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Author Topic: SSFP Mk 3  (Read 70109 times)

VDSL2User

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Re: SSFP Mk 3
« Reply #165 on: November 03, 2014, 04:21:04 PM »

Not for my line it would appear, was previously using a 1m CAT6e cable with RJ45 to RJ11
The current setup is starting to see more ES but is still lower than I have been seeing, only
a longer run of a few days will tell if there is a real improvement.
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Ixel

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Re: SSFP Mk 3
« Reply #166 on: November 03, 2014, 04:45:23 PM »

Have got the ferrite toroid this morning. So far it seems as if I'm getting more ES than when I didn't have it. I've got the standard RJ11 flat cable running through it on 5 turns. My statistics are on MyDSLWebStats for anyone curious.

http://82.68.184.44/dslstats/2014-11-03/Bitswap-2014-11-03-16.46.00.png

A lot of bitswapping going on around tones 3100 to 3400 or so. Could that perhaps be where the CRC blips are coming from?
« Last Edit: November 03, 2014, 04:49:52 PM by Ixel »
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Dray

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Re: SSFP Mk 3
« Reply #167 on: November 03, 2014, 04:53:58 PM »

Sorry, I don't know what CAT6e cable is. Is it shielded CAT6 ?
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VDSL2User

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Re: SSFP Mk 3
« Reply #168 on: November 03, 2014, 05:26:16 PM »

Yes CAT6e is the shielded version of CAT6 and currently the best version available for high speed.
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Dray

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Re: SSFP Mk 3
« Reply #169 on: November 03, 2014, 05:50:51 PM »

Was the shield grounded?
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VDSL2User

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Re: SSFP Mk 3
« Reply #170 on: November 03, 2014, 06:13:36 PM »

I don't know how anyone would ground the wrapped shielding on a wall to modem cable,
where would you ground it to ? and might this not create a voltage potential across the incoming
BT line ?
The cable that was in use was this one http://www.ebay.co.uk/itm/DSL-LEAD-CABLE-for-BT-INFINITY-FTTC-VDSL-Choose-CAT5E-CAT6-and-LENGTH-needed-/350682964560?pt=LH_DefaultDomain_3&var=&hash=item51a6556250
MY ES rate has increased again now, however it is always very bad from 5pm to 10pm so it will be interesting to
see how bad it gets and how well it does overnight.
I guess my line is just subject to a lot of external interference which is most noticeable in the early evenings.
It will only stay on fast path if speed limited to the speed normally obtained in interleave mode.
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Dray

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Re: SSFP Mk 3
« Reply #171 on: November 03, 2014, 06:51:58 PM »

From looking on Google as I've not heard of CAT6e, I thought the only difference was a grounded shield. But from the link you provided it doesn't say CAT6e anyway so I remain confused. To me, the important attributes are pure copper 0.5mm thick, twisted pair. Although one supplier I bought from supplied me with copper coated aluminium or aluminium magnesium copper alloy wires and when I complained, pointed out it wouldn't make a noticeable difference over 50cm anyway.
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les-70

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Re: SSFP Mk 3
« Reply #172 on: November 03, 2014, 07:12:27 PM »

  The vdsl signal gets all the way from the cabinet on CW1308 (CAT4) so the last metre does not make much difference and, whilst a twisted pair of the same CW1308 spec is ideal for the dsl lead, the last metre has little impact.
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pooclah

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Re: SSFP Mk 3
« Reply #173 on: November 07, 2014, 04:44:49 PM »

I swapped my MK3 back to the MK1 this morning, not much difference in the stats at the moment but I will keep an eye on it.  There was a bit of strangeness with the upstream SNRM immediately after the resynch (pic below)  but it seems to have settled now so probably something else disturbing the line.
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loonylion

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Re: SSFP Mk 3
« Reply #174 on: November 08, 2014, 03:48:27 PM »

Well I decided to get a 12 microhenry toroid to try it out, but before I got the chance to try it, my dad appropriated it for my sister's TV. 2 turns of the aerial cable around the toroid and 0% signal quality at 66% strength became 100% quality at 66% strength. Quite an impressive result for that particular application.
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NewtronStar

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Re: SSFP Mk 3
« Reply #175 on: November 08, 2014, 08:25:16 PM »

Well I decided to get a 12 microhenry toroid to try it out, but before I got the chance to try it, my dad appropriated it for my sister's TV. 2 turns of the aerial cable around the toroid and 0% signal quality at 66% strength became 100% quality at 66% strength. Quite an impressive result for that particular application.

Loonylion there is more to than winding the cable around a ferrite core so have injected a link into my post http://www.wirelesswaffle.com/index.php?entry=entry120211-055210
for the DIYers to look at.
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loonylion

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Re: SSFP Mk 3
« Reply #176 on: November 08, 2014, 09:30:53 PM »

I'm using vdsl and trying to reduce my error rates a bit, line is perfectly stable. Les-70 got interesting results wrapping the modem cable around a toroid so that's what I'm trying to replicate.
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NewtronStar

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Re: SSFP Mk 3
« Reply #177 on: November 09, 2014, 12:19:48 AM »

I'm using vdsl and trying to reduce my error rates a bit, line is perfectly stable. Les-70 got interesting results wrapping the modem cable around a toroid so that's what I'm trying to replicate.

No worrys give it a go  :) my link was to show the circuitry and componets needed to make a DIY RF3 unit. 
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les-70

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Re: SSFP Mk 3
« Reply #178 on: November 09, 2014, 10:59:14 AM »

  First let me warn that the 12microH Al toroid that I used is of an unspecified ferrite material that may or may not be ideal.  Given the high value of Al for the size it may be a lower frequency material that will be OK with lowish numbers of turns but may not be so effective with a high number of turns.
The working frequency drops with the number of turns.

 N*'s article is good in also having a bifilar choke but whilst the type of magnetic material is usefully noted the actual size and number of turns seem equally pot luck.   The low pass filter in the article should mention the need to check the operating frequency of the chokes is OK and all the filters noted would almost totally remove vdsl signals leaving just the adsl2 frequencies.  A vdsl version could be made with different value components.

The RF3 is just a common mode choke with no explicit low pass filter but the inevitable capacitances in any choke do give some differential mode low pass filtering and the RF3 takes about 10Mb/s off a vdsl line with an attainable of about 70-80.  The Mark2 and Mark3 SSFP's both include a common choke already and the ones used are intended for vdsl and only take about 0.5 to 1 Mb/s sync of a 70-80 vdsl line.  The extent of common mode removal would be expected to be better had the SSFP's used a bifilar choke. 

 My aim was just to do that bit better with a bifilar choke. On my line it gives reduction in the ES rate of 10-20% -- so little as to take days to be sure of it.  It does however at least halve the number of CRC and SES that I get. 

  Finally the input stage of the modem will to some extent do all these filtering operations.  I would guess most lines would not get a noticeable benefit unless the there really is a large common mode RFI/REIN  issue on the line.   If you are picking up differential mode interference no RF3 type of device will be of much help..

 
« Last Edit: November 09, 2014, 11:03:36 AM by les-70 »
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