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Signal Levels
Hi, ive been getting eratic speeds
and was told on the Virgin Media Community forum that my signal levels need sorting out, can anybody confirm? Thanks Connection -------------------------------------------------------------------------------- Startup Procedure Procedure Status Comment Acquire Downstream Channel 299000000 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 194 55616000 Kbits/sec 299000000 Hz -6.4 dBmV 38.8 dB Hybrid Locked QAM256 193 55616000 Kbits/sec 291000000 Hz -6.1 dBmV 38.3 dB Hybrid Locked QAM256 195 55616000 Kbits/sec 307000000 Hz -6.1 dBmV 39.0 dB Hybrid Locked QAM256 196 55616000 Kbits/sec 315000000 Hz -6.5 dBmV 38.5 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 1 20480 Kbits/sec 35800000 Hz 49.2 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 2224 Max Traffic Rate 102400000 bps Max Traffic Burst 10000 bytes Mix Traffic Rate 0 bps -------------------------------------------------------------------------------- Primary Upstream Service Flow Upstream(0) SFID 2223 Max Traffic Rate 10250000 bps Max Traffic Burst 16320 bytes Mix Traffic Rate 0 bps Max Concatenated Burst 16320 bytes Scheduling Type Best Effort Also got these errors, Event Log -------------------------------------------------------------------------------- Time Priority Description Sat Aug 27 23:18:09 2011 Critical (3) No UCDs Received - Timeout;;CM-MAC=a0:21:b7:22:3b:a8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; Sat Aug 27 23:17:50 2011 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=a0:21:b7:22:3b:a8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; Sat Aug 27 23:16:38 2011 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=a0:21:b7:22:3b:a8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; Sat Aug 27 23:15:51 2011 Critical (3) No UCDs Received - Timeout;;CM-MAC=a0:21:b7:22:3b:a8;CMTS-MAC=00:0d:66:22:f8:01;CM-QOS=1.0;CM-VER=3.0; Sat Aug 27 23:14:33 2011 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=a0:21:b7:22:3b:a8;CMTS-MAC=00:23:5e:6f:d1:74;CM-QOS=1.1;CM-VER=3.0; Sat Aug 27 23:14:01 2011 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=a0:21:b7:22:3b:a8;CMTS-MAC=00:23:5e:6f:d1:74;CM-QOS=1.1;CM-VER=3.0; Wed Aug 24 11:21:52 2011 Critical (3) SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=a0:21:b7:22:3b:a8;CMTS-MAC=00:23:5e:6f:d1:74;CM-QOS=1.1;CM-VER=3.0; just want confirmation, as ive got an engineer coming tomorrow, as over the years ive had repeated signal problems that keep being corrected by engineers by moving my cable up on the line tap in the cabinet.. but i suspect an engineer is moving it down again at a later date to fix somebody elses fault. So after I was told ive got signal problems again for what must be able the 4th time now, I wanted to try and get a thicker cable put in, as that was recomended when i first had the services installed 6 years ago, but the engineer who came down to fit the cable didnt have the cable with him and just moved my cable up the line tap in the cabinet instead fixing the problem.. but since then its been a reoccuring problem, that keeps coming back to haunt me. Ive got 2 V+ boxes, and 1 V box, so outside in the brown box there is a 3 way splitter, then inside the house on 1 outlet there is a 2 way splitter to split broadband and TV to one of the V+ boxes. want to also get Tivo, and 1 V+ box moved so then I will have 4 boxes.. which is also why id like to get these signal problems sorted now. on one of my V+ boxes, my signal levels are, SNR: 35.0 dB, 33,0dB, 34.0dB AGC Signal Level: -6dBmV, -5dBmV, -9dBmV Return Power: 46dBmV have no idea if any of these levels are normal. Thanks in advance. |
Re: Signal Levels
i tink techincally your downstream levels are ok but border line, they could defo do with being ramped up, they need to be a bit closer to 0
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Re: Signal Levels
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Hi, thats what I was also told, that they need increasing a bit. is there any way anybody knows of, of getting the drop cable changed to a thicker cable? because, i know its only borderline, and moving it up on the line tap will probably fix it. BUT every time this has been done in the past the problem has come back again. 4/5 times now with this same problem is not really acceptable any more, and a cable pull would probably sort it out properly. |
Re: Signal Levels
Engineer has just been
