As some of you are aware, my connection appears to have managed only 1 month of stability until FTTC & telephone services were both suddenly "accidentally" cut off for 4 days back in July 2011.
Ever since then, unlike most other users’ FTTC connections I have seen, I have been unable to maintain a connection for more than a few days at a time.
Along with this general instability, I occasionally lose my connection simply by picking up a telephone handset ready to make a call, or when the phone rings.
SNRM drops by as much as 7dB & when the norm for my connection appears to be around 6dB, a drop of 7dB causes a disconnection.
When my connection is behaving itself, I can use the telephone with only a 0.1 or 0.2 dB drop in SNRM.
I imagine these are perfectly acceptable & normal levels.
This particular issue usually only lasts for a couple of days, thus making identification & rectification work very difficult for any visiting engineers as their basic line tests usually return a LTOK result.
However, as it has now been ongoing since 25th March, I am hopeful that yet another engineer’s visit, about to be arranged by Plusnet, will now be able to identify the cause & effect a remedy, thus restoring my connection’s initial stability & decent Sync/throughput speeds.
To try to understand what may be causing these intermittent issues, I have selected the band plan (D2 band) where the issues appear more prevalent & have plotted the data accordingly.
I have cross-referenced my data with information provided in a number of JDSU documents, as that is one of the main tools currently used by BT OR engineers.
This is just one example JDSU document:-
http://www.jdsu.com/ProductLiterature/sctpsbridgedtap_an_tfs_tm_ae.pdfI have put together my own PDF document, showing a few example stats of when the connection looks fairly reasonable & when the issue(s) can be seen graphically.
The symptoms exhibited by my connection do have some similarities with the examples from the JDSU documents.
My document is located here, if anyone fancies a read/comment:-
Bald_Eagle1's Example StatsGrabbing the stats while the issue(s) is/are evident has not been easy due to the intermittent nature.
I am hopeful an experienced & specialist engineer will have much more success than I, especially if he/she will actually take a quick look at my example connection stats, that in my mind do prove that a repairable issue does actually exist.
One aspect that I have so far been unable to determine is the likely distance of the "problem(s)" from my master socket.
If you recall, a long time ago, one engineer removed a double-jumpered connection inside the cabinet.
The engineer was convinced he had resolved the issue(s), so the line wasn't retested to check, or to test for any further issue(s).
The removal of the double-jumpering had very little, if any effect - see the attached IP Profiles graph.
Despite me repeatedly requesting them via Plusnet, not one other visiting engineer has been instructed to (or been willing to) conduct another TDR test since.
The net result of these intermittent issues is much reduced Sync & therefore throughput speeds, frequent & random disconnections, & a “stuck” DLM Profile.
Currently my DLM Profile appears to be stuck again, at 24999 k, giving me an IP Profile of only 24.2Mb as reported in BT's Speed test & as calculated by the 96.79% method (24196.5 k).
EDIT:
I would just add that sometimes my connection is so poor that I get absolutely nothing from the D2 band (Attenuation too high or SNR too low?)[attachment deleted by admin]