What is 'LOS'?

Okay it means 'Loss Of Signal' but what does that imply?

I've just been migrated to ADSL2+ (curtesy of Be) and for the most part it's working well. There's an odd disparity between my sync (13Mb) and typical download speeds (10Mb aka 1.2MB/s). It piqued my curiousity so I got the stats from my DG834PN and noticed quite a lot of LOS events. Last night over a 6 hour period it had 88 of them.

What concerns me is that I need a stable connection and LOS doesn't sound too good. In fact it sounds like my modem keeps dropping and having to reconnect to the exchange - is that right?

Or does it just mean the modem/exchange 'hiccupped' and transmission will continue with only the smallest of delays?

I'm currently running the 9db noise margin and given the speed situation I can probably raise this to 12db without losing effective throughput.

FWIW:
Status: Showtime Channel: FAST, Upstream rate = 399 Kbps, Downstream rate = 14902 Kbps
Link Power State: L0
Mode: ADSL2+
Channel: Fast
Trellis: ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 4.8 34.1
Attn(dB): 36.5 18.0
Pwr(dBm): 19.2 12.0
Max(Kbps): 14766 1330
Rate (Kbps): 14902 399
G.dmt framing
K: 95(0) 11
R: 16 0
S: 1 1
D: 128 1
ADSL2 framing
MSGc: 67 18
B: 94 10
M: 1 1
T: 4 3
R: 16 0
S: 0.2200 0.9263
L: 4035 95
D: 128 1
Counters
SF: 551009 551007
SFErr: 768 1
RS: 160894652 0
RSCorr: 86502391 0
RSUnCorr: 2135 0

HEC: 283 5
OCD: 0 0
LCD: 0 0
Total Cells: 311120591 109366086
Data Cells: 159738 1192015
Drop Cells: 0
Bit Errors: 0 164

ES: 6212 1
SES: 1344 0
UAS: 213 4711
Total time = 14 hours 42 min 1 sec
SF = 3263835
CRC = 72051
LOS = 310
LOF = 0
ES = 6212
Latest 1 day time = 14 hours 42 min 1 sec
SF = 3263835
CRC = 72051
LOS = 310
LOF = 0
ES = 6212
Latest 15 minutes time = 12 min 1 sec
SF = 44933
CRC = 269
LOS = 2
LOF = 0
ES = 91
Previous 15 minutes time = 15 min 0 sec
SF = 56009
CRC = 73
LOS = 6
LOF = 0
ES = 61
Previous 1 day time = 0 sec
SF = 0
CRC = 0
LOS = 0
LOF = 0
ES = 0
15 minutes interval [-30 min to -15 min] time = 15 min 0 sec
SF = 56072
CRC = 222
LOS = 6
LOF = 0
ES = 100
15 minutes interval [-45 min to -30 min] time = 15 min 0 sec
SF = 55947
CRC = 44
LOS = 5
LOF = 0
ES = 29
15 minutes interval [-60 min to -45 min] time = 15 min 0 sec
SF = 56072
CRC = 109
LOS = 3
LOF = 0
ES = 69

I think it means loss of synchronization, but I'm not sure.

Have you been playing about with your downstream SNR margin?

That would probably explain it if you had been lowering it in the expectation of more speed.

I have been playing with it..I had it raised (actually after that log dump) to 9db.

Depending on what people reply here I might ask for it to be raised higher. The increase from 6db to 9db had no noticeable affect on throughput so I doubt if 12db would either. I'll be trying that tonight since I can temporarily raise the margin myself.

My problem is that I play an online game and I really, really don't want the connection to glitch. I've no idea what the tolerance on the game is but anything other than a few seconds would be a problem. I'm hoping that an LOS can resolve in fractions of a second (assuming the event itself is brief) but if it's something that requires the modem to resynchronise from scratch I can see that causing the game servers to assume that I've dropped.

As it stands ADSL2+ has pushed me from typical speeds of 4Mb (6.5Mb at the very best) to 9Mb typically and 10Mb on occasion. Since it's also saving me

Edited by Andrue (Tue 24-Apr-07 16:08:21)

Trust you to be different. I'm so used to posters tweaking their SNR margin lower and lower to get an extra few kbps I assumed that's what you were doing.

Well my view is that extra speed as the result of saving money is nice but I rarely download more than 1GB a month. Stability is my god