These are the new signal levels, all he did again was move it up on the line tap, but to me they seem like barely no improvement? just told me the tap has some corrosion and he will get networks onto it, and refused to do any more than that... so i guess now its wait and see what happens when networks change the tap. if its still like it, will i need to get another engineer down again? this is getting rediculas now. Connection Startup Procedure Procedure Status Comment Acquire Downstream Channel 299000000 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 194 55616000 Kbits/sec 299000000 Hz -6.1 dBmV 39.0 dB Hybrid Locked QAM256 193 55616000 Kbits/sec 291000000 Hz -5.8 dBmV 38.5 dB Hybrid Locked QAM256 195 55616000 Kbits/sec 307000000 Hz -5.9 dBmV 39.0 dB Hybrid Locked QAM256 196 55616000 Kbits/sec 315000000 Hz -6.3 dBmV 38.8 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 1 20480 Kbits/sec 35800000 Hz 49.2 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 2224 Max Traffic Rate 102400000 bps Max Traffic Burst 10000 bytes Mix Traffic Rate 0 bps Primary Upstream Service Flow Upstream(0) SFID 2223 Max Traffic Rate 10250000 bps Max Traffic Burst 16320 bytes Mix Traffic Rate 0 bps Max Concatenated Burst 16320 bytes Scheduling Type Best Effort I don't mean to complain, but I pay virgin media over £1000 a year for my services, ive been with them for over 6 years and this problem just wont go away. All I want is a permanent fix to it.. not get told every time i change my services ive got signal problems. Its frustrating. |
Re: Signal Levels
That excuse is BullSh*t. I dont buy it at all. Time to call back up and get some RG11 cable, if your on the highest tap you obviously need it
---------- Post added at 14:37 ---------- Previous post was at 14:27 ---------- if freq 299mhz -6 its amazing you can even watch tv channels at 609mhz as they'll be -10 or worse |
Re: Signal Levels
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when the engineer arrived, first thing i did was explain how when it was originally installed i was recomended a replacement cable which never happened and that this had been an ongoing problem.. then he plugged his signal meter into the broadband modem cable, and went to check the line taps... a while later he returned, and said theres some corrosion where a previous engineer hadnt closed it up properly and that he would get networks onto it... then logged onto the Superhub, disabled some of the features like the firewall, then looked at the status page with the signal levels. When he said he had this time put a tag on it to make sure another engineer doesnt move it down. I know he moved it again because the tv cut out for a while. So I asked if theres any way I can get another cable put in, and he told me that they will only do that if it is like worst case scenerio then went on to say that using the thicker drop cable is more a london architecture, not round here. Then he left, wasnt until after i checked the signal levels and theres barely any improvement.. i dont know what they should be but he might as well of not turned up for the difference its made.. but there wasnt much else I could do lol So you think I should phone back again? I know im not happy with it, the improvement is barely anything. TV Channels work ok, but i admit occasionally i do get interference on the channels like you do on freeview with a weak signal. Broadband speed is more erratic if nothing else. ---------- Post added at 15:21 ---------- Previous post was at 15:06 ---------- regarding tv, heres the signal levels. Default Frequency 411mhz V+ Box which is connected directly to the splitter in the brown box outside Tuner A Modulation Error Ratio: 33dB Input Signal Level: -8 dBmV Tuner B Modulation Error Ratio: 32dB Input Signal Level: -9 dBmV Tuner C Modulation Error Ratio: 33dB Input Signal Level: -8 dBmV V+ Box which is connect via a splitter with the broadband modem. Tuner A Modulation Error Ratio: 33dB Input Signal Level: -12 dBmV Tuner B Modulation Error Ratio: 32dB Input Signal Level: -11 dBmV Tuner C Modulation Error Ratio: 32dB Input Signal Level: -11 dBmV Also have a V box also, so 3 boxes and a broadband modem. He never checked those signal levels, just the signal level on the broadband modem. |
Re: Signal Levels
Go to settings, technical stuff dtv medic then enter the pin I'll pm u to have a look
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Re: Signal Levels
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on the V box, its an SA4200 and STB Medic wouldnt work, just kept coming back STB Poll Error. But the signal levels on the V Box are, AGC -8 dBmV Return Power 49 dBmV SNR 36.2 dBmV V Box is connected directly to the splitter in the brown box outside 3 way splitter in the brown box, 2 ways go to the V box and V+ box, 3rd way goes to a 2 way splitter for the other V+ box and Superhub Thanks for the reply again, much appreciated :) |
Re: Signal Levels
Just to see what it fails on
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Re: Signal Levels
i agree dude, he hasnt done anything to improve your signal levels at all. Ask JB66 what needs doing to fix it and then ring VM up and tell them you want another engineer out and what you want them to do to remedy the problem.
