Intermittent bad SNR + slow upload, new drop, wiring, modem.


Downstream 122723.00 MHz10.70 dBmV38.98 dB256QAM10584593800
Downstream 21597.00 MHz11.60 dBmV38.98 dB256QAM9176148800
Downstream 32603.00 MHz11.80 dBmV32.96 dB256QAM9379199535380182
Downstream 43609.00 MHz11.90 dBmV36.39 dB256QAM7201349500
Downstream 54615.00 MHz11.70 dBmV38.61 dB256QAM8927321500
Downstream 65621.00 MHz11.80 dBmV37.64 dB256QAM8626734700
Downstream 76627.00 MHz11.90 dBmV34.35 dB256QAM8640972200
Downstream 87633.00 MHz12.10 dBmV37.64 dB256QAM9506434600
Downstream 98639.00 MHz12.10 dBmV38.98 dB256QAM9286350900
Downstream 109645.00 MHz12.00 dBmV38.98 dB256QAM8733039300
Downstream 1110651.00 MHz11.80 dBmV38.98 dB256QAM8747542800
Downstream 1211657.00 MHz11.80 dBmV38.61 dB256QAM7345611600
Downstream 1312663.00 MHz11.80 dBmV38.61 dB256QAM6421939800
Downstream 1413669.00 MHz11.80 dBmV38.61 dB256QAM8813852900
Downstream 1514675.00 MHz11.90 dBmV38.61 dB256QAM8829018500
Downstream 1615681.00 MHz11.70 dBmV38.98 dB256QAM7301370200
Downstream 1716687.00 MHz11.30 dBmV38.61 dB256QAM8877898300
Downstream 1817693.00 MHz11.40 dBmV38.61 dB256QAM9397745800
Downstream 1918699.00 MHz11.40 dBmV38.61 dB256QAM8183213400
Downstream 2019705.00 MHz11.10 dBmV37.64 dB256QAM8516965400
Downstream 2120711.00 MHz11.20 dBmV37.64 dB256QAM8742120100
Downstream 2221717.00 MHz11.00 dBmV38.61 dB256QAM9285564900
Downstream 2323729.00 MHz10.70 dBmV37.64 dB256QAM8360602900
Downstream 2424735.00 MHz10.30 dBmV37.64 dB256QAM6529474200


 UCIDFreqPowerChannel TypeSymbol RateModulation
Upstream 14624.00 MHz35.00 dBmVDOCSIS2.0 (ATDMA)5120 kSym/s64QAM
Upstream 24836.80 MHz36.00 dBmVDOCSIS2.0 (ATDMA)5120 kSym/s64QAM
Upstream 34730.40 MHz35.75 dBmVDOCSIS2.0 (ATDMA)5120 kSym/s64QAM
Upstream 44519.20 MHz33.75 dBmVDOCSIS1.x (TDMA)2560 kSym/s16QAM


I live in Lexington KY, we have pretty decent infrastructure, and I normally get great speeds and reliability.


However, most nights, for the past few weeks, around 10 pm to 2 am, I've been getting significant slowdown on my upload and fluctuating download speeds.  Normally I get 350mb down and 23mb up, but it's not uncommon during those times to see 60-150 down and 0.01 to 6 up.  Mostly this presents as rubber-banding on online games and "robotic" or no outgoing voice when talking in voice services (Skype, Discord, etc.).  When it's especially bad, pages fail to load and I lose connection to most services. 


Last night was especially bad, when I lost connection multiple times, and after rebooting the modem, watched it sync downstream and upstream but fail to "lock on" to the headend/node.  Signal levels were great aside from lower-than-normal SNR, and I actually was getting no FEC errors at all during this time despite upload speeds of 0.01~ mbps. 


I'm a tech (contractor) and have been doing this for about 9~ years.  New drop (RG11, overkill at 100 feet).  New outlet less than 10 feet away from the house box, 6-foot jumper from the outlet to the also-new leased modem straight off my van.  Nothing older than 24 hours at this point between the router (a relatively new $180 tp-link, though I've also tried with one of our Sagemcom ones from my van and experienced the same issues) and the tap.


I'm guessing the issue is related to work that's been going on for the past few weeks, where I've noticed they're slowly replacing the poles out back throughout the neighborhood.  It looked like one of the hardlines to one side of my tap was a little bent, possibly during the pole transfer.  Not enough to cause problems, but I'm wondering if there was worse further up the line.


Is there any way to get directly to plant maintenence?  I don't have time to deal with a trouble call, and don't want anyone coming inside my house when everything is already brand-new.  Neighbors have also had issues, but they don't complain loudly because they mostly just watch TV and use facebook, so they don't notice the voice/gaming quality issues.


Also, the recieve numbers are a little high, I know.  I had a 7db attenuator on the line before and was having the same problems and similar SNR.  I removed it when I replaced the outlet.


Re: Intermittent bad SNR + slow upload, new drop, wiring, modem.

You're having broadcasy TV ingress from channels 36& 40... somethings corroded, broken or loose. might be that hardline. Do you have an egress receiver handy to see if there's a leak?



You also need 3-6 dB pf attenuation to get the DS level below +8... + 11, +12 will cause other issues Sweet spot is in the -5 to +8 range....the -15 to +15 spec is only on a lab quality connection and not with 100+ qam channels.



 What's your zip code, 



Re: Intermittent bad SNR + slow upload, new drop, wiring, modem.

Zip code is 40517, but there's several zip codes for Lexington.  40515 is less than a mile away.


Channel 36 here is WTVQ-DT (ABC).  It's on the northeast end of town, the tower is visible from about half the city. 


I don't have an egress reciever, the meters we use for installations only measure ingress on the connected drop and house wiring (there is none in this case; which makes sense because I've replaced everything up to the tap itself).  They seem to leave it up to PM techs to do egress sweeping here, from what I've seen.


I'll replace the attenuator tomorrow, but seem to be getting slightly less trouble with it removed.  I'm well aware of the sweet spots on signal ranges, but I'm getting less FEC errors with this signal range at the moment.  As I said, I previously kept it lower.


Re: Intermittent bad SNR + slow upload, new drop, wiring, modem.

Yeah, you have ingress, the only way you can find it is by looking for egress.... Stick a 6" piece of rg6 center conductor into your signal meter, see if you can detect it.

Also, any Idea if your outside plant uses a ALC pilot frequency that is a dead carrier rather than a qam channel?

Here we've got 445.250 (cable ch 61's video carrier) It's easily receivable on any ham 70cm handheld when there's any sort of leak rather than the one they've got in the aircraft band around 130 mHz...

Here's from antennaweb...

RF Channel: 40
6 miles at 60°
RF Channel: 36
6 miles at 54°
RF Channel: 39
6 miles at 60°
RF Channel: 31
11 miles at 133°
RF Channel: 42
11 miles at 135°
RF Channel: 21
47 miles at 102°



Re: Intermittent bad SNR + slow upload, new drop, wiring, modem.

The lower s/n on those channels should show up on your meter unless it has a simple Green./Yellow/ Red indication for s/n.

for a better indication of actual broadcast field strengths, go to, enter in your street address and use an "antenna" height of 100'  . Different channels use different antenna radiation paterns, I don't know how accurate their computations are or the accuracy of the FCC database that they've used.

looks like 36-40 are about the same but 39 might be different.

(and don't forget the TV channels are different from the cable channels as well as offset a bit)



Re: Intermittent bad SNR + slow upload, new drop, wiring, modem.

Somethings wrong with TV fools database..... doesn't show the 36,39,40 whereas does.....