerned and it's a bit slow logging onto IRC, but everything else is fine and fast.

[Davvo]

Chas can you tell me how you measured the power level? And at what frequencies? It's just that I am an NTL engineer and your figures don't seem to be in spec with the network.Normally the levels leaving the amplifiers in the cabinets are 128 mhz +40 db's and 544mhz are 50 db's giving a positive slope of 6-7 db's. The transport streams for digital are usually 10 db's lower than analogue. These are then passed to tap blocks which have set levels of attenuation, the lowest being 16 db and the highest 28 db. Therefore the highest output @544mhz would be 34 db and the lowest 22 db added to the attenuation caused by the cable to the customers house, which calculated @1.5 db per 10 m of cable. These figures match yours but an analogue stb only needs 5 to 8 db ( anymore or less causes bad pix and introduction of noise) and digital needs only - 3 db, more or less causes blocking and freezing. As for the upstream being 37 db the system is set up to provide a return path ( upstream @ 15 db) Let me know mate coz i would be quite interested to find out

Davvo

[ad]

davvo i hope your not the engineer coming out to sort me out, you were/are up too late. :) oh so am i.

[Davvo]

Sorry mate you mean up early, started work at 4 this maorning.Only another 9 hours to go:(

Davvo

[Chas]

Davvo, I obviously fooled you into thinking I actually knew what I was talking about ;), I just got the levels from http://192.168.100.1/signal.html., some Surfboard test site. Could you explain what you were getting at in slighlty simpler terms please:E.

Cheers,

Chas

[Edited by CHAS on 17-01-2001 at 11:08 AM]

[Bartflaster]

Well I just had NTL engineer round he told me power should be in range of -10 to +5 with 0 being optimum (they gotta sort my cable/junction box as mine currently -15).
And should be 30 db or better .. dunno if better is more or less tho !!

[Davvo]

I think the 30 db better is the SNR ( signal to noise ratio). This should be ideally 32 db.However the sytem was designed to work with an SNR of as low as 25 db. So by saying 32 db snr it allows for a little drift. Chas I will post the info you want but I need to condense it a bit.

Davvo

[Bartflaster]

OOO dear, so my 25db is not good either .. but its 4 or 5 better than b4 they came ... was 32/3 yesterday tho. :-(

[Pana]

i just had an engineer round as well. he asked what the problem was to which i replied packet loss,dl speeds,stablility. he said he had come to fix my tv connection. hehe

anyways he increased me powerlevels and i get 30snr,-3 down and 38 up. i now ping slightly higher :(
he said he could raise it more but it would affect my tv.

he said if it was no better or improved only slighty then they will come out again.