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it didnt fail on anything that I can see, But I have run that in the past, and it used to always fail on one of the tuners, didnt do it this time. ---------- Post added at 17:21 ---------- Previous post was at 17:14 ---------- Quote:
No he didnt do anything, the signals arent improved at all, just gave me rubbish about the cable pull, saying RG11 is only something used in london architecture, not around here (thurrock, essex) anyway, ive got fed up with it now, thanks for providing me with 2nd oppinions. CEO office has clearly been useless as they was the people who sent the engineer down, and this has been going on for 6 years now, was already annoyed they wouldnt give me tivo.. I was abroad for 8 weeks this year in the past 6 months and was late paying, now they refuse to give me tivo until near the end of the year.. apparently being a loyal customer for more than 6 years counts for nothing. They gave me the 100mbit Broadband upgrade though, thats how this signal problem all came to light again, and I was hoping after today it was going to be fixed.. as id contacted the CEO office and explained how annoyed i was and that this had been going on for 6 years now... with no proper solution. Then engineer comes down today and gives me some rubbish and does nothing. So after you offering me a 2nd oppinion JB66, which I appreciate, Thanks :) ive now contacted the department thinking of leaving us. Told them this has been going on for 6 years now, and no real solution has come about, explained im fed up with this reoccuring problem and said the engineer that came today was next to useless..and said if its not resolved I will be reducing or cancelling my services as im fed up with it. Then they got in touch with the area installs manager, and phoned me back.. and said they will contact me in due course to arrange a date for a repull using RG11 Just rediculas that it had to come to that.. they could of resolved the problem 6 years ago when an engineer recomended a repull, but instead dragged it out... but I have to say they soon did something about it when i threatened to leave. Will see what will happen now, hopefully I will get the RG11 repull. |
Re: Signal Levels
well that was a waste of time... so much for them agreeing to do a cable repull.
nobody called me as was supposed to. phoned retentions again, and was told "the area manager thinks you dont need a repull" so no repull will be done... passed me on to the 100mbit team... we will book another engineer for sunday morning. but i dont get what this engineer is going to do that the previous one couldnt? previous engineer fiddled with the tap, it made no difference.. then went.. said he couldnt do any more. so why send another engineer down? to waste my time? engineers have been fiddling with this signal issue for 6 years.. to no avail. So clearly something seriously is wrong, but nobody will give me a cable repull. |
Re: Signal Levels
Ok... another option. If they wont give you a repull then get an external HDU fitted to your omni, that will boost the signal by 6db (as a 3 way splitter looses 3db)
If they wont do that then ask the engineer to replace the 3 way splitter with a 3-way unbalanced splitter that will increase your downstream to -2 |
Re: Signal Levels
ok will do, thanks again
just dont understand why they cant just do a repull, its only a lump of cable, ok fair enough it costs money but surely no more than the total of all these engineers being sent out is costing them. just seems stupid... person on the 100mbit team even tried to say a cable repull would not increase my signal.. apparently he obviously doesnt know anything about signal losses over a length of cable. |
Re: Signal Levels
Hi, Engineer has just been, and done nothing, said its fine, as its ok down to -7 dBmV as problems dont start happening until it gets down to about 7.1 dBmV
Despite everyone telling me -6 is borderline and the 100mbit team on the phone, which was why they sent the engineer in the first place after they refused the repull. |
Re: Signal Levels
It should be between -3 and +6. Time to email CEO office
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Re: Signal Levels
