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 d_lBarsoomPremium,MVM
join:2002-12-08
Reno, NV
kudos:7 | reply to Krellan
Re: [Speed Problem] Lost high frequencies over last few weeks So there really does seem to be a reduction in the re-radiation of the AM signal from your power cords and power line when you use chokes. That's good.  When I wondered about the maxrate after re-syncs, I was also thinking about the long term results through the seasons. I also wonder if you could have detected the AM station signal reduction with a portable radio at all or if this is only detectable by your modem maxrate?
I pretty much only used clip on chokes with no windings of the cords to try to suppress impulse noise with mixed results. As I said, I used a Belkin shielded and twisted cord to protect my DSL patch cord from all the power cords near it and that resulted in the picked up a few bits out of the AM station notches.
I don't know how much AM RFI the modem wall wart might pass to the output (noisy DC output), but if it does allow any through the modem patch cord would lie right next to it for inductive coupling. | |
Krellan
join:2001-06-06
Castro Valley, CA | 
Final(?) Reading |
I put all the chokes that I could find, on the DSL modem.
One cylindrical choke is installed on all 3 wires: Ethernet, phone line, and power.
A figure-8 wrapping choke has been placed, with as many turns as I could physically squeeze in, has been placed around the power cord as well.
Another figure-8 wrapping choke has been placed around the phone line as well, but due to the thickness of my phone wire (I also am using twisted, insulated phone wire), I couldn't get very many turns on it there.
Here's a graph. My tool shows me a consistent 6292/843 theoretical speed, unfortunately it's not all that much above my plan's rated speed of 6016/768. My noise margin is 6.5 dB... just barely above the threshhold of 6.0 dB! Deblin's tool predicts a "maxrate" of 6020, that's right on the edge of my 6016.
I think I will leave it alone and not touch it for now, lest it go out again
Do you think it's worth bringing this up in SBC Direct? I'd really like them to go through my drop line and replace it, cleaning up the wiring. I'd be willing to pay for this service. I can't hire anybody else to do it, since beyond the NID box, it's the phone company's property, not mine.
What I'm trying to avoid is a mandatory downgrade to 3000/512 speed, or worse yet, "interleaved mode". For that reason, I've been hesitant to contact AT&T myself.
Thanks for all the help you've given me... and I still haven't gotten around to writing that application that would give you a real time readout of the graph from your DSL modem, without needing to run it through the Deblin tool every time!
Downstream Current Rate (Reported): 6016
Downstream Maxrate (Estimated): 6020
Downstream Bit Margin (Calculated): 428
Upstream Current Rate (Reported): 768
Upstream Maxrate (Estimated): 1105
Upstream Bit Margin (Reported): 96
Bit tones with notches/missing bits:
bit(s) 38:41 163.875 - 181.125 KHz
bit(s) 128:132 552 - 573.5625 KHz
bit(s) 138:145 595.125 - 629.625 KHz
bit(s) 155:163 668.4375 - 707.25 KHz
bit(s) 166:174 715.875 - 754.6875 KHz
bit(s) 179 771.9375 - 776.25 KHz
bit(s) 186:191 802.125 - 828 KHz
bit(s) 194:204 836.625 - 884.0625 KHz
bit(s) 208 897 - 901.3125 KHz
bit(s) 211 909.9375 - 914.25 KHz
bit(s) 214 922.875 - 927.1875 KHz
bit(s) 222:223 957.375 - 966 KHz
bit(s) 229 987.5625 - 991.875 KHz
bit(s) 234:235 1009.125 - 1017.75 KHz
bit(s) 240:255 1035 - 1104 KHz
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