dslreports logo
site
 
    All Forums Hot Topics Gallery
spc

spacer




how-to block ads


Search Topic:
uniqs
7
share rss forum feed


pflog
Bueller? Bueller?
Premium,MVM
join:2001-09-01
El Dorado Hills, CA
kudos:3
reply to cielbleu

Re: [Signals] Should SNR swing as much as 1dB with temperature?

said by cielbleu :

1 dB "swing" is nothing, you're funny! Don't worry, he broke nothing. Call back when you will get 3-4 dB SNR sudden drop.

The temperature variance right now is 15 degress. When it's swinging from 55 to 100, I'm almost certain it'll be there or worse.

What concerns me is that the SNR varied hardly at all, regardless of temperatures, until this tech came out...
--
"I drank what?" -Socrates


Johkal
Cool Cat
Premium,MVM
join:2002-11-13
Happy Valley
kudos:10

said by pflog:

said by cielbleu :

1 dB "swing" is nothing, you're funny! Don't worry, he broke nothing. Call back when you will get 3-4 dB SNR sudden drop.

What concerns me is that the SNR varied hardly at all, regardless of temperatures, until this tech came out...

I see your point. Whereas 1 dB can be a normal swing, I would be very curious why the 1 dB swing after the Tech left. Still could be coincidence, but I would keep an eye on it.
--
In God we trust; all others bring data!



pflog
Bueller? Bueller?
Premium,MVM
join:2001-09-01
El Dorado Hills, CA
kudos:3

said by Johkal:

I see your point. Whereas 1 dB can be a normal swing, I would be very curious why the 1 dB swing after the Tech left. Still could be coincidence, but I would keep an eye on it.

Yeah, guess I'll just keep an eye on it. Come to think of it, the lower SNR overall was after the tech left. I think the fluctuations actually started early last week after an outage overnight (coincidentally after which I lost my 3rd upstream channel, but got it back after rebooting the modem).
--
"I drank what?" -Socrates


pflog
Bueller? Bueller?
Premium,MVM
join:2001-09-01
El Dorado Hills, CA
kudos:3

Click for full size
Yeah, it was on the night of the 23rd (see attached).
--
"I drank what?" -Socrates


cielbleu

@videotron.ca

There isn't any tech who came here, but when i look at my signal, my snr always fluctuate of about 1 dB. It's normal...

You're right, in summer with high temperature, signal loss in a trunk or distribution coaxial cable is higher and lower in winter with colder temperature. If your cable plant is build with many cascaded distribution amplifiers with long run of cable between them, the lower signal at the input of each amplifier will cause the SNR to drop of several dB (4 to 10 dB). Same thing in cold temperature, too strong signal at the input of each amplifiers means overdriving amplifiers causing distorsion and SNR drop. It's why there's AGC (Automatic Gain Control) in amplifiers, but sometimes agc can be broken or an amplifier is let in manual mode instead of agc for some reason.

It's why maintenance technicians exist, to balance cable lines so the signal stay optimal all year long, it is called maintenance.

Don't worry for a 1 db SNR variation!!! There is no issue there.



pflog
Bueller? Bueller?
Premium,MVM
join:2001-09-01
El Dorado Hills, CA
kudos:3

Right I'm not so much worried about a 1dB swing as I am thus occurring g after an outrage and seeming to correlate with temperatures, since this area had a large temperature swing in the summer, sometimes as much as 50 degrees. Perhaps the AGC got screwed up when they did whatever maintenance they were working in. I'll just monitor it and see if any sync loss or other issues arrise, thanks.
--
"I drank what?" -Socrates



beachintech
There's sand in my tool bag
Premium
join:2008-01-06
kudos:5

said by pflog:

Right I'm not so much worried about a 1dB swing as I am thus occurring g after an outrage and seeming to correlate with temperatures, since this area had a large temperature swing in the summer, sometimes as much as 50 degrees. Perhaps the AGC got screwed up when they did whatever maintenance they were working in. I'll just monitor it and see if any sync loss or other issues arrise, thanks.

If that were true you would most like see a corresponding change in signal levels forward and return rather than purely a "change" in SNR calculation.