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regarding the CEOs office, I actually emailed them first originally because i was fed up of this 6 year ongoing issue of weak/borderline signals. all they did was send down an engineer, the first one.. and he did sod all... just told me RG11 was a london architecture, moved my line on the taps and said about the corrosion in the pit before promptly leaving. Then when he did nothing I phoned retentions, threatened to leave and they booked me a cable repull... which was cancelled because the area manager thought it un-necessary, that was when the 100mbit team said -6 dBmV was borderline and sent this engineer.. but hes turning around saying -7 dBmV is borderline as problems wont occur until it hits -7.1 dBmV, and -6 dBmV is fine.. and after phoning back 100mbit team they dont want to argue with this engineers verdict. Just seem to be going around in circles now. This engineer told me im the only person on this particular tap.. which means the signal coming out must be ok... and probably for normal customers with maybe 1-2 boxes and a modem is adequate... but because I have 3 boxes, and a modem... 4 way spliiter outside (3outputs, 1 input) and a 3 way splitter inside (2 outputs, 1 input) to split for modem and V+ my signal is significantly weakened.. and even if im only loosing 2-3 dBmV over the cable its enough to make my signal levels borderline. ---------- Post added at 12:57 ---------- Previous post was at 12:45 ---------- It occurs to me, that a lot of these engineers know I need a repull, but they cant do anything more themselves because im already on the highest tap, and the only cable on that tap. which is why they arent doing anything just leaving. But nobody will recomend a repull because they know I wont get one so its easier for them to fob me off with excuses. Just lost for ideas now. |
Re: Signal Levels
There's a reasoned explanation of attenuation between street cabinet and cable modem here.
How far are you from the street cabinet? There are attenuation points of 12, 15, 18 & 22 dB (if my memory serves me correctly) from which an engineer can choose for your case. So the highest leaving the tap point would be c. 30 dBmv (see the article) and then the losses on the way. |
Re: Signal Levels
Did you mention an HDU if they refused RG11? That will boost your downstream by 6db as they would remove the 3 way spitter and if they wired it properly removing the 2 way splitter you'd actually gain 10db
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Re: Signal Levels
JB - have you done these before? Like come straight into the house from outside and do the HDU inside, avoiding the outer wall box and connections?
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Re: Signal Levels
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if there is a 22 dB attenuation point, surely it shouldnt end up at -6 dBmV I know I have 2 splitters on the line, the 4 way with 3 outputs, and a further 3 way with 2 outputs connected to one of the ways on the 4 way. but ok, deduct 6 dBmV roughly for those splitters but surely on a 22 dB attenuation point I should be getting a better signal than that. I had a look at the link posted on the VM website you referenced. It does clearly say, QAM256 -3 dBmv to +7 dBmv So why is the 100mbit team telling me they wont argue with the engineers verdict, that -6 dBmV is fine, and the engineer saying he wouldnt be worried unless it is -7 dBmV? is this some kind of lack of traning or knowledge or something? ---------- Post added at 13:34 ---------- Previous post was at 13:32 ---------- Quote:
Yep, he wasnt interested.. just kept saying signal levels are fine, as they are above -7 dBmV and that i wont have problems unless it drops to - 7.1 dBmV lol, the amount of hastle this is creating, just to get it fixed it makes you wonder if its easier to just open up the pit one night when nobody is around and have a go moving yourself onto another tap... even though im sure thats highly illegal so i wont be doing that. |
Re: Signal Levels
It wasn't so much the -3 to +7 I was recommending to you. It was the 100 metre calculation of signla loss depending on the tap point you're on. You'd have to go to the cable type (e.g. RG11) web sites to get the attenuation calculation per metre at 400MHz.
Personally I have no doubt that -7 dBmv would be somewhat problematic. BTW, Masque of VM has posted -3 to +7 in this forum as the optimal 256QAM downstream power levels. |
Re: Signal Levels
You can get internal hdu and external, the internal has 1 input 4 outputs and 1 for the plug. Ok so your modem says -7 thats at mid range, your high frequencies are going to be near -15 as high frequencies drop of more.
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Re: Signal Levels
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For my mathematical mind (and the attenuation tables, of course, where do you put "mid range" as a frequency point? |
Re: Signal Levels
I usually test 104mhz for low 323, 331 for mid and 619 and 691 for high. A drop of 100m will seriously hamper your high frequencies, that's why rg11 is a better solution than an hdu.
