transient signal drop issues

FYI SNR can be -13db IF there is a faild component within the coaxial system, resulting in major signal loss/distortion, OR if underrated equipment is used ie: a signal with a total clock speed of 1,700 Mhz (1.7 Ghz) will push a splitter rated for 1000 Mhz to the limits, resulting in a shortened life span, xfinity tv with gig net signal is carried on to AM side bands; side band one is +700 Mhz, side band 2 is -700 Mhz the frequency, or carrier band is a stedy 1,000 Mhz (1 Ghz), therefore the side bands rapidly alternate between positve and negative to create a wave that A/V data can ride on through the center of the copper coated core, data is a direct 1:1 conversion, meaning 1 hz = 1 byte.

figuring out the SNR is simple math and dictates an infrastructure failure somewhere between the node and cunsumers equipment, visual inspections can identify aproximately 80% of all culprits.

I do have a degree in Electronic Tecnologies, so I know a thing or two about trancieving signals.

Sorry. The SNR can't go into negative numbers. That's the downstream power level figure.

As I was stating, my recieving equipment was NOT getting a clean full signal, resulting in the "impossible" SNR, I have replaced the splitter with one that is rated up to 2500 Mhz on each output, I have also replaced the improperly terminated RG6 cables with new cables, and properly bonded the lightng/surge coupling with a slightly larger guage solid strand ground jumper, bringing us to the final culprit, the drop line, which has visable damage to the messenger/insulating sheath/mesh, which as a cunsumer, is beyond my authorization to touch, however my equipment is running much more efficient, and data speeds have finally stabalized, however there is still some signal loss/distortion, just nowhere near as bad, I estimate my SNR to be somewhere within proper specs, (0 to +3db) still low, all I can do now is wait for maintenance to assess and repair/replace the areal drop line, beleive what you will about SNRs but I don't believe things just because a company claims it, ergo a negative SNR = failed component(s) replacing the failed component(s) will allieviate the issue, but you are right about SNRs being negative, you can not have a healthy network with negative SNRs if you do, then something(s) are allowing interference inside the coax, and needs to be corrected, otherwise recieving equipment ie: set top boxes modem/routers, will incure moderate to severe damage, which is what happened to me, however I fixed the obvious issues within my system that I was authorized to handle. All in all, you did answer my key question, and I have a maintenance tech scheduled NOT to be confused with the installers.

You do realise that we are arguing the same exact point, I stated that I was getting negative SNRs which indicates a failed component, you've stated that negatives are not possible, which are both correct, mathmatically, my signal was a negative integer due to a LEAK in my coaxial network, my modem and line tests came baclk -13bd, a tech improperly rewired my setup, which made things worse, and based on math I got a negative 14.74db, which tells me that an unknown unwanted signal of +13 to +14.74db was being introduced into the system, indicating faild shielding, problem I found and fixed was the install tech did not properly terminat the type F connector to the rg6 cable, the insulating/messenger mesh was pushed back and out of the pvc jacket, I replaced the bad cables, and removed the bad signal, bringing SNR to 0, I then replaced the old 2 Ghz splitter (1000 Mhz per output) with a 5 Ghz splitter (2,500 Mhz per output) thus reducing the attenuation at that specific weak point (weak points in a coax are usually located at each termination/splice) now I am back in spec with a true signal (no outside interference)  not everyone needs that fancy equipment to diagnose some common issues, if your math is good and you understand the nature of signal voltages, then you can identify the problem, and correct said problem accordingly, I do not no my current SNR, however, since removing the failed/underated components, I do KNOW that I am getting a pure signal, however due to the damaged drop line, that signal is low, causing fairly high pings, my current jitter is now between 0 - 2 milliseconds, which is way better than before I rewired my system. 

Also, a maintence tech was scheduled by an xfinity help desk agent (tech support) I even have the confirmation, this was NOT a general install tech, I know this because maintenace appointments have way larger windows, typically between 15 to 30 days after a maintenance order is submitted, if I where to have a general install tech visit, I would have an exact date and two hour window.