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Author Topic: SSFP Mk 3  (Read 70422 times)

les-70

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Re: SSFP Mk 3
« Reply #90 on: September 30, 2014, 07:32:45 PM »

  I have now completed 3 days of testing the NTE-2005 or the Mark 1, which as noted above, are basically the same and seem to show the same results.

  The error rate has remained about 10% less with the fixed sync speed testing  :) .

 As implied above it seems that likely that many higher speed lines of ~60Mb/s and above may benefit from a 1-2Mb/s increase in sync if they change their Mark 2 and or 3 to the NTE-2005 or Mark 1.  If are they confident with a soldering iron they should get the same result by shorting out the common mode toroid on the Mark 2 or 3. In the event that the impact is adverse it would suggest that the line has common mode noise that needs rejecting
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NewtronStar

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Re: SSFP Mk 3
« Reply #91 on: September 30, 2014, 08:13:58 PM »

Well les-70 have done most of the test's with RF3 in many location with and without the SSFP MK2 and found my line is better without any common mode toroid inplace, so I have replaced the BT80b RF3 with a standard BT80 and using the SSFP MK1.

All I can say is there great for adding a small amount of attenuation to your line and that's it, so my common mode testing has come to an end  :)
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JGO

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Re: SSFP Mk 3
« Reply #92 on: October 01, 2014, 07:02:43 PM »

As I read your graphs, the Mk3 degrades S/N above about tone 4000 , roughly 17 MHz ? 

This is academic for anyone on any version of ADSL and many on VDSL too in the absence of interference.  With appreciable interference, the loss may be acceptable to give a nett gain on S/N+I on the lower tones.

It cannot be over stressed that NO filter is lossless; so don't jump up and down over a slight interference loss. I am in the situation that a 2 bit dip on tone 46 is due to the Droitwich transmitter. It can be removed with a RF3, but there is a slight nett loss.

  In basic English "You can't have jam on it !"

Les - We all owe you thanks for finding the limitations of the RF3 type devices.

BUT, and I think you agree with me, it should not put off anyone on lower BW VDSL or any ADSL from using a potentially useful device.
It just isn't a magic cure all !!!   

     
« Last Edit: October 02, 2014, 01:42:50 PM by JGO »
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boost

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Re: SSFP Mk 3
« Reply #93 on: October 01, 2014, 07:30:20 PM »

I only load 6 bits on tone 46 too... this mk3 plate is akin to an RF3, yes?
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JGO

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Re: SSFP Mk 3
« Reply #94 on: October 01, 2014, 08:09:40 PM »

I only load 6 bits on tone 46 too... this mk3 plate is akin to an RF3, yes?

It contains a similar device yes. 

Two possibilities for you, - pickup on unprotected cable between faceplate and modem,
or/and pickup on the modem's powerline.
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les-70

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Re: SSFP Mk 3
« Reply #95 on: October 01, 2014, 08:13:57 PM »

I said before
  Please note that if your line is not using the higher frequency vdsl tones then I would expect that all the devices (SSFP's) would test as near identical.   
and
   In the event that the impact is adverse it would suggest that the line has common mode noise that needs rejecting

  Whilst I am getting a small positive impact from removing the common mode choke. I tried not to be prescriptive re other lines. The loss with Mark 2/3 is quite small and at the highest VDSL frequencies.  It is a matter of fact that you can't insert a common mode choke without some loss.  My impression is that a bifilar common mode choke could have reduced the loss and if BT wish to impose the common mode choke as default rather than as an option it is pity they did not use one.

   To Boost.  Others are more expert but I suspect the RF3 should be much better at common mode rejection in the ADSL tones than the Mark 2/3 common mode choke.  The Mark 2/3 choke is seeking to have limited attention of the high vdsl frequencies which will work against is being so effective at ADSL frequencies. 

 
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boost

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Re: SSFP Mk 3
« Reply #96 on: October 01, 2014, 08:43:56 PM »

Thanks.

Time to throw 3 quid into the cloud and then slap one of these just before the modem!
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burakkucat

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Re: SSFP Mk 3
« Reply #97 on: October 01, 2014, 09:06:55 PM »

Time to throw 3 quid into the cloud and then slap one of these just before the modem!

Perhaps do as N*Star did and customise an RJ11 - RJ11 lead so that the BT80B-RF3 is as close to the modem as possible?  :-\
« Last Edit: October 01, 2014, 11:15:58 PM by burakkucat »
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boost

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Re: SSFP Mk 3
« Reply #98 on: October 01, 2014, 10:35:11 PM »

I'll try :)
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loonylion

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Re: SSFP Mk 3
« Reply #99 on: October 04, 2014, 02:16:50 PM »

So if I'm reading this right, I should have no insertion loss from fitting one of these because the loss is all in the tone bands I already can't use? (using U0, U1, D1, D2)
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burakkucat

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Re: SSFP Mk 3
« Reply #100 on: October 04, 2014, 02:29:44 PM »

Er, not quite.  :-\

Insertion loss will be present across the entire spectrum but the devices have been designed such that in an average, typical case the benefit obtained by fitting such a device (by reducing the effect of RF ingress to the circuit) should outweigh the attenuation of the wanted signal.

Hopefully I have made sense . . . If not, I'm sure others (such as JGO) will assist.  ;)
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JGO

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Re: SSFP Mk 3
« Reply #101 on: October 04, 2014, 03:04:25 PM »

Er, not quite.  :-\

Insertion loss will be present across the entire spectrum but the devices have been designed such that in an average, typical case the benefit obtained by fitting such a device (by reducing the effect of RF ingress to the circuit) should outweigh the attenuation of the wanted signal.

Hopefully I have made sense . . . If not, I'm sure others (such as JGO) will assist.  ;)



Yes agree 100%  B'kat
The point is that the device has a limited bandwidth in Hz in which the loss is acceptable.  It is perfectly good for say ADSL suffering from moderate interference, but with Les-70's fast VDSL it has an adverse effect, unless there is a lot of interference. You have to weigh the loss of interference against loss of signal.

It will be pretty useless on the (lab tested only)  super VDSL !!!
 
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atkinsong

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Re: SSFP Mk 3
« Reply #102 on: October 05, 2014, 01:09:10 PM »

I wonder if BlackSheep could update us on whether the Mk3 has officially appeared within OR yet?

If so I would be interested to find out what the official line is.
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Black Sheep

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Re: SSFP Mk 3
« Reply #103 on: October 05, 2014, 08:55:54 PM »

Yes, it is now a stores item .......... however, we don't get the technical data afforded to the latest release !! Yes, it's a bl00dy joke that we don't, but it is what it is.  :)
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Alex Atkin UK

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Re: SSFP Mk 3
« Reply #104 on: October 05, 2014, 11:31:05 PM »

Kelly Communications fitted my brand new fibre install with a MK3 on 17th September, so they are definitely in circulation.

The engineer actually made a bit of a song and dance about it saying they were being told NOT to fit them but he personally always does because they are better.

Obviously what we have found here that its not exactly true, especially as I have a short line with an attainable rate of 95350, well above BTs profile cap.

Interestingly, my main line when on Digital Region (currently unused due to problems migrating back to BT) used to get an attainable rate of 108636.  I assumed that the lower rate I get now was down to being a physically different line perhaps combined with BT using different band plans.  However, it sounds like the MK3 may also be a factor and I'm really curious now to find out.

Unfortunately the NTE-2005 is busy connecting the extension on my main line so I would have to pick a time when I am unlikely to get any phone calls to test it.
« Last Edit: October 05, 2014, 11:34:55 PM by Alex Atkin UK »
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