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Re: Signal Levels
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because im being told no i cant have one, and when i did manage to get one booked the area manager cancelled it as he said it was not necessary.. no idea how he came to that conclusion though nobody came to check out my setup, or signal levels on each device. |
Re: Signal Levels
You shouldn't have to, you should ask the engineer to fix your net then let him work out the how
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Re: Signal Levels
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Re: Signal Levels
latest signal levels as of today.
Locked QAM256 194 55616000 Kbits/sec 299000000 Hz -6.4 dBmV 38.7 dB Hybrid Locked QAM256 193 55616000 Kbits/sec 291000000 Hz -6.1 dBmV 38.2 dB Hybrid Locked QAM256 195 55616000 Kbits/sec 307000000 Hz -6.1 dBmV 38.9 dB Hybrid Locked QAM256 196 55616000 Kbits/sec 315000000 Hz -6.6 dBmV 38.6 dB Hybrid |
Re: Signal Levels
so thats after loosing 4db on a 2 way splitter and 6db on a 3 way. if you got an HDU to replace both splitters they'd be sitting at a healthy 4db downstream and 41 upstream
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Re: Signal Levels
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yep, but the engineer just kept insisting the signal levels are fine, and that its only -7.1 he would expect problems. made it clear he wasnt going to do anything... I mentioned i was under the impression nearest to 0 is best and he just made a remark bless their cotton socks and laughed. said he wouldnt be supplying a HDU, and left. now, because ive had 2 engineers down who wont do anything.. previously 100mbit support was agreeing with me -6 was borderline and sending engineers.. but now they are just saying there are no problems, and they arent inclined to argue with the engineers oppinion and left it at that. Thats why now im fed up with bothering with them, and more inclined to do something about it myself. besides an RG11 repull, and HDU nothing more an engineer can do, as im the only person on the tap, and im already probably on the highest tap. the setup is, im connected to a tap inside a pit about 4/5 houses away down the road. then that tap pit is connected to a tap cabinet accross the road about the same distance again. which is why already i have a bit of a weaker signal, because im connected to a pit and not a cabinet... normally id guess the signal would be fine, but its the amount of devices I have, and the 2 splitters which are causing me to loose 10 dB. So, if they arent going to give me an RG11, and I cant be moved up on the tap, only solution left is to source a HDU myself, and remove 1 of those splitters. Which should then like you say give me a healthy signal...ive wasted my time calling them up complaining and getting engineers down who seem to be useless. |
Re: Signal Levels
My signals appear to be getting worse...
Downstream Channels Lock Status Modulation Channel ID Max Raw Bit Rate Frequency Power SNR Docsis/EuroDocsis locked Locked QAM256 194 55616000 Kbits/sec 299000000 Hz -6.7 dBmV 38.4 dB Hybrid Locked QAM256 193 55616000 Kbits/sec 291000000 Hz -6.5 dBmV 38.1 dB Hybrid Locked QAM256 195 55616000 Kbits/sec 307000000 Hz -6.5 dBmV 38.7 dB Hybrid Locked QAM256 196 55616000 Kbits/sec 315000000 Hz -6.8 dBmV 38.2 dB Hybrid |
Re: Signal Levels
A few posts back you said the engineer fiddled at the tap. Which tap? The one in the cabinet or the one in the pit?
If it wasn't the pit, he wouldn't have noticed whether or not the pit was flooded. |
Re: Signal Levels
If you have pits then only a network engineer would go into the cabs
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Re: Signal Levels
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1st engineer moved my line onto a different tap, because my services cut out briefly. Then told me there was corrosion where a previous engineer had not sealed it up properly or something, and that he would get networks onto it and left. So presumably after over a week that work should of been done if it needed doing, then last engineer also said he would get networks to take a look because he said my erratic speeds werent due to my poor signal levels.. and told me they normally come out within 4 hours so presumebly they had a look at the taps or cabinet also.. but didnt knock on my door. But last engineer said I was the only person on the tap, and presumebly I am already on the highest tap. However, my signal levels appear to be fluctuating, as before it was around 5.8 -6.1 But todays check shows 6.8 dBmV I dont believe im going to get any further with VM, getting engineers out or arguing this out over the phone unless my services stop working, as ive tried retentions, CEO office, 100mbit team etc already. So im going to stick to my plan to try and do anything I can to resolve this myself, i.e removing 1 of the splitters etc to give me a better signal. |
Re: Signal Levels
Fluctuation is normal and power levels will drop as weather cools :(
I'd say to hell with this and get your own HDU if you cannot get alternative services. |
Re: Signal Levels
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im going to remove one of the splitters, and change the the 3 way splitter in the brown box for a 4 way.. and give the modem its own feed. then if i can get hold of a HDU use that instead of the 4 way splitter. ive got the snap and seal connectors, EX6 which are exactly the same as what VM use, and the tool so they wont know anything has been touched by me. I know its against the terms of service, but as long as I dont cause any problems.. which I shouldnt anyway then they wont be none the wiser.. just rediculas that its got to a point where I am having to correct this situation myself. |
Re: Signal Levels
Stuff the terms of service.
