7800 (not N) SNR changes have no effect?

[durvin]

Hi,

So, I've just installed my new Billion 7800 (not 7800n) and have been attempting to play around with the SNR settings, but no matter what change I make, the SNR results are the same in the DSL stats page. I'm definitely hitting apply and then save changes (write to flash), even trying reboots. I'm on the latest firmware.

Thanks for any thoughts you might have.

Here's more info from DMT:

Down Up
G.dmt framing
--stats
adslctl: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 880 Kbps, Downstream rate = 7684 Kbps
Path: 0, Upstream rate = 812 Kbps, Downstream rate = 4512 Kbps

Link Power State: L0
Mode: ADSL2+
TPS-TC: ATM Mode
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 9.4 9.9
Attn(dB): 58.0 33.9
Pwr(dBm): 19.8 12.4

ADSL2 framing

MSGc: 59 10
B: 141 11
M: 1 16
T: 1 9
R: 16 16
S: 1.0000 7.4954
L: 1264 222
D: 64 4

Counters

SF: 272444 262532
SFErr: 0 0
RS: 17708904 2359673
RSCorr: 369 8
RSUnCorr: 0 0

HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 47109652 8438513
Data Cells: 155352 78028
Drop Cells: 0
Bit Errors: 0 0

ES: 0 0
SES: 0 0
UAS: 103 103
AS: 4427

INP: 3.24 1.15
PER: 16.25 16.86
delay: 16.00 7.49
OR: 32.00 7.58

Bitswap: 0 4

[Philip_L]

Hi

What values have you tried? Try something like 50 to see if that works.

Is the SNR always around 9db?

Regards

Phil

[durvin]

Exactly, no matter what values I put in there, 1, 25, 50...even tried the 65550 range, the number doesn't change, always 9db

[billion_fan]

Exactly, no matter what values I put in there, 1, 25, 50...even tried the 65550 range, the number doesn't change, always 9db

This means the BT profile is kicking in, and overriding your your SNR tweak. (the SNR tweak set on the 7800)

You will have to request a SNR change via your ISP.

[durvin]

Ok so I have requested that the modem be "retrained" and that's happening right now. The ISP technician swears that I should want to *increase* the SNR, can that be correct given the values here? These are two lines, both using 7800s.

He says I should increase SNR based on this:

6dB is the lowest for sync (don't forget Interleave)
7dB-10dB is fair but does not leave much room for variances in conditions
11dB-20dB is good with no synch problems
20dB-28dB is excellent
29dB or above is outstanding

Perhaps he's suggesting raising it for stability in exchange for speed?

Please note, this is Verizon DSL in the USA.

Line 1

MEASUREMENT Downstream Upstream
Initial 79364596 32908398
Final (+21) 79364617 (+22) 32908420
Relative Capacity[%] 98 98
Noise Margin [dB] 7 9
Transmit Signal Power [dBm] 19 12
Attenuation [dB] 61 34
Bit Rate [kb/s] 5888 704

Line 2

Sync Status: Sync, IS-NR Loopback Placed? No Loop Back
Card Type: ADSL2
Line Profile: MULTI_Notch_10up Service Profile: P5000-768-I
Operation Mode: ADSL2+ ATU-C Status: NORMAL
Latency: Interleaved
Downstream Upstream
Relative Capacity [%]: 77 95
Noise Margin [dB]: 7.3 10.6
Transmit Signal Power [dBm]: 17.5 12.2
Attenuation [dB]: 55.3 33.8
Bit Rate [kb/s]: 5888 791

[tinytim]

Is it possible that things are totally different in the US?

According to Kitz for UK ADSL2+ lines with your attenuation the max speed you should get is about 3200kb/s, but clearly you get far better than that.