Bicephale
join:2005-09-24
 ·TekSavvy Solutions..
| reply to Bicephale
Re: Tweaks
 .PNG/thumb.jpg "71044 bytes")
5 Chokes - Two Weeks record |  .PNG/thumb.jpg "44139 bytes")
3 Chokes - Two Hours record |
Here's an UpDate showing the progress made after i
installed toroïdal cores and got switched to 6016/
512 Kbps Interleaved. The top 2 weeks records can
speak for itself, the 2 hours one below provides a
clue as to what happens with no toroïdal chokes on
the phone line input - this record also speaks for
itself, it's demonstrating that sometimes we can't
just trust spectral response curves: the nice one
has the worst CRC Error count in this very case!!!
The customer's own wiring, Bicephale, 2008-Jan-14
REMEMBER!
The above image shows how i installed the toroïdal
chokes and this corresponds to the 2 weeks record.
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Guspaz
Guspaz
Premium,MVM
join:2001-11-05
Montreal, QC
·Colbanet
| If they make such a big difference, somebody should make a modem with this sort of filtering built-in. It's my firm belief that anything you can do to the line beyond shielding (such as filters, or coils) could also be built into the device using the line. After all, you're not doing anything that the device couldn't do if the manufacturer decided to do it.
One day, you should produce your own line of modems, with all sorts of line filtering equipment built-in. You can market it to all those pour souls stuck on noisy lines  |
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Bicephale
join:2005-09-24
·TekSavvy Solutions..
1 edit | reply to Bicephale
DSL (Phone) Line Input: "Choked" vs "Not Choked" |
the spectral response curves i had in mind, actually...
Well, and the contradictory numbers quite a bit too!...
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TakeTheFifth
join:2004-04-20
Anjou, QC
| said by Bicephale  :Well, and the contradictory numbers quite a bit too!... Not that contradictory when you think about it: the choke filters out some frequencies, so while the modem is training, it does not allocate bits to these buckets. The result is: less buckets, more bits per bucket, less SN ratio:
Without choke: 193 buckets are used (tones)
With choke: 214
Also, look at the number of bits per tone with and without the choke.
The logic is:
1- Find how many bits I can put in each bucket with SNR>=6
2- Use the better buckets (highest SNR), with the least amount of bits per bucket to support the required BW.
So, you most likely have less errors with the choke because you are removing the tones that are more susceptible to errors (and this is specific to your line). I bet you would get the same result if you you were able to «disable» these tones. |
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