Just make sure that the HDU is passive return ideally, or at very least has a return band of 5-65MHz with a forward band of 85MHz-1000MHz. Something like this: http://www.soontai.com/DA10.html DA10 - 65/8510 5 - 65 MHz by-pass 85 - 1000 MHz 10 dB Those kinda specs would be ideal. |
Re: Signal Levels
Hi, Thanks I will have a look for one of them.
I was looking for one of these, http://62.177.155.228/Portals/4/Down...DU-AppNote.pdf FDU-61 which I believe is what VM actually use, it doesnt actually amplify the signal though, it just has no signal loss unlike a splitter... so if like me im probably loosing about 10dB with the 2 splitters, by using one of those it would give me the same level signal going into the unit on any of the outputs. just been unable to find somewhere selling them lol, from what I can gather somebody used to sell them on eBay but i cant find any now. So probably only obtainable via a VM engineer. |
Re: Signal Levels
Just keep calling up when you get an issue. I'd have installed one if I was in your area
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Re: Signal Levels
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Will be some cases where this doesn't happen due to in-line amplifiers which respond to changes in temperature but the general trend should be increase in attenuation or a marginal drop at best - between zero and 30C you're talking 0.1dBmV per 30m. Cable Type Temperature Fahrenheit P3 500 CA 20 30 40 50 60 70 80 90 Frequency (MHz) 600 1.80 1.82 1.85 1.87 1.89 1.91 1.94 1.96 750 2.04 2.06 2.09 2.11 2.14 2.16 2.19 2.22 1000 2.37 2.41 2.44 2.47 2.50 2.52 2.56 2.59 |
Re: Signal Levels
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every time ive had my services changed, or problems it has always come down to signal problems, i was told i needed RG11 6 years ago, and for all that time ive repeatedly had to have engineers down... who have "claimed" to of fixed it... but now im fed up with it and persisting with this problem and doing my own investigations into it, I find that even though my services are working, my signal levels are borderline which has probably been the issue the whole time, I was just unaware of it. and so ive had 2 engineers down who have refused to do anything so that will typically be a continuing trend I feel now. I will see what the signal levels are like after ive removed one of the splitters.. but if it is still not ok, I will try to fit a HDU myself. It shouldnt be anything I cannot do myself, as its only a case of replacing the splitter with it, then running a separate cable to a power supply. |
Re: Signal Levels
Igni, I would expect metal to contract in winter, and if it contracts, it shortens and the attenuation falls; thus the power rises in the downstream direction.
Where have I got this wrong? If it's just due to less tight contact, I would have expected that to be designed out. My own power levels fell in the summer and always rose in the winter by c. 3 dBmv. |
Re: Signal Levels
Cold metal has less attenuation, I always get upstream power level issues in summer
a 4 way splitter looses 7db so your downstream will rise to -3 with a 4 way splitter |
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Re: Signal Levels
-3 is cool, -6/7 is a bit dodgy
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Re: Signal Levels
Borderline, I'd settle for that if your upstream is good (which it is) and your snr is fine.
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Re: Signal Levels
Hi, I will see what the signal is like then after ive made the changes.
if its still borderline, and likely to fluctuate down to -4 then i might be inclined to fit a HDU anyway to give peace of mind that the problem is properly resolved. Better to have a stronger signal and attenuate it. But I will see what happens, and feed back. |
Re: Signal Levels
I wouldnt attenuate at all, but if you really had to you'd be better with a 4db equaliser
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if the 4 way splitter looses 7db, and I end up with -3 the HDU would give me 4db which is about as near to perfect as it will get, well within spec then. |
Re: Signal Levels
Engineer number 3 came today, did more than the previous 2.. checked out my signal levels on the modem, V+ box, isolator, omni, and in the pit.. then said that there was a problem and he called networks.
