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[konrado5]

I've found attenuation graph at the mix of several of copper pairs.
It is on the page 95.
http://bookzz.org/dl/984278/250571

Best regards
konrado5

[Black Sheep]

Good find Konrado. Thanks. 

[burakkucat]

I've managed to take a look at the graph and the example circuit responsible for its production.

If the bridging tap is removed from the circuit and, thus, its effect from the graph what is then seen? Essentially an Hlog graph that is similar to Konrado5's graph, complete with "undulations" (or a "lazy" roll). 

So it does seem that my suggestion from some months ago -- that Konrado5's circuit consists of different lengths of different grade cable (different "poundage"; different electrical properties) -- has been shown to be correct.

Purrfect. 

[konrado5]

So it does seem that my suggestion from some months ago -- that Konrado5's circuit consists of different lengths of different grade cable (different "poundage"; different electrical properties) -- has been shown to be correct.

But I've also observer something what seems contradictory to this suggestion. One day when pavement resurfacing works took the place, I've had sligthly different Hlog graph: 23.5/20.2 dB instead 25.0/14.8 dB. The reflections were moved to the other frequiences. I've written about it in the following thread.
http://forum.kitz.co.uk/index.php?topic=14388.0

[burakkucat]

But I've also observer something what seems contradictory to this suggestion. One day when pavement resurfacing works took the place, I've had sligthly different Hlog graph: 23.5/20.2 dB instead 25.0/14.8 dB. The reflections were moved to the other frequiences. I've written about it in the following thread.
http://forum.kitz.co.uk/index.php?topic=14388.0

Yes, I remember that thread. There is not a lot that I can really say . . . other than working on the pavement with heavy equipment could distort the cable and temporarily perturb its properties. 

[konrado5]

But I've also observer something what seems contradictory to this suggestion. One day when pavement resurfacing works took the place, I've had sligthly different Hlog graph: 23.5/20.2 dB instead 25.0/14.8 dB. The reflections were moved to the other frequiences. I've written about it in the following thread.
http://forum.kitz.co.uk/index.php?topic=14388.0

Yes, I remember that thread. There is not a lot that I can really say . . . other than working on the pavement with heavy equipment could distort the cable and temporarily perturb its properties. 

But is it possible if undulances cause is mix of several copper pairs? Does reconnecting the cables cause moving the reflected frequiences? In the case of bridge tap, the reflected frequiences are depended on the lenght of bridge tap. I suspect in the case of different poundage cables it is similarly hard to move the reflected frequiences.

[burakkucat]

Yes, you raise some interesting and valid points. However I have not made an intense study of the subject. Like you, I am just an end-user who has read various documents, asked questions and performed experiments.

As I said some time ago, the undulations in the Hlog graph for your line are abnormal but do not appear to be detracting from its performance in any obvious way. When asked for my opinion as to what could be the cause, I mentioned the only possible reason of which I could think . . . changes in impedance (and other electrical characteristics) by having different grades of cables (I used the archaic term "poundage") making up your line. I appreciate that you want a definite answer -- but that is something I cannot give to you. By your own research you have, as far as I am concerned, found documentary evidence that supports the theory of different grades of cables making up your line. And for that, I congratulate you. 

[konrado5]

Yes, you raise some interesting and valid points.

I think it is something more than interesting and valid points. It seem to be contradiction with supposition that cause of my Hlog unduluations is having different grades of cables.

Do you think it is contradiction? Do you still think that oneday Glog is better than my usual and also today Hlog?

Best regards
konrado5

[konrado5]

I've found also that bad connectors cause impedance mismatch:

Impedance is a measurement of the resistance of the cable to alternating current (AC) and is measured in ohms. The normal impedance of a Category 5 cable is 100 ohms. If a connector is improperly installed on Category 5, it will have a different impedance value than the cable. This is called an impedance discontinuity or an impedance mismatch.

Impedance discontinuities cause attenuation because a portion of a transmitted signal is reflected back, like an echo, and does not reach the receiver. This effect is compounded if multiple discontinuities cause additional portions of the signal to be reflected back to the transmitter. When the reflected signal strikes the first discontinuity, some of the signal rebounds in the original direction, which creates multiple echo effects. The echoes strike the receiver at different intervals. This makes it difficult for the receiver to detect data values. This is called jitter and results in data errors.

The combination of the effects of signal attenuation and impedance discontinuities on a communications link is called insertion loss. Proper network operation depends on constant characteristic impedance in all cables and connectors, with no impedance discontinuities in the entire cable system.

http://dot-net.org/cisco/cisco1/CHAPID=knet-1061921696148/RLOID=knet-1062807120093/RIOID=knet-1062807120328/knet/1061921696148/content.html

[konrado5]

I've found additional paper on the mix of several wires:
http://www.johnhearfield.com/Telephone/Cable.htm

[NewtronStar]

It's all nice and easy on paper, it's putting that into a pysical theory test that's more difficult, you seem very clever and with all the knowledge it would be a shame if you could not test it out for yourself.

[konrado5]

Unfortunately JDSU is very expensive. Unfortunately my ISP's engineers does not use JDSU.

[boost]

So, if i'm understanding... replacing your internal wiring with cat5 may not be a brilliant idea? Even tho it should benefit from the better noise immunity of the twisted pair there will likely be an impedance mismatch from the change in gauge?

This must be very common from E to D to customer premises tho, in reality?

[NewtronStar]

Unfortunately JDSU is very expensive. Unfortunately my ISP's engineers does not use JDSU.

Konrado5 you don't need a JDSU when it comes to DIY home internal Broadband wiring this forum has all the info you need.

With my experince from dial-up to ADSL to FTTC most of the problems come from inside the end-users premises.

[konrado5]

Page 14-16. Additional attenuation graphs. Some graphs are little similar to my graph.
http://prr.hec.gov.pk/Chapters/294S-3.pdf