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Author Topic: DSL M framing parameter  (Read 269 times)

Weaver

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DSL M framing parameter
« on: March 10, 2019, 09:53:29 PM »

Eg G.992.3 sec 7.5 p 28 table 7-6 Framing Parameters

My question: I am wondering how the DSL M parameter is chosen in eg G.992.3 ? The rationale behind it.

Apologies in advance for stupidity, but in my case, as long as M*(B+1) remains constant, why not have M=1 and adjust B accordingly. I must be missing the point. I am really sorry.

My current values for my line 3 are M=4 downstream @3dB target SNRM, and M=16 upstream at 6dB target SNRM. Here are some of the stats right now :

Code: [Select]
xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason: 8000
Last initialization procedure status: 0
Max: Upstream rate = 315 Kbps, Downstream rate = 3280 Kbps
Bearer: 0, Upstream rate = 358 Kbps, Downstream rate = 2987 Kbps

Link Power State: L0
Mode: ADSL2 Annex A
TPS-TC: ATM Mode(0x0)
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 2.9 6.4
Attn(dB): 64.5 40.4
Pwr(dBm): 17.9 12.4

ADSL2 framing
Bearer 0
MSGc: 52 11
B: 34 4
M: 4 16
T: 3 9
R: 12 16
S: 1.4757 6.9818
L: 824 110
D: 2 4

Counters
Bearer 0
SF: 56375 54592
SFErr: 0 0
RS: 2452352 521094
RSCorr: 94 0
RSUnCorr: 0 0

ReXmt: 96 0
ReXmtCorr: 91 0
ReXmtUnCorr: 0 0

Bearer 0
HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 6416196 767497
Data Cells: 110814 32048
Drop Cells: 0
Bit Errors: 0 0

ES: 6301 1547
SES: 3631 294
UAS: 11571 9125
AS: 911

Bearer 0
INP: 26.00 2.00
INPRein: 0.00 0.00
delay: 8 7
PER: 16.04 16.69
OR: 28.91 8.14
AgR: 3002.37 365.23

Bitswap: 312/312 4/4

Total time = 7 days 19 hours 31 min 1 sec
FEC: 501974 1765921
CRC: 47118 911
ES: 6301 1547
SES: 3631 294
UAS: 11571 9125
LOS: 200 0
LOF: 608 0
LOM: 2346 0
Latest 15 minutes time = 1 min 1 sec
FEC: 3 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
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Weaver

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Re: DSL M framing parameter
« Reply #1 on: March 13, 2019, 03:47:24 AM »

Anyone else see the issue, agree / disagree, or canít see my point because Iím just being daft about nothing?
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ejs

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Re: DSL M framing parameter
« Reply #2 on: March 13, 2019, 07:03:27 PM »

I don't really know, but looking at G.993.2 Figure 7-7 on p 30, perhaps it has something to do with how frequently something wants to have a sync octet, so T comes into it also.
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Weaver

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Re: DSL M framing parameter
« Reply #3 on: March 14, 2019, 04:01:13 AM »

@ejs Yes, I noticed that. Without this detail, you canít vary that. You have a desire for one sync byte every n bytes. So itís to do with Ďrecognisabilityí, ease of re-syncing-up after loss of sync or something? Not sure of the function of the sync bytes, can only guess as I have not read that far.
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