Networks have just been, and sorted it, by the time I get a 4 way splitter fitted to eliminate the 2 way splitter, I should have a perfect signal level of around 0 dBmV modem levels are now, Downstream Channels Lock Status Modulation Channel ID Max Raw Bit Rate Frequency Power SNR Docsis/EuroDocsis locked Locked QAM256 194 55616000 Kbits/sec 299000000 Hz -2.1 dBmV 41.0 dB Hybrid Locked QAM256 193 55616000 Kbits/sec 291000000 Hz -1.7 dBmV 40.4 dB Hybrid Locked QAM256 195 55616000 Kbits/sec 307000000 Hz -1.9 dBmV 41.0 dB Hybrid Locked QAM256 196 55616000 Kbits/sec 315000000 Hz -2.1 dBmV 40.8 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 1 20480 Kbits/sec 35800000 Hz 44.5 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 and V+ box is -8 dBmV, -5 dBmV upstairs without the 2 way splitter. So now im wondering if the previous 2 engineers were just giving me rubbish about calling networks, as they was supposed to of been down twice previously and didnt make this fix, so now im going to persue a complaint, why 2 engineers, and 2 "supposed" networks visits could not fix this problem and I was given rubbish about my signal levels being fine and nothing could be done. When this engineer managed to get it fixed, with 1 call to networks and spent a lot more time investigating the problem. |
Re: Signal Levels
nice one dude. I wouldn't mind things going wrong if they acknowledged the fault and fixed it when you brought it to their attention. The things which pees everyone off is the rubbish they try to fob you off with and send you round in circles.
Kudos to the engineer that came out and fixed it |
Re: Signal Levels
yep, agreed, I was annoyed by the 2 engineers who did nothing and told me it was all fine.
couldnt admit there was a problem just kept telling me its fine. |
Re: Signal Levels
where do you live ?? may be able to help by getting hold of the AFM and may be able to put in a word if that would help.
Thank you Colbeck |
Re: Signal Levels
Quote:
I think the local depot that serves where I live is basildon. if you are able to, that would be great thanks. Because I would like to persue some kind of complaint, really not very happy about it.. feel lied to and fobbed off which as a customer who pays nearly £1400 a year i dont feel is acceptable. I know ive said it all already previously in this thread...but like I said first engineer, turned up.. did nothing then said nothing he could do and that he would get networks down regarding a corroded line tap in the pit. I have no way to know if networks were even called let alone came down... but nothing changed regarding the signals. then engineer number 2 came down, laughed and made a remark bless their cottom socks when I said that I thought ideal was nearest to 0 you can get.. then he told me -7 dBmV was acceptable, and with -6 dBmV it was fine.. no problems at all... checked the pit, said i was only person on the tap... but again said he would get networks down within 4 hours to take a look for any problems as to why I was getting erratic speeds. 4 hours came and gone, so again have no idea if networks were even called, all I know is again nothing was done. Then the 100mbit team even though they acknowledged -6 was borderline. Although after I realised it was actually -3 considered borderline which is worse still. Because 2 engineers had been down they just said its working, no problems at all.. I see -6 dBmV all the time.. and wouldnt send any more engineers. So I decided to phone up and report a fault with my TV (blocky picture) so they sent todays engineer down, and I was actually really pleased.. he checked the signal levels on the V+ box, then the modem... then checked them at the isolator... then the omni, before checking them at the pit.. really spent time tracing the problem backwards... then a while later he said that he had spoken with networks and there is definitely a problem... within an hour id guess, networks came down.. actually saw the guy this time, he spent about 5 minutes doing something... then knocked on our door to say the problem was fixed... and when I checked now I have quite reasonable signal levels. Therefore what im questioning now is... WHY didnt those 2 previous engineers do what this engineer today did? why so quick to say its fine, nothings wrong and leave... AND did they actually call networks? because if they did, the question I have is why did 2 networks team visits to that pit not resolve the problem? or even spot the problem? was only when networks guy number 3 come along.. problem solved within minutes... to me it looks like they wasnt even called out. |
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