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RadioDoc
Sortofadog
Premium,ExMod 2000-03
join:2000-05-11
Chicago, IL | reply to justbits
Re: Excelcus L-222RJDP RF Interference Filter
I haven't used that one in particular, but it looks like a common-mode noise filter. If you have enough RF in the immediate vicinity to cause problems with your phone devices it might help.
What are you trying to fix? | |
justbits
More fiber than ATT can handle
Premium
join:2003-01-08
Chicago, IL
 ·AT&T Midwest
·AT&T Yahoo
edit:
June 23rd, @03:18PM
| I was wondering if this product might be able to reduce the RF interference I seem to be getting.
For more of my background on what I'm trying to troubleshoot, check out this thread:
»Any 5100b technician page DMT/SNR data experts?
I've been having a repeating problem with noisy interference on my DSL line that recurrs every weekday. It also occurs at different times of day on weekends and holidays.
In the beginning the noisy interference was strong enough to cause my SpeedStream 5660, SBC SpeedStream 5360 and SBC SpeedStream 5100b to lose sync for the entire duration of the noisy interference signal. (Typically lasts almost exactly 45 minutes.) On June 7th, my pairs of wire were replaced... I went from 5.4/800 max attainable to 3.2/600 max attainable with this replacement pair of wires. And they also failed the same way for the next 3 days. As of June 11th, the noisy interference is not causing me to lose sync anymore, but it is causing the modem to reallocate DMT bit bins all over the place while the problem occurs. I have learned how to graph the 5100b SNRM & DMT bit bin data. From data I collect every 5 minutes (or more frequent), I produce graphs (and movies) that allow me to tell when the noisy interference is occuring and how long it lasts. The noisy interference acts the same way it has since May 1st. There's a ramp-up time where the SNRM on the lower download frequencies degrades. Then, the DMT bit bins start reallocating all over the place. Then, when the problem is over, the SNRM goes up and creates "spikes" at the frequencies where there were "DMT bit deficiencies" had formed during the noisy interference. (See the other thread for a better description.) If I power cycle or unplug & replug the DSL line, I get a perfect looking stairstep DMT bit bin chart and a nice flat plateau for the SNRM chart.
By the way, I have gone through extensive grounding precautions. Details in the other thread.
Just yesterday, the problem started manifesting differently. I had two random loses of sync during the afternoon and two periods of thousands of CRC errors for two 3-5 minute periods in the middle of this morning. The high CRC error count was enough both times to cause my PPPoE connection to drop... but not enough to cause a loss of DSL sync.
The current thought is that some cell tower upgrades in the area may be somehow affecting me. beach boy & crew and I have a pretty long thread going in SBC Direct.
Anybody in the Northwest Chicago area (Cumberland Ave & Montrose Ave, just south of Cumberland & I-90) have a spare spectrographic analyzer?  It needs to be able to hook up to an antenna as well as a telephone line. It needs to work in the 40 KHz to 1108 KHz range.
--justbits | |
RadioDoc
Sortofadog
Premium,ExMod 2000-03
join:2000-05-11
Chicago, IL
·AT&T Midwest
| If you've got a portable AM radio you may be able to figure this out without fancy test equipment. Any signal strong enough to kill your DSL will certainly show up in the lower end of the AM broadcast band.
Take the radio and set it near the modem, turn it to a 'quiet' spot near the low end of the dial and remember what the noise sounds like when the modem is working. Then, when it's not, listen again (without moving the radio or changing the tuning) and see of you can detect any difference.
The problem with that filter is that is it works with common mode noise only. Your modem should already be able to deal with quite a bit of that without any modification at all. Those are useful if you live next door to a transmitter.
Cellular/PCS/etc frequencies are more than 1,000 times higher than what DSL uses. It's almost certainly not the cell site.
Don't rule out ComEd. They may load switch at certain times of the day, and given their proclivity for not doing maintenance until the bright green flash indicates where it's sorely needed, the real problem may be a bad insulator, etc., on a pole nearby. | |
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